A convergent approach to cryptophycin 52 analogues: Synthesis and biological evaluation of a novel series of fragment A epoxides and chlorohydrins

J . Med. Chem. 2003, 46, 2985-3007

2985

A Con ver gen t Ap p r oa ch to Cr yp top h ycin 52 An a logu es: Syn th esis a n d

Biologica l Eva lu a tion of a Novel Ser ies of F r a gm en t A Ep oxid es a n d

Ch lor oh yd r in s

Rima S. Al-awar,* J ames E. Ray, Richard M. Schultz, Sherri L. Andis, J oseph H. Kennedy, Richard E. Moore,^†

J ian Liang,^†Trimurtulu Golakoti,^†Gottumukkala V. Subbaraju,^†and Thomas H. Corbett^‡

Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285,

Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, and Karmanos Cancer Institute,

Wayne State University School of Medicine, Detroit, Michigan 48201

Received September 10, 2002

Cryptophycin 52 is a synthetic derivative of Cryptophycin 1, a potent antimicrotubule agent

isolated from cyanobacteria. In an effort to increase the potency and water solubility of the

molecule, a structure-activity relationship study (SAR) was initiated around the phenyl ring

of fragment A. These Cryptophycin 52 analogues were accessed using a Wittig olefination

reaction between various triphenylphosphonium salts and a key intermediate aldehyde prepared

from Cryptophycin 53. Substitution on the phenyl ring of fragment A was well tolerated, and

several of these analogues were equally or more potent than Cryptophycin 52 when evaluated

in vitro in the CCRF-CEM leukemia cell line and in vivo against a murine pancreatic

adenocarcinoma.

In tr od u ction

Blue-green algae or cyanobacteria have been a source

of a wide range of novel and structurally complex cyclic

peptides and depsipeptides.¹The Cryptophycins are a

family of naturally occurring potent antitumor agents

originally isolated from terrestrial blue-green algae

Nostoc sp. ATCC 53789 by Schwartz et al.²and later

by Moore and co-workers³from Nostoc sp. GSV 224. The

depsipeptide, Cryptophycin 1 (Figure 1), was the main

component of the algal extract and accounted for most

of its antiproliferative activity.³The structure of this

16-membered depsipeptide can be divided into four

fragments A-D as shown in Figure 1. Through the

convergent assembly of the different fragments, Moore

F igu r e 1.

et al. were able to accomplish the first total synthesis

of Cryptophycin 1.⁴When first isolated in 1990, Cryp-

tophycin 1 was classified as an antifungal agent with

an unknown mechanism of action but was later found

to be an antimitotic agent that disrupted the micro-

tubule assembly in cultured cells.⁵Furthermore, this

novel macrocycle showed excellent in vivo activity

against both murine and human solid tumors.⁶

In addition to Cryptophycin 1, Moore isolated 24

minor natural Cryptophycins, with modifications in

fragments A through D, but none were as active as the

parent compound.⁷These included Cryptophycins lack-

F igu r e 2.

ing either the methyl group at C17 of fragment A or

the double bond of the enone moiety. Several structure-

activity relationship (SAR) observations can be made

from his synthetic work around position C18 and C19

of this fragment.^1bTwo semisynthetic prodrug deriva-

tives of Cryptophycin 1, the anti chloro and bromo-

hydrins (Figure 2), were also evaluated in vivo. The

chlorohydrin (or Cryptophycin 8) was markedly more

efficacious than Cryptophycin 1 or vinblastine when

evaluated against a panel of solid tumors. At doses 4-8-

fold higher than those of the parent compound, Cryp-

tophycin 8 was highly active and possessed a high

therapeutic window whereas the bromohydrin was more

toxic and less active than Cryptophycin 1.^1b,8A com-

pound containing a styrene, an R epoxide, or hydroxyls

at C18 and C19 instead of the naturally occurring â

* Corresponding Author: Rima S. Al-awar, Eli Lilly and Company,

Lilly Research Laboratories, 20 TW Alexander Drive, Research Tri-

angle Park, NC 27709. Phone: (919) 314-4205. Fax: (919) 314-4348.

E-mail: Al-awar_Rima_S@Lilly.com.

^†University of Hawaii at Manoa.

^‡Wayne State University School of Medicine.

Published on Web 05/22/2003

2986 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

ineffective in vivo.^1b,7bThis result is consistent with the

related natural product Arenastatin A (Figure 1), a

potent constituent of the Okinawan marine sponge

Dysidea arenaria.⁹Arenastatin A differs from the Cryp-

tophycins in that it lacks both the methyl group of the

â-alanine unit of fragment C and the chloro group on

the phenyl ring of the B fragment. Although Arenastatin

exhibited potent in vitro cytotoxicity it had marginal in

vivo activity. The methyl group in the â-alanine portion

of the Cryptophycins prevents hydrolysis of the labile

ester linkage between fragments C and D that is

thought to be critical for the antitumor activity of the

compounds.¹⁰

F igu r e 3.

epoxide functionality of fragment A had diminished

activity both in vitro and in vivo.^1b

Three of the compounds that Moore isolated with

modifications in fragment B lacked either the methoxy

or chloro group or possessed the demethylated chloro-

hydroxy functionality instead of the chloro-methoxy

present in Cryptophycin 1. He also isolated compounds

where the isobutyl group in fragment D was replaced

with n-propyl, isopropyl, or sec-butyl group, and these

were less active than the parent compound.^7aAlthough

a compound lacking the methyl group in fragment C

was active in vitro, it was found to be completely

Cryptophycin 52 (LY355703), a synthetic derivative

of the naturally occurring Cryptophycin 1, contains a

gem-dimethyl group at C6 of fragment C (Figure 1). Like

the natural product, Cryptophycin 52 inhibits the po-

lymerization of microtubules by suppressing micro-

tubule dynamics and hence arresting cells in the G₂/M

phase of the cell cycle.¹¹Unlike other antimitotic agents

such as paclitaxel, vincristine, and vinblastine, Cryp-

Sch em e 1^a

a

Reagents and conditions: (a) mCPBA, CH₂Cl₂, rt; (b) Reverse phase HPLC; (c) HClO₄, DME, H₂O, rt; (d) NaIO₄, THF, H₂O, rt; (e)

n-BuLi, THF, -78 °C to room temperature; (f) VAZO, PhSH, benzene ∆; (g) mCPBA, CH₂Cl₂, rt or dioxirane; (h) TMSCl, CHCl₃or HCl,

-60 °C to room temperature.

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 2987

Sch em e 2^a

a

Reagents and conditions: (a) n-BuLi, THF, -78 °C to room temperature; (b) VAZO, PhSH, benzene ∆, (36%); (c) Oxone, acetone,

H₂O, NaHCO₃, CH₂Cl₂, 0 °C; (d) reverse phase HPLC, (39%).

tophycin 52 maintained its excellent antiproliferative

activity against cancer cells that expressed multidrug

resistance phenotypes (MDR1 and MRP),¹²which re-

sulted in an excellent in vivo efficacy profile against a

wide range of resistant human xenografts and murine

solid tumors.

Ch em istr y

Our strategy involved the recycling of the undesired

Cryptophycin 53³¹(R epoxide) that is formed in the

process of preparing the more biologically relevant

Cryptophycin 52 (â epoxide) (Scheme 1). We envisioned

Wittig type couplings between various triphenylphos-

phonium salts and aldehyde 2, prepared from Crypto-

phycin 53, as an efficient and concise entry to various

analogues.¹⁹

Initial one-pot conversion of Cryptophycin 53 to the

aldehyde 2 utilizing periodic acid proved to be problem-

atic. The aldehyde generated in situ was unstable under

the reaction conditions and decomposed prior to con-

sumption of the starting material. Therefore, a two-step

transformation beginning with an epoxide opening with

aqueous perchloric acid was used to generate a mixture

of alcohols 1 (Scheme 1). Oxidative cleavage of the

resulting diols 1 by sodium periodate generated the key

intermediate aldehyde 2 as a solid in quantitative yield.

The labile aldehyde 2 could be stored at -23 °C for a

reasonable period of time and was utilized without

further purification.

As a general route to fragment A analogues (Scheme

1), the aldehyde 2 was coupled with an appropriate

phosphonium salt to generate a variable ratio of E and

Z alkene isomers. The isomerization of the styrene

mixtures, to the thermodynamically more stable E

isomer (4), was accomplished in benzene at reflux with

1,1′-azabis(cyclohexanecarbonitrile) (VAZO) as a radical

initiator in the presence of thiophenol.²⁰Subsequent

epoxidation of the E styrene was achieved with mCPBA

or dioxirane, depending on the substrate, to give a

mixture of R and â epoxides (5) which were separable

by preparative reverse phase high-pressure liquid chro-

matography (HPLC). The anti chlorohydrin 6 was

obtained by treatment of the epoxide mixture 5 with

chlorotrimethylsilane or hydrogen chloride solution

followed by normal phase silica gel chromatographic

separation of the diastereomeric chlorohydrins gener-

ated.

Due to their novelty and synthetically challenging

structures, the Cryptophycins have attracted the atten-

tion of many synthetic groups.¹³Most of the synthetic

efforts have centered around new approaches to frag-

ment A, the most challenging fragment due to its four

contiguous stereogenic centers. Several reports have

appeared which focus on SARs around fragments A

through D of the Cryptophycins: for example, Norman

and co-workers¹⁴prepared isosteres of fragments C and

D, whereas Patel and co-workers¹⁵reported their find-

ings on fragment B analogues. The preparation of 15-

membered macrocycles and fragment C analogues by

Shih¹⁰and Varie¹⁶demonstrated that a smaller ring size

and bulky substituents at C6 of the â alanine unit were

not favorable. In addition, Lavalee and co-workers¹⁷

suspected the poor correlation between in vitro (pico-

molar) to in vivo (∼30-40 mg/kg in mice) potencies of

Cryptophycin 1 might be due to the formation of inactive

metabolites of the epoxide. This hypothesis was tested

with over 30 analogues that involved replacing the

benzylic epoxide with enones (Figure 3) and ynones.

These electrophilic functionalities proved to be detri-

mental to activity and confirmed the importance of the

benzylic â epoxide and the C17 methyl group and their

relative stereochemistry to the biological activity of this

class of natural products.

Like Paclitaxel, the formulation of Cryptophycins 1

and 52 requires the excipient Cremophor EL for intra-

venous administration. An increase in the aqueous

solubility and potency of the Cryptophycins could lead

to a more practical clinical formulation for this class of

compounds. Hence, we embarked on a SAR study

around fragment A of Cryptophycin 52, where we hoped

to improve several of the molecule’s physical and

biological properties through the modification of the

phenyl ring.¹⁸We describe herein our synthetic ap-

proaches to fragment A analogues and report their in

vitro and in vivo biological evaluation.

The methyl-substituted compounds 8-16 (shown in

Table 2) were prepared following the same general

sequence described in Scheme 1. Epoxidation of styrenes

with a strong electron-donating or -withdrawing group

on the phenyl ring such as a methoxy group (17, Scheme

2988 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

Sch em e 3^a

a

Reagents and conditions: (a) NaH, DMF; (b) VAZO, PhSH, benzene ∆, (23%); (c) Oxone, acetone, H₂O, CH₂Cl₂, NaHCO₃, rt, (33%);

(d) reverse phase HPLC; (e) TMSCl, CHCl₃, -60 °C to room temperature, (30%).

Sch em e 4^a

a

Reagents and conditions: (a) TBAF, THF, -70 °C, (93%); (b) CDI, 45 °C to room temperature, (75%); (c) Oxone, acetone, H₂O, NaHCO₃,

CH₂Cl₂, 0 °C; (d) TMSCl, CHCl₃then HCl, -60 °C to room temperature; (e) reverse phase HPLC, (31%); (f) 4 M HCl, CH₂Cl₂, (95%).

2) or a methyl ester (19, Scheme 3) was problematic.

Use of 3-chloroperoxybenzoic acid in the case of styrene

17 led to the protonation and subsequent opening of the

epoxide mixture by the 3-chlorobenzoic acid, formed in

situ as a byproduct of the epoxidation. Neutralization

with sodium bicarbonate minimized this side reaction;

however, use of dioxirane prepared in situ at 0 °C

completely circumvented the problem (Scheme 2).

The methyl ester 19, with its electron-withdrawing

effect, led to a decrease in the reactivity of the styrene

alkene in comparison to the enone (Scheme 3). Epoxi-

dation of 19 required the use of the stronger oxidizing

agent, dioxirane, at room temperature which resulted

in the formation of bis-epoxide 20 along with the desired

diastereomeric mono-epoxide 21. These were separated

by reverse phase HPLC, and the mixture of diaster-

eomers 21 was treated with TMSCl to give, follow-

ing chromatographic separation, the anti chlorohydrin

22.

Condensation of 4-(tert-butyldimethylsiloxy)benzyl-

triphenylphosphonium chloride ylide 3f²¹with aldehyde

2 followed by deprotection of the resulting silyl ether

23 with TBAF furnished phenol 24 (Scheme 4). The

phenolic derivative 24 was coupled with Boc protected

3-amino-2-dimethyl propionic acid (fragment C′, 25) in

the presence of 1,1′-carbonyldiimidazole, at 45 °C, to

generate ester 26 in 75% yield. The epoxidation was in

turn accomplished with dioxirane, and the mixture of

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 2989

Sch em e 5^a

a

Reagents and conditions: (a) n-BuLi, THF, -78 °C to room temperature; (b) VAZO, PhSH, benzene, D, (92%); (c) mCPBA, CH₂Cl₂;

(d) reverse phase HPLC, (53%); (e) TBAF, THF, 0 °C to room temperature, (84%); (f) Boc-glycine, DCC, DMAP, CH₂Cl₂, rt, (72%); (g)

TMSCl, CHCl₃, -60 °C to room temperature, (35%); (h) 4 M HCl/dioxane, CH₂Cl₂, (100%).

epoxides was treated with chlorotrimethylsilane fol-

lowed by HCl to generate a mixture of diasteriomeric

chlorohydrins. The desired anti chlorohydrin 27 was

isolated in 31% yield for the two-step sequence.

With a few analogues possessing both electron-donat-

ing and electron-withdrawing functionalities in hand,

we turned our attention to substituents that might

increase the hydrophilicity of the Cryptophycins. Many

of the analogues we envisioned evaluating were syn-

thesized from benzyl alcohol 31b, prepared in four steps

as shown in Scheme 5, from aldehyde 2 and the ylide

of 4-(triisopropylsiloxymethyl)benzyltriphenylphosphon-

ium bromide 3g.²²Coupling of N-Boc-glycine and alcohol

31b in the presence of DCC and DMAP furnished ester

32 in 72% yield. The hydrochloride salt 34 was obtained

through opening of the epoxide with chlorotrimethyl-

silane and separation of the chlorohydrins, followed by

removal of the Boc group.

presence of sodium bicarbonate (Scheme 7). Simple

displacement of the benzylic chloride 39 with various

alkylamines led to the N-alkylated products 40a -c.

Opening of the respective epoxides with chlorotrimeth-

ylsilane or a 4 M solution of HCl in dioxane, with

concomitant removal of the Boc groups, yielded the

corresponding hydrochloride salts 41a -c.

In an attempt to prepare amide 44 (Scheme 8), the

benzylic alcohol 35 was converted to its corresponding

amine 43 via phthalimide 42 by a Mitsunobu protocol.²³

The primary amine 43 was coupled with Boc-protected

sarcosine in the presence of 1-hydroxybenzotriazole

hydrate (HOBT) and 1-(3-dimethylaminopropyl)-3-eth-

ylcarbodiimide hydrochloride (EDCI) in 71% yield. Ep-

oxidation of the styrene 44, preparation of the chloro-

hydrin 45, and deprotection of the Boc group was

accomplished in the usual manner already described to

give the sarcosine amide 46.

Alternatively, quantitative deprotection of silyl ether

29 with tetrabutylammonium fluoride provided alcohol

35 which in turn was coupled with acid 25 in the

presence of DCC and DMAP to furnish the hindered

ester 36 (Scheme 6). Epoxidation of 36 with mCPBA,

followed by subsequent treatment with chlorotrimeth-

ylsilane and hydrogen chloride, resulted in anti chloro-

hydrin 38.

Three amine hydrochloride salts (41a -c, Scheme 7)

were prepared to impart additional aqueous solubility

to the molecule. These were accessed from benzyl

chloride 39, obtained from the treatment of alcohol 31

with N-chlorosuccinimide and triphenylphosphine in the

Preparation of an acetic acid derivative 51 (Scheme

9) required the oxidation of hydroxyethyl intermediate

49 that was obtained in the usual manner from phos-

phonium salt 3h .²⁴Acid 51 was produced in a stepwise

fashion using two consecutive mild oxidations to ensure

the stability of the epoxide under the reaction condi-

tions. Initially, tetrapropylammonium perruthenate²⁵

was utilized, but it led to oxidation at the benzylic

position. The best sequence involved treatment of

alcohol 49 with the Dess-Martin²⁶periodinate reagent

and subsequent oxidation of the resulting aldehyde 50

with sodium chlorite²⁵to yield the desired acid 51 (37%).

The thiazole group which is present in many biologi-

2990 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

Sch em e 6^a

a

Reagents and conditions: (a) TBAF, THF, -70 °C, (99%); (b) DCC, DMAP, CH₂Cl₂, D, (85%); (c) mCPBA, CH₂Cl₂; (d) TMSCl, CHCl₃

then HCl -60 °C to room temperature; (e) reverse phase HPLC, (22%); (f) 4 M HCl/dioxane, CH₂Cl₂, (100%).

Sch em e 7^a

a

Reagents and conditions: (a) N-chlorosuccinimide, PPh₃, NaHCO₃, CH₂Cl₂; (b) amine, THF, rt; (c) TMSCl; (d) 4 M HCl/dioxane,

CH₂Cl₂.

cally active natural products was chosen to replace the

phenyl ring of fragment A with a heterocyclic one.²⁷This

bioisostere was prepared as described in Scheme 10

from the aldehyde 2 and triphenylphosphonium salt 3i²⁸

to give the trans olefin 52 in 34% yield. The desired â

epoxide 53 was isolated in 35% yield by reverse phase

HPLC, following the epoxidation of 52.

The stereoselective opening of the â epoxides was

found to be substrate and reagent dependent. Using the

pure â epoxide 9, these observations were confirmed by

a direct comparison of the two reagents, chlorotrimeth-

ylsilane and hydrogen chloride (Table 1). Three separate

experiments were conducted and the syn to anti chlo-

rohydrin ratio was determined from the crude reaction

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 2991

Sch em e 8^a

a

Reagents and conditions: (a) DEAD, PPh₃, THF, rt, (90%); (b) n-butylamine, EtOH, 75 °C, (57%); (c) Boc-sarcosine, EDCI, HOBT,

DMF, rt, (71%); (d) mCPBA, CH₂Cl₂; (e) TMSCl, CHCl₃, -50 °C to room temperature, (48%); (f) 4 M HCl/dioxane, CH₂Cl₂, rt, (100%).

Sch em e 9^a

a

Reagents and conditions: (a) n-BuLi, THF, -78 °C to room temperature; (b) VAZO, PhSH, benzene ∆, (68%); (c) mCPBA, CH₂Cl₂; (d)

reverse phase HPLC, (15%); (e) TBAF, THF, 0 °C to room temperature, (94%); (f) Dess-Martin, pyridine, CH₂Cl₂, (59%); (g) NaClO2,

NaH₂PO₄, 2-methyl-2-butene, THF, H₂O, (37%).

mixtures by reverse phase HPLC. Initially, the sub-

strate 9 in CHCl₃was treated with 5 equiv of TMSCl

at -60 °C. The reaction temperature was maintained

between -60 °C and -40 °C for 1 h and was slowly

allowed to rise to room temperature over 3 h (entry 1).

The second attempt at epoxide opening used 4 M

hydrogen chloride in dioxane under the same reaction

conditions described above (entry 2). The third experi-

ment also utilized hydrogen chloride, but the reaction

temperature was maintained between -78 °C and -60

°C for 2 h prior to warming up to room temperature

(entry 3). The results listed in Table 1 prove the

effectiveness of HCl in providing more of the desired

anti rather than syn chlorohydrin. Maintaining the

reaction at lower temperatures over a longer period of

time did not provide any significant advantage. It is

noteworthy that the stereochemistry of Cryptophycin 52

epoxide opening was not reagent specific in that when

treated with either HCl or TMSCl the undesirable syn

chlorohydrin was not detected by HPLC. The methyl

group on the phenyl ring of compound 9 must be

inductively influencing the stereoselectivity of the ep-

oxide opening.

In Vitr o Cell Gr ow th In h ibition . The growth

inhibitory effect of the Cryptophycin 52 fragment A

analogues were evaluated in human CCRF-CEM leu-

2992 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

Sch em e 10^a

nM). Chlorohydrins 34 (IC₅₀) 0.013 nM) and 38 (IC₅₀

) 0.004 nM) were ∼ 4 and >12-fold more potent cell

growth inhibitors than Cryptophycin 55 (IC₅₀) 0.05

nM). Evaluation of the unnatural R epoxide 31a (IC₅₀

) 0.29 nM) revealed a 73-fold loss in potency, in

comparison to the corresponding â epoxide 31b (IC₅₀

)

0.004 nM). These results were consistent with the 50-

fold difference in IC₅₀concentrations between the R and

â epoxides 16a (IC₅₀) 100 nM) and 16b (IC₅₀) 2.0

nM).

The IC₅₀concentrations for the more water soluble

amine hydrochloride salts 41a -c ranged between 0.005

and 0.092 nM and compared favorably with that of

Cryptophycin 55 (IC₅₀) 0.05 nM). The sarcosine amide

derivative 46 (IC₅₀) 0.04 nM) was equipotent to

Cryptophycin 55 but about 3-fold less potent than the

corresponding glycine ester 34 (IC₅₀) 0.013 nM).

However, the amide 46 was expected to be metabolically

more stable in vivo than the ester 34. With a 36-fold

lower potency than Cryptophycin 52, the acid 51 (IC₅₀

) 0.79 nM) revealed the negative impact of an acidic

functionality, whereas thiazole 53 (IC₅₀) 0.19 nM)

confirmed the importance of the phenyl ring of fragment

A to the antiproliferative activity of the Cryptophycins.

If compared to Cryptophycin 51, the IC₅₀concentrations

of all the olefins was predictive of the activity of their

corresponding â epoxides or chlorohydrins with the

exception of two (17 and 24). Although the phenolic

styrenes 17 (IC₅₀) 12 nM) and 24 (IC₅₀) 4 nM) were

a

Reagents and conditions: (a) n-BuLi, THF, -78 °C to room

temperature, (34%); (b) Oxone, acetone, H₂O, NaHCO₃, CH₂Cl₂, 0

°C; (d) reverse phase HPLC, (35%).

Ta ble 1. HCl vs TMSCl

equal to or more potent than Cryptophycin 51 (IC₅₀

)

14 nM), their corresponding epoxide 18 and chlorohy-

drin 28 were significantly less active than Cryptophy-

cins 52 and 55. Several of the fragment A analogues

listed in Table 2 had sufficient antiproliferative activity

warranting additional in vivo testing.

entry reagent

temperature

ratio anti: syn

1

2

3

TMSCl -60 °C to room temperature

HCl

1.4:1.0

3.2:1.0

3.8:1.0

-60 °C to room temperature

-60 °C

In Vivo An titu m or Activity. The in vivo evaluation

of these analogues utilized the drug sensitive murine

pancreatic adenocarcinoma (Panc-03). The effectiveness

of the drugs was determined with two parameters;

percent T/C and log kill values. A T/C equal to or less

than 42% is considered significant antitumor activity,

where T and C are the median tumor burden in the

treatment group and control group, respectively, mul-

tiplied by 100. Tumor cell kill is determined from the

difference in tumor growth delay in days, between the

treated and control animals, to reach 1000 mg in tumor

weight. Panc-03 (Table 3) was found to be more sensitive

to Paclitaxel (log kill ) 4.2) and Cryptophycin 55 (log

kill > 4.5) than to Doxorubicin (log kill ) 1.5) and

Cryptophycin 52 (log kill ) 1.9) administered at maxi-

mum tolerated doses. Cryptophycin 55 was the most

efficacious compound tested, requiring 6- to 12-fold

higher doses than Cryptophycin 52. It had a wider

therapeutic window than Cryptophycin 52 in that the

200 and 400 mg/kg total doses of Cryptophycin 55 were

equally effective and well tolerated.

kemia cells, following a 72 h exposure, as the IC₅₀

concentrations (nM) (Table 2). Cryptophycins 52 and 55

were very potent growth inhibitors in this cell line with

IC₅₀values of 0.022 and 0.05 nM, respectively. The IC₅₀

values for the 3-methyl (9), the 2,5- (16b), and the 3,4-

dimethyl (13) phenyl compounds indicated that a meta

(9, IC₅₀) 0.15 nM) or meta, para (13, IC₅₀) 0.05 nM)

substitution pattern on the phenyl ring was better

tolerated than the ortho, meta substitution pattern

(16b, IC₅₀) 2 nM).

Preliminary investigation of the effect of electron-

donating and -withdrawing groups at the para position

of the phenyl ring led to the preparation of the phenolic

derivatives 18, 28, and the methyl ester 22. The

4-methoxyphenyl â epoxide 18 (IC₅₀) 0.28 nM) was 13-

fold less potent than Cryptophycin 52 (IC₅₀) 0.022 nM).

Whereas the chlorohydrin 28 (IC₅₀) 0.79 nM) was 16-

fold less active than Cryptophycin 55 (IC₅₀) 0.05 nM),

the methyl ester 22 (IC₅₀) 0.037 nM) had comparable

activity to Cryptophycin 55 (IC₅₀) 0.05 nM). The

electronic effects of the phenyl ring substituents may

influence the stability, and hence the growth inhibitory

activity of the epoxide or chlorohydrin and might

account for the lower potency of analogues 18 and 28.

The key hydroxymethyl intermediate epoxide 31b and

its derivatives 32, 34, and 38 were all more potent than

Cryptophycins 52 or 55. Epoxides 31b (IC₅₀) 0.004 nM)

and 32 (IC₅₀) 0.0055 nM) were, respectively, 5.5- and

4-fold more active than Cryptophycin 52 (IC₅₀) 0.022

Chlorohydrin 11 was inactive in vivo (T/C ) 46) at

72 mg/kg total dose but showed marginal activity at 162

mg/kg total dose (log kill ) 1.5). The animals did not

experience weight loss and therefore, it is likely that

higher doses of chlorohydrin 11 would have been toler-

ated. With maximum tolerated doses of 3.5 to 6 mg/kg,

at least 5-fold lower than Cryptophycin 52, there is a

clear correlation between the in vitro and in vivo

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 2993

Ta ble 2. In Vitro Growth Inhibitory Activity in the Human CCRF-CEM Leukemia Cell Line

potencies of epoxide 31b. The glycinate ester salt 34 was

quite efficacious in producing a T/C of zero across three

dose levels and log kills of 3.6 and 3.7 at the nontoxic

total doses of 9 and 18 mg/kg. Unlike the epoxide 31b,

the piperizinyl dihydrochloride salt 41b was much more

potent in vivo than would be predicted from its relative

in vitro activity. At 1.6 mg/kg, the piperizinyl dihydro-

chloride salt 41b, produced a 16% average weight loss

in the animals and a 4.7 log kill value which was

comparable to log kill values for Cryptophycin 55, but

at 100 to 250-fold increased potency. Clearly, fragment

A analogues (31b, 34, and 41b) are effective against the

2994 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

Ta ble 3. In Vivo Antitumor Activity of Cryptophycin Analogues against Murine Pancreatic Adenocarcinoma

a

b

Days of treatment after tumor inplantation. Dose administered close to the maximum tolerated dose. ^cMaximal animal weight

d

loss. The ratio of the median tumor weight in the treatment group (T) over the median tumor weight in the control group (C) multiplied

by a 100. T/C is calculated when control median tumor weight is at 1 g. ^eLog cell kill of tumor bearing mice, a calculation based on tumor

growth delay.

murine Panc-03 tumor at much lower total doses than

are required for either Cryptophycin 52 or 55.

culture. This exciting antiproliferative activity trans-

lated to the in vivo setting in the case of the benzylic

alcohol 31b and its glycine ester derivative 34. Replace-

ment of the phenyl ring of fragment A with a thiazole

caused an >8-fold drop in potency in vitro as compared

to Cryptophycin 52. A similar decrease in antitumor

activity was observed with the phenolic derivatives 18,

28, and acid 51. The piperazine dihydrochloride salt

41b, while improving the aqueous solubility of the

molecule, was as active as Cryptophycin 55 in vitro

against the CCRF-CEM cells and was over a 100-fold

more potent and equally efficacious when tested in vivo

against the Panc-03 tumor. In summary, preparation

of novel Cryptophycin 52 fragment A analogues pro-

duced effective antitumor agents with potentially im-

proved physical, chemical, and biological profiles.

Con clu sion s

A Wittig approach involving the key intermediate

aldehyde 2, prepared from Cryptophycin 53, expedited

a SAR study around the fragment A of Cryptophycin

52. Several transformations were effected, while main-

taining the chemical integrity of the acid labile â

epoxide, with use of the benzyl chloride 39 or the benzyl

alcohol 31b as precursors in the preparation of several

analogues. When the phenyl ring is substituted, epoxide

opening to the chlorohydrin was found to be substrate

dependent, with hydrogen chloride providing the best

anti to syn chlorohydrin ratio.

The substitution pattern on the phenyl ring affected

the antiproliferative activity of analogues 9, 13, and 16b

with the less sterically demanding meta and para

positions being better tolerated than the ortho. Several

of these synthetic analogues (Table 2) compared favor-

ably with Cryptophycin 52 and 55 whereas the â

epoxides 31b, 32, 40a , and 40b were 4- to 20-fold more

potent than Cryptophycin 52 as growth inhibitors in cell

Exp er im en ta l Section

Gen er a l Exp er im en ta l P r oced u r e. Anhydrous solvents

were purchased from Aldrich Chemical Co. Proton NMR

spectra were obtained on a Varian 300 or 500 MHz Brucker

spectrometer. Carbon NMR spectra were obtained on a Bruck-

er AC-250. Proton NMR multiplicity data are denoted by s

(singlet), d (doublet), t (triplet), q (quartet), m (multiplet), and

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 2995

aldehyde 2 was used without further purification and was

b (broad). IR Spectra were recorded on Nicolet 510 P FT-IR

Spectrometer. High-resolution mass spectra were obtained on

a VG-ZAB2SE spectrometer. Optical rotation was measured

on an Autopol III automatic polarimeter. Combustion analyses

(C, H, N) were performed on a 440 Elemental Analyzer.

Separation of epoxide mixtures was achieved by reverse phase

HPLC on a Beckman instrument using a preparative C18

column and acetonitrile and water as solvents.

stored at -23 °C for stability reasons: [R]²⁰+23.0 (c 0.565,

D

1

CHCl₃); H NMR (300 MHz, CDCl₃) δ 9.64-9.63 (d, 1 H, J )

1.4 Hz), 7.28-7.26 (m, 1 H), 7.21-7.20 (d, 1 H, J ) 1.9 Hz),

7.08-7.05 (dd, 1 H, J ) 7.1, 1.7 Hz), 6.87-6.84 (d, 1 H, J )

8.5 Hz), 6.82-6.72 (m, 1 H), 5.80-5.75 (d, 1 H, J ) 15.0 Hz),

5.54-5.51 (d, 1 H, J ) 7.7 Hz), 5.40-5.33 (m, 1 H), 4.85-4.81

(dd, 1 H, J ) 9.7, 3.2 Hz), 4.78-4.71 (m, 1 H), 3.88 (s, 3 H),

3.46-3.39 (dd, 1 H, J ) 13.5, 8.6 Hz), 3.17-3.05 (m, 3 H),

2.68-2.35 (m, 3 H), 1.82-1.63 (m, 2 H), 1.45-1.37 (m, 1 H),

1.24 (s, 3 H), 1.19-1.16 (d, 3 H, J ) 7.1 Hz), 1.18 (s, 3 H),

0.94-0.92 (d, 3 H, J ) 6.5 Hz), 0.89-0.87(d, 3 H, J ) 6.5 Hz);

¹³C NMR (62.5 MHz, CDCl₃) δ 200.7, 177.8, 170.6, 170.1, 165.1,

153.9, 141.1, 130.7, 129.8, 128.1, 124.9, 122.3, 112.3, 73.4, 71.1,

56.0, 54.6, 49.9, 46.4, 42.7, 39.2, 36.1, 35.2, 24.7, 22.8, 22.7,

21.3, 10.7; IR (CHCl₃) 3422, 2964, 2936, 1755, 1730, 1718,

1678, 1529, 1504, 1487,1474, 1464, 1442, 1320, 1303, 1281,

1259, 1244, 1185, 1151, 1127, 1067 cm^-1. Anal. Calcd for

(C₂₉H₃₉ClN₂O₆): C, 60.15; H, 6.79; N, 4.84. Found: C, 60.36;

H, 6.94; N, 4.57.

In Vit r o Gr ow t h In h ib it ion Assa y. Concentration-

response curves were generated to determine the concentration

required for 50% inhibition of growth (IC₅₀). Test compounds

were dissolved initially in DMSO at a concentration of 0.2 mg/

mL. Serial 1:3 dilutions were made in DMSO using a Biomek

Automated Workstation (Beckman, Fullerton, CA). Micropipet

tips were changed with each dilution. We have previously

shown that cryptophycins need to be serially diluted in DMSO

to reduce drug adsorption onto plastic and glass surfaces.²⁹

Log-phase human CCRF-CEM leukemia cells were plated into

24-well plates (Costar, Cambridge, MA) at 4.8 × 10⁴cells/2

mL assay medium/well. Assay medium consisted of RPMI-1640

medium supplemented with 10% dialyzed fetal bovine serum

and 25 mM HEPES buffer. The series of compound dilutions

in DMSO were added to duplicate wells at 10 µL per well. Two

wells on each individual plate received 10 µL of DMSO without

compound as controls. The final concentration of DMSO per

well was 0.5%. Plates were incubated for 72 h at 37 °C in a

humidified 5% CO₂-in-air atmosphere. After incubation, the

number of leukemia cells in each well was determined using

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6R,7E)-5-h yd r oxy-6-m eth yl-8-[4-[[[tr is-

(1-m eth yleth yl)silyl]oxy]m eth yl]p h en yl]-2,7-octa d ien oyl-

3-ch lor o-O-m eth yl-^D-tyr osyl] (29). To 4-(triisopropylsiloxy-

methyl)benzyltriphenylphosphonium bromide (3g) (7.6 g, 12.2

mmol) in THF (100 mL) at -50 °C was added dropwise a 1.5

M solution of n-butyllithium (8.1 mL, 12.2 mmol). The mixture

was warmed slowly to room temperature and stirred for an

additional 30 min. To aldehyde 2 (2.95 g, 5.1 mmol) in THF

(100 mL) at -78 °C was added dropwise the red ylide solution

via a double-tipped needle. The resulting mixture was stirred

at -78 °C for 3 h and at room temperature for 45 min.

Saturated NH₄Cl (100 mL) was added along with ethyl acetate

(100 mL), the layers were separated, and the aqueous layer

was extracted with ethyl acetate (2 × 50 mL). The combined

organic layers were washed with water (3 × 40 mL) and brine,

dried over MgSO₄, filtered, and concentrated in vacuo. The

resulting yellow residue was purified by column chromatog-

raphy (silica gel, 10-50% EtOAc/hexanes) to give 3.6 g (84%)

of the desired styrene as a white solid and as a mixture of E:Z

isomers.

a

ZBI Coulter counter, and an IC₅₀was determined as

described previously.²⁹

In Vivo An titu m or Activity Exp er im en t. 1. BDF male

inbred mice (C57B1/6, C3H/He) were implanted bilaterally SC

on day zero with 30 to 60 mg tumor fragments of Panc03.

2. Chemotherapy, delivered iv bolus, was started either

within 3 days after implantation (early stage disease) or after

the tumors had grown to a palpable size, 200-700 mg in size

(upstaged disease).

3. Tumors were measured with caliper once or twice weekly

until either the tumors exceeded 1600 mg or cure was assured.

Tumor weights were estimated from two dimensional mea-

surements:

tumor weight (mg) ) (a × b²)/2 [a and b are tumor length

The mixture of isomers (7.3 g, 8.7 mmol) was dissolved in

benzene (240 mL) and heated to reflux in the presence of 1,1′-

azobis(cyclohexanecarbonitrile) (VAZO) (0.32 g, 0.87 mmol)

and thiophenol (3.7 mL, 4.0 mmol). Following 5 h at reflux,

the solution was concentrated, and the residue was purified

by column chromatography (silica gel, 5-50% EtOAc/hexanes)

and width (mm)]

End points used to assess antitumor activity were (1) tumor

growth delay (T - C value), (2) tumor cell kill, and (3) tumor

growth inhibition (% T/C value)

Most Cryptophycin analogues were formulated in propylene

glycol 2%, Cremophor EL 8%. Chlorohydrins were acidified

with 0.05% citric acid. All injections were carried out within

20 min of aqueous preparation from stock solutions.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6S)-5-h yd r oxy-6-m et h yl-7-oxo-2-h ep -

ten oyl-3-ch lor o-O-m eth yl-^D-tyr osyl] (2). To a solution of

Cryptophycin 53³¹(2.0 g, 2.99 mmol) in DME (30 mL) was

added a 2 M aqueous perchloric acid solution (15 mL, 30

mmol), and the resulting mixture was stirred for 6 h. Upon

careful neutralization with saturated NaHCO₃(50 mL), the

mixture was extracted with CH₂Cl₂(4 × 100 mL), and the

combined organic layers were dried over Na₂SO₄, filtered and

concentrated in vacuo. Purification by column chromatography

(silica gel, 5% MeOH/CH₂Cl₂) gave diols 1 (1.5 g) in 72% yield

as a 3:1 anti/syn mixture.

To a solution of diols 1 (1.0 g, 1.46 mmol) in THF (20 mL)

and water (15 mL) was added NaIO₄(1.9 g, 8.9 mmol), and

the mixture was stirred under nitrogen overnight. Upon

removing the bulk of the THF under reduced pressure, the

residue was diluted with water (100 mL) and extracted with

CH₂Cl₂(4 × 50 mL). The combined organic extracts were

washed with brine (1 × 25 mL), dried over Na₂SO₄, filtered,

and concentrated under vacuum. Residual benzaldehyde was

removed by dissolving the solid in toluene (100 mL) and

subsequently removing the toluene at 40 °C on a rotary

evaporator. Two additional evaporations from toluene gave the

aldehyde as a yellow foam (0.828 g) in 98% yield. The resulting

to give 6.7 g (92%) of the E isomer 29 as a white solid: [R]²⁰

D

1

+31.9 (c 1.0, CHCl₃); H NMR (300 MHz, CDCl₃) δ 7.3-7.22

(m, 5 H), 7.20-7.19 (d, 1 H, J ) 1.95 Hz), 7.07-7.04 (dd, 1 H,

J ) 8.4, 2.0 Hz), 6.85-6.82 (d, 1 H, J ) 8.5 Hz), 6.8-6.7 (m,

1 H), 6.4-6.38 (d, 1 H, J ) 15.8 Hz), 6.02-5.94 (dd, 1 H, J )

15.8, 8.8 Hz), 5.77-5.72 (d, 1 H, J ) 14.9 Hz), 5.56-5.54 (d, 1

H, J ) 7.9 Hz), 5.1-4.7 (m, 5 H), 3.9 (s, 3 H), 3.45-3.37 (dd,

1 H, J ) 13.5, 8.5 Hz), 3.2-3.0 (m, 3 H), 2.6-2.3 (m, 3 H),

1.7-1.5 (m, 2 H), 1.4-1.25 (m, 1 H), 1.24-1.0 (m, 30 H), 0.75-

0.71 (t, 6 H, J ) 6.1 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8,

170.5, 170.4, 165.2, 153.9, 142.1, 141.1, 135.2, 131.5, 130.8,

129.7, 129.6, 128.1, 125.9, 124.5, 122.4, 112.2, 77.0, 71.4, 64.7,

56.0, 54.4, 46.4, 42.7, 42.2, 39.4, 36.5, 35.3. 24.5, 22.8, 22.6,

22.5, 21.2, 17.9, 17.2, 11.9; IR (CHCl₃) 3423, 2962, 2945, 2867,

1746, 1712, 1681, 1652, 1528, 1503, 1485, 1473, 1464, 1303,

1259 cm^-1. Anal. Calcd for (C₄₆H₆₇ClN₂O₈Si): C, 65.81; H, 8.04;

N, 3.33. Found: C, 65.64; H, 7.98; N, 3.29.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6S)-5-h yd r oxy-6-[(2S,3S)-3-[4-[[[tr is(1-

m et h ylet h yl)silyl]oxy]m et h yl]p h en yl]oxir a n yl]-2-h ep -

ten oyl-3-ch lor o-O-m eth yl-^D-tyr osyl] (30a ) a n d Cyclo[2,2-

d im et h yl-â-a la n yl-(2S)-2-h yd r oxy-4-m et h ylp en t a n oyl-

(2E ,5S ,6S )-5-h yd r oxy-6-[(2R ,3R )-3-[4-[[[t r is(1-m e t h yl-

eth yl)silyl]oxy]m eth yl]p h en yl]oxir a n yl]-2-h ep ten oyl-3-

ch lor o-O-m eth yl-^D-tyr osyl] (30b). 3-Chloroperoxybenzoic

acid³⁰(0.27 g, 1.59 mmol) was added to a 0 °C solution of

styrene 29 (1.25 g, 1.49 mmol) in CH₂Cl₂(20 mL). The solution

2996 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

was stirred at 0 °C for 1 h and at room-temperature overnight.

It was concentrated in vacuo, and the resulting epoxides were

separated by reverse phase HPLC to yield 0.67 g of the â

epoxide 30b and 0.36 g of the R epoxide 30a as white solids in

80% combined yield. R epoxide 30a : [R]²⁰_D+16.1 (c 0.9, CHCl₃);

¹H NMR (300 MHz, CDCl₃) δ 7.4-7.2 (m, 6 H), 7.09-7.06 (d,

1 H, J ) 8.4 Hz), 6.86-6.83 (d, 1 H, J ) 8.3 Hz), 6.83-6.7 (m,

1 H), 5.9-5.6 (m, 2 H), 5.25-5.15 (m, 1 H), 4.95-4.85 (m, 1

H), 4.81 (s, 2 H), 4.8-4.7 (m, 1H), 3.9 (s, 3 H), 3.6 (s, 1 H),

3.47-3.4 (dd, 1 H, J ) 13.0, 8.7 Hz), 3.2-3.0 (m, 3 H), 2.92-

2.9 (d, 1 H, J ) 7.6 Hz), 2.8-2.5 (m, 2 H), 1.8-1.4 (m, 4 H),

1.3-1.0 (m, 30 H), 0.9-0.85 (t, 6 H, J ) 7.4 Hz); ¹³C NMR

(62.5 MHz, CDCl₃) δ 177.7, 170.6, 170.4, 165.3, 153.9, 141.9,

141.87, 135.4, 130.7, 129.9, 128.1, 125.8, 125.2, 124.6, 122.3,

112.2, 76.7, 71.3, 64.6, 63.1, 56.2, 56.0, 54.6, 46.4, 42.7, 40.8,

39.2, 36.7, 35.3, 24.7, 22.9, 22.8, 22.7, 21.3, 17.9, 13.4, 11.9;

IR (CHCl₃) 3422, 2963, 2945, 2867, 1750, 1712, 1681, 1528,

1503, 1485, 1473, 1259, 1191, 1151 cm^-1; HRMS (FAB, m/z)

calcd for C₄₆H₆₇ClN₂O₉Si (M⁺+ H) 855.4383, found 855.4371.

7.8 Hz), 7.28-7.2 (m, 5 H), 7.08-7.05 (dd, 1 H, J ) 8.3, 1.95

Hz), 6.86-6.84 (d, 1 H, J ) 8.3 Hz), 6.82-6.74 (m, 1 H), 5.81-

5.77 (dd, 1 H, J ) 15.1, 0.98 Hz), 5.54-5.52 (d, 1 H, J ) 7.8

Hz), 5.22-5.15 (m, 1 H), 4.93-4.9 (dd, 1 H, J ) 10.1, 3.2 Hz),

4.8-4.72 (m, 1 H), 4.7-4.69 (d, 1 H, J ) 5.4 Hz), 3.88 (s, 3 H),

3.6-3.59 (d, 1 H, J ) 1.95 Hz), 3.46-3.4 (dd, 1 H, J ) 13.6,

8.8 Hz), 3.16-3.08 (m, 3 H), 2.91-2.88 (dd, 1 H, J ) 7.8, 1.95

Hz), 2.74-2.54 (m, 2 H), 1.8-1.6 (m, 4 H), 1.5-1.4 (m, 1 H),

1.24 (s, 3 H), 1.18 (s, 3 H), 1.05-1.03 (d, 3 H, J ) 7.3 Hz),

0.91-0.89 (d, 3 H, J ) 6.35 Hz), 0.88-0.86 (d, 3 H, J ) 6.8

Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.9, 170.6, 170.5, 165.2,

154.1, 142.1, 141.3, 136.4, 130.9, 129.7, 128.3, 127.2, 125.7,

125.6, 124.7, 122.6, 112.4, 76.7, 71.4, 64.8, 63.3, 56.2, 54.5, 46.5,

42.8, 40.9, 39.3, 36.8, 35.3, 24.8, 23.0, 22.9, 22.7, 21.4, 13.4;

IR (CHCl₃) 3424, 2965, 2936, 2874, 1751, 1712, 1681, 1527,

1503, 1442, 1304, 1259, 1151, 1066 cm^-1. Anal. Calcd for

(C₃₇H₄₇ClN₂O₉): C, 63.56; H, 6.77; N, 4.01. Found: C, 63.34;

H, 6.94; N, 3.99.

P en ta n oic Acid , 3-Ch lor o-N-[(2E,5S,6S)-5-h yd r oxy-6-

[(2R,3R)-3-[4-(h yd r oxym eth yl)p h en yl]oxir a n yl]-1-oxo-2-

h ep t en yl]-O-m et h yl-^D-t yr osyl-2,2-d im et h yl-â-a la n yl-2-

h yd r oxy-4-m eth yl-, (3 f 1⁵)-la cton e, 1⁶-Ester w ith N-[(1,1-

Dim eth yleth oxy)ca r bon yl]glycin e, (2S)- (32). To a 0 °C

solution of alcohol 31b (0.08 g, 0.114 mmol), N-(tert-butoxy-

carbonyl)glycine (0.034 g, 0.194 mmol), and 4-(dimethylamino)-

pyridine (DMAP) (0.004 g, 0.034 mmol) in CH₂Cl₂(2.0 mL)

was added 1,3-dicyclohexylcarbodiimide (DCC) (0.040 g, 0.194

mmol). The mixture was stirred at 0 °C for 10 min and at room

temperature for 45 min, filtered, and concentrated in vacuo.

The resulting residue was purified by column chromatography

(silica gel, 70-80% EtOAc/hexanes) to give 0.07 g (72%) of

ester 32 as a white solid: [R]²⁰_D+18.5 (c 0.65, CHCl₃); ¹H NMR

(300 MHz, CDCl₃) δ 7.4-7.2 (m, 6 H), 7.11-7.08 (dd, 1 H, J )

8.4, 1.8 Hz), 6.9-6.87 (d, 1 H, J ) 8.4 Hz), 6.86-6.7 (m, 1 H),

5.78-5.73 (d, 1 H, J ) 15.2 Hz), 5.64-5.62 (d, 1 H, J ) 7.4

Hz), 5.3-5.22 (m, 1 H), 5.22 (s, 2 H), 5.1-5.0 (bs, 1 H), 4.9-

4.7 (m, 2 H), 4.0-3.99 (d, 2 H, J ) 5.4 Hz), 3.9 (s, 3 H), 3.73-

3.72 (d, 1 H, J ) 1.0 Hz), 3.5-3.43 (dd, 1 H, J ) 13.4, 8.6 Hz),

3.2-3.0 (m, 3 H), 2.95-2.92 (d, 1 H, J ) 6.4 Hz), 2.65-2.4 (m,

2 H), 1.8-1.6 (m, 3 H), 1.5 (s, 9 H), 1.45-1.3 (m, 1 H), 1.26 (s,

3 H), 1.2 (s, 3 H), 1.2-1.17 (d, 3 H, J ) 8.7 Hz), 0.9-0.86 (t,

6 H, J ) 6.3 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.7, 170.6,

170.3, 170.2, 165.1, 155.6, 153.8, 141.4, 137.1, 135.6, 130.6,

129.9, 128.6, 128.0, 125.7, 124.7, 122.2, 112.2, 79.9, 75.8, 70.9,

66.4, 63.1, 58.5, 56.0, 54.7, 48.9, 46.3, 42.7, 42.4, 40.5, 39.3,

36.8, 35.2, 28.2, 24.5, 22.8, 22.7, 22.6, 21.2, 13.5. Anal. Calcd

for (C₄₄H₅₈ClN₃O₁₂): C, 61.71; H, 6.83; N, 4.91. Found: C,

61.43; H, 6.92; N, 5.11.

â epoxide 30b: [R]²⁰+20.9 (c 0.76, CHCl₃); H NMR (300

1

D

MHz, CDCl₃) δ 7.35-7.33 (d, 2 H, J ) 7.8 Hz), 7.26-7.2 (m, 4

H), 7.05-7.02 (bd, 1 H, J ) 8.2 Hz), 6.84-6.81 (d, 1 H, J )

8.4 Hz), 6.81-6.65 (m, 1 H), 5.8-5.65 (m, 2 H), 5.25-5.15 (m,

1 H), 4.9-4.7 (m, 4 H), 3.9 (s, 3 H), 3.7 (s, 1 H), 3.46-3.42 (dd,

1 H, J ) 13.4, 8.8 Hz), 3.15-3.0 (m, 3 H), 2.93-2.9 (d, 1 H, J

) 7.3 Hz), 2.6-2.4 (m, 2 H), 1.8-1.6 (m, 3 H), 1.4-1.0 (m, 31

H), 0.83-0.79 (t, 6 H, J ) 5.3 Hz); ¹³C NMR (62.5 MHz, CDCl₃)

δ 177.7, 170.5, 170.4, 165.1, 153.9, 142.1, 141.6, 136.7, 135.1,

130.7, 129.8, 128.1, 125.9, 125.5, 124.6, 122.3, 112.2, 75.9, 71.0,

64.6, 63.0, 58.9, 56.0, 54.6, 46.3, 42.7, 40.5, 39.2, 36.8, 35.2.

24.2, 22.8, 22.7, 22.6, 18.0, 13.4, 11.9; IR (CHCl₃) 3424, 2962,

2945, 2867, 1751, 1712, 1682, 1528, 1503, 1485, 1473, 1464,

cm^-1. Anal. Calcd for (C₄₆H₆₇ClN₂O₉Si): C, 64.58; H, 7.89; N,

3.27. Found: C, 64.3; H, 7.92; N, 3.28.

P en ta n oic Acid , 3-Ch lor o-N-[(2E,5S,6S)-5-h yd r oxy-6-

[(2R,3R)-3-[4-(h yd r oxym eth yl)p h en yl]oxir a n yl]-1-oxo-2-

h ep t en yl]-O-m et h yl-^D-t yr osyl-2,2-d im et h yl-â-a la n yl-2-

h ydr oxy-4-m eth yl-, (3 f 1⁵)-lacton e, (2S)- (31b). Tetrabutyl-

ammonium fluoride (0.14 mL, 0.14 mmol), as a 1.0 M solution

in THF, was added dropwise to a 0 °C solution of the â epoxide

30b (0.1 g, 0.117 mmol) in THF (3.5 mL). The solution was

allowed to warm to room temperature, was stirred for another

20 min, and finally was quenched with water (10 mL) and

ethyl acetate (20 mL). The layers were separated, and the

aqueous one was extracted with CH₂Cl₂(3 × 20 mL). The

combined organic layers were dried over anhydrous Na₂SO₄,

filtered, and concentrated in vacuo to yield the free alcohol.

Purification by column chromatography (silica gel, 70-100%

EtOAc/hexanes) yielded 0.068 g (84%) of the pure alcohol 31b

P en tan oic Acid, 3-Ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

5,7-d ih yd r oxy-8-[4-(h yd r oxym eth yl)p h en yl]-6-m eth yl-1-

oxo-2-octen yl]-O-m eth yl-^D-tyr osyl-2,2-d im eth yl-â-a la n yl-

2-h yd r oxy-4-m et h yl-, (3 f 1⁵)-la ct on e, 1⁸-E st er w it h

N-[(1,1-Dim eth yleth oxy)car bon yl]glycin e, (2S)- (33). Chlo-

rotrimethylsilane (0.09 mL, 0.75 mmol) was added to a -60

°C solution of â epoxide 32 (0.16 g, 0.187 mmol) in CHCl₃(5.0

mL). Following 2 h of stirring between -60 °C to -40 °C, an

additional 0.09 mL of TMSCl was added, and stirring was

continued for 3 h. The solution was allowed to warm to room

temperature and was concentrated in vacuo. The two resulting

chlorohydrins were separated by reverse phase preparative

HPLC with (55:45) CH₃CN:H₂O to give 0.058 g (35%) of the

1

as a white solid: [R]²⁰+26.2 (c 0.435, CHCl₃); H NMR (300

D

MHz, CDCl₃) δ 7.39-7.36 (d, 2 H, J ) 7.8 Hz), 7.26-7.23 (d,

3 H, J ) 9.1 Hz), 7.18 (s, 1 H), 7.05-7.02 (d, 1 H, J ) 8.5 Hz),

6.85-6.82 (d, 1 H, J ) 8.2 Hz), 6.82-6.7 (m, 1 H), 5.72-5.67

(d, 1 H, J ) 15.1 Hz), 5.55-5.52 (d, 1 H, J ) 7.8 Hz), 5.22-

5.17 (m, 1 H), 4.85-4.7 (m, 4 H), 3.9 (s, 3 H), 3.7 (s, 1 H), 3.45-

3.38 (dd, 1 H, J ) 13.4, 9.3 Hz), 3.2-3.0 (m, 3 H), 2.92-2.89

(d, 1 H, J ) 7.6 Hz), 2.65-2.4 (m, 2 H), 1.8-1.6 (m, 4 H), 1.4-

1.2 (m, 1 H), 1.22 (s, 3 H), 1.16 (s, 3 H), 1.16-1.13 (d, 3 H, J

) 7.2 Hz), 0.86-0.82 (t, 6 H, J ) 6.5 Hz); ¹³C NMR (62.5 MHz,

CDCl₃) δ 177.8, 171.0, 170.4, 165.5, 153.8, 141.5, 141.4, 135.7,

133.5, 130.6, 130.0, 128.0, 127.1, 125.6, 124.6, 122.2, 112.3,

77.2, 76.5, 76.0, 71.0, 64.2, 63.1, 58.8, 56.0, 54.7, 46.3, 42.7,

40.5, 39.3, 36.9, 35.1, 24.5, 22.7, 22.5, 22.1, 13.4; IR (CHCl₃)

3422, 2992, 2963, 2936, 2874, 1751, 1713, 1682, 1651, 1504,

1486, 1303, 1259, 1186, 1165, 1151, 1067 cm^-1; HRMS (FAB,

m/z) calcd for C₃₇H₄₇ClN₂O₉(M⁺+ H) 699.3048, found 699.3054.

Anal. Calcd for (C₃₇H₄₇ClN₂O₉.0.5 H₂O): C, 62.75; H, 6.83; N,

3.96. Found: C, 62.97, H, 6.53; N, 3.78.

desired anti chlorohydrin 33 as a white solid: [R]²⁰+50.5 (c

D

1

1.075, CHCl₃); H NMR (300 MHz, CDCl₃) δ 7.42-7.2 (m, 6

H), 7.13-7.09 (dd, 1 H, J ) 8.4, 1.8 Hz), 6.9-6.87 (d, 1 H, J )

8.4 Hz), 6.85-6.7 (m, 1 H), 5.9-5.8 (m, 2 H), 5.2 (s, 3 H), 5.15-

5.05 (m, 1 H), 5.0-4.9 (m, 1 H), 4.8-4.72 (m, 1 H), 4.71-4.68

(d, 1 H, J ) 9.7 Hz), 4.07-4.03 (d, 1 H, J ) 9.3 Hz), 3.99-3.97

(d, 2 H, J ) 5.5 Hz), 3.9 (s, 3 H), 3.44-3.37 (dd, 1 H, J ) 13.6,

8.3 Hz), 3.23-3.14 (m, 2 H), 3.08-3.0 (dd, 1 H, J ) 14.5, 8.0

Hz), 2.75-2.4 (m, 3 H), 2.0-1.7 (m, 3 H), 1.5 (s, 10 H), 1.26 (s,

3 H), 1.21 (s, 3 H), 1.08-1.06 (d, 3 H, J ) 7.0 Hz), 0.98-0.94

(m, 6 H); ¹³C NMR (62.5 MHz, CDCl₃) 177.5, 170.5, 170.2,

170.1, 165.3, 153.9, 142.2, 139.0, 138.3, 136.1, 130.8, 129.9,

128.7, 128.2, 128.1, 124.5, 122.3, 112.2, 80.0, 76.1, 73.9, 71.1,

P en ta n oic Acid , 3-Ch lor o-N-[(2E,5S,6S)-5-h yd r oxy-6-

[(2S,3S)-3-[4-(h yd r oxym eth yl)p h en yl]oxir a n yl]-1-oxo-2-

h ep t en yl]-O-m et h yl-^D-t yr osyl-2,2-d im et h yl-â-a la n yl-2-

h yd r oxy-4-m eth yl-, (3 f 1⁵)-la cton e, (2S)- (31a ). Similarly

alcohol 31a was obtained as a white solid: [R]²⁰_D+24.1 (c 2.33,

1

CHCl₃); H NMR (300 MHz, CDCl₃) δ 7.37-7.35 (d, 2 H, J )

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 2997

66.2, 61.7, 56.1, 54.6, 46.4, 42.7, 42.3, 39.6, 38.4, 36.3, 35.1,

28.2, 24.8, 23.0, 22.9, 22.7, 21.5, 8.6; IR (CHCl₃) 3428, 3009,

2966, 2935, 1750, 1714, 1683, 1504, 1486, 1369, 1259, 1193,

1162, 1127, 1067; HRMS (FAB, m/z) calcd for C₄₄H₅₉Cl₂N₃O₁₂

Hz), 3.2-3.1 (m, 3 H), 2.98-2.95 (dd, 1 H, J ) 7.6, 1.6 Hz),

2.65-2.45 (m, 2 H), 2.32 (s, 3 H), 1.85-1.6 (m, 3 H), 1.4-1.25

(m, 1 H), 1.27 (s, 3 H), 1.21 (s, 3 H), 1.21-1.18 (d, 3 H, J ) 7.5

Hz), 0.90-0.86 (t, 6 H, J ) 6.13 Hz); ¹³C NMR (62.5 MHz,

CDCl₃) δ 177.8, 170.4, 165.0, 153.9, 141.7, 138.4, 136.6, 130.7,

129.6, 129.2, 128.5, 128.1, 126.0, 124.6, 122.8, 122.3, 112.2,

75.8, 71.0, 62.9, 59.0, 56.0, 54.4, 46.3, 42.7, 40.6, 39.2, 36.8,

35.2, 24.4, 22.8, 22.7, 22.6, 21.3, 21.1, 13.5; IR (CHCl₃) 3423,

2964, 2936, 2874, 1751, 1712, 1682, 1527, 1503, 1486, 1259,

(M⁺+ H) 892.3554, found 892.3565. Anal. Calcd for (C₄₄H₅₉

-

Cl₂N₃O₁₂^.1.0 H₂O): C, 58.02; H, 6.75; N, 4.61. Found: C, 58.4;

H, 6.65; N, 4.44.

P en ta n oic a cid , 3-ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

5,7-d ih yd r oxy-8-[4-(h yd r oxym eth yl)p h en yl]-6-m eth yl-1-

oxo-2-octen yl]-O-m eth yl-^D-tyr osyl-2,2-d im eth yl-â-a la n yl-

2-h yd r oxy-4-m et h yl-, (3 f 1⁵)-la ct on e, 1⁸-est er w it h

glycin e, m on oh yd r och lor id e, (2S)- (34). A 4 M solution of

hydrogen chloride in 1,4-dioxane (0.08 mL, 0.33 mmol) was

added to a solution of ester 33 (0.058 g, 0.065 mmol) in CH₂-

Cl₂(0.2 mL). The resulting mixture was stirred at room

temperature for 3 h, concentrated in vacuo and maintained

under vacuum for 3 days to remove the 1,4-dioxane thus giving

.

1188, 1152 cm^-1. Anal. Calcd for (C₃₇H₄₇ClN₂O₈0.2 H₂O): C,

64.7; H, 6.96; N, 4.08. Found: C, 64.47; H, 6.76; N, 4.21.

â Ep oxid e op en in g of 9 w ith TMSCl or HCl: P en ta n oic

acid, 3-ch lor o-N-[(2E,5S,6S,7R,8R)-8-ch lor o-5,7-dih ydr oxy-

6-m eth yl-8-(3-m eth ylp h en yl)-1-oxo-2-octen yl]-O-m eth yl-

D-tyr osyl-2,2-d im eth yl-â-a la n yl-2-h yd r oxy-4-m eth yl-, (3

f 1⁵)-la cton e, (2S)- (10). P en ta n oic a cid , 3-ch lor o-N-

[(2E,5S,6S,7R,8S)-8-ch lor o-5,7-d ih yd r oxy-6-m et h yl-8-(3-

m eth ylp h en yl)-1-oxo-2-octen yl]-O-m eth yl-^D-tyr osyl-2,2-

d im eth yl-â-a la n yl-2-h yd r oxy-4-m eth yl-, (3f1⁵)-la cton e,

(2S)- (11).

the desired hydrochloride salt 34 in quantitative yield: [R]²⁰

D

1

+26.2 (c 0.58, MeOH); H NMR (300 MHz, CD₃OD) δ 8.51-

8.48 (d, 1 H, J ) 7.6 Hz), 7.8-7.77 (d, 1 H, J ) 8.4 Hz), 7.45-

7.37 (m, 5 H), 7.26-7.25 (d, 1 H, J ) 1.56 Hz), 7.17-7.13 (dd,

1 H, J ) 8.5, 1.7 Hz), 6.96-6.94 (d, 1 H, J ) 8.5 Hz), 6.74-

6.64 (m, 1 H), 5.96-5.91 (d, 1 H, J ) 15.3 Hz), 5.26 (s, 2 H),

5.16-5.0 (m, 2 H), 4.8-4.77 (d, 1 H, J ) 9.6 Hz), 4.01-3.98

(d, 1 H, J ) 9.6 Hz), 3.86 (s, 2 H), 3.81 (s, 3 H), 3.5-3.42 (dd,

1 H, J ) 13.4, 10 Hz), 3.2-3.0 (m, 2 H), 2.8-2.65 (m, 2 H),

2.5-2.2 (m, 2 H), 1.85-1.45 (m, 3 H), 1.2 (s, 3 H), 1.16 (s, 3

H), 1.0-0.94 (m, 9 H); ¹³C NMR (62.5 MHz, CD₃OD) δ 178.9,

173.8, 171.9, 168.3, 155.3, 144.2, 141.8, 136.7, 132.3, 131.5,

129.75, 129.7, 129.4, 125.2, 123.3, 113.5, 77.2, 74.7, 72.6, 68.5,

63.5, 57.6, 56.7, 47.6, 44.1, 41.1, 40.4, 37.9, 36.5, 26.3, 23.6,

23.5, 22.2, 9.0; IR (KBr) 3412, 2961, 2935, 1752, 1722, 1669,

1504, 1473, 1279, 1259, 1207, 1151, 1126, 1065 cm^-1; HRMS

(FAB, m/z) calcd for C₃₉H₅₂Cl₃N₃O₁₀(M⁺- Cl) 792.3030, found

792.3020.

En tr y 1: To a solution of the â epoxide 9 (0.1 g, 0.147 mmol)

in CH₂Cl₂(5.0 mL) at -60 °C was added chlorotrimethylsilane

(0.093 mL, 0.74 mmol). The solution was allowed to warm to

room temperature over 4 h before being concentrated under

vacuum. The resulting residue, containing a 40:60 mixture of

the syn and anti chlorohydrins, was purified by reverse phase

HPLC with (45:55) CH₃CN:H₂O to yield 0.018 g of the syn

isomer 10: [R]²⁰-41.6 (c 1.25, CHCl₃); ¹H NMR (300 MHz,

D

CDCl₃) δ 7.35-7.15 (m, 6 H), 7.13-7.1 (dd, 1 H, J ) 10.3, 1.9

Hz), 6.89-6.87 (d, 1 H, J ) 8.5 Hz), 6.88-6.73 (m, 1 H), 5.77-

5.72 (d, 1 H, J ) 15.3 Hz), 5.63-5.60 (d, 1 H, J ) 7.7 Hz),

5.19-5.13 (t, 1 H, J ) 9.6 Hz), 4.98-4.92 (m, 1 H), 4.90-4.87

(d, 1 H, J ) 9.7 Hz), 4.8-4.72 (m, 1 H), 4.14-4.11 (dd, 1 H, J

) 9.4, 1.0 Hz), 3.91 (s, 3 H), 3.49-3.42 (dd, 1 H, J ) 13.5, 8.3

Hz), 3.25-3.0 (m, 3 H), 2.6-2.45 (m, 2 H), 2.4 (s, 3 H), 2.3-

2.15 (m, 1 H), 1.9-1.4 (m, 4 H), 1.28 (s, 3 H), 1.22 (s, 3 H),

1.02-0.99 (d, 3 H, J ) 6.7 Hz), 0.98-0.96 (d, 6 H, J ) 6.7 Hz);

¹³C NMR (62.5 MHz, CDCl₃) 177.8, 170.3, 170.0, 165.0, 142.4,

138.8, 138.0, 137.5, 130.8, 129.9, 129.6, 128.9, 128.2, 128.0,

124.3, 112.2, 75.8, 74.3, 71.2, 68.7, 56.0, 54.3, 46.4, 42.7, 39.6,

38.3, 36.2, 35.2, 24.8, 22.9, 22.8, 22.7, 21.7, 21.3, 8.6; IR (KBr)

3419, 3305, 2960, 2932, 2872, 1754, 1721, 1675, 1535, 1504,

1473, 1258, 1194, 1150, 1066 cm^-1; HRMS (FAB, m/z) calcd

for C₃₇H₄₉Cl₂N₂O₈(M⁺+H) 719.2866, found 719.2876. Anal.

Calcd for (C₃₇H₄₈Cl₂N₂O₈^.0.2 H₂O): C, 61.44; H, 6.74; N, 3.87.

Found: C, 61.18, H, 6.47; N, 3.77 and 0.030 g of the desired

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6R,7E)-5-h yd r oxy-6-m eth yl-8-(3-m eth -

ylp h en yl)-2,7-oct a d ien oyl-3-ch lor o-O-m et h yl-^D-t yr osyl]

(8). Styrene 8 (0.67 g) was prepared from aldehyde 2 (1.0 g,

1.73 mmol) and 3-methylbenzyl triphenylphosphonium chlo-

ride (3a ) (0.886 g, 2.2 mmol) in 58% yield according to the

procedure described for styrene 29: [R]²⁰+33.1 (c 1.0, CH₃-

D

1

OH); H NMR (300 MHz, CDCl₃) δ 7.24-7.0 (m, 7 H), 6.85-

6.82 (d, 1 H, J ) 8.4 Hz), 6.82-6.7 (m, 1 H), 6.39-6.34 (d, 1

H, J ) 15.8 Hz), 6.03-5.95 (dd, 1 H, J ) 15.8, 8.7 Hz), 5.78-

5.73 (d, 1 H, J ) 15.2 Hz), 5.67-5.64 (d, 1 H, J ) 7.8 Hz),

5.1-5.0 (m, 1 H), 4.87-4.83 (dd, 1 H, J ) 10.2, 3.5 Hz), 4.8-

4.7 (m, 1 H), 3.9 (s, 3 H), 3.45-3.38 (dd, 1 H, J ) 13.4, 8.6

Hz), 3.2-3.0 (m, 3 H), 2.6-2.3 (m, 3 H), 2.32 (s, 3 H), 1.75-

1.55 (m, 2 H), 1.4-1.25 (m, 1 H), 1.22 (s, 3 H), 1.15 (s, 3 H),

1.13-1.11 (d, 3 H, J ) 6.8 Hz), 0.75-0.72 (t, 6 H, J ) 5.7 Hz);

¹³C NMR (62.5 MHz, CDCl₃) δ 177.9, 170.5, 170.3, 165.1, 154.0,

142.1, 138.0, 136.6, 131.8, 130.8, 129.9, 129.6, 128.4, 128.22,

128.17, 126.7, 124.5, 123.3, 122.5, 112.3, 71.4, 56.1, 54.3, 46.4,

42.7, 42.2, 39.4, 36.5, 35.3, 24.5, 22.8, 22.6, 22.56, 21.2, 21.1,

17.2; IR (CHCl₃) 3424, 3021, 3017, 2965, 1747, 1711, 1680,

1652, 1528, 1503, 1485, 1259, 1151, 1067 cm^-1. Anal. Calcd

for (C₃₇H₄₇ClN₂O₇): C, 66.6; H, 7.1; N, 4.2. Found: C, 66.79;

H, 7.03; N, 4.25.

anti isomer 11 in a 46% combined yield: [R]²⁰+63.8 (c 1.27,

D

CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ 7.28-7.2 (m, 6 H), 7.13-

7.1 (dd, 1 H, J ) 8.3, 1.9 Hz), 6.91-6.88 (d, 1 H, J ) 8.5 Hz),

6.88-6.78 (m, 1 H), 5.86-5.81 (d, 1 H, J ) 15.0 Hz), 5.73-

5.71 (d, 1 H, J ) 7.8 Hz), 5.24-5.17 (t, 1 H, J ) 9.4 Hz), 5.0-

4.96 (dd, 1 H, J ) 9.6, 2.9 Hz), 4.81-4.74 (m, 1 H), 4.67-4.64

(d, 1 H, J ) 9.7 Hz), 4.06-4.03 (dd, 1 H, J ) 9.6, 1.1 Hz), 3.92

(s, 3 H), 3.47-3.39 (dd, 1 H, J ) 13.2, 8.3 Hz), 3.25-3.0 (m, 3

H), 2.8-2.7 (m, 1 H), 2.6-2.45 (m, 1 H), 2.4 (s, 3 H), 1.9-1.4

(m, 4 H), 1.28 (s, 3 H), 1.22 (s, 3 H), 1.09-1.07 (d, 3 H, J ) 7.0

Hz), 0.98-0.96 (d, 6 H, J ) 6.4 Hz); ¹³C NMR (62.5 MHz,

CDCl₃) 177.6, 170.4, 170.2, 165.2, 153.9, 142.4, 138.8, 138.2,

130.8, 129.8, 129.7, 128.8, 128.5, 128.1, 124.9, 124.4, 122.3,

112.2, 76.0, 73.8, 71.1, 62.0, 56.0, 54.4, 46.4, 42.7, 39.6, 38.3,

36.4, 35.2, 24.7, 23.0, 22.8, 22.7, 21.5, 21.3, 8.6; IR (CDCl₃)

3588, 3424, 2964, 2934, 1751, 1714, 1680, 1528, 1503, 1486,

1259, 1152 cm^-1. Anal. Calcd for (C₃₇H₄₈Cl₂N₂O₈): C, 61.75;

H, 6.72; N, 3.89. Found: C, 61.99; H, 6.61; N, 3.88.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p e n t a n oyl-(2E ,5S,6S)-5-h yd r oxy-6-[(2R,3R)-3-(3-m e t h -

ylp h en yl)oxir a n yl]-2-h ep ten oyl-3-ch lor o-O-m eth yl-^D-ty-

r osyl] (9). 3-Chloroperoxybenzoic acid (0.19 g, 1.1 mmol) was

added to styrene 8 (0.667 g, 1.0 mmol) in CH₂Cl₂(5.0 mL).

The resulting solution was stirred overnight, concentrated in

vacuo to give the â and R epoxides in a 1.8:1 ratio, in favor of

the â. Separation of the two epoxides by reverse phase HPLC

with (70:30) CH₃CN:H₂O gave 0.20 g of the major â epoxide 9

En tr y 2: To a solution of the â epoxide 9 (0.05 g, 0.073

mmol) in CH₂Cl₂(2.3 mL) at -60 °C, was added 4 M HCl in

dioxane (0.093 mL, 0.37 mmol). The solution was allowed to

warm to room temperature over 4 h before being concentrated

under vacuum. The resulting residue was analyzed by reverse

phase HPLC and was found to contain a 24:76 mixture of the

syn/anti chlorohydrins.

En tr y 3: To a solution of the â epoxide 9 (0.05 g, 0.073

mmol) in CH₂Cl₂(2.3 mL) at -70 °C was added 4 M HCl in

dioxane (0.093 mL, 0.37 mmol). The solution was maintained

as a white solid: [R]²⁰+21.9 (c 1.0, CHCl₃); ¹H NMR (300

D

MHz, CDCl₃) δ 7.3-7.0 (m, 7 H), 6.9-6.87 (d, 1 H, J ) 8.4

Hz), 6.87-6.75 (m, 1 H), 5.79-5.74 (d, 1 H, J ) 14.8 Hz), 5.54-

5.51 (d, 1 H, J ) 7.8 Hz), 5.28-5.22 (m, 1 H), 4.89-4.85 (dd,

1 H, J ) 10.4, 3.5 Hz), 4.82-4.75 (m, 1 H), 3.9 (s, 3 H), 3.69-

3.68 (d, 1 H, J ) 1.6 Hz), 3.51-3.44 (dd, 1 H, J ) 13.4, 8.6

2998 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

between -70 °C and -60 °C for 2 h before being warmed to

room temperature and concentrated under vacuum. The

resulting residue was analyzed by reverse phase HPLC and

was found to contain a 21:79 mixture of the syn and anti

chlorohydrins.

(300 MHz, CDCl₃) δ 7.26-7.0 (m, 6 H), 6.85-6.82 (d, 1 H, J )

8.4 Hz), 6.80-6.71 (m, 1 H), 5.71-5.66 (d, 1 H, J ) 15.1 Hz),

5.50-5.47 (d, 1 H, J ) 7.6 Hz), 5.13-5.08 (t, 1 H, J ) 8.8 Hz),

4.89-4.84 (m, 2 H), 4.81-4.71 (m, 1 H), 4.09-4.06 (d, 1 H, J

) 9.4 Hz), 3.87 (s, 3 H), 3.44-3.37 (dd, 1 H, J ) 13.4, 8.4 Hz),

3.16-3.06 (m, 3 H), 2.60-2.54 (m, 2 H), 2.26 (s, 6 H), 2.26-

2.14 (m, 1 H), 1.89-1.81 (m, 1 H), 1.70-1.62 (m, 1 H), 1.58-

1.46 (m, 2 H), 1.23 (s, 3 H), 1.17 (s, 3 H), 0.97-0.90 (m, 9 H);

¹³C NMR (62.5 MHz, CDCl₃) δ 177.7, 170.5, 170.1, 165.2, 153.9,

142.3, 137.7, 137.3, 135.1, 130.7, 130.2, 129.8, 128.5, 128.1,

124.6, 124.4, 122.3, 112.2, 75.9, 74.2, 71.2, 68.8, 56.0, 54.4, 46.4,

42.7, 39.6, 38.4, 36.2, 35.2, 24.8, 22.9, 22.8, 22.7, 21.7, 19.8,

19.5, 8.6; IR (KBr) 3421, 2960, 1756, 1721, 1675, 1504, 1258,

1195, 1151, 1126, 1066 cm^-1; HRMS (FAB, m/z) calcd for

C₃₈H₅₀Cl₂N₂O₈(M⁺+ H) 733.3022, found 733.3029. Anal. Calcd

for (C₃₈H₅₀Cl₂N₂O₈): C, 62.21; H, 6.87; N, 3.82. Found: C,

61.97; H, 6.61; N, 3.74.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6R,7E)-8-(3,4-d im et h ylp h en yl)-5-h y-

d r oxy-6-m eth yl-2,7-octa d ien oyl-3-ch lor o-O-m eth yl-^D-ty-

r osyl] (12). Styrene 12 (0.095 g) was prepared from aldehyde

2 (0.2 g, 0.345 mmol) and 3,4-dimethylbenzyl triphenylphos-

phonium chloride (3b) (0.26 g, 0.62 mmol) in 63% yield

according to the procedure described above for styrene 29:

[R]²⁰+27.8 (c 0.576, CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ

D

7.25-7.0 (m, 6 H), 6.87-6.81 (d, 1 H, J ) 8.3 Hz), 6.80-6.71

(m, 1 H), 6.40-6.30 (d, 1 H, J ) 15.8 Hz), 6.0-5.88 (dd, 1 H,

J ) 15.8, 8.8 Hz), 5.80-5.70 (d, 1 H, J ) 15.1 Hz), 5.55-5.45

(d, 1 H, J ) 7.7 Hz), 5.10-4.97 (m, 1 H), 4.90-4.80 (dd, 1 H,

J ) 9.4, 2.8 Hz), 4.80-4.70 (m, 1 H), 3.88 (s, 3 H), 3.45-3.37

(dd, 1 H, J ) 13.3, 8.54 Hz), 3.20-3.0 (m, 3 H), 2.60-2.48 (m,

2 H), 2.45-2.30 (m, 1 H), 2.24 (s, 3 H), 2.23 (s, 3 H), 1.80-

1.55 (m, 2 H), 1.40-1.30 (m, 1 H), 1.22 (s, 3 H), 1.16 (s, 3 H),

1.14-1.10 (d, 3 H, J ) 6.8 Hz), 0.77-0.73 (t, 6 H, J ) 5.57

Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.9, 170.5, 170.3, 165.1,

154.0, 142.2, 136.5, 135.9, 134.3, 131.6, 130.8, 129.7, 129.5,

128.8, 128.1, 127.2, 124.4, 123.6, 122.4, 112.2, 71.4, 56.0, 54.2,

46.4, 42.6, 42.1, 39.4, 36.4, 35.2, 24.5, 22.7, 22.6, 22.5, 21.1,

19.6, 19.3, 17.2; IR (CHCl₃) 3424, 2965, 2935, 1746, 1711, 1681,

1652, 1527, 1503, 1485, 1259, 1187, 1164, 1151, 1067, 970, 727

cm^-1; Calcd for (C₃₈H₄₉ClN₂O₇): C, 66.99; H, 7.25; N, 4.11.

Found: C, 66.78; H, 7.0; N, 4.12.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6R,7E)-8-(2,5-d im et h ylp h en yl)-5-h y-

d r oxy-6-m eth yl-2,7-octa d ien oyl-3-ch lor o-O-m eth yl-^D-ty-

r osyl] (15). Styrene 15 (0.44 g) was prepared from aldehyde

2 (0.5 g, 0.87 mmol) and 2,5-dimethylbenzyl triphenylphos-

phonium chloride (3c) (0.5 g, 1.2 mmol) in 75% yield according

to the procedure described above for styrene 29: [R]²⁰+36.2

D

(c 1.0, CHCl₃); ¹H NMR (500 MHz, CDCl₃) δ 7.3-7.2 (m, 3 H),

7.09-7.07 (dd, 1 H, J ) 8.4, 2.1 Hz), 7.05-7.04 (d, 1 H, J )

7.7 Hz), 6.99-6.97 (d, 1 H, J ) 7.7 Hz), 6.88-6.86 (d, 1 H, J

) 8.4 Hz), 6.84-6.78 (m, 1 H), 6.64-6.6 (d, 1 H, J ) 15.7 Hz),

5.95-5.91 (dd, 1 H, J ) 15.8, 8.8 Hz), 5.79-5.76 (dd, 1 H, J )

15.2, 1.1 Hz), 5.49-5.48 (d, 1 H, J ) 7.9 Hz), 5.12-5.09 (ddd,

1 H, J ) 11.2, 6.1, 1.7 Hz), 4.90-4.87 (dd, 1 H, J ) 10.3, 3.6

Hz), 4.8-4.76 (m, 1 H), 3.91 (s, 3 H), 3.46-3.42 (dd, 1 H, J )

13.6, 8.6 Hz), 3.17-3.11 (m, 3 H), 2.65-2.55 (m, 2 H), 2.5-2.4

(m, 1 H), 2.33 (s, 3 H), 2.31 (s, 3 H), 1.8-1.62 (m, 2 H), 1.43-

1.35 (m, 1 H), 1.26 (s, 3 H), 1.19 (s, 3 H), 1.17-1.16 (d, 3 H, J

) 6.8 Hz), 0.8-0.78 (d, 6 H, J ) 7.4 Hz); ¹³C NMR (62.5 MHz,

CDCl₃) δ 177.9, 170.5, 170.3, 165.0, 154.0, 142.2, 135.3, 131.8,

130.9, 130.8, 130.2, 129.5, 129.4, 128.2, 128.1, 125.8, 124.5,

122.4, 112.2, 71.4, 60.3, 56.0, 54.3, 46.4, 42.6, 42.3, 39.4, 36.5,

35.2, 24.5, 22.7, 22.6, 22.5, 21.1, 20.9, 19.2, 17.3, 14.1; IR

(CHCl₃) 3424, 2965, 2934, 2873, 2841, 1746, 1712, 1680, 1651,

1606, 1528, 1503, 1485, 1464, 1441, 1320, 1281, 1259, 1151

cm^-1; HRMS (FAB, m/z) calcd for C₃₈H₄₉ClN₂O₇(M⁺+ H)

697.3256, found 697.3249. Anal. Calcd for (C₃₈H₄₉ClN₂O₇): C,

67.0; H, 7.25; N, 4.11. Found: C, 66.96; H, 7.23; N, 3.95.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6S)-6-[(2R,3R)-3-(3,4-d im eth ylp h en yl)-

oxir a n yl]-5-h yd r oxy-2-h ep t en oyl-3-ch lor o-O-m et h yl-^D-

tyr osyl] (13). The â epoxide 13 (0.06 g) was prepared from

the styrene 12 (0.3 g, 0.44 mmol) and 3-chloroperoxybenzoic

acid (0.081 g, 0.47 mmol) in 20% yield according to the

procedure described for epoxide 30b: [R]²⁰+20.0 (c 1.43,

D

CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ 7.26-6.96 (m, 6 H),

6.84-6.82 (d, 1 H, J ) 8.5 Hz), 6.79-6.65 (m, 1 H), 5.73-5.68

(d, 1 H, J ) 14.9 Hz), 5.69-5.67 (d, 1 H, J ) 7.4 Hz), 5.29-

5.15 (m, 1 H), 4.83-4.76 (dd, 1 H, J ) 9.7, 2.8 Hz), 4.75-4.68

(m, 1 H), 3.86 (s, 3 H), 3.61-3.60 (d, 1 H, J ) 1.6 Hz), 3.46-

3.38 (dd, 1 H, J ) 13.4, 8.8 Hz), 3.14-2.97 (m, 3 H), 2.92-

2.89 (dd, 1 H, J ) 7.7, 1.6 Hz), 2.59-2.35 (m, 2 H), 2.25 (s, 6

H), 1.78-1.58 (m, 3 H), 1.21 (s, 4 H), 1.15 (s, 3 H), 1.15-1.12

(d, 3 H, J ) 7.8 Hz), 0.81-0.79 (d, 3 H, J ) 6.25 Hz), 0.8-0.78

(d, 3 H, J ) 6.29 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8,

170.4, 170.3, 164.9, 154.0, 141.7, 137.0, 136.9, 134.0, 130.8,

129.9, 129.5, 128.1, 126.7, 124.6, 123.2, 122.4, 122.3, 75.9,

71.04, 62.8, 59.1, 56.1, 54.3, 46.4, 42.7, 40.7, 39.2, 36.8, 35.2,

24.4, 22.8, 22.6, 21.0, 19.7, 19.4, 13.6; IR (KBr) 3419, 2962,

1752, 1721, 1681, 1654, 1534, 1504, 1473, 1442, 1302, 1282,

1259, 1192, 1126, 1066 cm^-1. Anal. Calcd for (C₃₈H₄₉ClN₂O₈):

C, 65.46; H, 7.08; N, 4.02. Found: C, 65.29; H, 6.98; N, 4.03.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6S)-6-[(2R,3R)-3-(2,5-d im eth ylp h en yl)-

oxir a n yl]-5-h yd r oxy-2-h ep t en oyl-3-ch lor o-O-m et h yl-^D-

tyr osyl] (16b). 3-Chloroperoxybenzoic acid (0.069 g, 0.4 mmol)

was added to the styrene 15 (0.26 g, 0.38 mmol) in CH₂Cl₂

(2.5 mL). The resulting solution was stirred overnight and

concentrated in vacuo to give the â and R epoxides in a 1.8:1

ratio, in favor of the â. Separation of the two epoxides by

reverse phase HPLC with (70:30) CH₃CN:H₂O, gave 0.140 g

of the major â epoxide and 0.08 g of the minor R epoxide (83%

P en ta n oic a cid , 3-ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

8-(3,4-d im eth ylp h en yl)-5,7-d ih yd r oxy-6-m eth yl-1-oxo-2-

octen yl]-O-m eth yl-^D-tyr osyl-2,2-d im eth yl-â-a la n yl-2-h y-

d r oxy-4-m eth yl-, (3 f 1⁵)-la cton e, (2S)- (14). To a solution

of styrene 12 (0.492 g, 0.72 mmol) in CH₂Cl₂(2.4 mL) at 0 °C

was added 3-chloroperoxybenzoic acid (0.137 g, 0.79 mmol) and

toluene (1.2 mL), and stirring was continued at 0 °C for 30

min. The ice-bath was removed, and the reaction mixture was

stirred at room temperature for 24 h. After diluting with CH₂-

Cl₂(10 mL), the solution was washed with 10% Na₂SO₃(1 ×

10 mL), H₂O (1 × 10 mL), and 10% NaHCO₃(1 × 10 mL) and

dried over Na₂SO₄. Concentration provided a mixture of the

â/R crude epoxides in a 2:1 ratio.

combined yield) as white solids. â epoxide 16b: [R]²⁰+30.6

D

(c 0.53, CHCl₃); ¹H NMR (500 MHz, CDCl₃) δ 7.25-7.22 (m, 2

H), 7.09-7.04 (m, 3 H), 6.95 (s, 1 H), 6.88-6.87 (d, 1 H, J )

8.4 Hz), 6.83-6.77 (m, 1 H), 5.76-5.73 (d, 1 H, J ) 15.1 Hz),

5.48-5.46 (d, 1 H, J ) 7.8 Hz), 5.26-5.24 (dd, 1 H, J ) 9.2,

2.8 Hz), 4.88-4.85 (dd, 1 H, J ) 9.9, 3.3 Hz), 4.8-4.76 (m, 1

H), 3.91 (s, 3 H), 3.89-3.88 (d, 1 H, J ) 1.23 Hz), 3.48-3.43

(dd, 1 H, J ) 13.5, 8.7 Hz), 3.14-3.11 (m, 3 H), 2.89-2.87 (dd,

1 H, J ) 7.0, 1.5 Hz), 2.63-2.5 (m, 2 H), 2.4 (s, 3 H), 2.3 (s, 3

H), 1.93-1.65 (m, 3 H), 1.42-1.32 (m, 1H), 1.26 (s, 3 H), 1.19

(s, 3 H), 1.18-1.16 (d, 3 H, J ) 6.9 Hz), 0.89-0.87 (d, 3 H, J

) 6.6 Hz), 0.87-0.85 (d, 3 H, J ) 6.5 Hz); ¹³C NMR (62.5 MHz,

CDCl₃) δ 177.8, 170.3, 164.9, 154.0, 141.7, 135.8, 134.5, 132.5,

130.8, 130.0, 129.6, 128.6, 128.1, 124.5, 122.4, 112.3, 75.7, 71.2,

62.5, 56.2, 56.1, 54.4, 46.4, 42.7, 40.1, 39.3, 36.6, 35.2, 24.5,

22.8, 22.7, 22.6, 21.2, 20.9, 18.4, 13.1; IR (CHCl₃) 3423, 2965,

2936, 2874, 2841, 1752, 1712, 1682, 1528, 1504, 1485, 1464,

The crude epoxides (0.445 g, 0.638 mmol) were dissolved in

dry CHCl₃(10 mL), cooled to -60 °C, and treated with

chlorotrimethylsilane (0.2 mL, 1.5 mmol). Stirring was con-

tinued for 90 min and the solution was concentrated in vacuo.

The crude chlorohydrins were purified by reverse-phase HPLC

(CH₃CN/H₂O) to give anti chlorohydrin 14 (0.115 g) in 21%

1

yield as a white solid: [R]²⁰-45.9 (c 0.59, CHCl₃); H NMR

D

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 2999

1303, 1259, 1189, 1151, 1067 cm^-1. Anal. Calcd for (C₃₈H₄₉

ClN₂O₈): C, 65.46; H, 7.08; N, 4.02. Found: C, 65.29; H, 6.98;

N, 4.06.

-

at -78 °C. The resulting mixture was warmed to room

temperature, stirred for an additional 2 h, and quenched with

saturated aq NH₄Cl (30 mL) and EtOAc (30 mL). The layers

were separated, and the aqueous one was extracted with

EtOAc (2 × 20 mL). The combined organic extracts were

washed with brine (30 mL), dried over MgSO₄, filtered, and

concentrated in vacuo. The crude styrene was purified by

column chromatography (silica gel, 50-65% EtOAc/hexanes)

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6R,7E)-5-h yd r oxy-8-(4-m et h oxyp h en -

yl)-6-m eth yl-2,7-octadien oyl-3-ch lor o-O-m eth yl-^D-tyr osyl]

(17). Styrene 17 (0.21 g) was prepared from aldehyde 2 (0.5

g, 0.87 mmol) and 4-methoxybenzyl triphenylphosphonium

chloride (3d ) (0.47 g, 1.12 mmol) in 36% yield according to the

procedure described above for styrene 29: [R]²⁰_D+31.6 (c 1.03,

to give styrene 19 (0.129 g) in 23% yield: [R]²⁰+29.7 (c 1.15,

D

1

CHCl₃); H NMR (300 MHz, CDCl₃) δ 8.03-8.0 (d, 2 H, J )

1

8.2 Hz), 7.44-7.41 (d, 2 H, J ) 8.3 Hz), 7.3-7.25 (m, 1 H),

7.24-7.23 (d, 1 H, J ) 1.6 Hz), 7.11-7.08 (dd, 1 H, J ) 8.3,

1.9 Hz), 6.89-6.86 (d, 1 H, J ) 8.5 Hz), 6.86-6.8 (m, 1 H),

6.52-6.46 (d, 1 H, J ) 15.9 Hz), 6.23-6.15 (dd, 1 H, J ) 15.8,

8.8 Hz), 5.83-5.8 (d, 1 H, J ) 15.3 Hz), 5.64-5.61 (d, 1 H, J

) 7.9 Hz), 5.14-5.09 (dd, 1 H, J ) 9.4, 6.5 Hz), 4.91-4.87 (dd,

1 H, J ) 10.2, 3.6 Hz), 4.85-4.75 (m, 1 H), 3.95 (s, 3 H), 3.91

(s, 3 H), 3.5-3.4 (dd, 1 H, J ) 13.5, 8.7 Hz), 3.2-3.1 (m, 3 H),

2.9-2.3 (m, 3 H), 1.8-1.6 (m, 2 H), 1.4-1.3 (m, 1 H), 1.26 (s,

3 H), 1.2 (s, 3 H), 1.2-1.18 (d, 3 H, J ) 6.9 Hz), 0.8-0.76 (t,

6 H, J ) 5.8 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 170.4,

166.7, 165.1, 153.9, 141.8, 141.1, 133.1, 130.8, 129.9, 129.7,

128.9, 128.2, 125.9, 124.6, 122.4, 112.2, 76.8, 71.3, 56.0, 54.4,

52.0, 46.4, 42.7, 42.2, 39.5, 36.5, 35.2, 24.5, 22.8, 22.6, 21.2,

17.1; IR (CHCl₃) 3424, 2964, 2936, 2874, 2841, 1748, 1716,

1681, 1608, 1528, 1503, 1485, 1437, 1283, 1259 cm^-1. Anal.

Calcd for (C₃₈H₄₇ClN₂O₉): C, 64.17; H, 6.66; N, 3.94. Found:

C, 63.95; H, 6.77; N, 3.66.

CHCl₃); H NMR (300 MHz, CDCl₃) δ 7.26-7.23 (d, 3 H, J )

8.4 Hz), 7.20-7.19 (d, 1 H, J ) 1.8 Hz), 7.07-7.03 (dd, 1 H, J

) 8.4, 1.9 Hz), 6.84-6.81 (d, 3 H, J ) 8.5 Hz), 6.80-6.7 (m, 1

H), 6.36-6.31 (d, 1 H, J ) 15.8 Hz), 5.89-5.81 (dd, 1 H, J )

15.8, 8.8 Hz), 5.78-5.73 (d, 1 H, J ) 13.7 Hz), 5.68-5.66 (d, 1

H, J ) 7.9 Hz), 5.05-4.99 (ddd, 1 H, J ) 10.6, 6.6, 1.6 Hz),

4.87-4.82 (dd, 1 H, J ) 9.7, 3.1 Hz), 4.78-4.7 (m, 1 H), 3.86

(s, 3 H), 3.79 (s, 3 H), 3.45-3.37 (dd, 1 H, J ) 13.4, 8.6 Hz),

3.15-3.0 (m, 3 H), 2.6-2.25 (m, 3 H), 1.7-1.3 (m, 3 H), 1.22

(s, 3 H), 1.15 (s, 3 H), 1.12-1.1 (d, 3 H, J ) 6.8 Hz), 0.76-0.73

(m, 6 H); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 170.5, 170.4,

165.1, 159.1, 153.9, 142.1, 135.8, 131.0, 130.8, 129.7, 129.5,

128.2, 127.9, 127.2, 124.5, 122.4, 113.9, 112.3, 77.1, 71.4, 56.0,

55.2, 54.4, 46.4, 42.7, 42.1, 39.4, 36.4, 35.3, 24.5, 22.8, 22.6,

21.2, 17.3; IR (CHCl₃) 3422, 3003, 2964, 2936, 2873, 2840,

1746, 1712, 1681, 1651, 1607, 1527, 1512, 1504, 1485, 1465,

1301, 1251 cm^-1. Anal. Calcd for (C₃₇H₄₇ClN₂O₈): C, 65.04;

H, 6.93; N, 4.1. Found: C, 64.98; H, 7.05; N, 3.98.

P en tan oic Acid, 3-Ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

5,7-d ih yd r oxy-8-[4-(m eth oxyca r bon yl)p h en yl]-6-m eth yl-

1-oxo-2-octen yl]-O-m eth yl-^D-tyr osyl-2,2-dim eth yl-â-alan yl-

2-h yd r oxy-4-m eth yl-, (3 f 1⁵)-La cton e, (2S)- (22). To

styrene 19 (0.42 g, 0.59 mmol) were added acetone (30 mL),

H₂O (15 mL), CH₂Cl₂(15 mL), and solid NaHCO₃(1.7 g, 20.2

mmol), and the mixture was cooled to 0 °C. A solution of Oxone

(1.4 g, 2.3 mmol) in H₂O (12 mL) was prepared and added (2

mL) to the cold styrene mixture. Following 30 min of vigorous

stirring at 0 °C, an additional 2 mL of Oxone solution was

added, and the solution was warmed to room temperature. An

additional 2 mL of Oxone solution was added every 30 min

until a total of 12 mL of oxone was consumed. The reaction

was stirred for a total of 5 h and was quenched with saturated

aq NaHCO₃(50 mL) and CH₂Cl₂(50 mL). The layers were

separated, and the organic layer was washed with aq 10% Na₂-

SO₃(50 mL), followed by saturated aq NaHCO₃(50 mL) then

brine, and finally was dried over Na₂SO₄, filtered, and

concentrated in vacuo. The crude mixture was purified by

reverse phase HPLC with (45:55) CH₃CN:H₂O to provide 0.14

g (33% yield) of the epoxides 21 and 0.14 g of the bisepoxides

20.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6S)-5-h yd r oxy-6-[(2R,3R)-3-(4-m eth oxy-

p h en yl)oxir a n yl]-2-h ep t en oyl-3-ch lor o-O-m et h yl-^D-t y-

r osyl] (18). To a 0 °C mixture of styrene 17 (0.3 g, 0.44 mmol)

in acetone (19 mL), H₂O (9 mL) and CH₂Cl₂(9 mL) were added

solid NaHCO₃(1.2 g, 14.5 mmol) and 2 mL of an Oxone

solution [(1.08 g, 1.8 mmol) in 9 mL of H₂O]. Following 30 min

of vigorous stirring at 0 °C, 2 mL of Oxone solution was added

and again another 2.0 mL following another 30 min, for a total

of 6 mL of Oxone solution. The reaction progress was moni-

tored by reverse phase HPLC and was completed after 2.5 h

of stirring. While still at 0 °C, the reaction was quenched with

saturated aq NaHCO₃(50 mL) and CH₂Cl₂(50 mL). The layers

were separated, and the organic layer was washed with aq

10% Na₂SO₃(50 mL), followed by saturated aq NaHCO₃(50

mL) then brine, and finally was dried over Na₂SO₄, filtered

and concentrated in vacuo. The mixture of â and R epoxides

was separated by reverse phase HPLC with (45:55) CH₃CN:

H₂O to provide 0.12 g of the â epoxide 18 as a white solid in

1

39% yield: [R]²⁰+25.8 (c 0.66, CHCl₃); H NMR (300 MHz,

D

CDCl₃) δ 7.26-7.15 (m, 4 H), 7.05-7.03 (d, 1 H, J ) 8.6 Hz),

6.9-6.87 (d, 2 H, J ) 8.6 Hz), 6.85-6.82 (d, 1 H, J ) 8.5 Hz),

6.82-6.7 (m, 1 H), 5.74-5.69 (d, 1 H, J ) 15.1 Hz), 5.54-5.52

(d, 1 H, J ) 7.8 Hz), 5.22-5.16 (m, 1 H), 4.84-4.7 (m, 2 H),

3.87 (s, 3 H), 3.81 (s, 3 H), 3.63 (s, 1 H), 3.46-3.38 (dd, 1 H, J

) 13.5, 8.8 Hz), 3.2-3.0 (m, 3 H), 2.91-2.89 (d, 1 H, J ) 7.4

Hz), 2.6-2.38 (m, 2 H), 1.8-1.6 (m, 3 H), 1.4-1.23 (m, 1 H),

1.22 (s, 3 H), 1.15 (s, 3 H), 1.15-1.12 (d, 3 H, J ) 8.9 Hz),

0.84-0.80 (t, 6 H, J ) 6.0 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ

177.7, 170.5, 170.4, 165.1, 159.8, 153.9, 141.6, 136.8, 130.7,

129.7, 128.6, 128.1, 126.9, 124.6, 122.3, 114.1, 112.2, 75.9, 71.0,

62.8, 58.9, 56.0, 55.2, 54.6, 46.3, 42.7, 40.6, 39.2, 36.8, 35.2,

24.4, 22.8, 22.7, 22.6, 21.1, 13.5; IR (CHCl₃) 3423, 3009, 2964,

2936, 2874, 2840, 1751, 1713, 1681, 1653, 1614, 1517, 1504,

The mixture of â/R epoxides 21 (0.14 g, 0.19 mmol) was

dissolved in CHCl₃(3.0 mL) and cooled to -60 °C. Chlorotri-

methylsilane (0.1 mL, 0.77 mmol) was added to the -60 °C

solution, and the mixture was stirred for 1.5 h. More TMSCl

(0.1 mL, 0.77 mmol) was added, and the solution was allowed

to warm to room temperature. Following 1 h of stirring at room

temperature, the solution was concentrated and purified by

radial PLC (1-2% MeOH/CH₂Cl₂) to give 0.044 g (30% yield)

of the desired chlorohydrin 22 as a white solid: [R]²⁰+50.0

D

1

(c 0.75, CHCl₃); H NMR (300 MHz, CDCl₃) δ 8.1-8.08 (d, 2

H, J ) 8.1 Hz), 7.54-7.51 (d, 2 H, J ) 8.2 Hz), 7.3-7.25 (m,

1 H), 7.25 (s, 1 H), 7.13-7.09 (dd, 1 H, J ) 8.5, 1.5 Hz), 6.91-

6.88 (d, 1 H, J ) 8.3 Hz), 6.87-6.78 (m, 1 H), 5.86-5.8 (d, 1

H, J ) 15.5 Hz), 5.7-5.6 (m, 1 H), 5.24-5.18 (t, 1 H, J ) 9.2

Hz), 4.99-4.95 (dd, 1 H, J ) 10.0, 3.6 Hz), 4.8-4.7 (m, 1 H),

4.76-4.73 (d, 1 H, J ) 9.5 Hz), 4.09-4.06 (d, 1 H, J ) 9.6 Hz),

3.97 (s, 3 H), 3.93 (s, 3 H), 3.45-3.38 (dd, 1 H, J ) 13.6, 8.6

Hz), 3.25-3.0 (m, 3 H), 2.75-2.62 (m, 1 H), 2.6-2.4 (m, 2 H),

1.9-1.6 (m, 3 H), 1.5-1.4 (m, 1 H), 1.27 (s, 3 H), 1.22 (s, 3 H),

1.1-1.07 (d, 3 H, J ) 6.95 Hz), 0.98-0.95 (t, 6 H, J ) 5.3 Hz);

¹³C NMR (62.5 MHz, CDCl₃) δ 177.5, 170.6, 170.3, 166.3, 165.4,

153.9, 143.8, 142.2, 138.7, 130.7, 130.4, 129.9, 128.1, 128.0,

124.6, 122.3, 112.2, 76.1, 73.8, 71.1, 61.4, 56.0, 54.6, 52.2, 46.4,

42.7, 39.6, 38.4, 36.3, 35.1, 24.8, 23.0, 22.9, 22.7, 21.5, 8.7; IR

1486, 1464, 1442, 1303, 1281, 1257, 1183, 1173, 1152 cm^-1

.

Anal. Calcd for (C₃₇H₄₇ClN₂O₉): C, 63.56; H, 6.78; N, 4.01.

Found: C, 63.28; H, 6.72; N, 3.99.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6R,7E)-5-h yd r oxy-8-[4-(m eth oxyca r bo-

n yl)p h en yl]-6-m eth yl-2,7-octa d ien oyl-3-ch lor o-O-m eth yl-

D-tyr osyl] (19). A suspension of sodium hydride (60% dispersion

in mineral oil) (0.041 g, 1.0 mmol) and 4-carbomethoxyben-

zyltriphenylphosphonium bromide (3e) (0.5 g, 1.0 mmol) in

THF (10 mL) was heated at 65 °C for 1 h and cooled back to

room temperature. This orange mixture was added dropwise

to a solution of aldehyde 2 (0.46 g, 0.79 mmol) in THF (10 mL)

3000 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

(CHCl₃) 3425, 2962, 2935, 2873, 2842, 1750, 1720, 1680, 1528,

h. Upon cooling to room temperature, the reaction mixture was

diluted with EtOAc (50 mL) and washed with 0.1 N HCl (1 ×

10 mL), water (1 × 10 mL), saturated aq NaHCO₃(1 × 10

mL), and brine (1 × 10 mL). The organic layer was dried over

MgSO₄, filtered, and concentrated in vacuo to provide the crude

ester as a yellow foam. Purification by radial PLC (silica gel,

1504, 1484, 1438, 1284, 1259, 1194, 1152, 1114, 1067 cm^-1

.

Anal. Calcd for (C₃₈H₄₈Cl₂N₂O₁₀): C, 59.76; H, 6.34; N, 3.67.

Found: C, 59.53; H, 6.61; N, 3.51.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p e n t a n oyl-(2E ,5S ,6R ,7E )-8-[4-[[(1,1-d im e t h yle t h yl)d i-

m eth ylsilyl]oxy]p h en yl]-5-h yd r oxy-6-m eth yl-2,7-octa d i-

en oyl-3-ch lor o-O-m eth yl-^D-tyr osyl] (23). Styrene 23 (0.649

g) was prepared from aldehyde 2 (0.911 g, 1.57 mmol) and

4-(tert-butyldimethylsiloxy)benzyltriphenylphosphonium chlo-

ride (3f) (1.7 g, 3.27 mmol) in 53% yield according to the

procedure described above for styrene 29: [R]²⁰_D+ 30.8 (c 0.52,

CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ 7.3-7.27 (m, 2 H), 7.26-

7.22 (d, 2 H, J ) 8.5 Hz), 7.12-7.06 (dd, 1 H, J ) 8.3, 1.6 Hz),

6.92-6.86 (d, 1 H, J ) 8.5 Hz), 6.85-6.76 (m, 3 H), 6.44-6.33

(d, 1 H, J ) 15.9 Hz), 5.95-5.85 (dd, 1 H, J ) 15.8, 8.8 Hz),

5.85-5.77 (d, 1 H, J ) 15.5 Hz), 5.68-5.55 (d, 1 H, J ) 7.9

Hz), 5.15-5.0 (m, 1 H), 4.95-4.80 (dd, 1 H, J ) 10.0, 3.0 Hz),

4.85-4.75 (m, 1 H), 3.91 (s, 3 H), 3.53-3.43 (dd, 1 H, J ) 13.4,

8.6 Hz), 3.23-3.08 (m, 3 H), 2.65-2.3 (m, 3 H), 1.78-1.6 (m,

2 H), 1.45-1.36 (m, 1 H), 1.27 (s, 3 H), 1.2 (s, 3 H), 1.16-1.13

(d, 3 H, J ) 6.8 Hz), 1.01 (s, 9 H), 0.85-0.74 (m, 6 H), 0.22 (s,

6 H); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 170.5, 170.4, 165.1,

155.2, 153.9, 142.1, 131.1, 130.8, 130.1, 129.7, 128.2, 128.1,

127.1, 124.5, 122.4, 120.2, 112.2, 77.1, 71.4, 56.0, 54.4, 46.4,

42.7, 42.2, 39.4, 36.5, 35.3, 25.6, 24.5, 22.8, 22.7, 21.2, 18.1,

17.3, -4.5; IR (CHCl₃) 3422, 3030, 3008, 2961, 2932, 2899,

2860, 1745, 1712, 1681, 1604, 1527, 1509, 1485, 1442, 1370,

1339, 1303, 1258, 1169, 1151, 1067, 1007, 970, 912, 841, 822,

50% EtOAc/hexanes) provided the pure ester 26 (0.097 g) in

1

75% yield as a yellow solid: [R]²⁰+17.2 (c 0.58, CHCl₃); H

D

NMR (300 MHz, CDCl₃) δ 7.40-7.34 (d, 2 H, J ) 8.5 Hz), 7.29-

7.22 (m, 2 H), 7.13-7.0 (m, 3 H), 6.92-6.86 (d, 1 H, J ) 8.8

Hz), 6.86-6.76 (m, 1 H), 6.50-6.38 (d, 1 H, J ) 15.9 Hz), 6.10-

5.97 (dd, 1 H, J ) 15.8, 8.8 Hz), 5.85-5.75 (d, 1 H, J ) 15.1

Hz), 5.55-5.45 (d, 1 H, J ) 7.9 Hz), 5.15-5.0 (m, 2 H), 4.95-

4.72 (m, 2 H), 3.92 (s, 3 H), 3.53-3.35 (m, 3 H), 3.22-3.06 (m,

3 H), 2.65-2.50 (m, 2 H), 2.48-2.35 (m, 1 H), 1.8-1.65 (m, 2

H), 1.49 (s, 10 H), 1.40 (s, 6 H), 1.27 (s, 3 H), 1.21 (s, 3 H),

1.20-1.15 (d, 3 H, J ) 6.9 Hz), 0.86-0.77 (d, 6 H, J ) 6.3 Hz);

¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 170.5, 170.4 165.1, 156.0,

153.9, 150.0, 142.0, 134.5, 130.8, 130.6, 130.4, 129.6, 128.2,

126.9, 124.6, 122.4, 121.5, 112.2, 79.2, 71.3, 56.0, 54.4, 48.2,

46.4, 44.0, 42.7, 42.1, 39.5, 36.5, 35.2, 28.3, 24.9, 24.5, 22.9,

22.8, 22.7, 21.3, 17.2; IR (CHCl₃) 3425, 2970, 2934, 2874, 1746,

1711, 1684, 1604, 1505, 1442, 1394, 1368, 1305, 1258, 1166,

1123, 1067, 1015, 971 cm^-1; HRMS (FAB, m/z) calcd for C₄₁H₅₅

-

ClN₃O₉(M⁺-Boc) 768.3627, found 768.3620. Anal. Calcd for

(C₄₆H₆₂ClN₃O₁₁): C, 63.62; H, 7.2; N, 4.84. Found: C, 63.32;

H, 6.94; N, 4.54.

P en tan oic Acid, 3-Ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

8-[4-[3-[[(1,1-d im e t h yle t h oxy)ca r b on yl]a m in o]-2,2-d i-

m eth yl-1-oxop r op oxy]p h en yl]-5,7-d ih yd r oxy-6-m eth yl-1-

oxo-2-octen yl]-O-m eth yl-^D-tyr osyl-2,2-d im eth yl-â-a la n yl-

2-h yd r oxy-4-m eth yl-, (3â1⁵)-La cton e, (2S)- (27). Styrene 26

(0.276 g, 0.32 mmol) was epoxidized similarly to styrene 17

with a total of 6 mL of a solution of Oxone (0.78 g, 1.27 mmol)

in H₂O to give 0.272 g of the crude epoxides as a yellow foam.

To a solution of the epoxide mixture in 4 mL of CH₂Cl₂at -60

°C was added chlorotrimethylsilane (0.2 mL, 1.54 mmol). After

3 h at -60 °C, 5 mL of 0.1 N HCl was added, and the mixture

was warmed to room temperature. The layers were separated,

and the organic layer was dried over MgSO₄, filtered, and

concentrated in vacuo. The crude chlorohydrins were purified

twice by radial PLC (silica gel, 50-100% EtOAc/hexanes) and

finally by reverse-phase HPLC (CH₃CN/H₂O) to give the

product 27 (0.090 g, 31%) as a white solid: [R]²⁰_D+42.7 (c 3.0,

792 cm^-1; HRMS (FAB, m/z) calcd for C₄₂H₅₉ClN₂O₈Si (M⁺

+

H) 783.3807, found 783.3798. Anal. Calcd for (C₄₂H₅₉ClN₂O₈-

Si): C, 64.39; H, 7.59; N, 3.58. Found: C, 64.69; H, 7.25; N,

3.28.

P en ta n oic Acid , 3-Ch lor o-N-[(2E,5S,6R,7E)-5-h yd r oxy-

8-(4-h yd r oxyp h en yl)-6-m et h yl-1-oxo-2,7-oct a d ien yl]-O-

m eth yl-^D-tyr osyl-2,2-dim eth yl-â-alan yl-2-h ydr oxy-4-m eth -

yl-, (3 f 1⁵)-La cton e, (2S)- (24). To a -78 °C solution of the

silyl protected phenol 23 (0.084 g, 0.107 mmol) in dry THF (4

mL) was added a 1.0 M THF solution of tetrabutylammonium

fluoride (TBAF) (0.11 mL, 0.11 mmol). The light yellow

solution was stirred at -78 °C for 30 min, then quenched with

saturated aq NH₄Cl (20 mL) and extracted with CH₂Cl₂(3 ×

25 mL). The combined organic layers were dried over MgSO₄,

filtered, and concentrated in vacuo. Purification of the crude

product by radial PLC (silica gel, 50-100% EtOAc/hexanes)

gave the desired alcohol 24 (0.067 g) in 93% yield as a white

solid: [R]²⁰_D+27.5 (c 0.47, CHCl₃); ¹H NMR (300 MHz, CDCl₃)

δ 7.40-7.2 (m, 4 H), 7.13-7.05 (dd, 1 H, J ) 8.3, 1.6 Hz), 6.95-

6.75 (m, 4 H), 6.57 (s, 1 H), 6.42-6.33 (d, 1 H, J ) 15.9 Hz),

5.93-5.83 (dd, 1 H, J ) 15.8, 8.8 Hz), 5.83-5.78 (d, 1 H, J )

15.5 Hz), 5.75-5.73(d, 1 H, J ) 7.9 Hz), 5.15-5.0 (m, 1 H),

4.93-4.85 (dd, 1 H, J ) 10.0, 3.0 Hz), 4.85-4.75 (m, 1 H), 3.90

(s, 3 H), 3.54-3.4 (dd, 1 H, J ) 13.4, 8.6 Hz), 3.25-3.02 (m, 3

H), 2.65-2.35 (m, 3 H), 1.80-1.60 (m, 2 H), 1.45-1.36 (m, 1

H), 1.27 (s, 3 H), 1.20 (s, 3 H), 1.17-1.12 (d, 3 H, J ) 6.8 Hz),

0.86-0.74 (d, 6 H, J ) 5.0 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ

177.9, 170.7, 170.6, 165.4, 156.0, 154.0, 142.6, 137.1, 131.3,

130.8, 129.5, 128.9, 128.1, 127.4, 124.3, 122.5, 115.6, 112.3,

77.2, 71.5, 56.1, 54.5, 46.5, 42.7, 42.1, 39.4, 36.5, 35.3, 24.6,

22.8, 22.7, 21.2, 17.3; IR (CHCl₃) 3597, 3421,3319. 2964, 2935,

2874, 2841, 1746, 1711, 1680, 1652, 1610, 1513, 1504, 1485,

1464, 1259, 1170, 1152, 1067 cm^-1; HRMS (FAB, m/z) calcd

for C₃₆H₄₅ClN₂O₈(M⁺+ H) 669.2943, found 669.2953. Anal.

Calcd for (C₃₆H₄₅ClN₂O₈): C, 64.61; H, 6.78; N, 4.19. Found:

C, 64.36; H, 6.51; N, 3.88.

1

CHCl₃); H NMR (300 MHz, CDCl₃) δ 7.48-7.44 (d, 1 H, J )

8.4 Hz), 7.31-7.26 (m, 3 H), 7.16-7.10 (m, 3 H), 6.92-6.89

(d, 1 H, J ) 8.4 Hz), 6.87-6.81 (m, 1 H), 5.84-5.79 (d, 1 H, J

) 15.1 Hz), 5.58-5.55 (d, 1 H, J ) 7.8 Hz), 5.24-5.19 (t, 1 H,

J ) 8.9 Hz), 5.05-4.95 (m, 2 H), 4.79-4.75 (m, 1 H), 4.72-

4.69 (d, 1 H, J ) 9.5 Hz), 4.04-4.01 (dd, 1 H, J ) 9.3, 1.3 Hz),

3.93 (s, 3 H), 3.47-3.40 (m, 3 H), 3.25-3.06 (m, 3 H), 2.75-

2.7 (m, 1 H), 2.55-2.41 (m, 2 H), 1.90-1.6 (m, 4 H), 1.48 (s, 9

H), 1.39 (s, 6 H), 1.28 (s, 3 H), 1.22 (s, 3 H), 1.09-1.06 (d, 3 H,

J ) 6.9 Hz), 1.0-0.96 (t, 6 H, J ) 5.9 Hz); ¹³C NMR (62.5 MHz,

CDCl₃) δ 177.6, 170.4, 170.2, 165.2, 153.9, 142.3, 136.1, 130.8,

129.7, 129.1, 128.2, 124.5, 122.4, 121.9, 112.2, 76.1, 74.0, 71.1,

61.5, 56.5, 54.4, 46.4, 44.1, 42.7, 39.6, 38.4, 36.3, 35.2, 28.3,

24.8, 22.9, 22.8, 22.7, 21.5, 8.6; IR (CHCl₃) 3417, 2974, 2934,

1755, 1720, 1677, 1505, 1473, 1368, 1320, 1258, 1205, 1167,

1153, 1123, 1066 cm^-1; HRMS (FAB, m/z) calcd for C₄₆H₆₃

-

Cl₂N₃O₁₂(M⁺-Boc) 820.3343, found 820.3354.

P en ta n oic Acid , N-[(2E,5S,6S,7R,8S)-8-[4-(3-Am in o-2,2-

dim eth yl-1-oxopr opoxy)ph e- n yl]-8-ch lor o-5,7-dih ydr oxy-

6-m et h yl-1-oxo-2-oct en yl]-3-ch lor o-O-m et h yl-^D-t yr osyl

-2,2-d im et h yl-â-a la n yl-2-h yd r oxy-4-m et h yl-, (3 f 1⁵)-

La cton e, Mon oh yd r och lor id e, (2S)- (28). To the BOC-

protected amine 27 (0.070 g, 0.067 mmol) in CH₂Cl₂(0.25 mL)

was added a 4 M HCl solution (0.1 mL, 0.4 mmol) in

1,4-dioxane. Following 2 h of stirring at room temperature,

the solvents were removed under vacuum, and the resulting

residue was maintained under high vacuum for 2 days to give

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6R,7E)-8-[4-[3-[[(1,1-d im et h ylet h oxy)-

ca r bon yl]a m in o]-2,2-d im eth yl-1-oxop r op oxy]p h en yl]-5-

h yd r oxy-6-m eth yl-2,7-octa d ien oyl-3-ch lor o-O-m eth yl-^D-

tyr osyl] (26). A solution of the acid 25 (0.040 g, 0.184 mmol)

and carbonyldiimidazole (CDI) (0.040 g, 0.25 mmol) in toluene

(2 mL) was heated under nitrogen at 45 °C for 45 min.

Following the addition of phenol 24 (0.10 g, 0.15 mmol) in

toluene (1 mL), the reaction was again heated at 45 °C for 4

the product 28 as a white solid (0.062 g) in 95% yield: [R]²⁰

D

+27.7 (c 2.52, MeOH); ¹H NMR (300 MHz, CDCl₃) δ 7.79-

7.76 (d, 1 H, J ) 7.9 Hz), 7.48-7.38 (m, 2 H), 7.27-7.26 (d, 1

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 3001

H, J ) 1.2 Hz), 7.17-7.08 (m, 4 H), 6.98-6.95 (d, 1 H, J ) 8.5

Hz), 6.71-6.60 (m, 1 H), 5.95-5.90 (d, 1 H, J ) 15.2 Hz), 5.14-

5.01 (m, 2 H), 4.85-4.8 (m, 1 H), 4.50-4.46 (dd, 1 H, J ) 11.0,

3.0 Hz), 3.99-3.96 (d, 1 H, J ) 9.1 Hz), 3.82 (s, 3 H), 3.49-

3.42 (m, 1 H), 3.19 (s, 2 H), 3.19-3.06 (m, 2 H), 2.77-2.68 (m,

2 H), 2.49-2.46 (t, 1 H, J ) 6.8 Hz), 2.44-2.31 (m, 1 H), 1.85-

1.5 (m, 4 H), 1.46 (s, 6 H), 1.20 (s, 3 H), 1.16 (s, 3 H), 1.08-

0.94 (m, 9 H); ¹³C NMR (62.5 MHz, CDCl₃) δ 178.9, 175.6,

173.8, 171.9, 168.3, 155.3, 151.8, 144.2, 139.5, 132.2, 131.5,

130.7, 129.4, 125.2, 123.3, 122.6, 113.5, 77.2, 74.8, 72.6, 63.2,

57.6, 56.7, 47.5, 44.1, 42.7, 41.1, 40.4, 37.8, 36.5, 28.8, 26.2,

23.6, 23.4, 22.2, 9.0; IR (KBr) 3418, 2961, 2934, 1751, 1724,

1671, 1608, 1505, 1474, 1464, 1442, 1303, 1282, 1259, 1203,

1169, 1152, 1126, 1065, 1018; HRMS (FAB, m/z) calcd for

C₄₁H₅₆Cl₃N₃O₁₀(M⁺-Cl) 820.3343, found 820.3354.

Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 170.4, 165.1, 153.9,

141.9, 136.7, 135.1, 131.1, 130.8, 129.7, 128.3, 128.2, 126.2,

124.6, 122.4, 112.2, 76.9, 71.3, 66.0, 56.0, 54.4, 48.2, 46.4, 43.7,

42.6, 42.2, 39.4, 36.4, 35.2, 28.3, 24.5, 22.8, 22.7, 22.6, 21.2,

17.2; IR (CHCl₃) 3426, 2968, 2935, 2874, 2841, 1746, 1713,

1684, 1652, 1504, 1486, 1474, 1368, 1318, 1304, 1259, 1244,

1165, 1151, 1067 cm^-1; HRMS (FAB, m/z) calcd for C₄₂H₆₄

-

ClN₃O₁₁(M⁺+ H - Boc) 782.3783, found 782.3788.

P en tan oic Acid, 3-Ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

8-[4-[[3-[[(1,1-d im et h ylet h oxy)ca r b on yl]a m in o]-2,2-d i-

m et h yl-1-oxop r op oxy]m et h yl]p h en yl]-5,7-d ih yd r oxy-6-

m eth yl-1-oxo-2-octen yl]-O-m eth yl-^D-tyr osyl-2,2-dim eth yl-

â-a la n yl-2-h yd r oxy-4-m eth yl-, (3 f 1⁵)-La cton e, (2S)- (37).

3-Chloroperoxybenzoic acid (0.092 g, 0.54 mmol) was added

to a 0 °C solution of alkene 36 (0.45 g, 0.51 mmol) in CH₂Cl₂

(9 mL). The solution was stirred at 0 °C for 1 h and at room-

temperature overnight. It was concentrated in vacuo, and the

resulting epoxides were dissolved in CHCl₃(10 mL) and cooled

to -60 °C.

P en ta n oic Acid , 3-Ch lor o-N-[(2E,5S,6R,7E)-5-h yd r oxy-

8-[4-(h yd r oxym eth yl)p h en yl]-6-m eth yl-1-oxo-2,7-octa d i-

en yl]-O-m eth yl-^D-tyr osyl-2,2-dim eth yl-â-alan yl-2-h ydr oxy-

4-m eth yl-, (3 f 1⁵)-Lacton e, (2S)- (35). Tetrabutylammonium

fluoride (TBAF) (4.0 mL, 4.1 mmol), as a 1.0 M solution in

THF, was added dropwise to a -78 °C solution of the silyl ether

29 (3.1 g, 3.69 mmol) in THF (120 mL). The solution was

stirred at -78 °C for 10 min, and the dry ice bath was removed,

allowing it to warm to room temperature. Following 30 min

at room temperature, the reaction was quenched with water

(80 mL) and ethyl acetate (100 mL). The layers were separated,

and the aqueous one was extracted with CH₂Cl₂(3 × 50 mL).

The combined organic layers were dried over anhydrous Na₂-

SO₄, filtered, and concentrated in vacuo to yield the free

alcohol. Purification by column chromatography (silica gel, 50-

100% EtOAc/hexanes) yielded 2.51 g (99%) of the pure alcohol

Chlorotrimethylsilane (0.25 mL, 1.95 mmol) was added to

the -60 °C solution, and the mixture was stirred for 1 h. More

TMSCl (0.5 mL, 3.9 mmol) was added and the stirring

continued between -60 °C to -40 °C for an additional 2 h.

The solution was warmed to room temperature, and additional

TMSCl (0.25 mL, 1.95 mmol) was added. Following 30 min of

stirring at room temperature the solution was concentrated

in vacuo and purified by preparative HPLC with (45:55) CH₃-

CN:H₂O to give 0.1 g (22%) of the desired chlorohydrin 37:

[R]²⁰_D+47.9 (c 0.75, CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ 7.5-

7.2 (m, 6 H), 7.13-7.10 (dd, 1 H, J ) 8.4, 1.9 Hz), 6.91-6.88

(d, 1 H, J ) 8.5 Hz), 6.87-6.75 (m, 1 H), 5.85-5.8 (d, 1 H, J

) 14.9 Hz), 5.75-5.6 (m, 1 H), 5.22-5.1 (m, 3 H), 5.0-4.9 (m,

2 H), 4.8-4.72 (m, 1 H), 4.71-4.68 (d, 1 H, J ) 9.6 Hz), 4.07-

4.03 (d, 1 H, J ) 9.5 Hz), 3.9 (s, 3 H), 3.45-3.38 (dd, 1 H, J )

13.4, 8.5 Hz), 3.31-3.26 (d, 2 H, J ) 6.4 Hz), 3.25-3.0 (m, 3

H), 2.8-2.65 (bd, 1 H), 2.6-2.35 (m, 2 H), 1.9-1.7 (m, 3 H),

1.47 (s, 10 H), 1.27-1.22 (m, 12 H), 1.09-1.07 (d, 3 H, J ) 7.0

Hz), 0.98-0.96 (m, 6 H); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.5,

170.5, 165.2, 153.9, 142.5, 137.0, 130.8, 129.8, 128.2, 124.5,

122.4, 112.2, 79.1, 76.1, 73.9, 71.1, 65.6, 61.7, 56.1, 54.5, 48.2,

46.4, 43.7, 42.7, 39.6, 38.4, 36.3, 35.2, 28.3, 24.8, 23.0, 22.9,

22.8, 22.7, 21.5, 8.6; IR (CHCl₃) 3426, 2967, 2934, 2873, 2841,

1715, 1684, 1605, 1504, 1485, 1474, 1442, 1368, 1305, 1258,

35 as a white solid: [R]²⁰+30.0 (c 1.0, CHCl₃); ¹H NMR (300

D

MHz, CDCl₃) δ 7.31 (s, 4 H), 7.26-7.21 (m, 1 H), 7.2-7.19 (d,

1 H, J ) 1.8 Hz), 7.07-7.03 (dd, 1 H, J ) 8.4, 1.7 Hz), 6.85-

6.82 (d, 1 H, J ) 8.4 Hz), 6.82-6.7 (m, 1 H), 6.43-6.37 (d, 1

H, J ) 15.9 Hz), 6.05-5.97 (dd, 1 H, J ) 15.9, 8.7 Hz), 5.77-

5.72 (d, 1 H, J ) 15.0 Hz), 5.58-5.55 (d, 1 H, J ) 7.9 Hz),

5.08-5.02 (dd, 1 H, J ) 9.4, 6.3 Hz), 4.87-4.83 (dd, 1 H, J )

10.2, 3.1 Hz), 4.8-4.67 (m, 1 H), 4.67 (s, 2 H), 3.87 (s, 3 H),

3.44-3.37 (dd, 1 H, J ) 13.5, 8.5 Hz), 3.2-3.0 (m, 3H), 2.6-

2.3 (m, 3 H), 1.8-1.6 (m, 3 H), 1.4-1.25 (m, 1 H), 1.22 (s, 3

H), 1.15 (s, 3 H), 1.14-1.12 (d, 3 H, J ) 6.8 Hz), 0.76-0.73 (t,

6 H, J ) 5.5 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.7, 170.7,

170.5, 165.4, 153.8, 142.0, 140.5, 135.9, 131.3, 130.7, 130.0,

129.9, 128.1, 127.1, 126.1, 124.5, 122.2, 112.2, 77.0, 71.3, 64.6,

56.0, 54.6, 46.4, 42.7, 42.1, 39.4, 36.4, 35.2, 24.5, 22.8, 22.6,

21.2, 17.2; IR (CHCl₃) 3423, 3011, 2965, 2935, 2874, 2841,

1747, 1712, 1681, 1652, 1528, 1503, 1485, 1442, 1371, 1303,

1259, 1151 cm^-1. Anal. Calcd for (C₃₇H₄₇ClN₂O₈): C, 65.04;

H, 6.93; N, 4.1. Found: C, 65.25; H, 6.66; N, 3.87.

1151 cm^-1; HRMS (FAB, m/z) calcd for C₄₇H₆₅Cl₂N₃O₁₂(M⁺

+

-

H - Boc) 834.3499, found 834.3487. Anal. Calcd for (C₄₇H₆₅

Cl₂N₃O₁₂‚0.2H₂O): C, 60.38; H, 7.01; N, 4.49. Found: C, 60.15;

H, 7.02; N, 4.48.

P en ta n oic Acid , N-[(2E,5S,6S,7R,8S)-8-[4-[(3-Am in o-

2,2-d im eth yl-1-oxop r op oxy)m eth yl]p h en yl]-8-ch lor o-5,7-

d ih yd r oxy-6-m eth yl-1-oxo-2-octen yl]-3-ch lor o-O-m eth yl-

D-tyr osyl-2,2-d im eth yl-â-a la n yl-2-h yd r oxy-4-m eth yl-, (3

f 1⁵)-La cton e, Mon oh yd r och lor id e, (2S)- (38). A 4 M

solution of hydrogen chloride in 1,4-dioxane (0.11 mL, 0.43

mmol) was added to a solution of chlorohydrin 37 (0.08 g, 0.086

mmol) in CH₂Cl₂(0.35 mL). The resulting mixture was stirred

at room temperature for 3 h, concentrated in vacuo, and

maintained under vacuum for 3 days to remove the 1,4-

dioxane, thus giving the desired hydrochloride salt 38 (0.075

g) in quantitative yield: [R]²⁰_D+28.0 (c 0.5, CH₃OH); ¹H NMR

(300 MHz, CD₃OH) δ 8.52-8.49 (d, 1 H, J ) 7.5 Hz), 7.84-

7.81 (d, 2 H, J ) 9.6 Hz), 7.49-7.39 (q, 5 H, J _AB) 8.3 Hz),

7.32-7.31 (d, 1 H, J ) 1.9 Hz), 7.22-7.19 (dd, 1 H, J ) 8.4,

2.1 Hz), 7.02-7.0 (d, 1 H, J ) 8.4 Hz), 6.8-6.7 (m, 1 H), 6.0-

5.9 (dd, 1 H, J ) 15.4, 1.0 Hz), 5.22 (s, 2 H), 5.2-5.0 (m, 2 H),

4.85-4.81 (d, 1 H, J ) 9.6 Hz), 4.6-4.5 (m, 1 H), 4.06-4.03

(dd, 1 H, J ) 9.6, 1.5 Hz), 3.9 (s, 3 H), 3.54-3.46 (dd, 1 H, J

) 13.5, 9.7 Hz), 3.25-3.11 (m, 2 H), 3.11 (s, 2 H), 2.8-2.7 (m,

2 H), 2.6-2.3 (m, 2 H), 1.9-1.5 (m, 3 H), 1.3 (s, 6 H), 1.25 (s,

3 H), 1.2 (s, 3 H), 1.06-0.99 (m, 9 H); ¹³C NMR (62.5 MHz,

CD₃OH) δ 178.9, 176.5, 173.8, 171.8, 168.3, 155.3, 144.2, 141.6,

137.4, 132.3, 131.5, 129.8, 129.4, 129.3, 125.2, 123.3, 113.5,

77.2, 74.7, 72.6, 67.8, 63.5, 57.6, 56.7, 47.7, 47.6, 44.1, 42.3,

41.1, 40.4, 37.9, 36.5, 26.2, 23.7, 23.4, 22.2, 9.0; IR (CHCl₃)

3421, 2964, 2935, 2873, 2841, 1717, 1676, 1528, 1504, 1477,

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6R,7E)-8-[4-[[3-[[(1,1-d im eth yleth oxy)-

carbonyl]amino]-2,2-dimethyl-1-oxopropoxy]methyl]phen-

yl]-5-h ydr oxy-6-m eth yl-2,7-octadien oyl-3-ch lor o-O-m eth yl-

D-tyr osyl] (36). A mixture of acid 25 (0.22 g, 1.02 mmol),

DMAP (0.032 g, 0.26 mmol), and DCC (0.21 g, 1.02 mmol) in

CH₂Cl₂(6.5 mL) was stirred at 0 °C for 30 min. Alcohol 35

(0.35 g, 0.51 mmol) in CH₂Cl₂(6 mL) was added dropwise via

a double-tipped needle. The mixture was stirred at 0 °C for

10 min and at room temperature for 24 h and finally was

heated at reflux for 3 h and cooled back to room temperature.

The reaction mixture was concentrated in vacuo and filtered

through Celite with EtOAc. The resulting residue was purified

by column chromatography (silica gel, 60-70% EtOAc/hex-

anes) to give 0.38 g (85%) of ester 36 as a white solid: [R]²⁰

D

+23.2 (c 1.0, CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ 7.4-7.2

(m, 6 H), 7.12-7.08 (dd, 1 H, J ) 8.4, 2.0 Hz), 6.9-6.87 (d, 1

H, J ) 8.5 Hz), 6.87-6.75 (m, 1 H), 6.47-6.42 (d, 1 H, J )

15.8 Hz), 6.11-6.03 (dd, 1 H, J ) 15.8, 8.8 Hz), 5.82-5.77 (d,

1 H, J ) 14.9 Hz), 5.61-5.58 (d, 1 H, J ) 7.8 Hz), 5.12 (s, 2

H), 5.12-4.75 (m, 4 H), 3.9 (s, 3 H), 3.49-3.42 (dd, 1 H, J )

13.4, 8.7 Hz), 3.29-3.27 (d, 2 H, J ) 6.5 Hz), 3.2-3.1 (m, 3

H), 2.65-2.3 (m, 3 H), 1.8-1.6 (m, 2 H), 1.47 (s, 9 H), 1.45-

1.3 (m, 1 H), 1.3-1.15 (m, 15 H), 0.79-0.75 (t, 6 H, J ) 6.4

3002 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

1464, 1405, 1282, 1259, 1185, 1152, 1067 cm^-1; HRMS (FAB,

alan yl-2-h ydr oxy-4-m eth yl-, (3 f 1⁵)-Lacton e, Mon oh ydr o-

ch lor id e, (2S)- (41a ). To a -66 °C solution of epoxide 40a

(0.05 g, 0.066 mmol) in CHCl₃(0.8 mL) was added dropwise a

4 M solution of HCl in 1,4-dioxane (0.04 mL, 0.166 mmol). The

mixture was stirred at -66 °C for 10 min upon which time

the dry ice bath was removed, allowing the solution to slowly

warm to room temperature. The solvents were removed in

vacuo, and the resulting salt was placed under high vacuum

for 3 days to remove the residual dioxane, hence yielding 0.054

m/z) calcd for C₄₂H₅₈Cl₃N₃O₁₀(M⁺- Cl) 834.3499, found 834.3504.

.

Anal. Calcd for (C₄₂H₅₈Cl₃N₃O₁₀1.0 H₂O): C, 56.73; H, 6.8;

N, 4.72. Found: C, 56.52; H, 6.4; N, 4.5.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

pen tan oyl-(2E,5S,6S)-6-[(2R,3R)-3-[4-(ch lor om eth yl)ph en -

yl]oxir a n yl]-5-h yd r oxy-2-h ep ten oyl-3-ch lor o-O-m eth yl-^D-

tyr osyl] (39). To a 0 °C solution of the alcohol 31 (0.32 g, 0.46

mmol) in CH₂Cl₂(8.5 mL) was added solid NaHCO₃(0.19 g,

2.29 mmol), triphenylphosphine (0.18 g, 0.69 mmol), and

N-chlorosuccinimide (0.092 g, 0.69 mmol). The mixture was

stirred at 0 °C for 20 min and quenched with saturated aq

NaHCO₃(20 mL). The layers were separated, and the aqueous

layer was extracted with CH₂Cl₂(3 × 10 mL). The combined

organic layers were washed with brine, dried over Na₂SO₄,

filtered, and concentrated in vacuo. The crude yellow solid was

purified by radial PLC (silica gel, 40-60% EtOAC/hexanes)

to give 0.26 g of benzyl chloride 39 as a white solid, contami-

nated with triphenylphosphine oxide. An analytical sample of

39 (0.07 g), as a white solid, was obtained by reverse phase

HPLC purification of 0.1 g of crude product with (50:50) CH₃-

g of the desired chlorohydin 41a in quantitative yield: [R]²⁰

D

1

+29.3 (c 1.0, MeOH); H NMR (300 MHz, MeOD) δ 8.5-8.47

(d, 1 H, J ) 7.5 Hz), 7.79-7.76 (d, 1 H, J ) 8.8 Hz), 7.53 (s, 4

H), 7.26-7.25 (d, 1 H, J ) 1.6 Hz), 7.17-7.14 (dd, 1 H, J )

8.6, 1.6 Hz), 6.97-6.94 (d, 1 H, J ) 8.4 Hz), 6.75-6.6 (m, 1

H), 5.96-5.90 (d, 1 H, J ) 15.3 Hz), 5.2-5.0 (m, 2 H), 4.85-

4.82 (m, 2 H), 4.5-4.4 (m, 1 H), 4.33 (s, 2 H), 4.02-3.98 (d, 1

H, J ) 9.3 Hz), 3.8 (s, 3 H), 3.49-3.42 (dd, 1 H, J ) 13.3, 9.9

Hz), 3.2-3.0 (m, 6 H), 2.8-2.6 (m, 2 H), 2.5-2.2 (m, 2 H), 1.8-

1.5 (m, 3 H), 1.34-1.3 (m, 7 H), 1.2 (s, 3 H), 1.15 (s, 3 H), 1.01-

0.94 (m, 9 H); ¹³C NMR (62.5 MHz, CDCl₃) δ 178.9, 173.8,

171.8, 168.3, 155.4, 144.1, 143.4, 132.3, 132.2, 131.5, 131.1,

130.4, 129.4, 125.2, 123.3, 113.5, 77.2, 74.8, 72.6, 63.2, 57.6,

56.7, 56.6, 48.0, 47.5, 44.1, 41.1, 40.4, 37.8, 36.5, 26.2, 23.6,

23.4, 22.2, 9.07, 9.0; IR (KBr) 3414, 2960, 2934, 1751, 1721,

1671, 1521, 1504, 1463, 1443, 1259, 1197, 1155, 1127, 1065

cm^-1; HRMS (FAB, m/z) calcd for C₄₁H₅₈Cl₃N₃O₈(M⁺-Cl)

790.3601, found 790.3609.

CN:H₂O: [R]²⁰+25.6 (c 0.9, CHCl₃); ¹H NMR (300 MHz,

D

CDCl₃) δ 7.4-7.38 (d, 2 H, J ) 7.9 Hz), 7.26-7.23 (d, 3 H, J

) 8.3 Hz), 7.19-7.18 (d, 1 H, J ) 1.9 Hz), 7.06-7.03 (dd, 1 H,

J ) 8.3, 1.9 Hz), 6.85-6.82 (d, 1 H, J ) 8.4 Hz), 6.8-6.7 (m,

1 H), 5.74-5.69 (d, 1 H, J ) 15.4 Hz), 5.49-5.47 (d, 1 H, J )

7.8 Hz), 5.22-5.17 (m, 1 H), 4.85-4.8 (dd, 1 H, J ) 9.7, 3.0

Hz), 4.78-4.7 (m, 1 H), 4.6 (s, 2 H), 3.9 (s, 3 H), 3.69-3.68 (d,

1 H, J ) 1.3 Hz), 3.45-3.38 (dd, 1 H, J ) 13.4, 8.6 Hz), 3.2-

3.0 (m, 3 H), 2.92-2.89 (dd, 1 H, J ) 7.6, 1.6 Hz), 2.6-2.4 (m,

2 H), 1.8-1.6 (m, 3 H), 1.4-1.3 (m, 1 H), 1.22 (s, 3 H), 1.16 (s,

3 H), 1.16-1.13 (d, 3 H, J ) 8.6 Hz), 0.86-0.82 (t, 6 H, J )

6.8 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 175.1, 170.4,

170.3, 164.9, 154.0, 141.6, 137.7, 137.1, 130.8, 129.5, 128.9,

128.1, 125.9, 124.6, 122.4, 112.3, 77.2, 75.8, 71.1, 63.1, 58.5,

56.1, 54.4, 46.4, 45.7, 42.7, 40.5, 39.3, 36.8, 35.2, 24.5, 22.8,

22.6, 21.2, 13.5; IR (CHCl₃) 3416, 3284, 2961, 2933, 2873, 2839,

1752, 1721, 1680, 1658, 1536, 1504, 1473, 1442, 1321, 1302,

1281, 1259, 1192, 1150, 1126, 1066 cm^-1. Anal. Calcd for

(C₃₇H₄₆Cl₂N₂O₈): C, 61.92; H, 6.46; N, 3.9. Found: C, 61.62;

H, 6.37; N, 3.61.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6S)-6-[(2R,3R)-3-[4-[[4-[(1,1-d im et h yl-

eth oxy)car bon yl]-1-piper azin yl]m eth yl]ph en yl]oxir an yl]-

5-h ydr oxy-2-h epten oyl-3-ch lor o-O-m eth yl-^D-tyr osyl] (40b).

Epoxide 40b (0.147 g) was prepared in 81% yield from benzyl

chloride 39 (0.15 g, 0.21 mmol) and N-(tert-butoxycarbonyl)-

piperazine (0.195 g, 1.05 mmol) according to the procedure

described for 40a : [R]²⁰+25.4 (c 0.65, CHCl₃); ¹H NMR (300

D

MHz, CDCl₃) δ 7.37-7.23 (m, 6 H), 7.11-7.08 (d, 1 H, J ) 8.6

Hz), 6.9-6.87 (d, 1 H, J ) 8.5 Hz), 6.86-6.72 (m, 1 H), 5.78-

5.73 (d, 1 H, J ) 15.2 Hz), 5.53-5.5 (d, 1 H, J ) 7.7 Hz), 5.28-

5.23 (m, 1 H), 4.88-4.70 (m, 2 H), 3.9 (s, 3 H), 3.7 (s, 1 H),

3.54 (s, 2 H), 3.5-3.4 (m, 5 H), 3.2-3.05 (m, 3 H), 3.0-2.95

(d, 1 H, J ) 7.4 Hz), 2.65-2.4 (m, 6 H), 1.85-1.6 (m, 3 H), 1.5

(s, 9 H), 1.45-1.4 (m, 1 H), 1.27 (s, 3 H), 1.2 (s, 3 H), 1.2-1.18

(d, 3 H, J ) 8.3 Hz), 0.91-0.87 (t, 6 H, J ) 6.1 Hz); ¹³C NMR

(62.5 MHz, CDCl₃) δ 177.9, 170.3, 170.2, 164.9, 154.7, 154.0,

141.7, 138.4, 135.6, 130.8, 129.5, 129.3, 128.1, 125.5, 124.6,

122.4, 112.3, 79.5, 77.2, 75.8, 71.1, 62.9, 62.6, 58.8, 56.1, 54.4,

52.8, 46.3, 42.7, 40.6, 39.3, 36.7, 35.2, 28.3, 24.5, 22.8, 22.6,

21.2, 13.4; IR (CHCl₃) 3425, 3008, 2965, 2937, 2874, 2817,

1752, 1709, 1683, 1527, 1484, 1463, 1459, 1427, 1367, 1259,

1167, 1150 cm^-1; HRMS (FAB, m/z) calcd for C₄₆H₆₃ClN₄O₁₀

(M⁺+ H) 867.4311, found 867.4300.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p e n t a n oyl-(2E ,5S ,6S )-6-[(2R ,3R )-3-[4-[(d ie t h yla m in o)-

m eth yl]ph en yl]oxir an yl]-5-h ydr oxy-2-h epten oyl-3-ch lor o-

O-m eth yl-^D-tyr osyl] (40a ). Diethylamine (0.09 mL, 0.84

mmol) was added to benzyl chloride 39 (0.03 g, 0.042 mmol)

in THF (0.3 mL). The mixture was stirred at room-temperature

overnight and quenched with saturated aq NaHCO₃(5 mL).

The aqueous layer was extracted with CH₂Cl₂(3 × 5 mL). The

combined organic layers were washed with brine, dried over

Na₂SO₄, filtered, and concentrated in vacuo. The crude yellow

solid was purified by radial PLC (silica gel, 50-80% EtOAc/

hexanes) to give 0.026 g of amine 40a in a 82% yield as a white

P en tan oic Acid, 3-Ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

8-[4-[[4-[(1,1-d im et h ylet h oxy)ca r b on yl]-1-p ip er a zin yl]-

methyl]phenyl]-5,7-dihydroxy-6-methyl-1-oxo-2-octenyl]-O-

m eth yl-^D-tyr osyl-2,2-dim eth yl-â-alan yl-2-h ydr oxy-4-m eth -

yl-, (3 f 1⁵)-La cton e, (2S)- (41b′). To a -66 °C solution of

the epoxide 40b (0.135 g, 0.156 mmol) in CHCl₃(3 mL) was

added dropwise chlorotrimethylsilane (0.16 mL, 1.2 mmol). The

mixture was stirred at -66 °C for 2 h, and additional TMSCl

was added (0.16 mL, 1.2 mmol). Following another 1 h at -66

°C, the ice bath was removed to allow the solution to slowly

warm to room temperature. The solvents were removed in

vacuo, and the resulting solid was purified by radial PLC (silica

solid: [R]²⁰+25.9 (c 0.9, CHCl₃); ¹H NMR (300 MHz, CDCl₃)

D

δ 7.35-7.32 (d, 2 H, J ) 7.9 Hz), 7.25-7.12 (m, 4 H), 7.06-

7.02 (dd, 1 H, J ) 8.4, 1.6 Hz), 6.84-6.82 (d, 1 H, J ) 8.5 Hz),

6.82-6.7 (m, 1 H), 5.74-5.69 (d, 1 H, J ) 15.2 Hz), 5.57-5.55

(d, 1 H, J ) 7.8 Hz), 5.22-5.17 (m, 1 H), 4.85-4.7 (m, 2 H),

3.86 (s, 3 H), 3.66 (s, 1 H), 3.57 (s, 2 H), 3.46-3.38 (dd, 1 H, J

) 13.4, 8.7 Hz), 3.2-3.0 (m, 3 H), 2.93-2.91 (d, 1 H, J ) 7.4

Hz), 2.6-2.4 (m, 6 H), 1.8-1.6 (m, 3 H), 1.4-1.3 (m, 1 H), 1.22

(s, 3 H), 1.15 (s, 3 H), 1.15-1.12 (d, 3 H, J ) 9.2 Hz), 1.07-

1.03 (t, 6 H, J ) 7.1 Hz), 0.86-0.82 (t, 6 H, J ) 6.3 Hz); ¹³C

NMR (62.5 MHz, CDCl₃) δ 177.9, 170.4, 170.3, 164.9, 154.0,

141.7, 140.1, 135.2, 130.8, 129.6, 129.1, 128.1, 125.4, 124.6,

122.4, 112.3, 77.2, 75.8, 71.1, 62.9, 58.9, 57.1, 56.0, 54.4, 46.6,

46.4, 42.7, 40.6, 39.3, 36.8, 35.2, 24.5, 22.8, 22.6, 21.2, 13.5,

11.5; IR (CHCl₃) 3424, 2969, 2936, 2874, 1752, 1711, 1682,

gel, 2-5% MeOH/CH₂Cl₂) to give 0.13 g of the anti chlorohy-

1

drin 41b′ in 92% yield: [R]²⁰+50.0 (c 1.0, CHCl₃); H NMR

D

(300 MHz, CDCl₃) δ 7.34 (s, 4 H), 7.21-7.2 (d, 2 H, J ) 1.4

Hz), 7.08-7.05 (dd, 1 H, J ) 8.6, 1.6 Hz), 6.86-6.83 (d, 1 H,

J ) 8.4 Hz), 6.82-6.7 (m, 1 H), 5.8-5.75 (d, 1 H, J ) 15.1

Hz), 5.65-5.62 (d, 1 H, J ) 7.8 Hz), 5.2-5.1 (t, 1 H), 5.0-4.7

(m, 2 H), 4.66-4.63 (d, 1 H, J ) 9.7 Hz), 4.02-4.0 (d, 1 H, J

) 9.6 Hz), 3.88 (s, 3 H), 3.49-3.48 (d, 2 H, J ) 4.2 Hz), 3.45-

3.3 (m, 5 H), 3.2-3.0 (m, 3 H), 2.7-2.3 (m, 7 H), 1.8-1.6 (m,

3 H), 1.45 (s, 10 H), 1.23 (s, 3 H), 1.17 (s, 3 H), 1.04-1.02 (d,

3 H, J ) 6.9 Hz), 0.93-0.91 (d, 6 H, J ) 6.3 Hz); ¹³C NMR

1605, 1527, 1503, 1485, 1303, 1259, 1190, 1151, 1067 cm^-1

.

Anal. Calcd for (C₄₁H₅₆ClN₃O₈): C, 65.28; H, 7.48; N, 5.57.

Found: C, 65.5; H, 7.5; N, 5.65.

P en tan oic Acid, 3-Ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

8-[4-[(dieth ylam in o)m eth yl]ph en yl]-5,7-dih ydr oxy-6-m eth -

yl-1-oxo-2-oct en yl]-O-m et h yl-^D-t yr osyl-2,2-d im et h yl-â-

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 3003

(62.5 MHz, CDCl₃) δ 177.5, 170.5, 170.2, 165.2, 154.6, 153.9,

142.3, 139.1, 137.3, 130.8, 129.8, 129.5, 128.1, 127.9, 124.5,

122.3, 112.2, 79.5, 76.0, 73.9, 71.1, 62.4, 61.9, 56.1, 54.5, 52.8,

46.4, 42.7, 39.6, 38.4, 36.4, 35.2, 28.3, 24.7, 23.0, 22.9, 22.7,

21.5, 8.6; IR (CHCl₃) 3424, 3007, 2966, 2936, 2872, 2820, 1751,

1712, 1682, 1528, 1504, 1483, 1426, 1367, 1259, 1168, 1150,

1127, 1067, 1006 cm^-1. Anal. Calcd for (C₄₆H₆₄Cl₂N₄O₁₀): C,

61.12; H, 7.14; N, 6.2. Found: C, 60.85; H, 7.09; N, 6.43.

8.52 (d, 1 H, J ) 7.7 Hz), 7.84-7.81 (dd, 1 H, J ) 8.8, 1.7 Hz),

7.63-7.53 (q, 4 H, J ) 20.0, 8.2 Hz), 7.31-7.3 (d, 1 H, J ) 2.0

Hz), 7.22-7.18 (dd, 1 H, J ) 8.4, 2.0 Hz), 7.02-6.99 (d, 1 H,

J ) 8.5 Hz), 6.8-6.7 (m, 1 H), 6.0-5.92 (d, 1 H, J ) 15.0 Hz),

5.2-5.0 (m, 2 H), 4.9-4.8 (m, 1 H), 4.6-4.4 (m, 1 H), 4.3 (s, 2

H), 4.07-4.03 (dd, 1 H, J ) 9.5, 1.4 Hz), 3.86 (s, 3 H), 3.6-3.1

(m, 7 H), 2.82-2.7 (m, 2 H), 2.6-2.3 (m, 2 H), 1.9-1.6 (m, 3

H), 1.25 (s, 3 H), 1.2 (s, 3 H), 1.05-0.99 (m, 9 H); ¹³C NMR

(62.5 MHz, CDCl₃) δ 178.8, 173.8, 171.9, 168.3, 155.3, 144.2,

143.1, 132.2, 131.5, 131.4, 130.3, 129.4, 125.2, 123.2, 113.5,

77.2, 74.7, 72.6, 63.2, 57.6, 56.7, 52.4, 47.5, 45.5, 44.1, 41.1,

40.3, 37.8, 36.9, 36.5, 26.3, 23.7, 23.5, 22.2, 9.0; IR (KBr) 3412,

2961, 2933, 1749, 1721, 1663, 1504, 1462, 1442, 1259, 1199,

P en tan oic Acid, 3-Ch lor o-N-[(2E,5S,6S,7R,8S)-8-ch lor o-

5,7-dih ydr oxy-6-m eth yl-1-oxo-8-[4-(1-piper azin ylm eth yl)-

p h en yl]-2-oct en yl]-O-m et h yl-^D-t yr osyl-2,2-d im et h yl-â-

alanyl-2-hydroxy-4-methyl-,(3f1⁵)-Lactone,Dihydrochloride,

(2S)- (41b). The dihydrochloride salt 41b (0.116 g) of the BOC-

protected piperazine (0.122 g, 0.13 mmol) was prepared with

4 M HCl in 1,4-dioxane (0.32 mL, 1.3 mmol) in quantitative

yield according to the procedure described for 28: [R]²⁰_D+26.3

1152, 1126, 1065 cm^-1; HRMS (FAB, m/z) calcd for C₃₉H₅₆

-

Cl₄N₄O₈(M⁺- HCl₂) 777.3397, found 777.3391; Anal. Calcd

.

for (C₃₉H₅₆Cl₄N₄O₈0.8 H₂O): C, 54.15; H, 6.71; N, 6.48.

1

Found: C, 54.02; H, 6.65; N, 6.29.

(c 0.7, MeOH); H NMR (300 MHz, MeOD) δ 8.47-8.45 (d, 1

H, J ) 7.5 Hz), 7.78-7.75 (d, 1 H, J ) 9.2 Hz), 7.6-7.52 (q, 5

H, J ) 16.9, 7.9 Hz), 7.27-7.26 (d, 1 H, J ) 1.15 Hz), 7.18-

7.14 (dd, 1 H, J ) 8.6, 1.8 Hz), 6.98-6.95 (d, 1 H, J ) 8.4 Hz),

6.75-6.6 (m, 1 H), 5.95-5.9 (d, 1 H, J ) 15.4 Hz), 5.2-5.0 (m,

2 H), 4.85-4.82 (m, 2 H), 4.5-4.4 (m, 1 H), 4.4 (s, 2 H), 4.0-

3.98 (d, 1 H, J ) 9.3 Hz), 3.8 (s, 3 H), 3.6-3.4 (m, 9 H), 3.32-

3.29 (d, 1 H, J ) 11.3 Hz), 3.19-3.13 (dd, 1 H, J ) 14.8, 3.5

Hz), 3.1-3.06 (d, 1 H, J ) 13.7 Hz), 2.8-2.6 (m, 2 H), 2.5-2.3

(m, 2 H), 1.85-1.5 (m, 3 H), 1.3-1.2 (m, 1 H), 1.2 (s, 3 H),

1.15 (s, 3 H), 1.02-0.95 (m, 9 H); ¹³C NMR (62.5 MHz, CDCl₃)

δ 178.8, 173.7, 171.9, 168.3, 155.4, 144.2, 143.7, 132.8, 132.2,

131.5, 130.4, 129.9, 129.4, 125.2, 123.3, 113.5, 77.2, 74.8, 72.6,

63.1, 61.2, 57.6, 56.7, 49.2, 47.5, 44.1, 42.1, 41.1, 40.3, 37.8,

36.5, 26.3, 23.7, 23.4, 22.2, 9.0; IR (KBr) 3415, 2960, 2933,

2455, 1749, 1721, 1671, 1504, 1475, 1442, 1304, 1258, 1197,

1152, 1126, 1065, 1012 cm^-1; HRMS (FAB, m/z) calcd for

C₄₁H₅₈Cl₄N₄O₈(M⁺- HCl₂) 803.3553, found 803.3563. Anal.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6R,7E)-8-[4-[(1,3-d ih yd r o-1,3-d ioxo-2H-

isoin d ol-2-yl)m eth yl]p h en yl]-5-h yd r oxy-6-m eth yl-2,7-oc-

ta d ien oyl-3-ch lor o-O-m eth yl-^D-tyr osyl] (42). To a solution

of alcohol 35 (0.13 g, 0.19 mmol) in THF (2 mL) was added

triphenylphosphine (0.065 g, 0.25 mmol), phthalimide (0.037

g, 0.25 mmol), and diethyl azodicarboxylate (DEAD) (0.04 mL,

0.25 mmol) dropwise. The resulting yellow solution was stirred

at room temperature for 2 h and quenched with H₂O (10 mL)

and CH₂Cl₂(10 mL). The layers were separated, and the

aqueous layer was extracted with CH₂Cl₂(2 × 10 mL). The

combined organic layers were dried over MgSO₄, filtered, and

concentrated in vacuo. The resulting residue was purified by

radial PLC (silica gel, 50-70% EtOAc/hexanes) to give

phthalimide 42 (0.14 g) as a white solid in 90% yield: [R]²⁰

D

+19.2 (c 1.0, CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ 7.9-7.8

(m, 2 H), 7.72-7.69 (m, 2 H), 7.39-7.36 (d, 2 H, J ) 8.0 Hz),

7.28-7.26 (d, 2 H, J ) 5.3 Hz), 7.25-7.2 (m, 1 H), 7.19-7.18

(d, 1 H, J ) 1.9 Hz), 7.06-7.03 (dd, 1 H, J ) 8.5, 1.9 Hz),

6.85-6.82 (d, 1 H, J ) 8.4 Hz), 6.81-6.7 (m, 1 H), 6.39-6.33

(d, 1 H, J ) 15.9 Hz), 6.01-5.93 (dd, 1 H, J ) 15.8, 8.8 Hz),

5.75-5.7 (d, 1 H, J ) 15.4 Hz), 5.47-5.44 (d, 1 H, J ) 7.9 Hz),

5.05-5.0 (dd, 1 H, J ) 9.4, 6.3 Hz), 4.8 (s, 2 H), 4.83-4.7 (m,

2 H), 3.87 (s, 3 H), 3.4-3.36 (dd, 1 H, J ) 13.4, 8.6 Hz), 3.18-

3.02 (m, 3 H), 2.6-2.25 (m, 3 H), 1.65-1.5 (m, 2 H), 1.35-

1.22 (m, 1 H), 1.21 (s, 3 H), 1.14 (s, 3 H), 1.12-1.09 (d, 3 H, J

) 6.8 Hz), 0.71-0.69 (d, 3 H, J ) 6.4 Hz), 0.65-0.63 (d, 3 H,

J ) 6.4 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 170.5, 170.4,

167.8, 165.2, 153.9, 142.0, 136.3, 135.6, 133.9, 131.9, 131.1,

130.7, 130.6, 129.8, 128.9, 128.6, 128.5, 128.1, 126.3, 124.6,

123.2, 122.3, 112.2, 76.9, 71.3, 56.0, 54.5, 46.4, 42.6, 42.1, 41.2,

39.4, 36.4, 35.2, 24.4, 22.8, 22.6, 22.5, 21.1, 17.2; IR (CHCl₃)

3421, 2967, 2935, 2873, 2840, 1747, 1716, 1682, 1527, 1503,

1485, 1433, 1395, 1259, 1151 cm^-1; HRMS (FAB, m/z) calcd

for C₄₅H₅₀ClN₃O₉(M⁺+ H) 812.3314, found 812.3307; Anal.

Calcd for (C₄₅H₅₀ClN₃O₉^.0.1 H₂O): C, 66.39; H, 6.22; N, 5.16.

Found: C, 66.03; H, 5.9; N, 4.81.

.

Calcd for (C₄₁H₅₈Cl₄N₄O₈0.5 H₂O): C, 55.6; H, 6.71; N, 6.33.

Found: C, 55.52; H, 6.97; N, 6.22.

P en ta n oic Acid , 3-Ch lor o-N-[(2E,5S,6S)-6-[(2R,3R)-3-[4-

[[[2-[[(1,1-d im eth yleth oxy)ca r bon yl]a m in o]eth yl]a m in o]-

m eth yl]p h en yl]oxir a n yl]-5-h yd r oxy-1-oxo-2-h ep ten yl]-O-

m e t h yl-^D-t yr osyl-2,2-d im e t h yl-â-a la n yl-2-h yd r oxy-4-

m eth yl-, (3 f 1)-La cton e, (2S)- (40c). Epoxide 40c (0.15 g)

was prepared in 78% yield from benzyl chloride 39 (0.16 g,

0.22 mmol) and tert-butyl-N-(2-aminoethyl)carbamate (0.35 g,

2.22 mmol) according to the procedure described for 40a : [R]²⁰

D

+22.3 (c 1.0, CHCl₃); ¹H NMR (300 MHz, CDCl₃) δ 7.41-7.38

(d, 2 H, J ) 7.8 Hz), 7.31 (s, 1 H), 7.26-7.24 (d, 3 H, J ) 8.0

Hz), 7.11-7.08 (dd, 1 H, J ) 8.4, 1.7 Hz), 6.88-6.86 (d, 1 H,

J ) 8.4 Hz), 6.86-6.72 (m, 1 H), 5.88-5.8 (bd, 1 H), 5.78-

5.73 (d, 1 H, J ) 15.2 Hz), 5.28-5.22 (m, 1 H), 5.2-5.08 (bs,

1 H), 4.95-4.7 (m, 2 H), 3.91 (s, 3 H), 3.87 (s, 2 H), 3.7 (s, 1

H), 3.45-3.38 (dd, 1 H, J ) 13.4, 8.4 Hz), 3.35-3.0 (m, 6 H),

2.96-2.93 (dd, 1 H, J ) 7.5, 1.2 Hz), 2.89-2.78 (m, 2 H), 2.65-

2.4 (m, 2 H), 1.85-1.65 (m, 3 H), 1.49 (s, 9 H), 1.48-1.3 (m, 1

H), 1.27 (s, 3 H), 1.2 (s, 3 H), 1.19-1.17 (d, 3 H, 7.1 Hz), 0.91-

0.87 (t, 6 H, J ) 6.8 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.7,

170.4, 165.0, 156.0, 153.9, 141.5, 139.9, 135.6, 130.7, 129.7,

128.5, 128.1, 125.6, 124.7, 122.3, 112.2, 77.2, 75.7, 71.0, 63.0,

58.8, 56.0, 54.5, 52.9, 48.5, 46.3, 42.7, 40.5, 39.3, 36.8, 35.2,

28.3, 24.5, 22.83, 22.8, 22.6, 21.2, 13.5; IR (CHCl₃) 3425, 3009,

2967, 2936, 2874, 2841, 1751, 1709, 1685, 1504, 1368, 1280,

1259, 1165, 1153, 1067 cm^-1; Anal. Calcd for (C₄₄H₆₁ClN₄O₁₀):

C, 62.81; H, 7.31; N, 6.66. Found: C, 62.77; H, 7.34; N, 6.81.

P en ta n oic Acid , N-[(2E,5S,6R,7E)-8-[4-(Am in om eth yl)-

p h en yl]-5-h ydr oxy-6-m eth yl-1-oxo-2,7-octa dien yl]-3-ch lo-

r o-O-m eth yl-^D-tyr osyl-2,2-d im eth yl-â-a la n yl-2-h yd r oxy-

4-m eth yl-, (3 f 1)-La cton e, (2S)- (43). To the phthalimide

42 (0.1 g, 0.123 mmol) in EtOH (1.8 mL) was added n-

butylamine (0.04 mL, 0.369 mmol). The solution was heated

at 75 °C for 2 days, concentrated in vacuo, and purified by

radial PLC (silica gel, 10-25% MeOH/CH₂Cl₂) to provide the

free amine 43 (0.048 g) in 57% yield.

P en ta n oic Acid , N-[(1,1-Dim eth yleth oxy)ca r bon yl]-N-

m eth ylglycyl-(2E,5S,6R,7E)-8-[4-(a m in om eth yl)p h en yl]-

5-h yd r oxy-6-m eth yl-2,7-octa d ien oyl-3-ch lor o-O-m eth yl-

D-tyr osyl-2,2-d im eth yl-â-a la n yl-2-h yd r oxy-4-m eth yl-, (5

f 2)-la cton e, (2S)- (44). To N-(tert-butoxycarbonyl)sarcosine

(0.07 g, 0.37 mmol) in DMF (1.5 mL) were added 1-hydroxy-

benzotriazole hydrate (HOBT) (0.05 g, 0.37 mmol) and 1-(3-

dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI)

(0.071 g, 0.37 mmol). Following 45 min of stirring at room

temperature, amine 43 (0.17 g, 0.25 mmol) in DMF (2.5 mL)

was added dropwise via a double-tipped needle to the solution.

P en ta n oic Acid , N-[(2E,5S,6S,7R,8S)-8-[4-[[(2-Am in o-

et h yl)a m in o]m et h yl]p h en yl]-8-ch lor o-5,7-d ih yd r oxy-6-

m eth yl-1-oxo-2-octen yl]-3-ch lor o-O-m eth yl-^D-tyr osyl-2,2-

d im eth yl-â-a la n yl-2-h yd r oxy-4-m eth yl-, (3 f 1⁵)-La cton e,

Dih yd r och lor id e, (2S)- (41c). To a -78 °C solution of the

epoxide 40c (0.065 g, 0.076 mmol) in CH₂Cl₂(0.9 mL) was

added dropwise 4 M HCl in 1,4-dioxane (0.09 mL, 0.38 mmol).

The solution was stirred at -78 °C for 30 min and was allowed

to slowly warm to room temperature. It was stirred at room

temperature an additional 2 h and was concentrated in vacuo

to yield the chlorohydrin 41c (0.063 g) in quantitative yield:

[R]²⁰_D+16.6 (c 1.0, MeOH); ¹H NMR (300 MHz, CDCl₃) δ 8.54-

3004 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

The resulting mixture was stirred for an additional 3 h,

quenched with H₂O (10 mL), and extracted with CH₂Cl₂(3 ×

10 mL). The combined organic layers were dried over MgSO₄,

filtered, and concentrated in vacuo. Purification of the result-

ing crude product by radial PLC (silica gel, 70-100% EtOAc/

MeOD) δ 8.47-8.45 (d, 1 H, J ) 7.7 Hz), 7.79-7.76 (d, 1 H, J

) 8.9 Hz), 7.39-7.36 (d, 2 H, J ) 8.1 Hz), 7.3-7.27 (d, 3 H, J

) 9.0 Hz), 7.17-7.14 (d, 1 H, J ) 8.5 Hz), 6.98-6.95 (d, 1 H,

J ) 8.5 Hz), 6.75-6.6 (m, 1 H), 5.94-5.89 (d, 1 H, J ) 15.1

Hz), 5.2-5.0 (m, 2 H), 4.78-4.75 (d, 1 H, J ) 9.4 Hz), 4.5-

4.42 (m, 1 H), 4.41 (s, 2 H), 4.01-3.98 (d, 1 H, J ) 9.5 Hz),

3.82 (s, 3 H), 3.8 (s, 2 H), 3.5-3.4 (m, 1 H), 3.19-3.13 (dd, 1

H, J ) 14.4, 3.4 Hz), 3.11-3.06 (dd, 1 H, J ) 13.2, 1.9 Hz),

2.8-2.6 (m, 2 H), 2.7 (s, 3 H), 2.5-2.2 (m, 2 H), 1.85-1.45 (m,

3 H), 1.3-1.2 (m, 1 H), 1.2 (s, 3 H), 1.15 (s, 3 H), 1.0-0.94 (q,

9 H, J ) 11.3, 6.0 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 178.9,

173.7, 171.9, 168.3, 166.3, 155.4, 144.2, 140.5, 139.7, 132.2,

131.5, 129.7, 129.4, 128.8, 125.2, 123.3, 113.5, 77.2, 74.7, 72.6,

63.7, 57.6, 56.6, 50.7, 47.4, 44.1, 43.9, 41.1, 40.4, 37.8, 36.5,

33.7, 26.2, 23.6, 23.4, 22.1, 9.0; IR (KBr) 3410, 3058, 2961,

2933, 1752, 1721, 1675, 1539, 1504, 1463, 1440, 1282, 1259,

1196, 1154, 1127, 1066 cm^-1; HRMS (FAB, m/z) calcd for

C₄₀H₅₅Cl₃N₄O₉(M⁺- Cl) 805.3346, found 805.3341; Anal.

Calcd for (C₄₀H₅₅Cl₃N₄O₉^.1.0 H₂O): C, 55.85; H, 6.68; N, 6.51.

Found: C, 55.69; H, 6.91; N, 6.49.

hexanes) gave the desired amide 44 (0.15 g) in 71% yield as a

1

white solid: [R]²⁰+22.4 (c 1.0, CHCl₃); H NMR (300 MHz,

D

CDCl₃) δ 7.27-7.1 (m, 6 H), 7.04-7.0 (dd, 1 H, J ) 8.5, 1.9

Hz), 6.82-6.79 (d, 1 H, J ) 8.5 Hz), 6.79-6.65 (m, 1 H), 6.38-

6.32 (d, 1 H, J ) 15.9 Hz), 6.32-6.1 (m, 1 H), 6.01-5.93 (dd,

1 H, J ) 15.9, 8.7 Hz), 5.75-5.70 (d, 1 H, J ) 15.0 Hz), 5.65-

5.6 (m, 1 H), 5.0-4.99 (dd, 1 H, J ) 9.3, 6.1 Hz), 4.84-4.79

(dd, 1 H, J ) 9.6, 3.6 Hz), 4.74-4.67 (m, 1 H), 4.42-4.4 (d, 2

H, J ) 5.7 Hz), 3.87 (s, 2 H), 3.84 (s, 3 H), 3.42-3.34 (dd, 1 H,

J ) 13.5, 8.6 Hz), 3.15-3.0 (m, 3 H), 2.9 (s, 3 H), 2.6-2.25 (m,

3 H), 1.8-1.5 (m, 2 H), 1.4 (s, 9 H), 1.39-1.25 (m, 1 H), 1.19

(s, 3 H), 1.12 (s, 3 H), 1.1-1.08 (d, 3 H, J ) 6.8 Hz), 0.73-0.69

(m, 6 H); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.7, 170.5, 170.4,

169.2, 165.2, 153.9, 141.9, 137.3, 136.0, 131.1, 130.7, 130.3,

129.8, 128.6, 128.1, 127.7, 126.3, 124.6, 122.3, 112.2, 80.6, 76.9,

71.3, 56.0, 54.5, 53.1, 46.4, 42.8, 42.7, 42.0, 39.4, 36.4, 35.8,

35.2, 28.2, 24.5, 22.8, 22.6, 21.2, 17.1; IR (CHCl₃) 3427, 2967,

2935, 2874, 2841, 1747, 1680, 1526, 1504, 1484, 1464, 1442,

1393, 1369, 1302, 1281, 1259, 1151, 1067 cm^-1; HRMS (FAB,

m/z) calcd for C₄₅H₆₁ClN₄O₁₀(M⁺- Boc + H) 753.3630, found

753.3621; Anal. Calcd for (C₄₅H₆₁ClN₄O₁₀): C, 63.33; H, 7.2;

N, 6.56. Found: C, 63.38; H, 7.07; N, 6.84.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6R,7E)-8-[4-[2-[[(1,1-d im eth yleth yl)d i-

methylsilyl]oxy]ethyl]phenyl]-5-hydroxy-6-methyl-2,7-octa-

d ien oyl-3-ch lor o-O-m eth yl-^D-tyr osyl] (47). Styrene 47 (1.2

g) as a mixture of E and Z isomers was prepared from aldehyde

2 (1.0 g, 1.73 mmol) and 4-(ethyl-2-tert-butyldimethylsiloxy)-

benzyl triphenylphosphonium bromide (3h ) (1.23 g, 2.08 mmol)

in 86% yield according to the procedure described above for

styrene 29.

P en ta n oic Acid , N-[(1,1-Dim eth yleth oxy)ca r bon yl]-N-

m eth ylglycyl-(2E,5S,6S,7R,8S)-8-[4-(am in om eth yl)ph en yl]-

8-ch lor o-5,7-d ih yd r oxy-6-m eth yl-2-octen oyl-3-ch lor o-O-

m e t h yl-^D-t yr osyl-2,2-d im e t h yl-â-a la n yl-2-h yd r oxy-4-

m eth yl-, (5 f 2⁵)-La cton e, (2S)- (45). Amide 44 (0.34 g, 0.398

mmol) was epoxidized with mCPBA (0.072 g, 0.42 mmol) in

CH₂Cl₂(1.2 mL) according to the previously described proce-

dure to give the â and R epoxides in a 2:1 ratio. The resulting

crude mixture of epoxides (0.3 g, 0.345 mmol) was dissolved

in CHCl₃(6.0 mL) and cooled to -60 °C. TMSCl (0.22 mL, 1.73

mmol) was added, and the solution was stirred between -50

°C and -20 °C for 2 h. More TMSCl (0.44 mL, 0.173 mmol)

was added, and the solution was allowed to warm to room

temperature. The solution was concentrated in vacuo, and the

resulting crude product was purified twice by column chro-

matography (70-80% EtOAc/hexanes) and twice by radial PLC

(silica gel, 2-5% MeOH/CH₂Cl₂) to give the anti chlorohydrin

The mixture of isomers was dissolved in toluene (50 mL)

and heated to reflux in the presence of 1,1′-azobis(cyclohex-

anecarbonitrile) (VAZO) (0.040 g, 0.16 mmol) and thiophenol

(0.061 mL, 0.59 mmol) for 3 h. After concentration the residue

was purified by radial PLC (20-75% EtOAc/hexanes) to give

the E isomer 47 (0.81 g, 68%) as a white foam: [R]²⁰_D+35.6 (c

1

0.56, MeOH); H NMR (300 MHz, CDCl₃) δ 7.26-7.12 (m, 6

H), 7.07-7.04 (d, 1 H, J ) 8.5 Hz), 6.85-6.82 (d, 1 H, J ) 8.4

Hz), 6.82-6.70 (m, 1 H), 6.40-6.35 (d, 1 H, J ) 15.8 Hz), 6.0-

5.92 (dd, 1 H, J ) 15.4, 8.7 Hz), 5.77-5.72 (d, 1 H, J ) 15.2

Hz), 5.46-5.43 (d, 1 H, J ) 7.7 Hz), 5.07-5.02 (m, 1 H), 4.86-

4.83 (m, 1 H), 4.82-4.74 (m, 1 H), 3.88 (s, 3 H), 3.78-3.74 (t,

2 H, J ) 7.1 Hz), 3.44-3.37 (dd, 1 H, J ) 12.5, 8.6 Hz), 3.15-

3.08 (m, 3 H), 2.81-2.77 (t, 2 H, J ) 7.1 Hz), 2.57-2.52 (m, 2

H), 2.43-2.35 (m, 1 H), 1.74-1.56 (m, 2 H), 1.38-1.23 (m, 1

H), 1.22 (s, 3 H), 1.16 (s, 3 H), 1.13-1.11 (d, 3 H, J ) 6.8 Hz),

0.88 (s, 9 H), 0.76-0.72 (t, 6 H, J ) 5.6 Hz), 0.0 (s, 6 H); ¹³C

NMR (62.5 MHz, CDCl₃) δ 177.9, 170.5, 170.3, 165.1, 154.0,

142.2, 138.6, 134.6, 131.5, 130.9, 129.6, 129.4, 129.3, 128.2,

126.0, 125.3, 124.5, 122.5, 112.3, 92.9, 77.0, 71.4, 64.4, 56.1,

54.3, 46.5, 42.7, 42.2, 39.4, 39.2, 36.5, 35.3, 25.9, 24.5, 22.8,

22.7, 22.6, 21.2, 17.2, -5.44; IR (CHCl₃) 3423, 2959, 2931,

2858, 1747, 1712, 1681, 1605, 1527, 1503, 1485, 1442, 1370,

1339, 1303, 1281, 1258, 1194, 1151, 1095, 1067, 1025, 1007,

838 cm^-1; Anal. Calcd for (C₄₄H₆₃ClN₂O₈Si): C, 65.12; H, 7.82;

N, 3.45. Found: C, 65.34; H, 7.79; N, 3.5.

45 (0.1 g) in 48% yield as a white solid: [R]²⁰+46.9 (c 0.85,

D

1

CHCl₃); H NMR (300 MHz, CDCl₃) δ 7.36-7.34 (d, 2 H, J )

7.9 Hz), 7.29-7.26 (d, 2 H, J ) 8.3 Hz), 7.21 (s, 2 H), 7.08-

7.05 (d, 1 H, J ) 8.3 Hz), 6.86-6.83 (d, 1 H, J ) 8.5 Hz), 6.8-

6.7 (m, 1 H), 6.5-6.2 (bs, 1 H), 5.79-5.74 (d, 1 H, J ) 15.2

Hz), 5.64-5.62 (d, 1 H, J ) 7.7 Hz), 5.18-5.12 (t, 1 H, J ) 9.1

Hz), 4.94-4.9 (dd, 1 H, J ) 9.9, 3.5 Hz), 4.8-4.67 (m, 1 H),

4.66-4.63 (d, 1 H, J ) 9.6 Hz), 4.47-4.45 (d, 2 H, J ) 5.3 Hz),

4.02-3.98 (d, 1 H, J ) 9.5 Hz), 3.89 (s, 2 H), 3.88 (s, 3 H),

3.41-3.34 (dd, 1 H, J ) 13.6, 8.5 Hz), 3.2-3.0 (m, 3 H), 2.94

(s, 3 H), 2.69-2.68 (bdd, 1 H, J ) 14.3, 2.1 Hz), 2.51-2.3 (m,

2 H), 1.8-1.6 (m, 3 H), 1.42 (s, 10 H), 1.22 (s, 3 H), 1.17 (s, 3

H), 1.03-1.01 (d, 3 H, J ) 6.9 Hz), 0.94-0.9 (t, 6 H, J ) 5.5

Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.6, 170.4, 170.2, 165.2,

153.9, 142.4, 139.1, 130.8, 129.7, 128.3, 128.2, 127.9, 124.4,

122.4, 112.2, 80.7, 76.1, 73.9, 71.2, 61.8, 56.1, 54.4, 53.1, 46.4,

42.7, 39.6, 38.4, 36.3, 35.9, 35.2, 28.2, 24.8, 23.0, 22.9, 22.7,

21.5, 8.5; IR (KBr) 3419, 3317, 2964, 2932, 1755, 1670, 1538,

1504, 1473, 1392, 1368, 1301, 1258, 1151, 1066; HRMS (FAB,

m/z) calcd for C₄₅H₆₂Cl₂N₄O₁₁(M⁺+ H) 905.3870, found

905.3876.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6S)-6-[(2R,3R)-3-[4-[2-[[(1,1-d im et h yl-

eth yl)dim eth ylsilyl]oxy]eth yl]ph en yl]oxir an yl]-5-h ydr oxy-

2-h ep ten oyl-3-ch lor o-O-m eth yl-^D-tyr osyl] (48). Epoxide 48

was prepared from the styrene 47 (2.77 g, 3.41 mmol) and

mCPBA (0.63 mL, 3.65 mmol) in CH₂Cl₂(11 mL) as was

previously described. Purification of 0.95 g of the crude mixture

by reverse phase HPLC with (45:55) CH₃CN:H₂O gave 0.42 g

of the â epoxide as a white solid: [R]²⁰_D+21.7 (c 0.55, CHCl₃);

¹H NMR (300 MHz, CDCl₃) 7.2-7.1 (m, 6 H), 7.06-7.03 (d, 1

H, J ) 8.16 Hz), 6.85-6.82 (d, 1 H, J ) 8.4 Hz), 6.82-6.7 (m,

1 H), 5.73-5.68 (d, 1 H, J ) 15.0 Hz), 5.46-5.43 (d, 1 H, J )

7.8 Hz), 5.22-5.17 (m, 1 H), 4.85-4.7 (m, 2 H), 3.87 (s, 3 H),

3.82-3.77 (t, 2 H, J ) 7.0 Hz), 3.65 (s, 1 H), 3.45-3.38 (dd, 1

H, J ) 13.6, 8.54 Hz), 3.15-3.05 (m, 3 H), 2.91-2.89 (d, 1 H,

J ) 7.4 Hz), 2.85-2.80 (t, 2 H, J ) 7.0 Hz), 2.6-2.35 (m, 2 H),

1.8-1.6 (m, 3 H), 1.4-1.25 (m, 1 H), 1.22 (s, 3 H), 1.15 (s, 3

H), 1.15-1.13 (d, 3 H, J ) 8.6 Hz), 0.87 (s, 9 H), 0.85-0.81 (t,

6 H, J ) 6.4 Hz), 0.0 (s, 6 H); ¹³C NMR (62.5 MHz, CDCl₃) δ

P en ta n oic Acid , N-Meth ylglycyl-(2E,5S,6S,7R,8S)-8-[4-

(a m in om eth yl)p h en yl]-8-ch lor o-5,7-d ih yd r oxy-6-m eth yl-

2-oct en oyl-3-ch lor o-O-m et h yl-^D-t yr osyl-2,2-d im et h yl-â-

alan yl-2-h ydr oxy-4-m eth yl-, (5 f 2⁵)-Lacton e, Mon oh ydr o-

ch lor id e, (2S)- (46). The hydrochloride salt 46 (0.041 g) of

the BOC-protected amine 45 (0.045 g, 0.05 mmol) was pre-

pared with 4 M HCl in 1,4-dioxane in quantitative yield

according to the previously described procedure for the prepa-

ration of 28: [R]²⁰_D+11.5 (c 0.47, MeOH); ¹H NMR (300 MHz,

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 3005

177.8, 170.4, 170.3, 164.9, 154.0, 141.7, 139.6, 137.2, 134.4,

130.8, 129.5, 129.4, 128.1, 125.4, 124.6, 122.4, 112.3, 75.9, 71.0,

64.2, 62.9, 58.9, 56.0, 54.4, 46.4, 42.7, 40.5, 39.3, 39.2, 36.8,

35.2, 25.8, 24.5, 22.8, 22.7, 22.6, 21.1, 18.2, 13.4, -5.4; IR

(CHCl₃) 3425, 2959, 2931, 1751, 1712, 1683, 1527, 1503, 1485,

(d, 1 H, J ) 15.3 Hz), 5.19-5.14 (dd, 1 H, J ) 11.0, 5.0 Hz),

4.94-4.9 (dd, 1 H, J ) 9.8, 3.2 Hz), 4.48-4.43 (dd, 1 H, J )

11.5, 3.5 Hz), 3.8 (s, 3 H), 3.77 (s, 1 H), 3.53 (s, 2 H), 3.5-3.4

(m, 1 H), 3.17-3.11 (dd, 1 H, J ) 14.3, 3.5 Hz), 3.05-3.0 (d, 1

H, J ) 13.6 Hz), 2.95-2.92 (dd, 1 H, J ) 7.7, 1.7 Hz), 2.8-2.6

(m, 2 H), 2.5-2.3 (m, 1 H), 1.8-1.6 (m, 3 H), 1.4-1.2 (m, 1 H),

1.17 (s, 3 H), 1.13 (s, 3 H), 1.13-1.1 (d, 3 H, J ) 9.2 Hz), 0.83-

0.81 (d, 6 H, J ) 6.3 Hz); ¹³C NMR (125 MHz, CDCl₃) δ 178.8,

173.7, 172.0, 168.2, 155.4, 143.4, 138.1, 136.7, 132.2, 131.4,

130.8, 129.3, 126.8, 125.4, 123.3, 113.5, 77.7, 72.4, 64.4, 60.0,

57.5, 56.6, 47.4, 44.1, 41.7, 40.7, 38.5, 36.4, 25.9, 23.4, 23.3,

21.6, 14.0; IR (KBr) 3417, 2961, 2934, 2874, 1750, 1721, 1674,

1463, 1258, 1189, 1151, 1067, 836 cm^-1. Anal. Calcd for (C₄₄H₆₃

-

ClN₂O₉Si): C, 63.86; H, 7.67; N, 3.39. Found: C, 63.77; H, 7.48;

N, 3.47.

P en ta n oic Acid , 3-Ch lor o-N-[(2E,5S,6S)-5-h yd r oxy-6-

[(2R,3R)-3-[4-(2-h yd r oxyeth yl)p h en yl]oxir a n yl]-1-oxo-2-

h ep t en yl]-O-m et h yl-^D-t yr osyl-2,2-d im et h yl-â-a la n yl-2-

h yd r oxy-4-m eth yl-, (3 f 1⁵)-La cton e, (2S)- (49). Alcohol

49 was prepared from the silyl ether 48 (0.37 g, 0.45 mmol)

and TBAF (0.45 mL, 0.45 mmol) in THF (2.5 mL) as was

previously described. Purification by radial PLC (silica gel, 70-

100% EtOAc/hexanes) provided the desired alcohol 49 (0.3 g),

1561, 1504, 1464, 1441, 1300, 1259, 1194, 1151, 1066 cm^-1

;

HRMS (FAB, m/z) calcd for C₃₈H₄₇ClN₂O₁₀(M⁺+ H) 727.2997,

found 727.3005.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6R,7E)-5-h yd r oxy-6-m eth yl-8-(2-m eth -

yl-5-t h ia zolyl)-2,7-oct a d ien oyl-3-ch lor o-O-m et h yl-^D-t y-

r osyl] (52). To a mixture of [(2-methyl-4-thiazolyl)methyl]-

triphenylphosphonium chloride (3i) (0.496 g, 1.2 mmol) in THF

(10 mL) at -78 °C was added dropwise a 1.6 M solution of

n-butyllithium (0.8 mL, 1.2 mmol). The mixture was warmed

slowly to room temperature and stirred for an additional 45

min. To aldehyde 2 (0.5 g, 0.865 mmol) in THF (15 mL) at

-78 °C was added dropwise the orange ylide solution via a

double-tipped needle. The resulting mixture was stirred at -78

°C for 2 h and at room temperature for 1.5 h. Saturated aq

NH₄Cl (30 mL) was added along with ethyl acetate (30 mL),

the layers were separated, and the aqueous one was extracted

with ethyl acetate (2 × 20 mL). The combined organic layers

were washed with water (2 × 20 mL) and brine, dried over

MgSO₄, filtered, and concentrated in vacuo. The resulting

yellow residue was purified by column chromatography (silica

gel, 50-70-80% EtOAc/hexanes) to give 0.4 g of the desired

styrene contaminated by triphenylphosphine oxide. The tri-

phenylphosphine oxide was easily removed by reverse phase

HPLC with CH₃CN:H₂O (50:50) to give 0.2 g (34%) of pure

in 94% yield as a white solid: [R]²⁰+32.5 (c 0.58, CHCl₃); ¹H

D

NMR (300 MHz, CDCl₃) 7.26-7.18 (m, 6 H), 7.06-7.02 (dd, 1

H, J ) 8.3, 1.9 Hz), 6.85-6.82 (d, 1 H, J ) 8.4 Hz), 6.77-6.72

(m, 1 H), 5.72-5.67 (d, 1 H, J ) 15.5 Hz), 5.54-5.52 (d, 1 H,

J ) 7.8 Hz), 5.22-5.17 (m, 1 H), 4.84-4.8 (dd, 1 H, J ) 10.2,

3.5 Hz), 4.78-4.7 (m, 1 H), 3.91-3.84 (m, 5 H), 3.66-3.65 (d,

1 H, J ) 1.6 Hz), 3.45-3.38 (dd, 1 H, J ) 13.4, 8.7 Hz), 3.12-

3.05 (m, 3 H), 2.92-2.86 (m, 3 H), 2.59-2.41 (m, 2 H), 1.8-

1.63 (m, 3 H), 1.49-1.45 (t, 1 H, J ) 5.8 Hz), 1.38-1.23 (m, 1

H), 1.22 (s, 3 H), 1.16 (s, 3 H), 1.16-1.13 (d, 3 H, J ) 8.2 Hz),

0.86-0.82 (t, 6 H, J ) 6.6 Hz); ¹³C NMR (62.5 MHz, CDCl₃) δ

177.8, 170.4, 170.35, 165.0, 153.9, 141.5, 139.1, 137.4, 134.8,

130.7, 129.7, 129.3, 128.1, 125.7, 124.6, 122.3, 112.2, 75.9, 71.1,

63.3, 62.9, 58.9, 56.1, 54.4, 46.4, 42.7, 40.6, 39.3, 38.8, 36.9,

35.2, 24.5, 22.8, 22.6, 21.2, 13.6; IR (CHCl₃) 3425, 2964, 2936,

1751, 1712, 1683, 1527, 1503, 1485, 1442, 1303, 1281, 1259,

1151, 1076, 1025, 1006, 908 cm^-1; MS (FD, m/z) calcd for

C₃₈H₄₉ClN₂O₉(M⁺+ H) 713, found 713.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6S)-5-h yd r oxy-6-[(2R,3R)-3-[4-(2-oxo-

eth yl)ph en yl]oxir a n yl]-2-h epten oyl-3-ch lor o-O-m eth yl-^D-

tyr osyl] (50). Pyridine (0.06 mL, 0.76 mmol) and the Dess-

Martin reagent (0.161 g, 0.379 mmol) were added to a 0 °C

solution of the alcohol 49 (0.135 g, 0.189 mmol) in CH₂Cl₂(4.5

mL). The mixture was stirred at 0 °C for 30 min, at room

temperature for 20 min, then was filtered through Celite with

EtOAc and was finally concentrated in vacuo. Quick purifica-

tion of the crude product by radial PLC (silica gel, 80-100%

EtOAc/CH₂Cl₂) provided the desired aldehyde 50 (0.08 g), in

59% yield as a white solid: ¹H NMR (300 MHz, CDCl₃) 9.77-

9.76 (t, 1 H, J ) 2.0 Hz), 7.3-7.2 (m, 6 H), 7.06-7.02 (dd, 1 H,

J ) 8.3, 2.0 Hz), 6.85-6.82 (d, 1 H, J ) 8.4 Hz), 6.81-6.7 (m,

1 H), 5.74-5.68 (d, 1 H, J ) 15.3 Hz), 5.51-5.48 (d, 1 H, J )

7.8 Hz), 5.22-5.17 (m, 1 H), 4.85-4.81 (dd, 1 H, J ) 10.3, 3.6

Hz), 4.77-4.71 (m, 1 H), 3.87 (s, 3 H), 3.72-3.71 (d, 2 H, J )

2.0 Hz), 3.69-3.68 (d, 1 H, J ) 1.5 Hz), 3.45-3.38 (dd, 1 H, J

) 13.5, 8.7 Hz), 3.17-3.0 (m, 3 H), 2.92-2.89 (dd, 1 H, J )

7.6, 1.8 Hz), 2.6-2.4 (m, 2 H), 1.8-1.6 (m, 3 H), 1.4-1.3 (m, 1

H), 1.22 (s, 3 H), 1.16 (s, 3 H), 1.16-1.13 (d, 3 H, J ) 8.3 Hz),

0.86-0.82 (t, 6 H, J ) 6.3 Hz).

styrene 52 as a white solid: [R]²⁰+16.7 (c 1.0, CHCl₃); ¹H

D

NMR (300 MHz, CDCl₃) δ 7.3-7.2 (m, 1 H), 7.18-7.17 (d, 1

H, J ) 1.7 Hz), 7.06-7.03 (dd, 1 H, J ) 8.5, 1.8 Hz), 6.83 (s,

1 H), 6.83-6.8 (d, 1 H, J ) 9.0 Hz), 6.8-6.67 (m, 1 H), 6.37-

6.35 (m, 2 H), 5.85-5.82 (d, 1 H, J ) 7.9 Hz), 5.76-5.71 (d, 1

H, J ) 15.1 Hz), 5.05-5.0 (dd, 1 H, J ) 9.0, 6.0 Hz), 4.86-

4.82 (dd, 1 H, J ) 10.2, 3.6 Hz), 4.77-4.68 (m, 1 H), 3.85 (s, 3

H), 3.44-3.37 (dd, 1 H, J ) 13.4, 8.6 Hz), 3.2-3.0 (m, 3 H),

2.68 (s, 3 H), 2.6-2.3 (m, 3 H), 1.8-1.6 (m, 2 H), 1.43-1.3 (m,

1 H), 1.2 (s, 3 H), 1.14 (s, 3 H), 1.12-1.1 (d, 3 H, J ) 6.9 Hz),

0.79-0.76 (m, 6 H); ¹³C NMR (62.5 MHz, CDCl₃) δ 177.8, 170.5,

166.0, 165.2, 153.9, 153.0, 142.1, 136.7, 132.7, 130.8, 129.8,

128.1, 124.6, 124.4, 122.3, 114.1, 112.2, 76.9, 71.4, 56.0, 54.4,

46.4, 42.7, 41.9, 39.3, 36.5, 35.3, 24.5, 22.8, 22.7, 22.6, 21.2,

19.2, 17.1; IR (CHCl₃) 3423, 3027, 3008, 2965, 2935, 2874,

1747, 1712, 1681, 1652, 1604, 1528, 1504, 1485, 1259, 1181,

1152, 1067 cm^-1. Anal. Calcd for (C₃₄H₄₄ClN₃O₇S): C, 60.57;

H, 6.58; N, 6.23. Found: C, 60.4; H, 6.62; N, 6.17.

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en ta n oyl-(2E,5S,6S)-5-h yd r oxy-6-[(2R,3R)-3-(2-m eth yl-

5-t h ia zolyl)oxir a n yl]-2-h ep t en oyl-3-ch lor o-O-m et h yl-^D-

tyr osyl] (53). To the styrene 52 (0.25 g, 0.37 mmol) were

added acetone (15 mL), H₂O (6 mL), CH₂Cl₂(6 mL) and solid

NaHCO₃(1.0 g, 11.9 mmol), and the mixture was cooled to 0

°C. A solution of Oxone (0.92 g, 1.5 mmol) in H₂O (8 mL) was

prepared and added (2 mL) to the cold styrene mixture.

Following 30 min of vigorous stirring at 0 °C, an additional 2

mL of Oxone solution was added, followed by another 2.0 mL,

with stirring for another 30 min, for a total of 6 mL of Oxone

solution. The reaction progress was monitored by reverse

phase HPLC and was found to be complete after 2.0 h of

stirring. While still at 0 °C the reaction was quenched with

saturated aqueous NaHCO₃(40 mL) and CH₂Cl₂(40 mL). The

layers were separated, and the organic layer was washed with

aq 10% Na₂SO₃(40 mL), followed by saturated aq NaHCO₃

(40 mL), then brine, and finally was dried over Na₂SO₄,

filtered, and concentrated in vacuo. The mixture of â and R

Cyclo[2,2-d im eth yl-â-a la n yl-(2S)-2-h yd r oxy-4-m eth yl-

p en t a n oyl-(2E,5S,6S)-6-[(2R,3R)-3-[4-(ca r b oxym et h yl)-

ph en yl]oxir an yl]-5-h ydr oxy-2-h epten oyl-3-ch lor o-O-m eth -

yl-^D-tyr osyl] (51). To a 0 °C solution of aldehyde 50 (0.08 g,

0.112 mmol) in THF (3.2 mL) and H₂O (3.2 mL) were added

2-methyl-2-butene (3.2 mL), NaClO₂(0.081 g, 0.896 mmol), and

NaH₂PO₄‚H₂O (0.139 g, 1.0 mmol). The mixture was allowed

to warm to room temperature and was stirred vigorously for

5 h. The solution was diluted with CH₂Cl₂(10 mL), and the

layers were separated. The aqueous layer was extracted with

CH₂Cl₂(3 × 10 mL), and the combined organic layers were

dried over Na₂SO₄, filtered, and concentrated in vacuo. The

crude product was purified twice by radial PLC (silica gel,

5-25% MeOH/CH₂Cl₂) to give 0.03 g of the carboxylic acid 51

in 37% yield as a white solid: [R]²⁰_D+24.5 (c 0.33, MeOH); ¹H

NMR (300 MHz, CD₃OD) δ 7.75-7.71 (dd, 1 H, J ) 10.3, 1.9

Hz), 7.31-7.2 (m, 5 H), 7.16-7.13 (dd, 1 H, J ) 8.4, 1.9 Hz),

6.97-6.95 (d, 1 H, J ) 8.4 Hz), 6.8-6.6 (m, 1 H), 5.87-5.81

3006 J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14

Al-awar et al.

Sebolt, J .; Bissery, M.-C.; Mattes, K.; Dzubow, J .; Rake, J .; Perni,

R.; Wentland, M.; Coughlin, S.; Shaw, J . M.; Liversidge, G.;

Liversidge, E.; Bruno, J .; Sarpotdar, P.; Moore, R.; Patterson,

G. Tumor Models and the Discovery and Secondary Evaluation

of Solid Tumor Active Agents. Int. J . Pharmacogn. 1995, 33,

102-122. (b) Corbett, T. H.; Valeriote, F. A.; Demchik, L.;

Lowichik, N.; Polin, L.; Panchapor, C.; Pugh, S.; White, K.;

Kuchner, J .; Rake, J .; Wentland, M.; Golakoti, T.; Hetzel, C.;

Ogino, J .; Patterson, G.; Moore, R. Discovery of Cryptophycin-1

and BCN-183577: Examples of Strategies and Problems in the

Detection of Antitumor Activity in Mice. Invest. New Drugs 1997,

15, 207-218.

epoxides (54:46) was separated by reverse phase HPLC with

(50:50) CH₃CN:H₂O to provide 0.09 g of â epoxide 53 as a white

1

solid in 35% yield: [R]²⁰+26.0 (c 1.0, CHCl₃); H NMR (300

D

MHz, CDCl₃) δ 7.19-7.18 (d, 2 H, J ) 1.8 Hz), 7.1 (s, 1 H),

7.06-7.03 (dd, 1 H, J ) 8.5, 1.9 Hz), 6.85-6.82 (d, 1 H, J )

8.4 Hz), 6.82-6.7 (m, 1 H), 5.76-5.71 (d, 1 H, J ) 15.2 Hz),

5.49-5.47 (d, 1 H, J ) 7.8 Hz), 5.23-5.18 (m, 1 H), 4.88-4.84

(dd, 1 H, J ) 10.3, 3.6 Hz), 4.8-4.7 (m, 1 H), 3.88 (s, 3 H),

3.79 (d, 1 H, J ) 0.93 Hz), 3.45-3.38 (dd, 1 H, J ) 13.4, 8.6

Hz), 3.35-3.32 (d, 1 H, J ) 7.2 Hz), 3.2-3.0 (m, 3 H), 2.7 (s,

3 H), 2.6-2.4 (m, 2 H), 1.8-1.6 (m, 3 H), 1.4-1.3 (m, 1 H),

1.23 (s, 3 H), 1.16 (s, 3 H), 1.14-1.12 (d, 3 H, J ) 6.8 Hz),

0.89-0.87 (d, 3 H, J ) 6.5 Hz), 0.86-0.84 (d, 3 H, J ) 6.4 Hz);

¹³C NMR (62.5 MHz, CDCl₃) δ 177.9, 170.33, 170.3, 166.9,

165.0, 154.0, 151.9, 141.8, 130.8, 129.5, 128.2, 124.5, 122.4,

116.4, 112.3, 75.8, 71.1, 61.3, 56.1, 55.2, 54.3, 46.4, 42.7, 40.3,

39.3, 36.6, 35.2, 24.5, 22.85, 22.8, 22.6, 21.2, 19.1, 13.3; IR

(CHCl₃) 3425, 3007, 2964, 2936, 2874, 2841, 1751, 1711, 1682,

1604, 1528, 1503, 1485, 1464, 1303, 1259, 1185, 1152, 1067

cm^-1; HRMS (FAB, m/z) calcd for C₃₄H₄₅ClN₃O₈S (M⁺+ H)

690.2616, found 690.2621. Anal. Calcd for (C₃₄H₄₄ClN₃O₈S):

C, 59.16; H, 6.42; N, 6.09. Found: C, 59.11; H, 6.34; N, 6.27.

(7) (a) Golakoti, T.; Ogino, J .; Heltzel, C. E.; Husebo, T. L.; J ensen,

C. M.; Larsen, L. K.; Patterson, G. M. L.; Moore, R. E.; Mooberry,

S. L.; Corbett T. H.; Valeriote, F. A. Structure Determination,

Conformational Analysis, Chemical Stability Studies, and An-

titumor Evaluation of the Cryptophycins. Isolation of 18 New

Analogues from Nostoc sp. Strain GSV 224. J . Am. Chem. Soc.

1995, 117, 12030-12049. (b) Subbaraju G. V.; Golakoti, T.;

Patterson, G. M. L.; Moore, R. E. Three New Cryptophycins from

Nostoc sp. GSV 224. J . Nat. Prod. 1997, 60, 302-305.

(8) (a) Corbett, T. H.; Valeriote, F. A.; Demchik, L.; Polin, L.;

Panchapor, C.; Pugh, S.; White, K.; Knight, J .; J ones, J .; J ones,

L.; LoRusso, P.; Foster, B.; Wiegand, R. A.; Lisow, L.; Golakoti,

T.; Heltzel, C. E.; Ogino, J .; Patterson, G. M. L.; Moore, R. E.

Preclinical Anticancer Activity of Cryptophycin-8. J . Exp. Ther.,

Oncol. 1996, 1, 95-108. (b) Georg, G. I.; Ali, S. M.; Stella, V. J .;

Waugh, W. N.; Himes, R. H. Halohydrin Analogues of Crypto-

phycin 1: Synthesis and Biological Activity. Bioorg. Med. Chem.

Lett. 1998, 8, 1959-1962.

(9) (a) Kobayashi, M.; Aoki, S.; Ohyabu, N.; Kurosu, M.; Wang, W.;

Kitagawa, I. Arenastatin A, a Potent Cytotoxic Depsipeptide

from the Okinawan Marine Sponge Dysidea Arenaria. Tetrahe-

dron Lett. 1994, 35, 7969-7972. (b) Kobayashi, M.; Kurosu, M.;

Ohyabu, N.; Wang, W.; Fujii, S.; Kitagawa, I. The Absolute

Stereostructure of Arenastatin A, a Potent Cytotoxic Depsipep-

tide from the Okinawan Marine Sponge Dysidea Arenaria.

Chem. Pharm. Bull. 1994, 42, 2196-2198. (c) Kobayashi, M.;

Kurosu, M.; Wang, W.; Kitagawa, I. A Total Synthesis of

Arenastatin A, an Extremely Potent Cytotoxic Depsipeptide,

from the Okinawan Marine Sponge Dysidea Arenaria. Chem.

Pharm. Bull. 1994, 42, 2394-2396. (d) Kobayashi, M.; Wang,

W.; Ohyabu, N.; Kurosu, M.; Kitagawa, I. Improved Total

Synthesis and Structure-Activity Relationship of Arenastatin

A, a Potent Cytotoxic Spongean Depsipeptide. Chem. Pharm.

Bull. 1995, 43, 1598-1600. (e) Morita, K.; Koiso, Y.; Hashimoto,

Y.; Kobayashi, M.; Wang, W.; Ohyabu, N.; Iwasaki, S. Interaction

of Arenastatin A with Porcine Brain Tubulin. Biol. Pharm. Bull.

1997, 20, 171-174. (f) Eggen, MJ .; Mossman, C. J .; Buck, S. B.;

Nair, S. K.; Bhat, L.; Ali, A. M.; Reiff, E. A.; Boge, T. C.; Georg,

G. Total Synthesis of Cryptophycin-24 (Arenastatin A) Amenable

to Structural Modifications in the C16 Side Chain. J . Org. Chem.

2000, 65, 7792-7799.

Note Ad d ed a fter ASAP P ostin g

The version of this paper posted May 22, 2003, was

missing an author name in the byline. This name is

included in the new version posted J une 3, 2003.

Ack n ow led gm en t. We wish to thank Drs. Chuan

Shih and Michael Martinelli for their scientific leader-

ship and contributions to this work. We thank our

colleagues in Process R&D for helpful discussions and

for providing us with generous quantities of key inter-

mediates. We recognize the Physical Chemistry depart-

ment at Eli Lilly for their assistance. The authors also

thank Drs. Louis J ungheim, Chuan Shih, J ean Takeu-

chi, and Beverly Teicher for their editorial input.

Refer en ces

(1) (a) Moore, R. E. Cyclic Peptides and Depsipeptides from Cyano-

bacteria: A Review. J . Ind. Microbiol. 1996, 16, 134-143. (b)

Moore, R. E.; Corbett, T. H.; Patterson, G. M. L.; Valeriote, F.

A. The Search for New Antitumor Drugs from Blue-Green Algae.

Curr. Pharm. Design 1996, 2, 317-330.

(2) Schwartz, R. E.; Hirsch, C. F.; Sesin, D. F.; Flor, J . E.; Chartrain,

M.; Fromtling, R. E.; Harris, G. H.; Salvatore, M. J .; Liesch, J .

M.; Yudin, K. Pharmaceuticals from Cultured Algae. J . Ind.

Microbiol. 1990, 5, 113-124.

(3) Trimurtulu, G.; Ohtani, I.; Patterson, G. M. L.; Moore, R. E.;

Corbett, T. H.; Valeriote, F. A.; Demchik, L. Total Structures of

Cryptophycins, Potent Antitumor Depsipeptides from the Blue-

Green Alga Nostoc sp. Strain GSV 224. J . Am. Chem. Soc. 1994,

116, 4729-4737.

(4) Barrow, R. A.; Hemscheidt, T.; Liang, J .; Paik, S.; Moore, R. E.;

Tius, M. A. Total Synthesis of Cryptophycins. Revision of the

Structures of Cryptophycins A and C. J . Am. Chem. Soc. 1995,

117, 2479-2490.

(5) (a) Kerksiek, K.; Mejillano, M. R.; Schwartz, R. E.; Georg, G. I.;

Himes, R. H. Interaction of Cryptophycin 1 with Tubulin and

Microtubules. FEBS Lett. 1995, 377, 59-61. (b) Smith, C. D.;

Zhang, X. Mechanism of Action of Cryptophycin. J . Biol. Chem.

1996, 271, 6192-6198. (c) Mooberry, S. L.; Taoka, C. R.;

Busquets, L. Cryptophycin 1 Binds to Tubulin at a Site Distinct

from the Colchicine Binding Site and at a Site That May Overlap

the Vinca Binding Site. Cancer Lett. 1996, 107, 53-57. (d) Bai,

R.; Schwartz, R. E.; Kepler, J . A.; Pettit, G. R.; Hamel, E.

Characterization of the Interaction of Cryptophycin 1 with

Tubulin: Binding in the Vinca Domain, Competitive Inhibition

of Dolastatin 10 Binding, and an Unusual Aggregation Reaction.

Cancer Res. 1996, 56, 4398-4406. (e) Mooberry, S. L.; Busquets,

L.; Tien, G. Induction of Apoptosis by Cryptophycin 1, A New

Antimicrotubule Agent. Int. J . Cancer 1997, 73, 440-448. (f)

Panda, D.; Himes, R. H.; Moore, R. E.; Wilson, L.; J ordan, M. A.

Mechanism of Action of the Unusually Potent Microtubule

Inhibitor Cryptophycin 1. Biochem. 1997, 36, 12948-12953.

(6) (a) Corbett, T. H.; Valeriote, F. A.; LoRusso, P.; Polin, L.;

Panchapor, C.; Pugh, S.; White, K.; Knight, J .; Demchik, L.;

J ones, J .; J ones, L.; Lowichik, N.; Biernat, L.; Foster, B.;

Wozniak, A.; Lisow, L.; Valdivieso, M.; Baker, L.; Leopold, W.;

(10) Shih, C.; Gossett, L. S.; Gruber, J . M.; Grossman, C. S.; Andis,

S. L.; Schultz, R. M.; Worzalla, J . F.; Corbett, T. H.; Metz, J .

T.Synthesis and Biological Evaluation of Novel Cryptophycin

Analogues with Modification in the â-Alanine Region. Bioorg.

Med. Chem. Lett. 1999, 9, 69-74.

(11) (a) Panda, D.; DeLuca, K.; Williams, D.; J ordan, M. A.; Wilson,

L. Antiproliferative Mechanism of Action of Cryptophycin 52:

Kinetic Stabilization of Microtubule Dynamics by High-Affinity

Binding to Microtubule Ends. Proc. Natl. Acad. Sci. 1998, 95,

9313-9318. (b) Von Angerer, E. New Inhibitors of Tubulin

Polymerization. Expert Opin. Ther. Pat. 1999, 9, 1069-1081. (c)

Panda, D.; Ananthnarayan, V.; Larson, G.; Shih, C.; J ordan, M.

A.; Wilson, L. Interaction of the Antitumor Compound Crypto-

phycin-52 with Tubulin. Biochemistry 2000, 39, 14121-14127.

(d) Correia, J . J .; Lobert, S. Physiochemical Aspects of Tubulin-

interacting Antimitotic Drugs. Curr. Pharm. Design 2001, 7,

1213-1228. (e) Barbier, P.; Gregoire, C.; Devred, F.; Sarrazin,

M.; Peyrot, V. In Vitro Effect of Cryptophycin 52 on Microtubule

Assembly and Tubulin: Molecular Modeling of the Mechanism

of Action of a New Antimitotic Drug. Biochemistry 2001, 40,

13510-13519. (f) Fahy, J .; Hill, B. T. Tubulin-interacting Agents.

Epilogue. Curr. Pharm. Design 2001, 7, 1297-1301. (g) J ordan,

M. A. Mechanism of Action of Antitumor Drugs that Interact

with Microtubules and Tubulin. Curr. Med. Chem.: Anti-Cancer

Agents 2002, 2, 1-17.

(12) (a) Smith, C. D.; Zhang, X.; Mooberry, S. L.; Patterson, G. M.

L.; Moore, R. E. Cryptophycin: A New Antimicrotubule Agent

Active Against Drug-Resistant Cells. Cancer Res. 1994, 54,

3779-3784. (b) Wagner, M. M.; Paul, D. C.; Shih, C.; J ordan,

M. A.; Wilson, L.; Williams, D. In Vitro Pharmacology of

Cryptophycin 52 (LY355703) in Human Tumor Cell Lines.

Cancer Chemother. Pharmacol. 1999, 43, 115-125.

(13) (a) Salamonczyk, G. M.; Han, K.; Guo, Z.; Sih, C. J . Total

Synthesis of Cryptophycins Via a Chemoenzymatic Approach.

J . Org. Chem. 1996, 61, 6893-6900. (b) Gardinier, K. M.; Leahy,

Convergent Approach to Cryptophycin 52 Analogues

J ournal of Medicinal Chemistry, 2003, Vol. 46, No. 14 3007

J . W. Enantiospecific Total Synthesis of the Potent Antitumor

Macrolides Cryptophycins 1 and 8. J . Org. Chem. 1997, 62,

7098-7099. (c) Ali, S. M.; Georg, G. I. Formal Syntheses of

Cryptophycin A and Arenastatin A. Tetrahedron Lett. 1997, 38,

1703-1706. (d) Furuyama, M.; Shimizu, I. A Short Enantiose-

lective Synthesis of a Component of Cryptophycin A and Are-

nastatin A. Tetrahedron: Asymmetry 1998, 9, 1351-1357. (e)

Dhokte, U. P.; Khau, V. V.; Hutchison, D. R.; Martinelli, M. J .

A Novel Approach for Total Synthesis of Cryptophycins via

Asymmetric Crotylboration Protocol. Tetrahedron Lett. 1998, 39,

8771-8774. (f) Varie, D.; Brennan, J .; Briggs, B.; Cronin, J . S.;

Hay, D. A.; Rieck, J . A.; Zmijewski, M. J . Bioreduction of (R)-

Carvone and Regioselective Baeyer-Villiger Oxidations: Ap-

plication to the Asymmetric Synthesis of Cryptophycin Fragment

A. Tetrahedron Lett. 1998, 39, 8405-8408. (g) Eggen, M.; Georg,

G. I. Enantioselective Synthesis of a 3′-Dephenylcryptophycin

Synthon. Bioorg. Med. Chem. Lett. 1998, 8, 3177-3180. (h)

White, J . D.; Hong, J .; Robarge, L. A. Total Synthesis of

Cryptophycins-1, -3, -4, -24 (Arenastatin A), and -29, Cytotoxic

Depsipeptides from Cyanobacteria of the Nostocaceae. J . Org.

Chem. 1999, 64, 6206-6216. (i) Chakraborty, T. K.; Das, S.

Diastereoselective Opening of Trisubstituted Epoxy Alcohols:

Application in the Studies Directed Toward the Synthesis of

Octenoic Acid Moiety of Cryptophycins. J . Indian Chem. Soc.

1999, 76, 611-616. (j) Liang, J .; Hoard, D. W.; Khau, V. V.;

Martinelli, M. J .; Moher, E. D.; Moore, R. E.; Tius, M. A.

Synthesis of Unit A of Cryptophycin via a [2,3]-Wittig Rear-

rangement. J . Org. Chem. 1999, 64, 1459-1463. (k) Christopher,

J . A.; Kocienski, P. J .; Kuhl, A.; Bell, R. A Synthesis of

Cryptophycin 4 Using a Planar Chiral Molybdenum Cationic

Complex. Synlett. 2000, 4, 463-466. (l) Ghosh, A. K.; Bischoff,

A. A Convergent Synthesis of (+)-Cryptophycin B, a Potent

Antitumor Macrolide from Nostoc sp. Cyanobacteria Org. Lett.

2000, 2, 1575-1576. (m) Barrow, R. A.; Moore, R. E.; Li, L.-H.;

Tius, M. A. Synthesis of 1-Aza-cryptophycin 1, an Unstable

Cryptophycin. An Unusual Skeletal Rearrangement. Tetrahe-

dron 2000, 56, 3339-3351. (n) Liang, J .; Moher, E. D.; Moore,

R. E.; Hoard, D. W. Synthesis of Cryptophycin 52 Using the

Sharpless Asymmetric Dihydroxylation: Diol to Epoxide Trans-

formation Optimized for a Base-Sensitive Substrate. J . Org.

Chem. 2000, 65, 3143-3147. (o) Eggen, MJ .; Nair, S. K.; Georg,

G. I. Rapid Entry into the Cryptophycin Core Via an Acyl-â-

lactam Macrolactonization: Total Synthesis of Cryptophycin-

24. Org. Lett. 2001, 3, 1813-1815. (p) Smith, A. B., III; Cho, Y.

S.; Zawacki, L. E.; Hirschmann, R.; Pettit, G. R. First Generation

Design, Synthesis, and Evaluation of Azepine-Based Crypto-

phycin Analogues. Org. Lett. 2001, 3, 4063-4066. (q) Pousset,

C.; Haddad, M.; Larcheveque, M. Diastereocontrolled Synthesis

of Unit A of Cryptophycin. Tetrahedron 2001, 57, 7163-7167.

(r) Shih, C.; Al-awar, R. S.; Fray, A. H.; Martinelli, M. J .; Moher,

E. D.; Norman, B. H.; Patel, V. F.; Schultz, R. M.; Toth, J . E.;

Varie, D. L.; Corbett, T. H.; Moore, R. E. Synthesis and

(18) (a) Al-awar, R. S.; Ray, J ., Schultz, R., Andis, S., Worzalla, J .,

Kennedy, J . and Corbett, T. The Synthesis and Evaluation of

Novel Cryptophycin Analogues. Proc. Am. Assoc. Cancer Res.

1998, Abstract 2895, 39, 425. (b) Al-awar, R. S.; Shih, C., Ray,

J . E., Gossett, L. S., Gruber, J . M., Grossman, C. S., Schultz,

R., Andis, S., Worzalla, J ., Kennedy, J ., Corbett, T. The Synthesis

and Evaluation of Novel Cryptophycin Analogues. 10th NCI-

EORTC Symposium on New Drugs in Cancer Therapy 1998,

Abstract 340, 90.

(19) Maryanoff, B. E.; Reitz, A. B. The Wittig Olefination Reaction

and Modifications Involving Phosphoryl-Stabilized Carbanions.

Stereochemistry, Mechanism, and Selected Synthetic Aspects.

Chem. Rev. 1989, 89, 863-927.

(20) Schwarz, M.; Graminski, G. F.; Waters, R. M. Insect sex

pheromones. Stereospecific synthesis of (E)-13, 13-dimethyl-11-

tetradecen-1-ol acetate via a thiophenol-mediated olefin inver-

sion. J . Org. Chem. 1986, 51, 260-263.

(21) Ashton, W. T.; Chang, L. L.; Hannah, J .; Rasmusson, G. H.;

Tolman, R. L. Preparation of Antiviral Peptides. US Patent 89-

447357, 1989.

(22) Bayle-Lacoste, M.; Moulines, J .; Collignon, N.; Boumekouez, A.;

Tinguy-Moreaud, E.; Neuzil, E. Synthesis of 4-Phosphono- and

of 4-(Phosphonomethyl)-DL-Phenylalanine, Two Analogues of

O-Phosphotyrosine. Tetrahedron 1990, 46, 7793-7802.

(23) Mitsunobu, O. The Use of Diethyl Azodicarboxylate and Tri-

phenylphosphine in Synthesis and Transformation of Natural

Products. Synthesis 1981, 1-28.

(24) Nevill, C. R.; J akubowski, J . A.; Fuchs, P. L. Synthesis Via Vinyl

sulfones. Triply convergent Synthesis of Two Sets of Homochiral

Cyclopent[a]indene Carbacyclin Analogues. Bioorg. Med. Chem.

Lett. 1991, 1, 83-86.

(25) (a) Griffith, W. P.; Ley, S. V. Tetra-n-Propylammonium Perru-

thenate, a Mild and Convenient Oxidant for Alcohols. Aldrichim.

Acta 1990, 23, 13-19. (b) Ley, S. V.; Armstrong, A.; Diez-Martin,

D.; Ford, M. J .; Grice, P.; Knight, J . G.; Kolb, H. C.; Madin, A.;

Marby, C. Total Synthesis of the Anthelmintic Macrolide Aver-

mectin B1a. J . Chem. Soc., Perkin Trans. 1 1991, 4, 667-692.

(c) Crimmins, M. T.; Al-awar, R. S.; Vallin, I. M.; Hollis, W. G.;

O′Mahony, R.; Lever, J . G.; Bankaitis-Davis, D. M. Asymmetric

Total Synthesis of (+)-Milbemycin D. J . Am. Chem. Soc. 1996,

118, 7513-7528.

(26) Dess, D. B.; Martin, J . C. Readily Accessible 12-I-5 Oxidant for

the Conversion of Primary and Secondary Alcohols to Aldehydes

and Ketones. J . Org. Chem. 1983, 48, 4155-4156.

(27) (a) Bollag, D. M.; McQueney, P. A.; Zhu, J .; Hensens, O.; Koupal,

L.; Liesch, J .; Goetz, M.; Lazaridis, E.; Woods, C. M. Epothilones,

a New Class of Microtubule-Stabilizing Agents with a Taxol-

like Mechanism of Action. Cancer Res. 1995, 55, 2325-2333. (b)

Nicolaou, K. C.; Ninkovic, S.; Sarabia, F.; Vourloumis, D.; He,

Y.; Vallberg, H.; Finlay, M. R. V.; Yang, Z. Total Syntheses of

Epothilones A and B via a Macrolactonization-Based Strategy.

J . Am. Chem. Soc. 1997, 119, 7974-7991. (c) Meng, D.; Berti-

nato, P.; Balog, A.; Su, D.-S.; Kamenecka, T.; Sorensen, E.;

Danishefsky, S. J . Total Syntheses of Epothilones A and B. J .

Am. Chem. Soc. 1997, 119, 10073-10092.

(28) Dondoni, A.; Fantin, G.; Fogagnolo, M.; Dedici, A.; Pedrini, P.

Thiazolylmethylenetriphenylphosphorane and its Benzo Deriva-

tive: Stable and Practical Wittig Reagents for the Synthesis of

Vinylthiazoles and Vinylbenzothiazoles. Two-carbon Homologa-

tion of Aldehydes. Tetrahedron 1988, 44, 2021-2031. (e) Wil-

liams, D. R.; Brooks, D. A.; Moore, J . L.; Stewart, A. O. The

Preparation and Wittig Condensations of C-4 Thiazole Phos-

phonium Methylides. Tetrahedron Lett. 1996, 37, 983-986.

(29) (a) Shultz, R. M.; Shih, C.; Wood, P. L.; Harrison, S. D.; Ehlhardt,

W. J . Binding of the Epoxide Cryptophycin Analogue, LY355703

to Albumin and Its Effect on the In Vitro Antiproliferative

Activity. Oncol. Rep. 1998, 5, 1089-1094. (b) Song, D.; Hsu, L.-

F.; J essie, L.-S. Binding of Taxol to Plastic and Glass Containers

and Protein under in Vitro Conditions. J . Pharm. Sci. 1996, 85,

29-31.

Structure-activity Relationship Studies of Cryptophycins:

a

Novel Class of Potent Antimitotic Antitumor Depsipeptides. ACS

Symp. Ser. 2001, 796 (Anticancer Agents), 171-189. (s) Eggen,

MJ .; Georg, G. I. The Cryptophycins: Their Synthesis and

Anticancer Activity. Med. Res. Rev. 2002, 22, 85-101. (t)

Martinelli, M. J .; Vaidyanathan, R.; Khau, VV.; Staszak, M. A.

Reaction of Cryptophycin 52 with thiols. Tetrahedron Lett. 2002,

43, 3365-3367. (u) Tius, M. A. Synthesis of the Cryptophycins.

Tetrahedron 2002, 58, 4343-4367.

(14) Norman,B. H.; Hemscheidt, T.; Schultz, R. M.; Andis, S. L. Total

Synthesis of Cryptophycin Analogues. Isosteric Replacement of

the C-D Ester. J . Org. Chem. 1998, 63, 5288-5294.

(15) Patel, V. F.; Andis, S. L.; Kennedy, J . H.; Ray, J . E.; Schultz, R.

M. Novel Cryptophycin Antitumor Agents: Synthesis and Cy-

totoxicity of Fragment “B” Analogues. J . Med. Chem. 1999, 42,

2588-2603.

(16) Varie, D. L.; Shih, C.; Hay, D. A.; Andis, S. L.; Corbett, T. H.;

Gossett, L. S.; J anisse, S. K.; Martinelli, M. J .; Moher, E. D.;

Schultz, R. M.; Toth, J . E. Synthesis and Biological Evaluation

of Cryptophycin Analogues with Substitution at C-6 (Fragment

C Region). Bioorg. Med. Chem. Lett. 1999, 9, 369-374.

(17) (a) De Muys, J .; Rej, R.; Nguyen, D.; Go, B.; Fortin, S.; Lavallee,

J . Synthesis and In Vitro Cytotoxicity of Cryptophycins and

Related Analogues. Bioorg. Med. Chem. Lett. 1996, 6, 1111-

1116. (b) Rej, R.; Nguyen, D.; Go, B.; Fortin, S.; Lavallee, J . Total

Synthesis of Cryptophycins and Their 16-(3-Phenylacryloyl)

Derivatives. J . Org. Chem. 1996, 61, 6289-6295.

(30) 3-Chloroperoxybenzoic acid was purified before use according

to Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory

Chemicals, 3rd ed.; Pergamon Press: New York, 1988; p 123

(31) We thank Dr. Michael Martinelli and his group in Chemical

Process R & D Division of Lilly Research Laboratories for the

supply of Cryptophycin 53.

J M0203884

Article Doi

A convergent approach to cryptophycin 52 analogues: Synthesis and biological evaluation of a novel series of fragment A epoxides and chlorohydrins

DOI: 10.1021/jm0203884

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