Synthesis and biological assessment of simplified analogues of the potent microtubule stabilizer (+)-discodermolide

Bioorganic & Medicinal Chemistry 11 (2003) 3335–3357

Synthesis and Biological Assessment of Simpliﬁed Analogues of

the Potent Microtubule Stabilizer (+)-Discodermolide^§

Jose M. Mınguez,^aSun-Young Kim,^aKenneth A. Giuliano,^bRaghavan Balachandran,^c

Charitha Madiraju,^cBilly W. Day^aand Dennis P. Curran^a,*

^aDepartment of Chemistry, Chevron Science Center, 219 Parkman Avenue, Pittsburgh, PA 15260, USA

^bCellomics, Inc., Pittsburgh, PA 15238, USA

^cDepartment of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261, USA

Received 26 September2002; accepted 21 January 2003

Abstract—An eﬃcient, convergent and stereocontrolled synthesis of simpliﬁed analogues of the potent antimitotic agent (+)-dis-

codermolide has been achieved and several small libraries have been prepared. In all the libraries, the discodermolide methyl groups

at C14 and C16 and the C7 hydroxy group were removed and the lactone was replaced by simple esters. Other modiﬁcations

introduced in each series of analogues were related to C11, C17 and C19 of the natural product. Key elements of the synthetic

strategy included (a) elaboration of the main subunits from a common intermediate and (b) fragment couplings using Wittig reactions

to install the (Z)-oleﬁns. Library components were analyzed for microtubule-stabilizing actions in vitro, for displacement of

[³H]paclitaxel from its binding site on tubulin, for antiproliferative activity against human carcinoma cells, and for cell signaling

and mitotic spindle alterations by a multiparameter ﬂuorescence cell-based screening technique. The results show that even sig-

niﬁcant structural simpliﬁcation can lead to analogues with actions related to microtubule targeting.

Introduction

mitotic agent was discovered.⁴Discodermolide arrests

the cell cycle in the G2/M phase by stabilizing micro-

tubules and promoting the polymerization of tubulin.

This mechanism of action similarto that of paclitaxel

(Taxol), but discodermolide is the superior microtubule

stabilizer. Beyond its potent antiproliferative, micro-

tubule-stabilizing and apoptosis-inducing actions, dis-

codermolide has some advantages over other classes of

microtubule stabilizing agents (taxanes, epothilones,

eleutherobin), particularly in its eﬀects on isolated

tubulin. Importantly, (+)-discodermolide is active

against cancer cell lines expressing altered b-tubulins

that make the cells resistant to taxanes, and has the

unique property of being synergistic with paclitaxel.^5,6

(+)-Discodermolide (1) is a polyketide natural product

isolated from the marine sponge Discodermia dissoluta

by Gunasekera and co-workers in 1990.¹Its structure,

shown in Figure 1, comprises a linear polypropionate

backbone with 13 stereogenic centers, three (Z) double

bonds at C8–C9, C13–C14 and C21–C22, a tetra-

substituted lactone (C1–C5), a carbamate (C19) and a

terminal cis-diene (C21–C24). Discodermolide adopts a

U-shape conformation in the solid state and also in

solution to minimize the A(1,3) strain and syn-pentane

interactions.²

Discodermolide was initially found to be a potent

immunosuppressive agent and also displayed antifungal

activity.³Subsequently, its potent activity as an anti-

The remarkable biological proﬁle and novel structure of

discodermolide make it a promising candidate for clinical

development as a chemotherapeutic agent. These prop-

erties, along with the scarcity of the natural material,

have stimulated intensive synthetic eﬀort. To date, sev-

eral total syntheses of (+)-discodermolide and its

enantiomerhave been developed. These elegant synth-

eses have not proven simple—all requiring 30 or more

steps from commercially available starting materials to

*Corresponding author. Tel.: +1-412-624-8240; fax: +1-412-624-

9861; e-mail:

^§Information on synthesis and characterization of intermediates can

be seen in the supplementary data associated with this article, which be

found at doi:10.1016/S0968-0896(03)00186-X and at http://pre-

print.chemweb.com

6

doi:10.1016/S0968-0896(03)00186-X

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3336

arrive at the ﬁnal product. Consequently, few analogues

have been reported and structure–activity relationship

data are sparse.^6a,7

The methodology that we established forthe synthesis

inﬂuenced ourchoice of tagret analogues. The modiﬁ-

cations introduced in the design of the series of analo-

gues were:

Our goal in this study was to prepare simpler analogues

of discodermolide in fewer synthetic steps than neces-

sary for the natural product and the full length con-

geners reported to date. Herein, we describe libraries of

simpliﬁed discodermolide analogues that diﬀer from the

natural product in that the methyl groups at C14 and

C16 as well as C7 hydroxyl group are omitted and the

left side lactone moiety is replaced by simple esters (see

boxes in Fig. 1).

. Replacement of the lactone with simple esters

(domain A).

. Replacements of the carbamate on C19 with an

acetoxy group (domain B).

. Inversion of the conﬁguration of the C17 stereo-

center and derivatization of its hydroxy group,

keeping the hydroxy group at C19 free (domain

C).

. Inversion of the C11 stereocenter (domain D).

The biological activities of all the library members were

examined in order to expand structure–activity rela-

tionships. These and previously reported results⁸show

that even drastic structural simpliﬁcations and varia-

tions can lead to analogues with microtubule targeting

actions.

Synthetic plan

The synthetic design of the simpliﬁed analogues was

based on a highly convergent approach (Scheme 1).

Retrosynthetically, the polypropionate backbone was

divided into three fragments disconnecting at the C8–C9

and C13–C14 double bonds: a THP-protected phos-

phonium salt as the ‘left display’; a diene phosphonium

salt as the ‘right display’; and an aldehyde as the central

fragment or ‘scaﬀold’.

Results and Discussion

Design of structural and variations in the analogues:

Ourﬁsrt objective was to synthesize simpliﬁed analo-

gues of discodermolide bearing structural modiﬁcations

with respect to the natural product. The goal was to

study the inﬂuence that variations in some areas of the

molecule would provoke on microtubule assembly-

inducing properties, on the ability to displace paclitaxel

from its binding site on tubulin and on antiproliferative

actions.

A common stereochemical triad appears in the central

and right fragments that can be retrosynthetically

reduced to a common intermediate (CI). This homo-

allylic alcohol is readily prepared in high diastereomeric

excess from the commercially available methyl (S)-(+)-

3-hydroxy-2-methylpropionate (+)-2 via protection and

addition of a Roush chiral crotylboronates.⁹An inter-

esting feature of the synthesis arises from the pseudo

C2-symmetry of the targets. By switching the order of the

Wittig couplings, it is possible to synthesize analogues with

inversion of the conﬁguration of the C11 hydroxy group.

All the derivatives prepared retained key structural

properties of discodermolide including the two (Z)-

alkenes of the central core (C8 and C13 discodermolide

numbering) that give the molecule its characteristic

shape, and Z-diene ‘display’ (C21–24) (Fig. 2).

Synthesis of 11S, 17R, 19S-carbamoyloxy analogues

The synthetic methodology for all the analogue librar-

ies—with appropriate modiﬁcations in each series—

began with commercially available hydroxy ester (+)-2.

Protection as the TBS ether 3 (not shown) and reduc-

tion with DIBAL provided alcohol 4¹⁰(Scheme 2).

Swern oxidation¹¹then furnished aldehyde 5,¹⁰which

was used without puriﬁcation in an asymmetric crotyla-

tion reaction with Roush chiral (R,R)-diisopropyl tartrate

E-crotylboronate 6¹²to give the common intermediate,

homoallylic alcohol 7⁹(76% yield, 15:1 d.r.).

Figure 1. Discodermolide with areas targeted for simpliﬁcation in

boxes.

Protection of 7 as its p-methoxybenzyl (PMB) ether

underbasic conditions porvided oleﬁn

8, which was

oxidatively cleaved to yield the aldehyde 9 (not shown).

Wittig oleﬁnation reaction of 9 with the ylide derived

from phosphonium salt 10¹³(NaHMDS, THF,

ꢀ78 ^ꢁC!rt) aﬀorded oleﬁn 11 in 79% yield with excel-

lent Z-selectivity (>20:1).

We also explored the alternative Wittig reaction for the

synthesis of oleﬁn 11 (Scheme 3). Starting from 8, ozo-

Figure 2. Simpliﬁed analogues of discodermolide: domains of variation.

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3337

Scheme 1.

Scheme 4.

Scheme 2.

Scheme 5.

The synthesis of the C14–C24 cis diene fragment started

from the common intermediate 7. TBS protection of the

secondary alcohol (TBSOTf, Et₃N) and selective depro-

tection of the primary silyl ether with HF-pyridine

furnished alcohol 17 (90%, two steps). Dess–Martin

oxidation¹⁶provided aldehyde 18, which was treated

with 3-(t-butyldimethylsilyloxy)propyl magnesium bro-

mide 19 to give a 2:1 mixture of the epimeric alcohols 20

and 21 in 72% yield. The majorcompound 20 had the

desired R conﬁguration at the position equivalent to

discodermolide C17.⁸Protection of the hydroxy group

in 20 was achieved by using high-purity p-methoxy-

benzyl trichloroacetimidate and triﬂic acid (0.3 mol%)¹⁷

to provide oleﬁn 22 (Scheme 4). Introduction of the

terminal C21–C24 (Z)-diene unit was achieved by using

a three-step protocol. First, ozonolysis of 22 aﬀorded

aldehyde 23 (not shown). Nozaki–Hiyama reaction

Scheme 3.

nolysis and subsequent reduction with NaBH₄provided

alcohol 12, which was converted to the iodide 13 by

using modiﬁed Garegg conditions¹⁴(I₂, PPh₃, imida-

zole, Et₂O/PhH 2:1). Treatment of the iodide with

excess triphenylphosphine (5 equiv) in dry benzene at

80 ^ꢁC generated the phosphonium salt 14 (92% yield,

not shown). Unfortunately, this salt was more hygro-

scopic than the analogous salt 10, and its Wittig cou-

pling with the aldehyde 15¹⁵always gave oleﬁn 11 in

lower yield, especially when reactions were performed at

the multigram scale.

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3338

aﬀord 31 in 80% yield.

We also explored the alternative Wittig reaction,

switching the aldehyde and the phosphonium salt frag-

ment. Thus, alcohol 26 was iodinated to furnish iodide

32 (not shown), which upon treatment with PPh₃at

80 ^ꢁC in dry benzene provided the phosphonium salt 33

(Scheme 6). To build the right side in this coupling

scheme, the alcohol 28 was oxidized with Dess–Martin

reagent to aldehyde 34. The branched phosphonium salt

33 was extremely hygroscopic and very diﬃcult to han-

dle; its reaction with 34 aﬀorded 31 in low yields (7–

30%), especially on large scale. The main product of the

reaction was the corresponding diphenyl phosphine

oxide derived from 33.

The synthesis of the ﬁrst library of analogues was com-

pleted in a further ﬁve steps (Scheme 7). Deprotection of

the TBS etherof 31 with TBAF provided 35 (not

shown) with the free alcohol at position C19. The C19

carbamate moiety was installed following the Kocovsky

protocol.²⁰Reaction of 35 with trichloroacetyl isocya-

nate and in situ hydrolysis of the trichloroacetyl deriva-

tive with Al₂O₃provided the carbamate ester 36 (89%

yield, not shown). Deprotection of the THP ether with

catalytic pPTS in EtOH gave the alcohol 37. Esteriﬁca-

tion reactions of 37 with diﬀerent acyl chlorides (alka-

noyl, benzoyl, heteroaroyl) followed by the oxidative

removal of both PMB groups (DDQ, NaHCO₃,

CH₂Cl₂) provided the library of 11S, 17R, 19S-carba-

moyloxy analogues 38–43 (75–85% yield, two steps).

This ﬁrst library of discodermolide analogues was

obtained in about 5% overall yield (21 steps in the

longest linearsequence).

Scheme 6.

between this aldehyde and the allyl chromium reagent

generated in situ from 1-bromoallyl-trimethylsilane 24

and chromium chloride in THF¹⁸provided the inter-

mediate hydroxy silanes. These crude products were

then directly subjected to Peterson-type syn elimina-

tion¹⁹with NaH in THF to give the desired (Z)-diene 25

exclusively (76%, three steps from 22).

The second Wittig coupling scheme began with the

fragments 11 and 25. Deprotection of the TBS ether 11

(TBAF, THF) and Dess–Martin oxidation of the inter-

mediate alcohol 26 (not shown) furnished aldehyde 27

in high yield (89%, two steps). From the fragment 25,

selective primary silyl ether deprotection (HF-pyridine)

aﬀorded an alcohol 28 (not shown). Iodination (iodine,

PPh₃, imidazole, 89%) gave an iodide 29, which upon

treatment with excess of triphenylphosphine at 80 ^ꢁC

furnished the phosphonium salt 30 (Scheme 5). Depro-

tonation of 30 with sodium bis(trimethylsilyl)amide in

THF gave the ylide, which underwent (Z)-selective

Wittig coupling [(Z)/(E)>20:1] with aldehyde 27 to

With the exception of compound 42, these analogues

showed a weak but consistent ability to cause assembly

of isolated bovine brain tubulin (Table 1).⁸Moreover,

when present in a 2-fold molar excess over that of

[³H]paclitaxel stoichiometrically bound to preformed

microtubules induced to assemble with dideoxyGTP,

compounds 38–41 displaced appreciable amounts of the

radiolabel from the protein, suggesting they bound at a

site coincident with orovelrapping that of paclitaxel.

The analogues were not as potent as discodermolide in

Table 1. Biological activities of discodermolide analogues 38–43

Compd

MT assembly (%)^a

GI₅₀(mM)^b

Displacement of

[³H]paclitaxel (%)^c

MDA-MB231 (breast)

PC-3 (prostate)

2008 (ovarian)

38

39

40

41

42

43

13

5

14

10

<5

21

>100

100

7.2ꢂ0.4

12ꢂ1

11ꢂ1

6.6ꢂ0.3

3.0ꢂ0.8

15ꢂ2

7.7ꢂ0.5

5.8ꢂ0.7

19ꢂ3

19ꢂ4

32ꢂ6

23ꢂ9

23ꢂ1

18ꢂ1

64ꢂ2

37ꢂ1

2.6ꢂ0.9

1.5ꢂ1.0

8.0ꢂ0.3

7.1ꢂ0.6

41ꢂ2

>50

24ꢂ2

7.5ꢂ0.1

14ꢂ1

6.4ꢂ0.6

1

Paclitaxel

0.016ꢂ0.003

0.067ꢂ0.004

0.072ꢂ0.005

0.0024ꢂ0.0016

0.015ꢂ0.002

0.0092ꢂ0.0016

^aPercent assembly of bovine brain tubulin into microtubules induced by test agent at 10 mM versus that caused by 10 mM paclitaxel (100%) and by

DMSO (vehicle, 0%); single determinations at 30 ^ꢁC.

^bConcentration at which test agent caused 50% inhibition of cell growth; means (N=4 over5–10 concentrations)+S.D. after72 h of continuous

exposure to the agent.

^cPercent displacement by 4 mM test agent of 2 mM [³H]paclitaxel bound to microtubules formed from 2 mM tubulin and 20 mM dideoxyGTP.

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3339

Scheme 7.

Scheme 8.

Table 2. Biological activities of discodermolide analogues 46–48

Compd

MT assembly (%)^a

GI₅₀(mM)^b

Displacement of

[³H]paclitaxel (%)^c

MDA-MB231 (breast)

PC-3 (prostate)

2008 (ovarian)

46

47

48

18

9

8

22ꢂ2

20ꢂ2

25ꢂ4

21ꢂ2

14ꢂ1

15ꢂ1

20ꢂ2

14ꢂ2

19ꢂ2

17ꢂ1

24ꢂ2

6.8ꢂ1.9

^a,b,cSee legend of Table 1.

these two assays. Analogues 38–41 and 43 had 50%

growth inhibitory concentrations against human breast

(MDA-MB231), prostate (PC-3) and ovarian (2008)

carcinoma cells in the low micromolar range, whereas

compound 42 was much less active. These anti-

proliferative activities were considerably less than that

of (+)-discodermolide, whose potency against the

breast carcinoma cells is in the low nanomolar range.^4a

deprotection of the THP group to give primary

alcohol 45. Reaction with diﬀerent acyl chlorides and

ﬁnally deprotection of the p-methoxybenzyl groups

aﬀorded C19 acetoxy derivatives 46–48 (70–95%, two

steps).

The introduction of the acetoxy group at C19 in place

of the carbamate proved somewhat detremental to

biological activity (Table 2). Microtubule assembly-

inducing actions were decreased only slightly, but anti-

proliferative potencies decreased by a factor of 2–10.

The methodology established in the preparation of 38–

43 served as the basis for making several other series of

analogues.

Synthesis of 11S,17S,19S-carbamoyloxy analogues

Synthesis of 11S,17R,19S-acetoxy analogues

The 17S-analogues, with opposite conﬁguration of dis-

codermolide, were prepared from intermediate alcohol

21 (produced as minor product in the Grignard reaction

that formed 20). Alcohol 21 was protected as its PMB

ether with PMB-trichloroimidate to aﬀord 49. By fol-

lowing the same sequence used forthe 17 R series, the

cis-diene 51 was installed (75% yield, three steps).

The next modiﬁcation explored was the introduction of

an ester (acetoxy) group at C19 in place of the carba-

mate to check if the lattermoiety was essential for

activity (Scheme 8). Thus, the intermediate alcohol 35

was acetylated (acetyl chloride, pyridine, 95% yield)

to provide 44 (not shown), which was subjected to

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3340

Scheme 9.

Selective deprotection of the primary alcohol, iodina-

tion and subsequent formation of the corresponding

phosphonium salt provided 54 (Scheme 9). The Wittig

oleﬁnation reaction of the ylide derived from 54 and the

aldehyde 27 using NaHMDS as base aﬀorded the oleﬁn

55 in respectable yield (76%) and with good Z-selectiv-

ity. The carbamate was introduced as above to give 57

(not shown). Deprotection of the THP ether, esteriﬁca-

tion of the alcohol 58 with several acyl chlorides, and

oxidative removal of the PMB protective groups with

DDQ (54–85%, two steps) furnished the 17S,19S-car-

bamoyloxy analogues 59–62.

Synthesis of 11S,17R-carbamoyloxy or 11S,17R-acetoxy

analogues

While attempting PMB protection of alcohol 20, under

basic conditions we observed that the product 63 was

obtained in 91% yield (Scheme 10). The formation of 63

is due to a migration of the t-butyldimethyl silyl group²¹

from C19 alcohol to the less hindered C17⁸alcohol

underthe basic conditions of the reaction. Aftermigra-

tion, subsequent protection of the free C19 alcohol with

the PMB group occurred.

Following the same overall synthetic strategy, we were

therefore able to obtain analogues with a carbamate or

acetoxy groups at C17 from 63 (Scheme 10). Thus, the

introduction of the terminal diene from 63 provided 65

(66%, three steps). Selective deprotection of the primary

Although some microtubule formation-inducing and

paclitaxel-displacing activity was retained by these ana-

logues, a decrease in antiproliferative potency occurred

on inversion of the conﬁguration at C17 (Table 3).

Table 3. Biological activities of discodermolide analogues 59–62

Compd

MT assembly (%)^a

GI₅₀(mM)^b

Displacement of

[³H]paclitaxel (%)^c

MDA-MB231 (breast)

PC-3 (prostate)

2008 (ovarian)

59

60

61

62

7

24ꢂ1

20ꢂ2

>50

19ꢂ0

23ꢂ2

>50

23ꢂ1

27ꢂ1

21ꢂ3

>50

20ꢂ7

17ꢂ1

11ꢂ2

18ꢂ0

20ꢂ4

17

15

20

^a,b,cSee legend of Table 1.

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3341

Scheme 10.

Synthesis of 11R,17R-carbamoyloxy and 11R,17R-acetoxy

analogues

silyl etherfollowed by Dess–Martin oxidation aﬀorded

aldehyde 67. Oleﬁnation of 67 with the hygroscopic

phosphonium salt 33 furnished exclusively the (Z)-oleﬁn

68, although in a low yield (27%). The carbamate or

the acetoxy group at C17, and the diﬀerent esters in the

left display, were introduced as described above. After

ﬁnal PMB deprotection, the derivatives 74–78 were

formed.

Finally, by switching the order of the two Wittig cou-

plings, we could obtain inverted 11R analogues of dis-

codermolide. For the synthesis of these products, the

ﬁrst Wittig reaction coupled the central part and the

right fragment. Thus, the reaction of phosphonium salt

14 and aldehyde 67 with NaHMDS provided oleﬁn 79

in 61% yield with good cis-selectivity (Scheme 11).

Selective deprotection of the primary TBS ether (HF-

pyridine, 89%), iodination and treatment of the iodide

with excess of triphenylphosphine aﬀorded the salt 82

(not shown, 99%, two steps). Subsequent Wittig reac-

tion of 82 with aldehyde 15 furnished 83 (61% yield).

Following a similar route to that for the other series, the

carbamate or acetoxy groups were introduced at C17,

Analogues 74–77 caused some microtubule formation

from isolated tubulin, while compound 78 was inactive

in this assay (Table 4). Analogues 75 and 76 also dis-

placed a small amount of radiolabeled paclitaxel from

polymer. The presence of the carbamate moiety at C17

was not as detrimental to antiproliferative activity in

general as was inversion of stereochemistry at this posi-

tion, especially with the ovarian carcinoma cells.

Table 4. Biological activities of discodermolide analogues 74–78

Compd

MT assembly (%)^a

GI₅₀(mM)^b

Displacement of

[³H]paclitaxel (%)^c

MDA-MB231 (breast)

PC-3 (prostate)

2008 (ovarian)

74

75

76

77

78

12

13

18

10

11ꢂ2

15ꢂ0

>50

20ꢂ3

15ꢂ1

>50

2.7ꢂ3.5

21ꢂ2

15ꢂ3

12ꢂ5

10ꢂ4

21ꢂ3

16ꢂ2

>50

5.8ꢂ2.2

3.0ꢂ0.9

20ꢂ4

20ꢂ3

<5

25ꢂ6

>50

^a,b,cSee legend of Table 1.

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3342

Scheme 11.

Table 5. Biological activities of discodermolide analogues 89–98

Compd

MT assembly (%)^a

GI₅₀(mM)^b

Displacement of [³H]paclitaxel (%)^c

MDA-MB231 (breast)

PC-3 (prostate)

2008 (ovarian)

89

90

91

92

93

94

95

96

97

98

<5

>50

22ꢂ2

25ꢂ6

>50

33ꢂ1

20ꢂ1

>50

43ꢂ11

26ꢂ6

>50

31ꢂ4

33ꢂ1

26ꢂ4

>50

41ꢂ5

29ꢂ2

>50

21ꢂ2

19ꢂ2

17ꢂ1

18ꢂ1

15ꢂ1

17ꢂ2

20ꢂ5

16ꢂ2

>50

12ꢂ5

23ꢂ1

7.0ꢂ3.0

>50

^a,b,cSee legend of Table 1.

and diﬀerent alkanoyl and benzoyl esters were installed

in the left display. Afterthe PMB deprotections, 10 11 R

derivatives 89–98 were obtained in moderate to good

yields (33–95%, two steps).

(+)-discodermolide. Despite drastic modiﬁcations,

including the wholesale removal of the lactone and the

deletion of three other substituents, many of the com-

pounds retain biological activity and exhibit dis-

codermolide-like behavior in tubulin assays. Because of

this, important structure–activity information can be

gleaned from the substituent alterations within and

especially across libraries. In particular, analogues

lacking the carbamate moiety at C-19 are devoid of sig-

niﬁcant microtubule assembly-enhancing or cell growth

inhibitory eﬀects. Some detriment in biological activity

results when the carbamoyl moiety is moved from C-19

to C-17. Furthermore, an acetyl group is not bioisos-

teric with the carbamate. It appears that conﬁgurations

of the C-11 and C-17 hydroxyls are important factors in

both the interactions with tubulin as well as cell growth

inhibition. Most importantly, when the C-19 carbamate

Inversion of stereochemistry at C11 proved highly det-

rimental to biological activity (Table 5). None of the

compounds caused microtubule assembly in vitro. Ana-

logues 91, 92, 96 and 97 were weakly antiproliferative,

but the remainder of the compounds in this series were

essentially inactive in all biological assays.

Conclusion

In conclusion, we have prepared a series of 28 simpliﬁed

analogues of the antimitotic marine natural product

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3343

is intact and stereochemistries of C-11 and C-17 match

that of the natural product, the left-side lactone moiety

of discodermolide can be replaced with some success by

simple alkanoyl esters. This raises the possibility that

drastically simpliﬁed yet still highly active analogues of

discodermolide can be identiﬁed.

mL, 100.2 mmol) under argon. After 20 min of stirring

at room temperature, the mixture was cooled to ꢀ78 ^ꢁC

and then the aldehyde 5 (13.5 g, 66.83 mmol) in toluene

(56 mL) was slowly added by syringe. After 3 h at

ꢀ78 ^ꢁC, the reaction was quenched with NaBH₄(423

mg) in 6 mL of EtOH and warmed to 0 ^ꢁC. At this

point, 1 N NaOH (180 mL) was added. After stirring

vigorously for 30 min, the layers were separated, and

the aqueous phase was extracted with ether (5ꢃ200

mL). The combined organic layer was dried over anhy-

drous MgSO₄and concentrated under vacuum. The

residue was puriﬁed by chromatography (hexane/ether

19:1) to yield 13.1 g (76%) of the alcohol 7 as a yellow-

ish oil.^{9 1}H NMR (300 MHz, CDCl₃) 5.84 (ddd, 1H,

J=17.3, 10.3, 8.3 Hz), 5.12 (d, 1H, J=17.3 Hz), 5.09 (d,

1H, J=10.3 Hz), 3.77–3.68 (m, 2H), 3.55 (dd, 1H,

J=8.7, 2.2 Hz), 2.30–2.23 (m, 1H), 1.84–1.78 (m, 1H),

0.96 (d, 3H, J=7.0 Hz), 0.95 (d, 3H, J=7.0 Hz), 0.90 (s,

9H), 0.07 (s, 6H).

Experimental

Chemistry

General experimental methods. Unless otherwise noted,

all the reactions were performed under argon atmo-

sphere. All reagents used in chemical syntheses were

purchased from Aldrich Chemical Co. and used without

further puriﬁcation. Nuclear magnetic resonance (¹H

NMR and ¹³C NMR) spectra were obtained on Bruker

DPX-300 orDPX-500 spectormetesr at ambient tem-

perature in the solvent speciﬁed. Chemical shifts are

reported in parts per million (d) downﬁeld from tetra-

methylsilane and proton-proton coupling constants (J)

are in Hz. Infrared (IR) spectra were recorded on an

ATI Mattson Genesis Series Fourier transform spectro-

meter. Low resolution electron ionization (EI) mass

spectra were obtained on a Hewlett Packard-9000 GC–

MS, and high resolution spectra were obtained on a VG

70-G or Micromass Autospec double focusing instru-

ment underEI orfast atom bombardment (FAB)—with

NaI or m-nitrobenzyl alcohol (MNBA) as a matrix—

modes. Optical rotations were recorded on a Perkin–

Elmer241 digital polairmeterwith a sodium lamp at

(2S,3S,4S)-1-(tert-Butyldimethylsilanyloxy)-3-(4-methoxy-

benzyloxy)-2,4-dimethylhex-5-ene (8). To an ice-cold

suspension of sodium hydride (2.67 g, 95% purity,

106.45 mmol) in 10 mL of THF and 10 mL of DMF

was slowly added a solution of the alcohol 7 (8.66 g,

34.34 mmol) in 18 mL of THF. The mixture was stirred

for10 min and then PMBBr(16.31 mL, 89.28 mmol)

was added. After being stirred at ambient temperature

for 48 h, the reaction mixture was poured into 200 mL

of 10ꢃ PBS buﬀerand diluted with 300 mL of diethyl

ether. The organic layer was washed with 3ꢃ50 mL of

10ꢃPBS buﬀer, dried over K₂CO₃, concentrated and

chromatographed using hexane/ether 19:1 as eluent, to

provide 11.5 g (89%) of the PMB ether 8 as a colorless

oil.^{6a 1}H NMR (300 MHz, CDCl₃) 7.27 (d, 2H, J=8.6

Hz), 6.86 (d, 2H, J=8.6 Hz), 5.94 (ddd, 1H, J=17.8,

10.3, 6.9 Hz), 5.07 (d, 1H, J=17.8 Hz), 5.02 (d, 1H,

J=10.3 Hz), 4.54 (d, 1H, J=10.7 Hz), 4.47 (d, 1H,

J=10.7 Hz), 3.81 (s, 3H), 3.58–3.45 (m, 2H), 3.37 (dd,

1H, J=6.9, 3.9 Hz), 2.47 (ddq, 1H, J=6.9, 6.9, 6.9 Hz),

1.90–1.83 (m, 1H), 1.02 (d, 3H, J=6.9 Hz), 0.92–0.89

(m, 12H), 0.04 (s, 6H).

^ꢁC

ambient temperature and are reported as [a] l (cg/100

mL). Flash chromatography puriﬁcations were done on

silica gel (ICN silica gel 60, 230–400 mesh) with the

designated solvents. Reactions were monitored by thin

layer chromatography on Kieselgel 60 F₂₅₄silica gel

plates.

(2S,3S,4S)-(1-tert-Butyldimethylsilanyloxy)-2,4-dimethyl-

hex-5-en-3-ol (7). A solution of oxalyl chloride (9.3 mL,

106.4 mmol) in 440 mL of dry dichloromethane was

cooled to ꢀ78 ^ꢁC and DMSO (17.74 mL, 248.3 mmol)

was added dropwise. After 5 min, a solution of the

alcohol 4 (18.1 g, 88.7 mmol) in 90 mL of dichloro-

methane was slowly added to the solution at ꢀ78 ^ꢁC.

The resulting white slurry was stirred for 1 h and then

triethylamine (61.83 mL, 443.6 mmol) was slowly

added. After5 min, the white foam was wamr ed to

room temperature, and stirred at that temperature for 1

more hour. Then, the mixture was diluted with di-

chloromethane (400 mL), washed with ice-cold 0.5 N

HCl (800 mL) and with water(600 mL). The aqueous

phases were extracted with dichloromethane (3ꢃ100

mL), and the combined organic layer was dried over

MgSO₄and concentrated to give 15.5 g of (S)-3-(tert-

butyldimethylsilanyloxy)-2-methylpropionaldehyde 5,¹⁰

as a yellowish oil. The crude aldehyde was used for the

next step without further puriﬁcation.

(2R,3R,4S)-5-(tert-Butyldimethylsilanyloxy)-3-(4-methoxy-

benzyloxy)-2,4-dimethylpentanal (9). To

a

cooled

(ꢀ78 ^ꢁC) solution of 0.5 g (1.32 mmol) of the oleﬁn 8 in

12 mL of MeOH and 4 mL of CH₂Cl₂containing 0.1

mL of pyridine was bubbled a stream of ozone until the

colorof the solution became blue. The solution was

treated with 3.3 mL of dimethyl sulﬁde, stirred 30 min

at ꢀ78 ^ꢁC and then stirred at room temperature for 3 h.

The solution was concentrated under vacuum, diluted

with EtOAc (30 mL) and washed with NH₄Cl (20 mL),

H₂O (20 mL) and brine (20 mL). The organic phase was

dried over MgSO₄, and concentrated under vacuum, to

yield the aldehyde 9^6a(0.5 g) that was used crude in the

following reaction. ¹H NMR (300 MHz, CDCl₃) 9.75 (s,

1H), 7.24 (d, 2H, J=8.6 Hz), 6.87 (d, 2H, J=8.6 Hz),

4.55 (d, 1H, J=10.8 Hz), 4.48 (d, 1H, J=10.8 Hz), 3.86

(dd, 1H, J=7.5, 3.4 Hz), 3.79 (s, 3H), 3.59–3.54 (m,

2H), 2.78–2.70 (m, 1H), 1.91–1.82 (m, 1H), 0.99 (d, 3H,

J=6.7 Hz), 0.92 (d, 3H, J=6.9 Hz), 0.91 (s, 9H), 0.06

(s, 6H).

˚

To a slurry of powdered 4-A molecularsieves (1.18 g) in

56 mL of dry toluene was added (R,R)-diisopropyl tar-

trate (E)-crotylboronate 6¹²(1.0 M in toluene, 100.2

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3344

4-(Tetrahydropyran-2-yloxy)-butyl triphenylphosphonium

iodide (10). 4-Iodobutan-1-ol, tetrahydropyran-2-yl

ether¹³(2.7 g, 9.5 mmol) was dissolved in 5 mL of dry

benzene with PPh₃(7.47 g, 28.50 mmol) and the mixture

was heated at 80 ^ꢁC for36 h in the dakr. The solvent

was evaporated, and the residue was chromatographed

(CHCl₃to CHCl₃/MeOH 19:1) to provide 2.6 g (51%)

of the phosphonium salt 10¹³as a white solid that was

azeotropically dried with benzene, and dried under

vacuum before using. ¹H NMR (300 MHz, CDCl₃)

7.87–7.80 (m, 9H), 7.74–7.70 (m, 6H), 4.49 (dd, 1H,

J=6.0, 2.4 Hz), 3.85–3.70 (m, 4H), 3.58–3.42 (m, 2H),

2.04–1.96 (m, 2H), 1.88–1.63 (m, 4H), 1.58–1.36 (m,

4H).

colorless oil. IR (thin ﬁlm/NaCl) 2927, 2851, 1473, 1251,

1093, 1045, 835 cm^ꢀ1; ¹H NMR (300 MHz, CDCl₃) 5.86

(ddd, 1H, J=17.1, 10.5, 7.6 Hz), 5.02 (d, 1H, J=17.1

Hz), 4.99 (d, 1H, J=10.5 Hz), 3.72 (dd, 1H, J=5.1, 3.2

Hz), 3.48–3.38 (m, 2H), 2.38 (ddq, 1H, J=7.6, 6.9, 3.2

Hz), 1.84–1.75 (m, 1H), 1.02 (d, 3H, J=6.9 Hz), 0.93 (s,

9H), 0.92 (s, 9H), 0.88 (d, 3H, J=6.9 Hz), 0.08 (s, 6H),

0.06 (s, 6H); ¹³C NMR (75 MHz, CDCl₃) 141.7, 113.9,

75.2, 66.0, 43.2, 39.2, 25.8, 17.7, 17.0, 11.7, ꢀ4.2, ꢀ5.3;

MS (EI, m/z) 372 (M)⁺, 371, 357, 329, 317, 315, 143, 73;

HRMS (EI) calcd forC ₁₆H₃₇O₂Si₂(MꢀC₄H₇)⁺

317.2332, found 317.2326; [a]²_D⁰+2.0 (c 0.75, CHCl₃).

(2S,3S,4S)-3-(tert-Butyldimethylsilanyloxy)-2,4-dimethyl-

hex-5-en-1-ol (17). To a solution of TBS ether 16 (5.0 g,

13.7 mmol) in 60 mL of THF was slowly added HF-pyr/

pyr(250 mL, prepared by slow addition of 130 mL of

pyridine to 34 mL of THF-pyr at 0 ^ꢁC followed by

dilution with 320 mL of THF) via cannula. The mixture

was stirred 12 h at room temperature and then, it was

slowly quenched with saturated NaHCO₃(600 mL).

The aqueous layer was separated and extracted with di-

chloromethane (3ꢃ300 mL). The combined organic

extracts were washed with saturated CuSO₄(3ꢃ200

mL), dried over anhydrous MgSO₄, and concentrated.

Flash chromatography of the crude residue using hex-

ane/ether3:2 as eluent aﬀodred 3.38 g (95%) of the

alcohol 17 as a colorless oil. IR (thin ﬁlm, NaCl) 3386,

(Z)-(2S,3S,4S)-3-(4-Methoxybenzyloxy)-2,4-dimethyl-9-

(tetrahydropyran-2-yloxy)non-5-en-1-ol, tert-butyldime-

thylsilyl ether (11). At 0 ^ꢁC, to a solution of phospho-

nium salt 10 (1 g, 1.83 mmol) dried with benzene and

undervacuum, in THF (1.5 mL) was slowly added

NaHMDS (1.0 M in THF, 2 mL, 2 mmol), and the

resulting red solution was stirred for 50 min at room

temperature. The solution was then cooled to ꢀ78 ^ꢁC,

and a solution of the aldehyde 9 (0.5 g, 1.28 mmol) in

1.5 mL of THF was added dropwise. The reaction was

stirred for 20 min at ꢀ78 ^ꢁC and warmed to room tem-

perature. After 5 h of stirring at room temperature, the

reaction was quenched with saturated NH₄Cl (25 mL)

and extracted with ether (3ꢃ25 mL). The combined

organic layer was washed with saturated NaCl (2ꢃ25

mL), dried over MgSO₄, and concentrated under

vacuum. Flash chromatography of the resulting residue

gave 0.55 g (81%) of the Wittig product 11 as a colorless

oil. IR (thin ﬁlm/NaCl) 2928, 1612, 1514, 1249, 1036

2958, 2885, 1637, 1472, 1359, 1253, 1043 cm^ꢀ^{1 1}H

;

NMR (300 MHz, CDCl₃) 5.93 (ddd, 1H, J=17.1, 10.3,

7.9 Hz), 5.05 (d, 1H, J=17.1 Hz), 5.01 (d, 1H, J=10.3

Hz), 3.70–3.63 (m, 2H), 3.48 (dd, 1H, J=10.5, 5.7 Hz),

2.47–2.37 (m, 1H), 1.96–1.86 (m, 1H), 1.04 (d, 3H,

J=6.9 Hz), 0.92 (s, 9H), 0.89 (d, 3H, J=6.9 Hz), 0.09

(s, 3H), 0.08 (s, 3H); ¹³C NMR (75 MHz, CDCl₃) 141.5,

114.2, 76.8, 65.5, 42.0, 39.5, 25.9, 18.1, 17.9, 12.2, ꢀ4.0,

ꢀ4.2; MS (EI m/z) 258 (M)⁺, 257, 243, 227, 203, 159,

145, 119; HRMS (EI) calcd forC ₁₄H₃₀O₂Si (M)⁺

258.2015, found 258.2021; [a]²_D⁰ꢀ0.6 (c 0.65, CHCl₃).

1

cm^ꢀ1; H NMR (300 MHz, CDCl₃) 7.26 (d, 2H, J=8.5

Hz), 6.86 (d, 2H, J=8.5 Hz), 5.48–5.34 (m, 2H), 4.57–

4.54 (m, 1H), 4.56 (d, 1H, J=10.6 Hz), 4.45 (d, 1H,

J=10.6 Hz), 3.89–3.81 (m, 1H), 3.80 (s, 3H), 3.75–3.69

(m, 1H), 3.55–3.34 (m, 5H), 2.78 (ddq, 1H, J=6.8, 6.8,

6.8 Hz), 2.26–2.05 (m, 2H), 1.88–1.82 (m, 2H), 1.76–

1.51 (m, 7H), 0.96 (d, 3H, J=6.8 Hz), 0.92 (d, 3H,

J=6.8 Hz), 0.91 (s, 9H), 0.05 (s, 3H), 0.04 (s, 3H); ¹³C

NMR (75 MHz, CDCl₃) 158.8, 133.7, 131.7, 129.1,

128.7, 113.5, 98.8, 82.9, 74.1, 67.0, 65.7, 62.2, 55.2, 38.5,

34.9, 30.7, 29.8, 25.9, 25.5, 24.2, 19.6, 18.4, 18.2, 11.4,

ꢀ5.4; MS (EI, m/z) 520 (M)⁺, 435, 379, 205, 121;

HRMS (EI) calcd forC ₂₅H₄₃O₄Si (MꢀTHP)⁺

435.2930, found 435.2929.

(2R,3S,4S)-3-(tert-Butyldimethylsilanyloxy)-2,4-dimethyl-

hex-5-enal (18). To a solution of the alcohol 17 (3.38 g,

13.10 mmol) in 35 mL of dichloromethane at 0 ^ꢁC was

added 7.2 g (17.0 mmol) of Dess–Martin periodinane.

The resulting slurry was stirred at room temperature for

1 h, diluted with ether(200 mL), and pouerd into 100

mL of saturated NaHCO₃and 100 mL of saturated

Na₂S₂O₃. The layers were separated and the organic

layerwas washed with saturated NaHCO ₃(3ꢃ100 mL),

dried over anhydrous MgSO₄, ﬁltered, and con-

centrated, to yield the aldehyde 18 (3.3 g) that was used

crude in the following reaction without further pur-

iﬁcation. ¹H NMR (300 MHz, CDCl₃) 9.18 (s, 1H),

5.87–5.75 (m, 1H), 5.04 (d, 1H, J=10.6 Hz), 5.03 (d,

1H, J=17.4 Hz), 4.00 (dd, 1H, J=4.4, 4.4 Hz), 2.63–

2.55 (m, 1H), 2.47–2.40 (m, 1H), 1.10 (d, 3H, J=7.0

Hz), 1.05 (d, 3H, J=6.9 Hz), 0.90 (s, 9H), 0.09 (s, 3H),

0.04 (s, 3H).

(2S,3S,4S)-1-(tert-Butyldimethylsilanyloxy)-2,4-dimethyl-

5-en-3-ol, tert-butyldimethyl silyl ether (16). To a cooled

(0 ^ꢁC) solution of 3.50 g (13.56 mmol) of the alcohol 7 in

40 mL of dichloromethane was added 3.77 mL (27.13

mmol) of triethylamine followed by the addition drop-

wise of TBSOTf (5.38 g, 20.35 mmol). The solution was

stirred at 0 ^ꢁC for30 min when 40 mL of satuarted

NaCl was added. The mixture was warmed to ambient

temperature, the aqueous phase was separated, and

extracted with 3ꢃ50 mL of dichloromethane. The com-

bined organic layers were dried over MgSO₄, ﬁltered,

and concentrated under vacuum. The residue was pur-

iﬁed by column chromatography (hexane to hexane/

ether19:1) to give 4.9 g (95%) of the silyl ether 16 as a

(4R,5S,6S,7S)-1,6-Bis(tert-butyldimethylsilanyloxy)-5,7-

dimethylnon-8-en-4-ol (20). A ﬂame-dried 3-neck ﬂask

equipped with a reﬂux condenser was charged with Mg

(330 mg, 13.4 mmol), 1,2-dibromoethane (0.1 mL), and

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3345

THF (2.0 mL). The mixture was brieﬂy heated at 50 ^ꢁC

and cooled to room temperature. At this point, a solu-

tion of (3-bromopropoxy)-tert-butyldimethylsilane²²

(2.71 g, 10.8 mmol) in 50 mL of THF was slowly added,

and the resulting gray mixture was stirred for 1 h at

ambient temperature. A solution of the crude aldehyde

18 (8.98 mmol) in 20 mL of THF was then slowly added

to the mixture. After 10 h of stirring, the reaction was

diluted with ether(30 mL) and quenched with saturated

NH₄Cl (100 mL). The separated aqueous layer was

extracted with ether (3ꢃ100 mL), and the combined

organics were washed with saturated NaCl (2ꢃ100 mL)

and dried over MgSO₄. Chromatography of the residue

(hexane/ether19:1) aﬀodred 950 mg (24%) of the less

polaralcohol 21 and 1.83 g (48%) of the more polar

alcohol 20. IR (thin ﬁlm, NaCl) 2978, 2935, 1613, 1383,

1123, 845 cm^ꢀ1; ¹H NMR (300 MHz, CDCl₃) 5.93 (ddd,

1H, J=17.2, 11.6, 7.7 Hz), 5.04 (d, 1H, J=17.2 Hz),

5.02 (d, 1H, J=11.6 Hz), 3.73–3.65 (m, 4H), 2.47 (ddq,

1H, J=7.7, 6.9, 3.7 Hz), 2.36 (bs, 1H), 1.68–1.51 (m,

5H), 1.05 (d, 3H, J=6.9 Hz), 0.93 (s, 9H), 0.92 (d, 3H,

J=7.0 Hz), 0.91 (s, 9H), 0.08 (s, 6H), 0.06 (s, 6H); ¹³C

NMR (75 MHz, CDCl₃) 141.7, 114.8, 78.5, 72.4, 63.6,

42.6, 41.7, 32.5, 29.9, 26.3, 26.2, 18.5, 17.5, 9.6, ꢀ3.4,

ꢀ3.8, ꢀ5.1; MS (EI, m/z) 430 (M)⁺, 261, 203, 185, 145,

107, 75; HRMS (FAB) calcd forC ₂₃H₅₁O₃Si₂(M+H)⁺

431.3376, found 431.3378; [a]²_D⁰+0.7 (c 1.09, CHCl₃).

2.26 (m, 1H), 1.84–1.74 (m, 1H), 1.65–1.44 (m, 4H), 0.93

(d, 3H, J=7.2 Hz), 0.91–0.90 (m, 21H), 0.05 (s, 12H);

¹³C NMR (75 MHz, CDCl₃) 159.2, 141.3, 131.1, 129.4,

114.3, 113.7, 79.9, 75.7, 70.9, 63.2, 55.2, 43.0, 38.8, 30.3,

29.7, 28.9, 27.1, 26.2, 26.0, 16.9, 11.0, ꢀ3.4, ꢀ3.7, ꢀ5.3;

MS (EI, m/z) 550 (M⁺), 535, 493, 373, 225, 199, 122;

t

HRMS (EI) calcd forC ₂₇H₄₉O₄Si₂(Mꢀ Bu)⁺493.3169,

found 493.3168; [a]²_D⁰ꢀ9.4 (c 0.875, CHCl₃).

(2R,3R,4S,5R)-3,8-Bis(tert-butyldimethylsilanyloxy)-5-

(4-methoxybenzyloxy)-2,4-dimethyloctanal (23). To a

cooled (ꢀ78 ^ꢁC) solution of the alkene 22 (895 mg, 1.63

mmol) in 24 mL of MeOH and 8 mL of dichloro-

methane containing 0.2 mL of pyridine was bubbled a

stream of ozone until the color of the solution became

blue. The solution was treated with 6 mL of dimethyl

sulﬁde, stirred for 30 min at ꢀ78 ^ꢁC and then 3 h at

room temperature. The solution was concentrated

undervacuum, diluted with EtOAc (75 mL) and washed

with saturated NH₄Cl (50 mL), H₂O (50 mL) and brine

(50 mL). The organic layer was dried over anhydrous

MgSO₄, ﬁltered and evaporated under vacuum, to give

the aldehyde 23, which was used immediately without

1

further puriﬁcation. H NMR (300 MHz, CDCl₃) 9.69

(s, 1H), 7.22 (d, 2H, J=8.6 Hz), 6.85 (d, 2H, J=8.6

Hz), 4.45 (d, 1H, J=11.1 Hz), 4.28 (d, 1H, J=11.1 Hz),

3.94 (dd, 1H, J=5.5, 4.0 Hz), 3.79 (s, 3H), 3.60 (t, 2H,

J=6.0 Hz), 3.40–3.34 (m, 1H), 2.66–2.58 (m, 1H), 1.92–

1.84 (m, 1H), 1.67–1.59 (m, 2H), 1.55–1.45 (m, 2H), 1.02

(d, 3H, J=7.0 Hz), 0.98 (d, 3H, J=7.0 Hz), 0.89 (s,

9H), 0.86 (s, 9H), 0.05 (s, 3H), 0.04 (s, 9H).

(4S,5S,6S,7S)-1,6-Bis(tert-butyldimethylsilanyloxy)-5,7-

dimethylnon-8-en-4-ol (21). IR (thin ﬁlm, NaCl) 2980,

1

1614, 1444, 1382, 1126, 845 cm^ꢀ1; H NMR (300 MHz,

CDCl₃) 5.98 (ddd, 1H, J=17.3, 10.3, 7.9 Hz), 5.04 (d,

1H, J=17.3 Hz), 5.00 (d, 1H, J=10.3 Hz), 3.84 (dd, 1H,

J=4.2, 2.5 Hz), 3.72–3.66 (m, 3H), 3.46 (bs, 1H), 2.52–

2.42 (m, 1H), 1.74–1.62 (m, 4H), 1.37–1.30 (m, 1H), 1.04

(d, 3H, J=7.0 Hz), 0.92 (s, 9H), 0.90 (s, 9H), 0.84 (d,

3H, J=7.0 Hz), 0.11 (s, 3H), 0.08 (s, 3H), 0.06 (s, 6H);

¹³C NMR (75 MHz, CDCl₃) 141.8, 114.5, 78.5, 72.8,

63.7, 42.8, 41.9, 31.9, 28.5, 26.3, 26.2, 18.9, 18.5, 12.8,

ꢀ3.8, ꢀ4.0, ꢀ5.1; MS (EI, m/z) 430 (M)⁺, 241, 185,

149, 107, 75; [a]_D²⁰ꢀ14.6 (c 0.675, CHCl₃).

(Z)-(4R,5S,6S,7S)-1,6-Bis(tert-butyldimethylsilanyloxy)-

5,7-dimethylundeca-8,10-dien-4-ol, 4-methoxybenzyl ether

(25). To a solution of aldehyde 23 (1.63 mmol) in THF

(25 mL) was added (1-bromoallyl)-trimethylsilane 24^18a

(1.57 g, 8.13 mmol). The mixture was added to a sus-

pension of CrCl₂(1.66 g, 13.50 mmol) in 16 mL of THF

via cannula and stirred at room temperature for 16 h.

The solvent was removed in vacuo, and the brownish

residue was taken up in a minimal amount of ether. The

chromium salts were precipitated with hexane and the

mixture was ﬁltered through a short pad of Celite

washing with hexane (300 mL). The ﬁltrate was con-

centrated, and the oily brown residue was used imme-

diately for the next reaction. This product (1.63 mmol)

in THF (40 mL) was cooled to 0 ^ꢁC, and NaH (411 mg,

95% purity, 16.3 mmol) was added in one portion. The

ice bath was removed after 15 min, and the mixture was

stirred for 1 h at room temperature, at which time

anotherpotrion of NaH (411 mg) was added. The

resulting suspension was stirred for an additional 2 h,

cooled to 0 ^ꢁC, quenched carefully with H₂O (50 mL),

and extracted with ether (3ꢃ50 mL). The combined

organics were washed with brine (50 mL), dried over

MgSO₄and concentrated. The residue was chromato-

graphed on silica gel (hexane/ether 9:1) to aﬀord the cis-

diene 25 as a colorless oil (0.71 g, 76% overall yield for

three steps from oleﬁn 22). IR (thin ﬁlm, NaCl) 2954,

2931, 2857, 1608, 1513, 1463, 1251, 1098, 1047 cm^ꢀ1; ¹H

NMR (300 MHz, CDCl₃) 7.26 (d, 2H, J=8.6 Hz), 6.89

(d, 2H, J=8.6 Hz), 6.41 (ddd, 1H, J=16.7, 11.0, 10.1

Hz), 5.97 (dd, 1H, J=11.0, 11.0 Hz), 5.50 (dd, 1H,

(4R,5S,6S,7S)-1,6-Bis(tert-butyldimethylsilanyloxy)-5,7-

dimethylnon-8-en-4-ol, 4-methoxybenzyl ether (22). To a

solution of the alcohol 20 (1.01 g, 2.35 mmol) and

p-methoxybenzyltrichloroacetimidate (1.31 g, 4.65

mmol) in 15 mL of etherat ꢀ10 ^ꢁC was added dropwise

triﬂic acid (0.3 mol%, 0.25 mL of a 0.028 N solution in

Et₂O). After 24 h at room temperature, a second allot-

ment of acetimidate was added (1.31 g) and after48 h,

the reaction was quenched with saturated NaHCO₃(30

mL). The aqueous phase was extracted with ether (3ꢃ25

mL) and the combined organic layers were washed with

brine (2ꢃ25 mL). Afterdyring overMgSO

and con-

4

centration, the residue was puriﬁed by chromatography

(hexane/ether9:1) to give 0.90 g (69%) of the PMB

ether 22. IR (thin ﬁlm, NaCl) 2942, 2857, 1613, 1514,

1463, 1250, 1098, 1041 cm^ꢀ^{1 1}H NMR (300 MHz,

;

CDCl₃) 7.26 (d, 2H, J=8.8 Hz), 6.89 (d, 2H, J=8.8

Hz), 5.83 (ddd, 1H, J=17.7, 10.3, 7.6 Hz), 4.98 (d, 1H,

J=10.3 Hz), 4.96 (d, 1H, J=17.7 Hz), 4.45 (d, 1H,

J=11.1 Hz), 4.37 (d, 1H, J=11.1 Hz), 3.82 (s, 3H),

3.64–3.57 (m, 3H), 3.30 (dt, 1H, J=5.3, 5.3 Hz), 2.34–

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3346

J=10.3, 10.3 Hz), 5.15 (dd, 1H, J=16.7, 1.8 Hz), 5.06 (d,

1H, J=10.1 Hz), 4.51 (d, 1H, J=11.4 Hz), 4.35 (d, 1H,

J=11.4 Hz), 3.81 (s, 3H), 3.63–3.57 (m, 3H), 3.28 (dt,

1H, J=5.5, 5.5 Hz), 2.70 (ddq, 1H, J=10.3, 6.9, 3.2 Hz),

1.73–1.58 (m, 3H), 1.50–1.44 (m, 2H), 0.94 (d, 3H, J=6.9

Hz), 0.93–0.91 (m, 21H), 0.06 (s, 6H), 0.05 (s, 6H); ¹³C

NMR (75 MHz, CDCl₃) 159.1, 134.8, 132.5, 131.0, 129.5,

128.9, 117.1, 113.7, 78.9, 76.6, 70.7, 63.2, 55.2, 40.0, 36.4,

31.6, 28.7, 26.2, 26.0, 18.9, 18.5, 18.3, 10.9, ꢀ3.3, ꢀ3.4,

ꢀ5.3; MS (EI, m/z) 576 (M⁺), 519, 467, 387, 357, 293,

(28). To a solution of TBS ether 25 (0.68 g, 1.18 mmol)

in THF (2.5 mL) was slowly added HF-pyr/pyr (21.7

mL, prepared by slow addition of 6.5 mL of pyridine to

1.66 mL of THF-pyrat 0 ^ꢁC followed by dilution with

16.0 mL of THF) via cannula. The mixture was stirred

for 12 h at room temperature and then it was slowly

quenched with saturated NaHCO₃(50 mL). The aqu-

eous layer was separated and extracted with dichloro-

methane (3ꢃ50 mL). The combined organic extracts

were washed with saturated CuSO₄(3ꢃ50 mL), dried

overanhydrous MgSO ₄, and concentrated. Flash chro-

matography of the crude residue using hexane/ether 3:7

as eluent aﬀorded 0.46 g (85%) of the alcohol 28 as a

colorless oil. IR (thin ﬁlm, NaCl) 3385, 2929, 2859,

1612, 1513, 1462, 1248, 1042 cm^ꢀ1; ¹H NMR (300 MHz,

CDCl₃) 7.26 (d, 2H, J=8.6 Hz), 6.89 (d, 2H, J=8.6

Hz), 6.43 (ddd, 1H, J=16.6, 11.0, 10.2 Hz), 5.98 (dd,

1H, J=11.0, 11.0 Hz), 5.50 (dd, 1H, J=10.4, 10.4 Hz),

5.17 (d, 1H, J=16.6 Hz), 5.07 (d, 1H, J=10.2 Hz), 4.49

(d, 1H, J=11.3 Hz), 4.38 (d, 1H, J=11.3 Hz), 3.82 (s,

3H), 3.63–3.58 (m, 3H), 3.30 (dt, 1H, J=5.3, 5.3 Hz),

2.73 (ddq, 1H, J=10.4, 6.9, 3.3 Hz), 1.79–1.71 (m, 1H),

1.66–1.47 (m, 4H), 0.95 (d, 3H, J=6.9 Hz), 0.94 (d, 3H,

J=6.9 Hz), 0.91 (s, 9H), 0.07 (s, 3H), 0.06 (s, 3H); ¹³C

NMR (75 MHz, CDCl₃) 159.1, 134.9, 132.4, 130.7,

129.6, 128.9, 117.2, 113.7, 79.0, 76.3, 70.9, 62.9, 55.2,

39.7, 36.5, 28.6, 27.2, 26.2, 18.7, 18.4, 11.0, ꢀ3.3, ꢀ3.5;

MS (EI, m/z) 462 (M⁺), 405, 345, 225, 173, 137, 122, 73;

t

225, 121; HRMS (EI) calcd forC ₂₉H₅₁O₄Si₂(Mꢀ Bu)⁺

519.3326, found 519.3332; [a]²_D⁰ꢀ18.8 (c 0.75, CHCl₃).

(Z)-(2S,3S,4S)-3-(4-Methoxybenzyloxy)-2,4-dimethyl-9-

(tetrahydropyran-2-yl-oxy)-non-5-en-1-ol (26). To

a

solution of 0.69 g (1.32 mmol) of 11 in 88 mL of dry

THF, was added slowly TBAF (1.0 M in THF, 13.2 mL,

13.2 mmol). The mixture was stirred at room tempera-

ture for 1 h, quenched with saturated NaCl (100 mL)

and extracted with EtOAc (3ꢃ100 mL). The combined

organic layer was washed with water (100 mL), brine

(100 mL), dried over MgSO₄and concentrated under

vacuum. The residue was puriﬁed by chromatography

(hexane/EtOAc 4:1 to hexane/EtOAc 1:1) to yield the

alcohol 26 as a colorless oil (0.48 g, 89%). IR (thin ﬁlm/

NaCl) 3436, 2939, 1613, 1514, 1248, 1034 cm^ꢀ^{1 1}H

;

NMR (300 MHz, CDCl₃) 7.26 (d, 2H, J=8.6 Hz), 6.86

(d, 2H, J=8.6 Hz), 5.52–5.35 (m, 2H), 4.58 (d, 1H,

J=10.8 Hz), 4.56–4.53 (m, 1H), 4.46 (d, 1H, J=10.8

Hz), 3.89–3.81 (m, 1H), 3.79 (s, 3H), 3.78–3.69 (m, 1H),

3.60 (dd, 1H, J=10.6, 6.9 Hz), 3.52–3.47 (m, 2H), 3.43–

3.33 (m, 2H), 2.82 (ddq, 1H, J=6.9, 4.2, 2.3 Hz), 2.16–

2.04 (m, 3H), 1.97–1.91 (m, 1H), 1.86–1.80 (m, 1H),

1.70–1.63 (m, 3H), 1.58–1.49 (m, 3H), 0.97 (d, 3H,

J=6.9 Hz), 0.95 (d, 3H, J=6.9 Hz); ¹³C NMR

(75 MHz, CDCl₃) 159.0, 133.3, 130.9, 129.3, 128.9,

113.6, 98.7, 84.1, 73.7, 66.9, 66.0, 62.3, 55.1, 37.6, 34.4,

30.7, 29.6, 25.4, 24.2, 19.6, 18.5, 11.5; MS (EI, m/z) 406

(M)⁺, 321, 205, 121; HRMS (EI) calcd forC ₂₄H₃₈O₅

(M)⁺406.2719, found 406.2718.

t

HRMS (EI) calcd forC ₂₃H₃₇O₄Si (Mꢀ Bu)⁺405.2461,

found 405.2456; [a]²_D⁰ꢀ18.7 (c 0.9, CHCl₃).

(Z)-(5S,6S,7S,8R)-11-Iodo-8-(4-methoxybenzyloxy)-5,7-

dimethylundeca-1,3-dien-6-ol, tert-butyldimethylsilyl ether

(29). To a solution of the alcohol 28 (0.33 g, 0.71

mmol) in 5 mL of benzene and 10 mL of diethyl ether,

was added PPh₃(0.28 g, 1.07 mmol) and imidazole (73

mg, 1.07 mmol) until complete dissolution. Then iodine

(0.27 g, 1.07 mmol) was added at room temperature,

and the resulting mixture was stirred in the dark at

room temperature for 1 h. The reaction was diluted with

ether(25 mL) and washed with satuarted Na ₂S₂O₃

(3ꢃ20 mL), H₂O (25 mL) and saturated NaCl (25 mL).

The organic layer was dried over anhydrous MgSO₄,

concentrated and puriﬁed by column chromatography

(hexane/EtOAc 19:1) to provide 360 mg (89%) of the

iodide 29 as a colorless oil. IR (thin ﬁlm, NaCl) 2940,

2923, 2851, 1612, 1509, 1465, 1299, 1247, 1045 cm^ꢀ1; ¹H

NMR (300 MHz, CDCl₃) 7.27 (d, 2H, J=8.6 Hz), 6.90

(d, 2H, J=8.6 Hz), 6.39 (ddd, 1H, J=16.9, 11.0, 10.1

Hz), 5.98 (dd, 1H, J=11.0, 11.0 Hz), 5.50 (dd, 1H,

J=10.4, 10.4 Hz), 5.18 (dd, 1H, J=16.9, 1.5 Hz), 5.09

(d, 1H, J=10.1 Hz), 4.49 (d, 1H, J=11.4 Hz), 4.37 (d,

1H, J=11.4 Hz), 3.81 (s, 3H), 3.60 (dd, 1H, J=5.8, 3.4

Hz), 3.28 (dt, 1H, J=5.4, 5.4 Hz), 3.14 (t, 2H, J=6.2

Hz), 2.69 (ddq, 1H, J=10.4, 6.8, 3.2 Hz), 1.81–1.64 (m,

5H), 0.96 (d, 3H, J=6.8 Hz), 0.94 (d, 3H, J=6.8 Hz),

0.92 (s, 9H), 0.08 (s, 6H); ¹³C NMR (75 MHz, CDCl₃)

159.1, 134.6, 132.3, 130.6, 129.6, 128.9, 117.4, 113.7,

77.8, 76.3, 70.7, 55.2, 39.8, 36.3, 31.6, 29.2, 26.2, 22.6,

18.8, 18.4, 11.1, 7.4, ꢀ3.3, ꢀ3.4; MS (EI, m/z) 572

(M⁺), 515, 491, 440, 355, 293, 225, 172, 137, 122;

HRMS (EI) calcd forC ₂₃H₃₆IO₃Si (M-^tBu)⁺515.1478,

found 515.1471; [a]²_D⁰ꢀ22.0 (c 0.7, CHCl₃).

(Z)-(2R,3S,4S)-3-(4-Methoxybenzyloxy)-2,4-dimethyl-9-

(tetrahydropyran-2-yl-oxy)-non-5-enal (27). To a solu-

tion of 0.15 g (0.36 mmol) of the alcohol 26 in 5 mL of

CH₂Cl₂at 0 ^ꢁC was added Dess–Martin periodinane

(0.2 g, 0.47 mmol). The mixture was stirred at room

temperature for 1 h, then poured into 10 mL of satu-

rated NaHCO₃and 10 mL of saturated Na₂S₂O₃, and

diluted with 20 mL of ether. The organic layer was

washed with saturated NaHCO₃(2ꢃ10 mL), dried over

MgSO₄and concentrated under vacuum, to provide

0.13 g of the aldehyde, that was used crude in the fol-

1

lowing reaction. H NMR (300 MHz, CDCl₃) 9.72 (s,

1H), 7.24 (d, 2H, J=8.5 Hz), 6.88 (d, 2H, J=8.6 Hz),

5.44–5.39 (m, 2H), 4.57–4.54 (m, 1H), 4.53 (d, 1H,

J=10.9 Hz), 4.47 (d, 1H, J=10.9 Hz), 3.88–3.84 (m,

1H), 3.81 (s, 3H), 3.77–3.72 (m, 1H), 3.69 (dd, 1H,

J=5.0, 5.0 Hz), 3.52–3.35 (m, 2H), 2.88–2.73 (m, 1H),

2.64–2.55 (m, 1H), 2.22–1.97 (m, 2H), 1.89–1.52 (m,

8H), 1.17 (d, 3H, J=7.0 Hz), 1.04 (d, 3H, J=6.9 Hz).

(Z)-(4R,5S,6S,7S)-6-(tert-Butyldimethylsilanyloxy)-4-(4-

methoxybenzyloxy)-5,7-dimethylundeca-8,10-dien-1-ol

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3347

(Z)-(4R,5S,6S,7S)-[6-(tert-Butyldimethylsilanyloxy)-4-

(4-methoxybenzyloxy)-5,7-dimethylundeca-8,10-dienyl]-

triphenylphosphonium iodide (30). A mixture of the

iodide 29 (0.34 g, 0.59 mmol) and triphenylphosphine

(0.78 g, 2.90 mmol) in 2 mL of benzene was heated at

80 ^ꢁC for 40 h in the dark. The solvent was evaporated

under vacuum, and the residue was chromatographed

(CHCl₃to CHCl₃/MeOH 19:1) to give 0.39 g (80%) of

the phosphonium salt 30 as a white solid which was

dried azeotropically with benzene, and dried under

vacuum before its use. Mp 121–123 ^ꢁC; IR (thin ﬁlm,

NaCl) 2928, 2856, 1611, 1512, 1462, 1438, 1249, 1132,

25.4, 24.1, 23.6, 19.6, 18.8, 18.5, 17.3, 10.9, ꢀ3.3, ꢀ3.4;

MS (EI, m/z) 832 (M⁺), 751, 635, 549, 495, 457, 373,

345, 121. HRMS (EI) calcd forC ₄₇H₇₁O₇Si

(MꢀC₄H₉)⁺775.4969, found 775.4980.

(Z,Z,Z)-(5S,6S,7S,8R,13S,14S,15S)-8,14-Bis(4-methoxy-

benzyloxy)-5,7,13,15-tetramethyl-20-(tetrahydropyran-2-

yloxy)eicosa-1,3,11,16-tetraen-6-ol (35). To a solution

of 49 mg (0.06 mmol) of 31 in THF (7 mL) was added

TBAF (1.0 M in THF, 0.6 mL, 0.6 mmol) and the

resulting yellowish solution was stirred 24 h at room

temperature. The reaction was quenched with saturated

NaCl (25 mL) and the aqueous layerwas extracted with

EtOAc (3ꢃ25 mL). The combined organic layer was

dried over MgSO₄, and concentrated under vacuum.

Flash chromatography of the residue using hexane/ether

1:1 as eluent gave 36 mg (84%) of the alcohol 35. IR

(thin ﬁlm, NaCl) 3437, 2948, 2865, 1611, 1514, 1453,

1

1041 cm^ꢀ1; H NMR (300 MHz, CDCl₃) 7.84–7.65 (m,

15H), 7.25 (d, 2H, J=8.6 Hz), 6.80 (d, 2H, J=8.6 Hz),

6.29 (ddd, 1H, J=16.8, 11.0, 10.1 Hz), 5.76 (dd, 1H,

J=11.0, 11.0 Hz), 5.40 (dd, 1H, J=10.3, 10.3 Hz), 4.93

(d, 1H, J=16.8 Hz), 4.89 (d, 1H, J=10.1 Hz), 4.48–4.40

(m, 2H), 3.77 (s, 3H), 3.65–3.48 (m, 3H), 3.31 (dt, 1H,

J=5.5, 5.5 Hz), 2.68–2.58 (m, 1H), 2.06–1.88 (m, 2H),

1.63–1.48 (m, 3H), 0.88 (d, 3H, J=6.9 Hz), 0.87 (s, 9H),

0.84 (d, 3H, J=7.0 Hz), 0.05 (s, 3H), 0.01 (s, 3H); ¹³C

NMR (75 MHz, CDCl₃) 158.6, 134.7, 134.6, 133.2,

133.1, 131.8, 131.6, 131.4, 130.1, 130.0, 129.5, 129.2,

128.3, 128.1, 128.0, 118.0, 116.9, 116.8, 113.1, 77.2, 75.5,

69.9, 54.9, 38.9, 35.9, 30.3, 25.7, 22.7, 22.0, 18.3, 17.9,

10.6, ꢀ3.6, ꢀ3.8; MS (EI, m/z) 707 (MꢀI)⁺, 659, 608,

515, 440; [a]²_D⁰ꢀ20.0 (c 0.695, CHCl₃).

1

1363, 1247, 1075 cm^ꢀ1; H NMR (300 MHz, CDCl₃)

7.26 (d, 2H, J=8.5 Hz), 7.23 (d, 2H, J=8.5 Hz), 6.87

(d, 2H, J=8.5 Hz), 6.84 (d, 2H, J=8.6 Hz), 6.60 (ddd,

1H, J=16.9, 11.0, 10.3 Hz), 6.09 (dd, 1H, J=11.0, 11.0

Hz), 5.48 (dd, 1H, J=10.3, 10.3 Hz), 5.42–5.26 (m, 4H),

5.20 (d, 1H, J=16.9 Hz), 5.10 (d, 1H, J=10.3 Hz),

4.59–4.48 (m, 4H), 4.35 (d, 1H, J=10.9 Hz), 3.87–3.78

(m, 1H), 3.80 (s, 3H), 3.78 (s, 3H), 3.74–3.66 (m, 1H),

3.51–3.43 (m, 3H), 3.40–3.31 (m, 1H), 3.06 (dd, 1H,

J=7.6, 3.7 Hz), 2.84 (s, 1H), 2.81–2.70 (m, 2H), 2.68–

2.60 (m, 1H), 2.20–1.93 (m, 4H), 1.82–1.77 (m, 2H),

1.68–1.50 (m, 9H), 1.02 (d, 6H, J=6.7 Hz), 0.97 (d, 3H,

J=7.0 Hz), 0.91 (d, 3H, J=6.7 Hz); ¹³C NMR

(75 MHz, CDCl₃) 159.2, 159.1, 135.7, 134.0, 132.6,

132.4, 131.3, 130.3, 130.1, 129.5, 129.2, 129.0, 128.3,

117.9, 113.9, 113.7, 98.8, 88.0, 83.0, 78.1, 74.8, 70.9,

67.2, 67.1, 62.4, 55.3, 36.6, 36.2, 35.9, 35.3, 30.8, 30.5,

29.9, 25.5, 24.2, 23.7, 19.7, 18.8, 17.6, 17.4, 6.8. MS (EI)

718 (M)⁺, 633, 492, 474; HRMS (EI) calcd for

C₄₅H₆₆O₇(M)⁺718.4809, found 718.4815.

(Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-(tert-Butyldi-

methylsilanyloxy)-7,13-bis(4-methoxybenzyloxy)-6,8,14,16-

tetramethyleicosa-4,9,17,19-tetraen-1-ol, tetrahydropyran-

2-yl ether (31). To an ice-cold solution of the phospho-

nium salt 30 (0.38 g, 0.46 mmol) in 0.5 mL of dry THF

was slowly added NaHMDS (1.0 M in THF, 0.41 mL,

0.41 mmol) and the resulting red solution was stirred at

room temperature for 45 min. The mixture was then

cooled to ꢀ78 ^ꢁC and a solution of the aldehyde 27 (0.13

g, 0.32 mmol) in 1 mL of THF was added dropwise. The

reaction was stirred for 20 min at ꢀ78 ^ꢁC and warmed

to room temperature. After 12 h at ambient tempera-

ture, the reaction was quenched with saturated NH₄Cl

(10 mL) and extracted with ether (3ꢃ10 mL). The com-

bined organics were washed with saturated NaCl (2ꢃ10

mL), dried over anhydrous MgSO₄, concentrated and

chromatographed (hexane/ether 9:1) to give 0.214 g

(80%) of the Wittig product 31 as a colorless oil. IR

(thin ﬁlm, NaCl) 2954, 2857, 1613, 1514, 1463, 1248,

Carbamic acid, (Z,Z)-(1S,2S,3R,8S,9S,10S)-3,9-bis(4-

methoxybenzyloxy)-2,8,10-trimethyl-1-[(Z)-(S)-1-methyl-

penta-2,4-dienyl]-15-(tetrahydropyran-2-yloxy)pentadeca-

6,11-dienyl ester (36). To a solution of 36 mg (50 mmol)

of the alcohol 35 in 3 mL of dichloromethane was added

trichloroacetylisocyanate (8 mL, 65 mmol) and the mix-

ture was stirred for 30 min at room temperature. Alu-

mina (neutral, Brockmann I, activated, 390 mg) was

then added to the reaction mixture, and the resulting

suspension was stirred at room temperature for 6 h. The

mixture was ﬁltered through a short pad of silica gel

washing with EtOAc, and the ﬁltrate was concentrated

under vacuum and chromatographed (CH₂Cl₂/EtOAc

9:1) to aﬀord 34 mg (89%) of the carbamate 36 as a

colorless oil. IR (thin ﬁlm, NaCl) 3356, 3318, 2933,

1

1119, 1036 cm^ꢀ1; H NMR (300 MHz, CDCl₃) 7.31–

7.25 (m, 4H), 6.90 (d, 2H, J=8.7 Hz), 6.88 (d, 2H,

J=8.7 Hz), 6.42 (ddd, 1H, J=16.8, 11.0, 10.1 Hz), 5.97

(dd, 1H, J=11.0, 11.0 Hz), 5.54–5.45 (m, 2H), 5.40–5.27

(m, 3H), 5.16 (d, 1H, J=16.8 Hz), 5.07 (d, 1H, J=10.1

Hz), 4.60–4.49 (m, 4H), 4.35 (d, 1H, J=11.4 Hz), 3.89–

3.84 (m, 1H), 3.81 (s, 3H), 3.80 (s, 3H), 3.78–3.70 (m,

1H), 3.59 (dd, 1H, J=6.1, 3.2 Hz), 3.53–3.46 (m, 1H),

3.41–3.32 (m, 1H), 3.28 (dt, 1H, J=5.8, 5.8 Hz), 3.07

(dd, 1H, J=7.3, 3.9 Hz), 2.80–2.60 (m, 3H), 2.18–1.80

(m, 4H), 1.74–1.52 (m, 11H), 1.03 (d, 6H, J=6.7 Hz),

0.95–0.92 (m, 15H), 0.07 (s, 6H); ¹³C NMR (75 MHz,

CDCl₃) 159.1, 159.0, 134.6, 133.6, 132.6, 132.3, 131.3,

130.9, 129.5, 129.0, 128.9, 128.8, 128.4, 117.1, 113.6,

113.5, 98.7, 87.9, 78.7, 76.5, 74.6, 70.7, 67.0, 66.9, 62.2,

55.2, 39.8, 36.4, 35.5, 35.1, 31.2, 30.7, 29.8, 29.6, 26.2,

2870, 1728, 1162, 1513, 1248, 1035 cm^ꢀ^{1 1}H NMR

;

(300 MHz, CDCl₃) 7.31–7.27 (m, 4H), 6.91 (d, 2H,

J=8.9 Hz), 6.89 (d, 2H, J=8.9 Hz), 6.38 (ddd, 1H,

J=16.9, 11.0, 10.1 Hz), 6.00 (dd, 1H, J=11.0, 11.0 Hz),

5.48 (dd, 1H, J=11.0, 10.0 Hz), 5.40–5.25 (m, 4H), 5.19

(dd, 1H, J=16.9, 1.8 Hz), 5.08 (d, 1H, J=10.1 Hz), 4.83

(dd, 1H, J=5.9, 5.9 Hz), 4.60–4.47 (m, 6H), 4.36 (d, 1H,

J=11.4 Hz), 3.90–3.83 (m, 1H), 3.82 (s, 3H), 3.81 (s,

3H), 3.79–3.69 (m, 1H), 3.54–3.47 (m, 1H), 3.43–3.35

´

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3348

(m, 1H), 3.25 (dt, 1H, J=5.5, 5.5 Hz), 3.07 (dd, 1H,

J=7.6, 3.8 Hz), 2.82–2.72 (m, 2H), 2.67–2.58 (m, 1H),

2.13–1.81 (m, 5H), 1.72–1.50 (m, 10H), 1.04 (d, 3H,

J=6.7 Hz), 1.03 (d, 3H, J=6.9 Hz), 0.98 (d, 3H, J=6.9

Hz), 0.94 (d, 3H, J=6.8 Hz); ¹³C NMR (75 MHz,

CDCl₃) 159.1, 159.0, 157.1, 133.6, 133.2, 132.5, 132.1,

131.3, 130.8, 129.7, 129.5, 129.1, 128.8, 128.4, 117.6,

113.7, 113.6, 99.8, 87.9, 78.2, 74.7, 70.5, 67.1, 67.0, 62.2,

55.2, 37.5, 35.7, 35.1, 34.2, 30.7, 30.5, 29.8, 25.4, 24.1,

23.5, 19.6, 18.6, 17.7, 17.4, 9.6; MS (EI, m/z) 761 (M⁺),

676, 540, 504; HRMS (EI) calcd forC ₄₆H₆₇NO₈(M)⁺

761.4867, found 761.4870.

Benzoic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-

carbamoyloxy-7,13-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (38). Following the general

procedure, a mixture of 3.5 mg (5.1 mmol) of the alcohol

37, pyridine and benzoyl chloride was stirred for 16 h.

After concentration and puriﬁcation, the corresponding

benzoic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-

carbamoyloxy-7,13-bis(4-methoxybenzyloxy)-6,8,14,16-

tetramethyleicosa-4,9,17,19-tetraenyl ester was obtained.

¹H NMR (300 MHz, CDCl₃) 8.04 (d, 2H, J=8.5 Hz),

7.53–7.41 (m, 3H), 7.29–7.26 (m, 4H), 6.88 (d, 2H,

J=8.6 Hz), 6.86 (d, 2H, J=8.6 Hz), 6.36 (ddd, 1H,

J=16.8, 11.0, 10.1 Hz), 5.98 (dd, 1H, J=11.0, 11.0 Hz),

5.52 (dd, 1H, J=11.0, 9.8 Hz), 5.40–5.24 (m, 4H), 5.17

(d, 1H, J=16.8 Hz), 5.06 (d, 1H, J=10.1 Hz), 4.81 (dd,

1H, J=5.9, 5.9 Hz), 4.59 (bs, 2H), 4.57–4.48 (m, 3H),

4.34 (d, 1H, J=11.5 Hz), 4.29 (t, 2H, J=6.6 Hz), 3.80

(s, 3H), 3.79 (s, 3H), 3.23 (dt, 1H, J=5.7, 5.7 Hz), 3.05

(dd, 1H, J=7.4, 4.0 Hz), 2.81–2.69 (m, 2H), 2.64–2.57

(m, 1H), 2.29–2.16 (m, 2H), 2.12–1.74 (m, 5H), 1.69–

1.52 (m, 2H), 1.02 (d, 3H, J=6.7 Hz), 1.01 (d, 3H,

J=6.9 Hz), 0.96 (d, 3H, J=6.9 Hz), 0.92 (d, 3H, J=6.8

Hz).

Carbamic acid, (Z,Z)-(1S,2S,3R,8S,9S,10S)-15-hydroxy-

3,9-bis(4-methoxybenzyloxy)-2,8,10-trimethyl-1-[(Z)-(S)-

1-methylpenta-2,4-dienyl]pentadeca-6,11-dienyl

ester

(37). To a solution of the THP ether 36 (30 mg, 39

mmol) in 3 mL of EtOH was added PPTS (0.039 M

solution in EtOH, 0.150 mL, 5.9 mmol). The mixture

was heated at 55 ^ꢁC. After8 h, the solution was con-

centrated under vacuum, and the residue was puriﬁed

by chromatography using CH₂Cl₂/EtOAc 3:2 as eluent,

to provide 25 mg (93%) of the alcohol 37. IR (thin ﬁlm,

NaCl) 3357, 2960, 2870, 1720, 1612, 1514, 1323, 1248,

1

1038 cm^ꢀ1; H NMR (300 MHz, CDCl₃) 7.29 (d, 2H,

J=8.6 Hz), 7.28 (d, 2H, J=8.6 Hz), 6.88 (d, 2H, J=8.7

Hz), 6.87 (d, 2H, J=8.7 Hz), 6.41 (ddd, 1H, J=16.8,

11.0, 10.1 Hz), 5.99 (dd, 1H, J=11.0, 11.0 Hz), 5.48 (dd,

1H, J=11.0, 9.7 Hz), 5.38–5.27 (m, 4H), 5.18 (dd, 1H,

J=16.8, 1.9 Hz), 5.07 (d, 1H, J=10.1 Hz), 4.80 (dd, 1H,

J=5.9, 5.9 Hz), 4.56–4.47 (m, 5H), 4.37 (d, 1H, J=11.3

Hz), 3.81 (s, 3H), 3.79 (s, 3H), 3.54 (t, 2H, J=6.2 Hz),

3.23 (dt, 1H, J=5.7, 5.7 Hz), 3.07 (dd, 1H, J=7.0, 4.5

Hz), 2.84–2.71 (m, 2H), 2.66–2.58 (m, 1H), 2.13–1.83

(m, 5H), 1.70–1.51 (m, 4H), 1.03 (d, 3H, J=6.5 Hz),

1.01 (d, 3H, J=6.7 Hz), 0.98 (d, 3H, J=6.9 Hz), 0.93

(d, 3H, J=6.8 Hz); ¹³C NMR (75 MHz, CDCl₃) 159.1,

159.0, 156.9, 133.6, 133.4, 132.8, 132.2, 131.1, 130.8,

129.8, 129.5, 129.2, 128.7, 128.6, 117.7, 113.7, 113.6,

87.9, 78.7, 78.2, 77.1, 75.0, 70.8, 62.0, 55.3, 37.7, 35.6,

35.3, 34.4, 32.4, 30.7, 23.6, 23.5, 18.9, 17.7, 16.9, 9.8; MS

(FAB in MNBA/NaCl, m/z) 700 (M+Na)⁺, 678

(M+H)⁺, 645; HRMS (FAB) calcd forC ₄₁H₆₀NO₇

(M+H)⁺678.4370, found 678.4368; [a]²_D⁰+45.4 (c

0.65, CHCl₃).

To the esterabove obtained (3.0 mg, 3.8 mmol) was

added NaHCO₃and DDQ, Chromatography of the

crude residue using CH₂Cl₂to CH₂Cl₂/EtOAc 1:1 as

eluent, gave 1.9 mg (95%) of the analogue 38 as a col-

orless oil.

¹H NMR (300 MHz, CDCl₃) 8.06 (d, 2H, J=7.4 Hz),

7.61–7.55 (m, 1H), 7.48–7.43 (m, 2H), 6.61 (ddd, 1H,

J=16.7, 11.0, 10.1 Hz), 6.05 (dd, 1H, J=11.0, 11.0 Hz),

5.57–5.49 (m, 1H), 5.42–5.31 (m, 4H), 5.23 (d, 1H,

J=16.7 Hz), 5.13 (d, 1H, J=10.1 Hz), 4.76 (dd, 1H,

J=6.5, 4.6 Hz), 4.60 (bs, 2H), 4.37–4.29 (m, 2H), 3.67–

3.62 (m, 1H), 3.23 (dd, 1H, J=5.7, 5.7 Hz), 3.00 (ddq,

1H, J=10.3, 6.9, 3.3 Hz), 2.68–2.60 (m, 2H), 2.32–2.05

(m, 4H), 1.92–1.71 (m, 3H), 1.53–1.46 (m, 2H), 1.01 (d,

3H, J=6.9 Hz), 0.98 (d, 3H, J=6.9 Hz), 0.97 (d, 3H,

J=6.9 Hz), 0.93 (d, 3H, J=6.9 Hz); MS (FAB in gly-

cerol/ m/z) 542 (M+H)⁺, 524, 463, 393, 301, 225, 185;

HRMS (FAB in glycerol) calcd for C₃₂H₄₈NO₆

(M+H)⁺542.3484, found 542.3481; [a]²_D⁰+64.4 (c

0.09, CHCl₃).

General procedure for the synthesis of (17R,19S)-carba-

moyloxy analogues of discodermolide

Acetic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-

carbamoyloxy-7,13-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (39). Following the general

procedure, a mixture of 37 (4.0 mg, 5.9 mmol), pyridine

and acetyl chloride was stirred for 16 h. After chro-

matography of the residue, acetic acid, (Z,Z,Z)-

(6S,7S,8S,13R,14S,15S,16S) - 15 - carbamoyloxy - 7,13 -

bis(4 - methoxybenzyloxy) - 6,8,14,16 - tetramethyleicosa-

4,9,17,19-tetraenyl ester was obtained.

To a solution of the alcohol 37 (10 mmol) in 1 mL of

dichloromethane was added pyridine (50 mmol) fol-

lowed by the corresponding acyl chloride (30 mmol).

The mixture was stirred at room temperature for the

required time, concentrated under vacuum and puriﬁed

by column chromatography (CH₂Cl₂to CH₂Cl₂/EtOAc

9:1) to aﬀord the corresponding esters.

To the esters obtained (10 mmol) in 1 mL of dichloro-

methane, was added NaHCO₃(40 mg) and DDQ (30

mmol). The mixture was stirred at room temperature for

1 h, concentrated and the crude residue was puriﬁed by

chromatography to provide the (17R,19S)-carbamoyl-

oxy analogues of discodermolide.

¹H NMR (300 MHz, CDCl₃) 7.29–7.26 (m, 4H), 6.89 (d,

2H, J=8.6 Hz), 6.85 (d, 2H, J=8.5 Hz), 6.37 (ddd, 1H,

J=16.9, 11.0, 10.2 Hz), 5.98 (dd, 1H, J=11.0, 11.0 Hz),

5.50 (dd, 1H, J=10.2, 10.2 Hz), 5.38–5.24 (m, 4H), 5.17

(d, 1H, J=16.9 Hz), 5.07 (d, 1H, J=10.2 Hz), 4.81 (dd,

1H, J=5.9, 5.9 Hz), 4.57–4.45 (m, 5H), 4.35 (d, 1H,

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3349

J=11.4 Hz), 4.03 (t, 2H, J=6.5 Hz), 3.81 (s, 3H), 3.79

(s, 3H), 3.23 (dt, 1H, J=5.6, 5.6 Hz), 3.05 (dd, 1H,

J=7.5, 3.8 Hz), 2.79–2.67 (m, 2H), 2.65–2.55 (m, 1H),

2.15–2.01 (m, 1H), 2.03 (s, 3H), 1.99–1.79 (m, 3H),

1.73–1.56 (m, 5H), 1.02 (d, 3H, J=6.8 Hz), 1.00 (d, 3H,

J=6.7 Hz), 0.96 (d, 3H, J=6.9 Hz), 0.92 (d, 3H, J=6.8

Hz).

(m, 4H), 1.81–1.66 (m, 3H), 1.59–1.51 (m, 2H), 1.23 (s,

9H), 1.03 (d, 3H, J=6.8 Hz), 1.01 (d, 3H, J=6.8 Hz),

1.00 (d, 3H, J=6.9 Hz), 0.96 (d, 3H, J=6.9 Hz); ¹³C

NMR (75 MHz, CDCl₃) 178.3, 157.3, 133.5, 133.4,

132.4, 132.1, 130.2, 130.0, 128.7, 118.0, 79.7, 79.0, 72.8,

63.8, 39.9, 38.7, 35.3, 34.9, 34.7, 34.5, 28.7, 27.2, 24.2,

24.1, 18.0, 17.6, 15.3, 7.9; MS (FAB in glycerol/NaCl,

m/z) 544 (M+Na)⁺, 443, 301, 245, 191; HRMS (FAB

in glycerol) calcd for C₃₀H₅₂NO₆(M+H)⁺522.3795,

found 522.3798; [a]²_D⁰+67.0 (c 0.27, CHCl₃).

The esterabove obtained (3.0 mg, 4.1 mmol) was treated

with NaHCO₃and DDQ, according to the general

method. Flash chromatography of the crude residue

(CH₂Cl₂to CH₂Cl₂/EtOAc 1:1) yielded 1.6 mg (82%) of

the acetyl analogue 39 as a colorless oil. ¹H NMR

(300 MHz, CDCl₃) 6.63 (ddd, 1H, J=16.8, 11.0, 10.1

Hz), 6.06 (dd, 1H, J=11.0, 11.0 Hz), 5.52–5.33 (m, 5H),

5.23 (d, 1H, J=16.8 Hz), 5.14 (d, 1H, J=10.1 Hz), 4.76

(dd, 1H, J=6.7, 4.5 Hz), 4.58 (bs, 2H), 4.10–4.05 (m,

2H), 3.69–3.62 (m, 1H), 3.24 (dd, 1H, J=5.8, 5.8 Hz),

3.06–2.97 (m, 1H), 2.70–2.58 (m, 2H), 2.20–2.03 (m,

4H), 2.06 (s, 3H), 1.78–1.64 (m, 3H), 1.57–1.48 (m, 2H),

1.01 (d, 3H, J=6.9 Hz), 1.00 (d, 3H, J=6.8 Hz), 0.99

(d, 3H, J=6.9 Hz), 0.94 (d, 3H, J=6.9 Hz); MS (FAB

in glycerol/NaCl, m/z) 502 (M+Na)⁺, 469, 301, 207;

[a]²_D⁰+73.7 (c 0.08, CHCl₃).

Thiophene 2-carboxylic acid, (Z,Z,Z)-(6S,7S,8S,13R,

14S,15S,16S)-15-carbamoyloxy-7,13-dihydroxy-6,8,14,

16-tetramethyleicosa-4,9,17,19-tetraenyl ester (41). A

mixture of 7.0 mg (10 mmol) of the alcohol 37, pyridine

and 2-thiophene carbonyl chloride was stirred for 18 h.

Following the general procedure thiophene 2-carboxylic

acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-carba-

moyloxy-7,13-bis(4-methoxybenzyloxy)-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester was obtained.

¹H NMR (300 MHz, CDCl₃) 7.80 (d, 1H, J=3.9 Hz),

7.54 (dd, 1H, J=4.9, 0.8 Hz), 7.30–7.26 (m, 4H), 7.10

(dd, 1H, J=4.8, 3.9 Hz), 6.89 (d, 2H, J=8.5 Hz), 6.87

(d, 2H, J=8.5 Hz), 6.37 (ddd, 1H, J=18.0, 11.0, 10.1

Hz), 5.98 (dd, 1H, J=11.0, 11.0 Hz), 5.52 (dd, 1H,

J=11.0, 9.8 Hz), 5.41–5.24 (m, 4H), 5.18 (d, 1H,

J=18.0 Hz), 5.07 (d, 1H, J=10.1 Hz), 4.82 (dd, 1H,

J=5.9, 5.9 Hz), 4.58–4.49 (m, 5H), 4.35 (d, 1H, J=11.4

Hz), 4.27 (t, 2H, J=6.3 Hz), 3.81 (s, 3H), 3.80 (s, 3H),

3.24 (dt, 1H, J=5.5, 5.5 Hz), 3.06 (dd, 1H, J=7.5, 3.8

Hz), 2.82–2.70 (m, 2H), 2.64–2.55 (m, 1H), 2.25–2.15

(m, 1H), 2.08–1.90 (m, 2H), 1.89–1.57 (m, 6H), 1.02 (d,

3H, J=6.8 Hz), 1.01 (d, 3H, J=6.8 Hz), 0.96 (d, 3H,

J=6.9 Hz), 0.93 (d, 3H, J=6.9 Hz).

2,2-Dimethylpropionic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,

15S,16S)-15-carbamoyloxy-7,13-dihydroxy-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester (40). A mixture of

37 (4.0 mg, 5.9 mmol), pyridine and pivaloyl chloride

was stirred for 17 h following the general procedure, to

obtain the compound 2,2-dimethylpropionic acid,

(Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-carbamoyloxy-

7,13 - bis(4 - methoxybenzyloxy) - 6,8,14,16 - tetramethyl-

eicosa-4,9,17,19-tetraenyl ester.

¹H NMR (300 MHz, CDCl₃) 7.30–7.27 (m, 4H), 6.89 (d,

2H, J=8.6 Hz), 6.87 (d, 2H, J=8.6 Hz), 6.36 (ddd, 1H,

J=17.1, 11.0, 10.2 Hz), 5.98 (dd, 1H, J=11.0, 11.0 Hz),

5.50 (dd, 1H, J=11.0, 9.8 Hz), 5.39–5.24 (m, 4H), 5.17

(dd, 1H, J=17.1, 1.4 Hz), 5.07 (d, 1H, J=10.2 Hz), 4.81

(dd, 1H, J=5.9, 5.9 Hz), 4.56 (bs, 2H), 4.57–4.48 (m,

3H), 4.35 (d, 1H, J=11.4 Hz), 4.02 (t, 2H, J=6.5 Hz),

3.81 (s, 3H), 3.80 (s, 3H), 3.23 (dt, 1H, J=5.6, 5.6 Hz),

3.06 (dd, 1H, J=7.5, 3.8 Hz), 2.82–2.67 (m, 2H), 2.65–

2.54 (m, 1H), 2.20–2.04 (m, 1H), 2.02–1.77 (m, 4H),

1.72–1.54 (m, 4H), 1.20 (s, 9H), 1.02 (d, 3H, J=6.7 Hz),

1.01 (d, 3H, J=6.8 Hz), 0.96 (d, 3H, J=6.8 Hz), 0.92

(d, 3H, J=6.8 Hz).

The esterabove obtained (8.0 mg, 10.1 mmol) was trea-

ted with NaHCO₃and DDQ following the general pro-

tocol. Chromatography of the crude residue (CH₂Cl₂/

EtOAc 1:1) yielded 41 as a colorless oil (3.9 mg, 72%).

IR (thin ﬁlm, NaCl) 3418, 2962, 2925, 1712, 1695, 1600,

1

1418, 1265, 1101 cm^ꢀ1; H NMR (300 MHz, CDCl₃)

7.81 (dd, 1H, J=3.7, 1.2 Hz), 7.56 (dd, 1H, J=5.0, 1.2

Hz), 7.11 (dd, 1H, J=5.0, 3.7 Hz), 6.62 (ddd, 1H,

J=16.9, 11.0, 10.1 Hz), 6.05 (dd, 1H, J=11.0, 11.0 Hz),

5.55–5.47 (m, 1H), 5.42–5.31 (m, 4H), 5.22 (d, 1H,

J=16.9 Hz), 5.13 (d, 1H, J=10.1 Hz), 4.76 (dd, 1H,

J=6.7, 4.6 Hz), 4.58 (bs, 2H), 4.37–4.25 (m, 2H), 3.67–

3.62 (m, 1H), 3.23 (dd, 1H, J=5.7, 5.7 Hz), 3.05–2.95

(m, 1H), 2.69–2.61 (m, 2H), 2.30–2.05 (m, 3H), 1.88–

1.72 (m, 4H), 1.53–1.45 (m, 2H), 1.00 (d, 3H, J=7.0

Hz), 0.98 (d, 3H, J=7.0 Hz), 0.97 (d, 3H, J=6.8 Hz),

0.93 (d, 3H, J=7.0 Hz); MS (FAB in MNBA, m/z) 548

(M+H)⁺, 487, 391, 257, 227, 154, 136; HRMS (FAB in

MNBA) calcd forC ₃₀H₄₆NO₆S (M+H)⁺548.3046,

found 548.3039; [a]²_D⁰+60.5 (c 0.185, CHCl₃).

To 3.0 mg (3.9 mmol) of the esterabove obtained were

added NaHCO₃and DDQ. Chromatography of the

crude residue using CH₂Cl₂to CH₂Cl₂/EtOAc 1:1

provided 1.9 mg (95%) of the analogue 40 as a yellow

oil.

IR (thin ﬁlm, NaCl) 3437, 2916, 2846, 1713, 1653, 1457,

1162, 1045 cm^ꢀ^{1 1}H NMR (300 MHz, CDCl₃) 6.62

;

(ddd, 1H, J=16.8, 11.0, 10.1 Hz), 6.07 (dd, 1H, J=11.0,

11.0 Hz), 5.58–5.46 (m, 1H), 5.42–5.32 (m, 4H), 5.25 (d,

1H, J=16.8 Hz), 5.16 (d, 1H, J=10.1 Hz), 4.78 (dd, 1H,

J=6.7, 4.6 Hz), 4.60 (bs, 2H), 4.15–4.05 (m, 2H), 3.69–

3.64 (m, 1H), 3.25 (dd, 1H, J=5.7, 5.7 Hz), 3.02 (ddq,

1H, J=10.0, 6.8, 3.3 Hz), 2.71–2.58 (m, 2H), 2.23–2.04

Hydroxyacetic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-

15-carbamoyloxy-7,13-dihydroxy-6,8,14,16-tetramethyl-

eicosa-4,9,17,19-tetraenyl ester (42). A mixture of 37

(7.0 mg, 10 mmol), (4-methoxybenzyloxy) acetic acid (20

mmol), EDCI (20 mmol) and DMAP (0.5 mmol) was

stirred at room temperature for 40 h. After chromato-

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3350

graphy of the residue using CH₂Cl₂/EtOAc 9:1, (4-

methoxybenzyloxy) acetic acid, (Z,Z,Z)-(6S,7S,8S,

13R,14S,15S,16S)-15-carbamoyloxy-7,13-bis(4-methoxy-

benzyloxy)-6,8,14,16-tetramethyleicosa-4,9,17,19-tetra-

enyl ester was obtained.

residue by chromatography (CH₂Cl₂/EtOAc 1:1) aﬀor-

ded 4.0 mg (80%) of the corresponding analogue 43.

IR (thin ﬁlm, NaCl) 3405, 2964, 2919, 1713, 1580, 1397,

1

1299, 1122, 1046 cm^ꢀ1; H NMR (300 MHz, CDCl₃)

7.58 (dd, 1H, J=1.7, 0.8 Hz), 7.18 (dd, 1H, J=3.5, 0.8

Hz), 6.62 (ddd, 1H, J=16.8, 10.9, 10.1 Hz), 6.52 (dd,

1H, J=3.5, 1.7 Hz), 6.05 (dd, 1H, J=10.9, 10.9 Hz),

5.55–5.32 (m, 5H), 5.23 (dd, 1H, J=16.8, 1.8 Hz), 5.13

(d, 1H, J=10.1 Hz), 4.76 (dd, 1H, J=6.6, 4.6 Hz), 4.59

(bs, 2H), 4.37–4.25 (m, 2H), 3.68–3.62 (m, 1H), 3.23

(dd, 1H, J=5.7, 5.7 Hz), 3.04–2.94 (m, 1H), 2.69–2.60

(m, 2H), 2.30–2.09 (m, 3H), 1.92–1.71 (m, 4H), 1.56–

1.46 (m, 2H), 1.01 (d, 3H, J=7.0 Hz), 0.98 (d, 6H,

J=6.8 Hz), 0.93 (d, 3H, J=7.0 Hz); MS (FAB in

MNBA, m/z) 532 (M+H)⁺, 507, 391, 307, 257, 154,

136; HRMS (FAB in MNBA) calcd forC ₃₀H₄₆NO₇

(M+H)⁺532.3274, found 532.3279; [a]²_D⁰+71.6 (c

0.19, CHCl₃).

¹H NMR (300MHz, CDCl₃) 7.31–7.26 (m, 6H), 6.90–

6.86 (m, 6H), 6.35 (ddd, 1H, J=16.6, 11.0, 10.1 Hz), 5.98

(dd, 1H, J=11.0, 11.0 Hz), 5.50 (dd, 1H, J=11.0, 10.0

Hz), 5.38–5.23 (m, 4H), 5.17 (d, 1H, J=16.6 Hz), 5.07 (d,

1H, J=10.1 Hz), 4.81 (dd, 1H, J=5.8, 5.8 Hz), 4.55–4.48

(m, 7H), 4.35 (d, 1H, J=11.4 Hz), 4.13 (t, 2H, J=6.3

Hz), 4.05 (s, 2H), 3.81 (s, 3H), 3.80 (s, 3H), 3.79 (s, 3H),

3.23 (dt, 1H, J=5.7, 5.7 Hz), 3.04 (dd, 1H, J=7.5, 3.8

Hz), 2.79–2.55 (m, 3H), 2.15–1.78 (m, 5H), 1.71–1.60 (m,

4H), 1.02 (d, 3H, J=6.8 Hz), 1.00 (d, 3H, J=6.8 Hz),

0.96 (d, 3H, J=6.9 Hz), 0.92 (d, 3H, J=6.8 Hz).

The esterabove obtained (3.8 mg, 4.4 mmol) was treated

with NaHCO₃and DDQ (22 mmol). After6 h of sti-r

ring, the residue was puriﬁed by chromatography

(EtOAc) to provide 1.5 mg (71%) of the corresponding

analogue 42.

General procedure for the synthesis of (17R,19S)-acet-

oxy analogues of discodermolide

To a solution of the alcohol 45 (10 mmol) in 1 mL of

dichloromethane was added pyridine (50 mmol) fol-

lowed by the corresponding acyl chloride (30 mmol).

The mixture was stirred at room temperature for the

required time, concentrated under vacuum and puriﬁed

by column chromatography (CH₂Cl₂to CH₂Cl₂/EtOAc

19:1) to aﬀord the corresponding esters.

¹H NMR (300 MHz, CDCl₃) 6.62 (ddd, 1H, J=17.0,

11.0, 10.2 Hz), 6.04 (dd, 1H, J=11.0, 11.0 Hz), 5.50–5.30

(m, 5H), 5.23 (dd, 1H, J=17.0, 1.3 Hz), 5.14 (d, 1H,

J=10.2 Hz), 4.77–4.72 (m, 1H), 4.61 (bs, 2H), 4.21 (t, 2H,

J=6.4 Hz), 4.17 (s, 2H), 3.67–3.62 (m, 1H), 3.24 (dd, 1H,

J=5.7, 5.7 Hz), 3.03–2.95 (m, 1H), 2.68–2.54 (m, 2H),

2.18–2.05 (m, 2H), 1.78–1.47 (m, 7H), 1.01 (d, 3H, J=6.8

Hz), 1.00 (d, 3H, J=6.8 Hz), 0.99 (d, 3H, J=6.8 Hz),

0.94 (d, 3H, J=7.0 Hz); [a]²_D⁰+76.0 (c 0.025, CHCl₃).

To the esters above obtained (10 mmol) in 1 mL of di-

chloromethane, was added NaHCO₃(30 mg) and DDQ

(30 mmol). The mixture was stirred at room temperature

for 1 h, concentrated and the crude product was puriﬁed

by chromatography to aﬀord the (17R,19S)-acetoxy

analogues of discodermolide.

Furan-2-carboxylic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,

16S)-15-carbamoyloxy-7,13-dihydroxy-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester (43). Following

the general procedure, a mixture of 7.0 mg (10.0 mmol)

of 37, pyridine and 2-furoyl chloride was stirred for 14 h.

After concentration and chromatography, the corres-

ponding furan 2-carboxylic acid, (Z,Z,Z)-(6S,7S,8S,

13R,14S,15S,16S)-15-carbamoyloxy-7,13-bis(4-methoxy-

benzyloxy)-6,8,14,16-tetramethyleicosa-4,9,17,19-tetra-

enyl ester was obtained.

Acetic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-

acetoxy - 7,13 - dihydroxy - 6,8,14,16 - tetramethyleicosa -

4,9,17,19-tetraenyl ester (46). Following the general

procedure, a mixture of 7.5 mg (11.0 mmol) of 45, pyri-

dine and acetyl chloride was stirred for 20 h. After con-

centration and chromatography, the corresponding

acetic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-

acetoxy-7,13-bis(4-methoxybenzyloxy)-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester was obtained.

IR (thin ﬁlm, NaCl) 3360, 2960, 1721, 1609, 1513, 1298,

1248, 1036 cm^ꢀ^{1 1}H NMR (300 MHz, CDCl₃) 7.57

;

(d, 1H, J=1.7 Hz), 7.30–7.26 (m, 4H), 7.17 (d, 1H,

J=3.3 Hz), 6.90 (d, 2H, J=8.5 Hz), 6.88 (d, 2H, J=8.6

Hz), 6.51 (dd, 1H, J=3.3, 1.7 Hz), 6.37 (ddd, 1H,

J=18.0, 11.0, 10.1 Hz), 5.99 (dd, 1H, J=11.0, 11.0 Hz),

5.52 (dd, 1H, J=11.0, 9.8 Hz), 5.40–5.25 (m, 4H), 5.18

(d, 1H, J=18.0 Hz), 5.08 (d, 1H, J=10.1 Hz), 4.82

(dd, 1H, J=5.9, 5.9 Hz), 4.58–4.46 (m, 5H), 4.36 (d,

1H, J=11.4 Hz), 4.28 (t, 2H, J=6.4 Hz), 3.81 (s, 3H),

3.80 (s, 3H), 3.24 (dt, 1H, J=5.8, 5.8 Hz), 3.07 (dd, 1H,

J=7.4, 3.9 Hz), 2.82–2.70 (m, 2H), 2.70–2.60 (m, 1H),

2.27–2.16 (m, 1H), 2.06–1.95 (m, 2H), 1.91–1.58 (m, 6H),

1.03 (d, 3H, J=6.8 Hz), 1.02 (d, 3H, J=6.9 Hz), 0.97

(d, 3H, J=6.9 Hz), 0.93 (d, 3H, J=6.8 Hz).

¹H NMR (300 MHz, CDCl₃) 7.30–7.26 (m, 4H), 6.89 (d,

2H, J=8.7 Hz), 6.88 (d, 2H, J=8.6 Hz), 6.38 (ddd, 1H,

J=16.8, 11.0, 10.1 Hz), 5.97 (dd, 1H, J=11.0, 11.0 Hz),

5.49 (dd, 1H, J=11.0, 9.7 Hz), 5.34–5.26 (m, 4H), 5.17

(dd, 1H, J=16.8, 1.9 Hz), 5.08 (d, 1H, J=10.1 Hz), 4.97

(dd, 1H, J=5.9, 5.9 Hz), 4.58–4.45 (m, 3H), 4.34 (d, 1H,

J=11.4 Hz), 4.09–3.98 (m, 2H), 3.81 (s, 3H), 3.80 (s, 3H),

3.21 (dt, 1H, J=5.7, 5.7 Hz), 3.06 (dd, 1H J=7.5, 4.0 Hz),

2.82–2.67 (m, 2H), 2.65–2.57 (m, 1H), 2.24–2.05 (m, 1H),

2.03 (s, 3H), 1.99 (s, 3H), 1.98–1.82 (m, 3H), 1.70–1.53 (m,

5H), 1.03 (d, 3H, J=6.7 Hz), 1.01 (d, 3H, J=6.7 Hz), 0.95

(d, 3H, J=6.9 Hz), 0.89 (d, 3H, J=6.8 Hz).

To the esterabove obtained (7.8 mg, 10.1 mmol) was

added NaHCO₃and DDQ. Puriﬁcation of the crude

To the esterabove obtained (4.8 mg, 6.6 mmol) was

added NaHCO₃and DDQ. Chromatography of the

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3351

crude product using CH₂Cl₂to CH₂Cl₂/EtOAc 7:3 gave

3.1 mg (95%) of the analogue 46 as a yellowish oil.

118.1, 79.1, 78.4, 72.6, 64.4, 39.7, 35.4, 34.9, 34.6, 33.7,

28.8, 28.0, 24.2, 21.1, 18.0, 17.6, 15.4, 8.3; MS (FAB in

MNBA/Na, m/z) 563 (M+Na)⁺, 520, 461, 391, 336,

227, 176, 154; [a]²_D⁰+71.4 (c 0.175, CHCl₃).

IR (thin ﬁlm, NaCl) 3469, 2966, 2931, 2867, 1739, 1735,

1453, 1370, 1239, 1045 cm^ꢀ^{1 1}H NMR (300 MHz,

;

CDCl₃) 6.62 (ddd, 1H, J=16.8, 11.0, 10.1 Hz), 6.04 (dd,

1H, J=11.0, 11.0 Hz), 5.52–5.28 (m, 5H), 5.23 (dd, 1H,

J=16.8, 1.9 Hz), 5.14 (d, 1H, J=10.1 Hz), 4.94 (dd, 1H,

J=6.4, 5.1 Hz), 4.13–4.01 (m, 2H), 3.63–3.58 (m, 1H),

3.23 (dd, 1H, J=5.7, 5.7 Hz), 3.01 (ddq, 1H, J=10.1,

6.8, 3.2 Hz), 2.71–2.56 (m, 2H), 2.21–2.04 (m, 2H), 2.06

(s, 3H), 2.02 (s, 3H), 1.79–1.53 (m, 5H), 1.53–1.46 (m,

2H), 1.00 (d, 3H, J=6.8 Hz), 0.99 (d, 6H, J=6.8 Hz),

0.93 (d, 3H, J=6.9 Hz); MS (FAB in MNBA/Na, m/z)

501 (M+Na)⁺, 462, 401, 383, 257, 176, 154, 136;

HRMS (FAB in MNBA) calcd forC ₂₈H₄₇O₆(M+H)⁺

479.3373, found 479.3379; [a]²_D⁰+74.2 (c 0.155, CHCl₃).

2,2-Dimethylpropionic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,

15S,16S)- 15-acetoxy- 7,13 -dihydroxy- 6,8,14,16 -tetra-

methyleicosa-4,9,17,19-tetraenyl ester (48). Following

the general procedure a mixture of 45 (7.5 mg, 11.0

mmol), pyridine and pivaloyl chloride was stirred for 18

h. Afterusual puirﬁcation, 2,2-dimethylpropionic acid,

(Z,Z,Z)-(6S,7S,8S,13R,14S, 15S,16S)-15-acetoxy-7,13-

bis(4 -methoxybenzyloxy) -6,8,14,16- tetramethyleicosa-

4,9,17,19-tetraenyl ester was obtained.

¹H NMR (300 MHz, CDCl₃) 7.30–7.26 (m, 4H), 6.89 (d,

2H, J=8.6 Hz), 6.87 (d, 2H, J=8.7 Hz), 6.36 (ddd, 1H,

J=16.8, 11.0, 10.1 Hz), 5.97 (dd, 1H, J=11.0, 11.0 Hz),

5.49 (dd, 1H, J=11.0, 9.7 Hz), 5.35–5.25 (m, 4H), 5.17

(dd, 1H, J=16.8, 1.9 Hz), 5.07 (d, 1H, J=10.1 Hz), 4.97

(dd, 1H, J=5.9, 5.9 Hz), 4.56 (d, 1H, J=11.4 Hz), 4.54–

4.48 (m, 2H), 4.33 (d, 1H, J=11.4 Hz), 4.06–3.98 (m,

2H), 3.81 (s, 3H), 3.80 (s, 3H), 3.21 (dt, 1H, J=5.6, 5.6

Hz), 3.06 (dd, 1H, J=7.4, 4.0 Hz), 2.80–2.67 (m, 2H),

2.64–2.55 (m, 1H), 2.17–2.03 (m, 2H), 1.99 (s, 3H),

1.96–1.82 (m, 3H), 1.69–1.53 (m, 4H), 1.20 (s, 9H), 1.03

(d, 3H, J=6.7 Hz), 1.01 (d, 3H, J=6.9 Hz), 0.94 (d, 3H,

J=6.9 Hz), 0.89 (d, 3H, J=6.8 Hz).

Benzoic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-15-

acetoxy - 7,13 - dihydroxy - 6,8,14,16 - tetramethyleicosa-

4,9,17,19-tetraenyl ester (47). A mixture of 45 (7.5 mg,

11.0 mmol), pyridine and benzoyl chloride was stirred for 17

h following the general method. After puriﬁcation of the

residue, benzoic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,

15S,16S)-15-acetoxy-7,13-bis(4-methoxybenzyloxy)-6,8,

14,16-tetramethyleicosa-4,9,17,19-tetraenyl ester was

obtained.

¹H NMR (300 MHz, CDCl₃) 8.04 (d, 2H, J=7.6 Hz),

7.58–7.53 (m, 1H), 7.43 (t, 2H, J=7.6 Hz), 7.28 (d, 2H,

J=8.6 Hz), 7.27 (d, 2H, J=8.6 Hz), 6.88 (d, 2H, J=8.6

Hz), 6.86 (d, 2H, J=8.6 Hz), 6.37 (ddd, 1H, J=16.8,

11.0, 10.1 Hz), 5.97 (dd, 1H, J=11.0, 11.0 Hz), 5.51 (dd,

1H, J=11.0, 9.7 Hz), 5.40–5.25 (m, 4H), 5.17 (dd, 1H,

J=16.8, 1.8 Hz), 5.07 (d, 1H, J=10.1 Hz), 4.96 (dd, 1H,

J=5.9, 5.9 Hz), 4.56–4.48 (m, 3H), 4.32 (d, 1H, J=11.4

Hz), 4.31–4.22 (m, 2H), 3.80 (s, 3H), 3.79 (s, 3H), 3.21

(dt, 1H, J=5.6, 5.6 Hz), 3.05 (dd, 1H, J=7.4, 4.0 Hz),

2.81–2.70 (m, 2H), 2.67–2.57 (m, 1H), 2.34–2.17 (m,

1H), 2.10–1.96 (m, 2H), 1.98 (s, 3H), 1.95–1.74 (m, 4H),

1.61–1.55 (m, 2H), 1.02 (d, 3H, J=6.7 Hz), 1.01 (d, 3H,

J=6.9 Hz), 0.94 (d, 3H, J=6.9 Hz), 0.88 (d, 3H, J=6.8

Hz).

To the esterabove obtained (6.0 mg, 7.9 mmol) was

added NaHCO₃and DDQ. Puriﬁcation of the crude

product by column chromatography (CH₂Cl₂to

CH₂Cl₂/EtOAc 7:3) provided 2.8 mg (70%) of the ana-

logue 48 as a colorless oil.

IR (thin ﬁlm, NaCl) 3434, 2965, 2922, 2871, 1724, 1715,

1455, 1364, 1237, 1161, 1019 cm^ꢀ1; ¹H NMR (300 MHz,

CDCl₃) 6.62 (ddd, 1H, J=16.8, 11.0, 10.1 Hz), 6.04 (dd,

1H, J=11.0, 11.0 Hz), 5.53–5.30 (m, 5H), 5.23 (dd, 1H,

J=16.8, 1.9 Hz), 5.14 (d, 1H, J=10.1 Hz), 4.94 (dd, 1H,

J=6.4, 5.1 Hz), 4.13–4.00 (m, 2H), 3.63–3.58 (m, 1H),

3.23 (dd, 1H, J=5.7, 5.7 Hz), 3.00 (ddq, 1H, J=10.1,

6.7, 3.3 Hz), 2.71–2.56 (m, 2H), 2.22–2.00 (m, 3H), 2.02

(s, 3H), 1.78–1.62 (m, 4H), 1.53–1.45 (m, 2H), 1.21 (s,

9H), 0.99 (d, 3H, J=6.8 Hz), 0.98 (d, 6H, J=6.8 Hz),

0.93 (d, 3H, J=6.9 Hz); MS (FAB in MNBA/Na, m/z)

543 (M+Na)⁺, 503, 426, 340, 154, 121; HRMS (FAB

in MNBA) calcd forC ₃₁H₅₃O₆(M+H)⁺521.3842,

found 521.3835; [a]²_D⁰+79.3 (c 0.14, CHCl₃).

The esterabove obtained (7.4 mg, 9.4 mmol) was treated

with NaHCO₃and DDQ, according to the general pro-

cedure. Flash chromatography of the crude product

using CH₂Cl₂/EtOAc 7:3 yielded 3.5 mg (70%) of the

corresponding benzoyl analogue 47.

IR (thin ﬁlm, NaCl) 3453, 2962, 2923, 1730, 1719, 1453,

1370, 1271, 1113, 1022 cm^{ꢀ1 1}H NMR (300 MHz,

;

General procedure for the synthesis of 17S-dis-

codermolide analogues

CDCl₃) 8.05 (d, 2H, J=7.7 Hz), 7.60–7.54 (m, 1H), 7.45

(t, 2H, J=7.7 Hz), 6.61 (ddd, 1H, J=16.9, 11.0, 10.1

Hz), 6.03 (dd, 1H, J=11.0, 11.0 Hz), 5.55–5.32 (m, 5H),

5.22 (d, 1H, J=16.9 Hz), 5.13 (d, 1H, J=10.1 Hz), 4.94

(dd, 1H, J=6.3, 5.2 Hz), 4.38–4.29 (m, 2H), 3.63–3.57

(m, 1H), 3.22 (dd, 1H, J=5.7, 5.7 Hz), 3.00 (ddq, 1H,

J=10.1, 6.7, 3.4 Hz), 2.69–2.60 (m, 2H), 2.29–2.00 (m,

3H), 2.01 (s, 3H), 1.88–1.70 (m, 4H), 1.50–1.45 (m, 2H),

1.06–0.96 (m, 9H), 0.92 (d, 3H, J=6.9 Hz); ¹³C NMR

(125 MHz, CDCl₃) 171.3, 166.7, 133.7, 133.5, 133.0,

132.7, 132.1, 130.4, 130.2, 130.0, 129.6, 128.7, 128.4,

To a solution of the alcohol 58 (10 mmol) in 1 mL of

dichloromethane was added pyridine (50 mmol) fol-

lowed by the corresponding acyl chloride (30 mmol).

The mixture was stirred at room temperature for the

required time, concentrated under vacuum and puriﬁed

by chromatography (CH₂Cl₂to CH₂Cl₂/EtOAc 9:1) to

provide the corresponding esters.

The esters obtained (10 mmol) were dissolved in di-

chloromethane (1 mL) and NaHCO₃(30 mg) was added

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3352

to the solution, followed by the addition of DDQ (30

mmol). The mixture was stirred for 1 h at room tem-

perature, concentrated and the crude residue puriﬁed by

chromatography to aﬀord the corresponding (17S)-

analogues of discodermolide.

Hz), 6.84 (d, 2H, J=8.6 Hz), 6.62 (ddd, 1H, J=16.9,

11.0, 10.1 Hz), 6.06 (dd, 1H, J=11.0, 11.0 Hz), 5.56–

5.26 (m, 5H), 5.22 (d, 1H, J=16.9 Hz), 5.13 (d, 1H,

J=10.1 Hz), 4.91 (dd, 1H, J=6.5, 5.1 Hz), 4.85 (bs,

2H), 4.55 (d, 1H, J=10.6 Hz), 4.49 (d, 1H, J=10.6 Hz),

4.40 (d, 1H, J=10.5 Hz), 4.32–4.25 (m, 3H), 3.79 (s, 3H),

3.77 (s, 3H), 3.32–3.25 (m, 1H), 3.06 (dd, 1H, J=7.2, 4.1

Hz), 2.90 (ddq, 1H, J=10.0, 6.7, 3.3 Hz), 2.80–2.62 (m,

2H), 2.25–1.97 (m, 5H), 1.85–1.71 (m, 2H), 1.56–1.48 (m,

2H), 1.02 (d, 3H, J=6.7 Hz), 1.00 (d, 3H, J=7.0 Hz), 0.98

(d, 3H, J=7.0 Hz), 0.89 (d, 3H, J=6.9 Hz).

2,2-Dimethylpropionic acid, (Z,Z,Z)-(6S,7S,8S,13S,14S,

15S,16S)-15-carbamoyloxy-7,13-dihydroxy-6,8,14,16-

tetramethyleicosa-4,9,17,19-tetraenyl ester (59). Follow-

ing the general procedure, a mixture of 6.5 mg (9.6

mmol) of 58, pyridine and pivaloyl chloride was stirred

for 16 h. After concentration and chromatography, the

product 2,2-dimethylpropionic acid, (Z,Z,Z)-(6S,7S,8S,

13S,14S,15S,16S)-15-carbamoyloxy-7,13-bis(4-methoxy-

benzyloxy)-6,8,14,16-tetramethyleicosa-4,9,17,19-tetra-

enyl ester was obtained.

To the esterobtained above (7.2 mg, 9.2 mmol) was

added NaHCO₃and DDQ. Chromatography of the

crude product using CH₂Cl₂/EtOAc 1:1 gave 3.6 mg

(72%) of the benzoyl analogue 60.

¹H NMR (300 MHz, CDCl₃) 7.29 (d, 4H, J=8.6 Hz),

6.89 (d, 2H, J=8.6 Hz), 6.87 (d, 2H, J=8.5 Hz), 6.64

(ddd, 1H, J=16.7, 11.0, 10.1 Hz), 6.08 (dd, 1H, J=11.0,

11.0 Hz), 5.56–5.29 (m, 5H), 5.24 (d, 1H, J=16.7 Hz),

5.15 (d, 1H, J=10.1 Hz), 4.91 (dd, 1H, J=6.5, 5.2 Hz),

4.62–4.50 (m, 4H), 4.42 (d, 1H, J=10.6 Hz), 4.29 (d,

1H, J=10.6 Hz), 4.09–4.00 (m, 2H), 3.82 (s, 3H), 3.80

(s, 3H), 3.34–3.28 (m, 1H), 3.09 (dd, 1H, J=7.2, 4.1

Hz), 2.92 (ddq, 1H, J=10.0, 6.8, 3.3 Hz), 2.79–2.62 (m,

2H), 2.20–1.99 (m, 5H), 1.71–1.51 (m, 4H), 1.21 (s, 9H),

1.05 (d, 3H, J=6.8 Hz), 1.03 (d, 3H, J=6.9 Hz), 1.01

(d, 3H, J=6.9 Hz), 0.92 (d, 3H, J=6.9 Hz).

IR (thin ﬁlm, NaCl) 3345, 2964, 2927, 1712, 1696, 1602,

1400, 1321, 1276, 1119, 1030 cm^ꢀ1; ¹H NMR (300 MHz,

CDCl₃) 8.08 (d, 1H, J=7.0 Hz), 8.05 (d, 1H, J=7.0

Hz), 7.55–7.40 (m, 3H), 6.65 (ddd, 1H, J=16.7, 10.9,

10.2 Hz), 6.05 (dd, 1H, J=10.9, 10.9 Hz), 5.55–5.28 (m,

5H), 5.23 (d, 1H, J=16.7 Hz), 5.13 (d, 1H, J=10.2 Hz),

4.84 (dd, 1H, J=9.7, 1.5 Hz), 4.72 (bs, 2H), 4.40–4.26

(m, 2H), 3.22 (dd, 1H, J=5.9, 5.9 Hz), 3.19 (td, 1H,

J=9.3, 2.2 Hz), 2.96 (ddq, 1H, J=9.6, 7.0, 2.8 Hz),

2.70–2.57 (m, 2H), 2.30–2.15 (m, 4H), 1.90–1.80 (m,

2H), 1.72–1.60 (m, 2H), 1.46–1.40 (m, 1H), 0.98 (d, 3H,

J=6.9 Hz), 0.96 (d, 6H, J=7.0 Hz), 0.87 (d, 3H, J=6.9

Hz); MS (FAB in MNBA/Na, m/z) 564 (M+Na)⁺,

543, 521, 487, 437, 313, 241, 154; HRMS (FAB in

MNBA) calcd forC ₃₂H₄₈NO₆(M+H)⁺542.33482,

found 542.3487; [a]²_D⁰+86.7 (c 0.18, CHCl₃).

The ester(6.0 mg, 7.8 mmol) was treated with NaHCO₃

and DDQ following the general method. Chromato-

graphy of the residue in CH₂Cl₂/EtOAc 1:1 aﬀorded 3.4

mg (84%) of the analogue 59 as a colorless oil.

Hydroxyacetic acid, (Z,Z,Z)-(6S,7S,8S,13S,14S,15S,

16S)-15-carbamoyloxy-7,13-dihydroxy-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester (61). A mixture of

58 (6.5 mg, 9.6 mmol), (4-methoxybenzyloxy) acetic acid

(19.2 mmol), EDCI (19.2 mmol) and DMAP (0.48 mmol)

was stirred at room temperature for 48 h. After pur-

iﬁcation of the residue by chromatography using

CH₂Cl₂/EtOAc 1:1, (4-methoxybenzyloxy)acetic acid,

(Z,Z,Z)-(6S,7S,8S,13S,14S,15S,16S)-15-carbamoyloxy-

7,13 - bis(4 - methoxybenzyloxy) - 6,8,14,16 - tetramethyl-

eicosa-4,9,17,19-tetraenyl ester was obtained.

IR (thin ﬁlm, NaCl) 3431, 2966, 2930, 1715, 1703, 1456,

1398, 1325, 1161, 1034 cm^ꢀ^{1 1}H NMR (300 MHz,

;

CDCl₃) 6.65 (ddd, 1H, J=17.0, 11.0, 10.1 Hz), 6.04 (dd,

1H, J=11.0, 11.0 Hz), 5.53–5.28 (m, 5H), 5.23 (dd, 1H,

J=17.0, 1.7 Hz), 5.13 (d, 1H, J=10.1 Hz), 4.83 (dd, 1H,

J=9.7, 1.6 Hz), 4.57 (bs, 2H), 4.11–4.00 (m, 2H), 3.24–

3.17 (m, 2H), 2.95 (ddq, 1H, J=9.6, 7.0, 2.6 Hz), 2.70–

2.56 (m, 2H), 2.24–2.03 (m, 4H), 1.75–1.58 (m, 4H),

1.49–1.40 (m, 1H), 1.21 (s, 9H), 0.99 (d, 3H, J=7.0 Hz),

0.98 (d, 3H, J=6.9 Hz), 0.96 (d, 3H, J=6.8 Hz), 0.87

(d, 3H, J=7.0 Hz); MS (FAB in MNBA/Na, m/z) 544

(M+Na)⁺, 522 (M+H)⁺, 413, 340, 176, 154; HRMS

(FAB) calcd forC ₃₀H₅₂NO₆(M+H)⁺522.3795, found

522.3790; [a]²_D⁰+92.2 (c 0.155, CHCl₃).

¹H NMR (300MHz, CDCl₃) 7.31–7.26 (m, 6H), 6.92–

6.83 (m, 6H), 6.62 (ddd, 1H, J=17.4, 11.0, 10.1 Hz), 6.06

(dd, 1H, J=11.0, 11.0 Hz), 5.54–5.27 (m, 5H), 5.21 (d,

1H, J=17.4 Hz), 5.13 (d, 1H, J=10.1 Hz), 4.88 (dd, 1H,

J=6.4, 5.3 Hz), 4.63–4.51 (m, 6H), 4.40 (d, 1H, J=10.6

Hz), 4.26 (d, 1H, J=10.6 Hz), 4.12 (t, 2H, J=6.7 Hz),

4.05 (s, 2H), 3.81 (s, 3H), 3.80 (s, 3H), 3.78 (s, 3H), 3.29

(td, 1H, J=6.2, 4.1 Hz), 3.06 (dd, 1H, J=7.2, 4.1 Hz),

2.90 (ddq, 1H, J=10.1, 7.0, 3.2 Hz), 2.74–2.61 (m, 2H),

2.15–1.95 (m, 4H), 1.70–1.59 (m, 2H), 1.58–1.46 (m, 3H),

1.02 (d, 3H, J=7.0 Hz), 1.00 (d, 3H, J=7.0 Hz), 0.98 (d,

3H, J=6.8 Hz), 0.90 (d, 3H, J=7.0 Hz).

Benzoic acid, (Z,Z,Z)-(6S,7S,8S,13S,14S,15S,16S)-15-

carbamoyloxy-7,13-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (60). Following the general

procedure, a mixture of 6.5 mg (9.6 mmol) of 58, pyri-

dine and benzoyl chloride was stirred for 20 h. After

puriﬁcation, benzoic acid, (Z,Z,Z)-(6S,7S,8S,13S,

14S,15S,16S) - 15 - carbamoyloxy - 7,13 - bis(4 - methoxy-

benzyloxy)-6,8,14,16-tetramethyleicosa-4,9,17,19-tetra-

enyl ester was obtained.

The esterobtained above (4.4 mg, 5.1 mmol) was treated

with NaHCO₃and DDQ (25 mmol). After5 h of sti-r

ring, the residue was chromatographed using EtOAc as

eluent to provide 1.1 mg (54%) of the analogue 61.

¹H NMR (300 MHz, CDCl₃) 8.12 (d, 2H, J=7.1 Hz),

7.65–7.58 (m, 1H), 7.55–7.49 (m, 2H), 7.28 (d, 2H,

J=8.6 Hz), 7.27 (d, 2H, J=8.6 Hz), 6.86 (d, 2H, J=8.6

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3353

¹H NMR (300 MHz, CDCl₃) 6.65 (ddd, 1H, J=16.7,

11.0, 10.1 Hz), 6.05 (dd, 1H, J=11.0, 11.0 Hz), 5.51–

5.28 (m, 5H), 5.23 (dd, 1H, J=16.7, 1.9 Hz), 5.13

(d, 1H, J=10.1 Hz), 4.83 (dd, 1H, J=9.8, 1.6 Hz),

4.63 (bs, 2H), 4.29–4.17 (m, 2H), 4.17 (s, 2H), 3.22

(dd, 1H, J=5.8, 5.8 Hz), 3.17 (td, 1H, J=9.5, 2.0 Hz),

3.02–2.92 (m, 1H), 2.71–2.56 (m, 2H), 2.26–2.10 (m,

4H), 1.78–1.38 (m, 5H), 0.99 (d, 3H, J=6.9 Hz), 0.98 (d,

3H, J=6.8 Hz), 0.96 (d, 3H, J=6.8 Hz), 0.87 (d, 3H,

J=6.9 Hz); MS (FAB in MNBA, m/z) 496 (M+H)⁺,

391, 368, 307, 289, 154, 136; [a]²_D⁰+72.0 (c 0.05,

CHCl₃).

General procedure for the 17R-carbamoyloxy or 17R-

acetoxy analogues of discodermolide

To a solution of the alcohols 72 or 73 (10 mmol) in 1 mL

of dichloromethane was added pyridine (50 mmol) fol-

lowed by the corresponding acyl chloride (30 mmol).

The mixture was stirred at room temperature for the

required time, concentrated under vacuum and puriﬁed

by chromatography (CH₂Cl₂to CH₂Cl₂/EtOAc 95/5) to

provide the corresponding esters.

The esters above obtained (10 mmol) were dissolved in 1

mL of dichloromethane and NaHCO₃(40 mg) was

added to the solution, followed by the addition of DDQ

(30 mmol). The mixture was stirred at room temperature

for 1 h, concentrated and the crude residue was puriﬁed

by chromatography to aﬀord the corresponding 17-car-

bamoyloxy or17-acetoxy analogues of discodermolide.

Furan-2-carboxylic acid, (Z,Z,Z)-(6S,7S,8S,13S,14S,

15S,16S)-15-carbamoyloxy-7,13-dihydroxy-6,8,14,16-tet-

ramethyleicosa-4,9,17,19-tetraenyl ester (62). Following

the general procedure, a mixture of the alcohol 58 (6.5

mg, 9.6 mmol), pyridine and 2-furoyl chloride (20 mmol)

was stirred for 20 h to obtain furan-2-carboxylic acid,

(Z,Z,Z)-(6S,7S,8S,13S,14S,15S,16S)-15-carbamoyloxy-

7,13 - bis(4 - methoxybenzyloxy) - 6,8,14,16 - tetramethyl-

eicosa-4,9,17,19-tetraenyl ester.

2,2-Dimethylpropionic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,

15S,16S)-13-carbamoyloxy-7,15-dihydroxy-6,8,14,16-tet-

ramethyleicosa-4,9,17,19-tetraenyl ester (74). Following

the general procedure, a mixture of 2.0 mg (2.9 mmol) of

72, pyridine and pivaloyl chloride was stirred for 24 h.

After concentration and chromatography, the product

2,2-dimethylpropionic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,

15S,16S)-13-carbamoyloxy-7,15-bis(4-methoxybenzyl-

oxy)-6,8,14,16-tetramethyleicosa-4,9,17,19-tetraenyl ester

was obtained.

¹H NMR (300 MHz, CDCl₃) 7.63–7.60 (m, 1H), 7.28 (d,

4H, J=8.5 Hz), 7.15 (d, 1H, J=3.2 Hz), 6.87 (d, 2H,

J=8.5 Hz), 6.84 (d, 2H, J=8.5 Hz), 6.62 (ddd, 1H,

J=16.8, 11.0, 10.2 Hz), 6.49 (dd, 1H, J=3.3, 1.7 Hz),

6.06 (dd, 1H, J=11.0, 11.0 Hz), 5.51 (dd, 1H, J=10.6,

10.6 Hz), 5.48–5.27 (m, 4H), 5.22 (d, 1H, J=16.8 Hz),

5.13 (d, 1H, J=10.2 Hz), 4.89 (dd, 1H, J=5.8, 5.8 Hz),

4.57–4.47 (m, 4H), 4.40 (d, 1H, J=10.6 Hz), 4.30–4.24

(m, 3H), 3.80 (s, 3H), 3.78 (s, 3H), 3.28 (td, 1H, J=6.2,

4.1 Hz), 3.06 (dd, 1H, J=7.2, 4.1 Hz), 2.90 (ddq, 1H,

J=10.0, 6.8, 3.4 Hz), 2.80–2.62 (m, 2H), 2.20–1.97 (m,

4H), 1.80–1.69 (m, 2H), 1.58–1.47 (m, 3H), 1.02 (d, 3H,

J=6.7 Hz), 1.00 (d, 3H, J=6.8 Hz), 0.98 (d, 3H, J=7.0

Hz), 0.89 (d, 3H, J=6.9 Hz).

¹H NMR (300 MHz, CDCl₃) 7.28 (d, 4H, J=8.4 Hz),

6.87 (d, 4H, J=8.4 Hz), 6.72 (ddd, 1H, J=17.2, 11.0,

10.1 Hz), 6.04 (dd, 1H, J=11.0, 11.0 Hz), 5.55–5.42 (m,

2H), 5.40–5.25 (m, 3H), 5.19 (d, 1H, J=17.2 Hz), 5.12

(d, 1H, J=10.2 Hz), 4.88–4.79 (m, 1H), 4.60–4.44 (m,

6H), 4.03 (t, 2H, J=6.4 Hz), 3.81 (s, 6H), 3.22–3.07 (m,

3H), 2.77–2.58 (m, 2H), 2.15–1.90 (m, 4H), 1.87–1.50

(m, 5H), 1.19 (s, 9H), 1.09 (d, 3H, J=6.7 Hz), 1.01 (d,

9H, J=6.7 Hz).

The esterabove obtained (6.0 mg, 7.7 mmol) was

treated with NaHCO₃and DDQ, according to the

general procedure. Chromatography of the crude

product using CH₂Cl₂/EtOAc 19:1 to 1:1 yielded 3.1 mg

(78%) of the corresponding analogue 62 as a colorless

oil.

The esterabove obtained (1.3 mg, 1.7 mmol) was treated

with NaHCO₃and DDQ, following the general method.

Flash chromatography of the residue using CH₂Cl₂to

CH₂Cl₂/EtOAc 1:1 gave 0.6 mg (70%) of the analogue 74.

IR (thin ﬁlm, NaCl) 3420, 2864, 2927, 1713, 1584,

1399, 1299, 1181, 1122 cm^ꢀ^{1 1}H NMR (300 MHz,

;

¹H NMR (300 MHz, CDCl₃) 6.67 (ddd, 1H, J=16.5,

10.7, 10.1 Hz), 6.15 (dd, 1H, J=10.7, 10.7 Hz), 5.51–

5.46 (m, 1H), 5.39–5.28 (m, 4H), 5.25 (d, 1H, J=16.5

Hz), 5.17 (d, 1H, J=10.1 Hz), 4.87 (dt, 1H, J=12.4, 5.1

Hz), 4.58 (bs, 2H), 4.09–4.02 (m, 2H), 3.40 (dd, 1H,

J=7.6, 3.3 Hz), 3.21 (dd, 1H, J=5.8, 5.8 Hz), 2.89–2.83

(m, 1H), 2.65–2.57 (m, 2H), 2.18–1.97 (m, 4H), 1.90–

1.81 (m, 2H), 1.75–1.58 (m, 3H), 1.21 (s, 9H), 0.99–0.96

(m, 12H); MS (EI, m/z) 503 (Mꢀ18)⁺, 429, 355, 281,

221, 207; HRMS (EI) calcd forC ₃₀H₄₉NO₅(MꢀH₂O)⁺

503.3610, found 503.3594; [a]²_D⁰+28.0 (c 0.025, CHCl₃).

CDCl₃) 7.60–7.58 (m, 1H), 7.18 (d, 1H, J=3.6 Hz),

6.65 (ddd, 1H, J=16.5, 10.9, 10.2 Hz), 6.52 (dd,

1H, J=3.6, 1.7 Hz), 6.04 (dd, 1H, J=10.9, 10.9

Hz), 5.56–5.30 (m, 5H), 5.23 (d, 1H, J=16.5 Hz),

5.13 (d, 1H, J=10.2 Hz), 4.83 (dd, 1H, J=9.7, 1.5

Hz), 4.59 (bs, 2H), 4.39–4.24 (m, 2H), 3.22 (dd, 1H,

J=5.8, 5.8 Hz), 3.18 (td, 1H, J=9.1, 2.0 Hz), 2.96

(ddq, 1H, J=9.6, 7.0, 2.8 Hz), 2.73–2.55 (m, 2H),

2.27–2.12 (m, 4H), 1.87–1.58 (m, 4H), 1.48–1.39 (m,

1H), 0.98 (d, 3H, J=6.7 Hz), 0.97 (d, 3H, J=6.7

Hz), 0.96 (d, 3H, J=6.8 Hz), 0.87 (d, 3H, J=6.9

Hz); MS (FAB in MNBA/Na, m/z) 554 (M+Na)⁺,

532 (M+H)⁺, 413, 329, 307, 176, 154; HRMS

(FAB in MNBA) calcd forC ₃₀H₄₆NO₇(M+H)⁺

532.3274, found 532.3277; [a]²_D⁰+85.8 (c 0.155,

CHCl₃).

Benzoic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-13-

carbamoyloxy-7,15-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (75). A mixture of 72 (4.5 mg,

6.6 mmol), pyridine and benzoyl chloride was stirred for

20 h. Following the general procedure, benzoic acid,

(Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-13-carbamoyloxy-

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J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3354

7,15 - bis(4 - methoxybenzyloxy) - 6,8,14,16 - tetramethyl-

eicosa-4,9,17,19-tetraenyl ester was obtained.

¹H NMR (300 MHz, CDCl₃) 6.68 (ddd, 1H, J=17.3,

10.9, 10.1 Hz), 6.16 (dd, 1H, J=10.9, 10.9 Hz), 5.50–

5.29 (m, 5H), 5.26 (d, 1H, J=17.3 Hz), 5.17 (d, 1H,

J=10.1 Hz), 4.91–4.85 (m, 1H), 4.60 (bs, 2H), 4.09–4.01

(m, 2H), 3.43–3.39 (m, 1H), 3.22 (dd, 1H, J=8.8, 5.8

Hz), 2.92–2.84 (m, 1H), 2.65–2.54 (m, 2H), 2.18–2.02

(m, 2H), 2.06 (s, 3H), 1.86–1.84 (m, 1H), 1.75–1.59 (m,

6H), 1.01–0.97 (m, 12H); MS (EI, m/z) 480 (M+H)⁺,

467, 398, 337, 324, 319, 301; HRMS (EI) calcd for

C₂₁H₃₆NO₆(MꢀC₆H₉)⁺398.2543, found 398.2544;

[a]²_D⁰+53.3 (c 0.045, CHCl₃).

¹H NMR (300 MHz, CDCl₃) 8.04 (dd, 2H, J=8.3, 1.3

Hz), 7.55–7.48 (m, 1H), 7.46–7.42 (m, 2H), 7.28 (d, 4H,

J=8.7 Hz), 6.86 (d, 4H, J=8.7 Hz), 6.70 (ddd, 1H,

J=16.7, 11.0, 10.0 Hz), 6.02 (dd, 1H, J=11.0, 11.0 Hz),

5.51 (dd, 1H, J=10.5, 10.5 Hz), 5.53–5.48 (m, 1H),

5.41–5.21 (m, 3H), 5.18 (d, 1H, J=16.7 Hz), 5.11 (d,

1H, J=10.0 Hz), 4.84–4.79 (m, 1H), 4.58–4.44 (m, 6H),

4.29 (t, 2H, J=6.5 Hz), 3.81 (s, 3H), 3.80 (s, 3H), 3.21–

3.11 (m, 2H), 3.04 (dd, 1H, J=7.5, 4.0 Hz), 2.75–2.66

(m, 1H), 2.63–2.56 (m, 1H), 2.12–2.07 (m, 1H), 2.03–

1.96 (m, 1H), 1.88–1.76 (m, 4H), 1.62–1.50 (m, 3H), 1.09

(d, 3H, J=6.7 Hz), 1.02-0.98 (m, 9H).

2,2-Dimethylpropionic acid, (Z,Z,Z)-(6S,7S,8S,13R,

14S,15S,16S)-13-acetoxy-7,15-dihydroxy-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester (77). Following

the general procedure, a mixture of the alcohol 73 (1.9 mg,

2.8 mmol), pyridine and pivaloyl chloride was stirred for

40 h. After puriﬁcation of the crude product, 2,2-di-

methylpropionic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,

16S)-13-acetoxy-7,15-bis(4-methoxybenzyloxy)-6,8,14,16-

tetramethyleicosa-4,9,17,19-tetraenyl ester was obtained.

The esterabove obtained (4.0 mg, 5.1 mmol) was treated

with NaHCO₃and DDQ according to the general pro-

tocol. Chromatography of the crude product using

CH₂Cl₂to CH₂Cl₂/EtOAc 7:3 yielded 2.0 mg (77%) of

the corresponding analogue 75.

¹H NMR (300 MHz, CDCl₃) 8.05 (dd, 2H, J=8.5, 1.4

Hz), 7.57–7.54 (m, 1H), 7.47–7.43 (m, 2H), 6.65 (ddd,

1H, J=17.6, 10.9, 10.1 Hz), 6.15 (dd, 1H, J=10.9, 10.9

Hz), 5.52 (dd, 1H, J=10.5, 10.5 Hz), 5.41–5.31 (m, 4H),

5.24 (d, 1H, J=17.6 Hz), 5.16 (d, 1H, J=10.1 Hz), 4.86

(dt, 1H, J=5.2, 5.2 Hz), 4.58 (bs, 2H), 4.35–4.30 (m,

2H), 3.39 (dd, 1H, J=7.5, 3.7 Hz), 3.21 (dd, 1H, J=5.9,

5.9 Hz), 2.90–2.84 (m, 1H), 2.66–2.57 (m, 2H), 2.33–

2.05 (m, 4H), 1.92–1.77 (m, 3H), 1.69–1.62 (m, 2H), 0.96

(d, 12H, J=6.7 Hz); MS (EI, m/z) 460 (MꢀC₆H₉)⁺,

433, 417, 399, 247, 105; HRMS (EI) calcd for

C₂₆H₃₈NO₆(MꢀC₆H₉)⁺460.2699, found 460.2704;

[a]²_D⁰+44.7 (c 0.085, CHCl₃).

¹H NMR (300 MHz, CDCl₃) 7.27 (d, 4H, J=8.1 Hz),

6.89 (d, 4H, J=8.1 Hz), 6.70 (ddd, 1H, J=16.3, 10.9,

10.0 Hz), 6.03 (dd, 1H, J=10.9, 10.9 Hz), 5.51 (dd, 1H,

J=10.1, 10.1 Hz), 5.53–5.48 (m, 1H), 5.33–5.25 (m,

3H), 5.23 (d, 1H, J=16.3 Hz), 5.14 (d, 1H, J=10.0 Hz),

4.99–4.93 (m, 1H), 4.58–4.52 (m, 3H), 4.47 (d, 1H, J=10.5

Hz), 4.06–4.02 (m, 2H), 3.82 (s, 6H), 3.16–3.05 (m, 3H),

2.74–2.67 (m, 1H), 2.63–2.55 (m, 1H), 2.12–1.92 (m, 4H),

2.06 (s, 3H), 1.84–1.80 (m, 2H), 1.70–1.55 (m, 3H), 1.21 (s,

9H), 1.09 (d, 3H, J=6.7 Hz), 1.02–0.98 (m, 9H).

To the esterabove obtained (1.6 mg, 2.1 mmol) was

added NaHCO₃and DDQ. Flash chromatography of

the residue (CH₂Cl₂to CH₂Cl₂/EtOAc 7:3) aﬀorded 0.7

mg (70%) of the corresponding analogue 77.

Acetic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-13-

carbamoyloxy-7,15-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (76). Following the general

procedure, a mixture of 4.5 mg (6.6 mmol) of the alcohol

72, pyridine and acetyl chloride was stirred for 40 h.

After puriﬁcation of the crude product, acetic acid,

(Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-13-carbamoyloxy-

7,15 - bis(4 - methoxybenzyloxy) - 6,8,14,16 - tetramethyl-

eicosa-4,9,17,19-tetraenyl ester was obtained.

¹H NMR (300 MHz, CDCl₃) 6.66 (ddd, 1H, J=16.3,

10.8, 10.2 Hz), 6.16 (dd, 1H, J=10.8, 10.8 Hz), 5.50–

5.45 (m, 1H), 5.38–5.23 (m, 5H), 5.17 (d, 1H, J=10.2

Hz), 5.05–5.00 (m, 1H), 4.11–4.03 (m, 2H), 3.36 (dd,

1H, J=7.6, 3.5 Hz), 3.20 (dd, 1H, J=5.8, 5.8 Hz), 2.85–

2.78 (m, 1H), 2.63–2.57 (m, 2H), 2.16–2.00 (m, 2H), 2.06

(s, 3H), 1.92–1.85 (m, 1H), 1.76–1.58 (m, 6H), 1.21 (s,

9H), 1.00–0.97 (m, 12H); MS (FAB in MNBA/NaCl, m/

z) 543 (M+Na)⁺, 521 (M+H)⁺, 483, 462, 448, 413;

[a]²_D⁰+56.6 (c 0.03, CHCl₃).

¹H NMR (300 MHz, CDCl₃) 7.28 (d, 4H, J=8.6 Hz),

6.87 (d, 4H, J=8.6 Hz), 6.70 (ddd, 1H, J=16.8, 11.0,

10.0 Hz), 6.02 (dd, 1H, J=11.0, 11.0 Hz), 5.52 (dd, 1H,

J=10.5, 10.5 Hz), 5.50 (dd, 1H, J=11.0, 11.0 Hz), 5.36–

5.21 (m, 3H), 5.18 (d, 1H, J=16.8 Hz), 5.12 (d, 1H,

J=10.0 Hz), 4.82 (dt, 1H, J=8.4, 5.2 Hz), 4.57 (bs, 2H),

4.56–4.51 (m, 3H), 4.47 (d, 1H, J=10.3 Hz), 4.03 (t, 2H,

J=6.6 Hz), 3.81 (s, 6H), 3.21 (dd, 1H, J=7.1, 3.7 Hz),

3.19–3.12 (m, 1H), 3.05 (dd, 1H, J=7.5, 4.0 Hz), 2.71–

2.64 (m, 1H), 2.64–2.58 (m, 1H), 2.06–2.01 (m, 2H), 2.05

(s, 3H), 1.90–1.79 (m, 2H), 1.67–1.55 (m, 5H), 1.09 (d,

3H, J=6.7 Hz), 1.01 (d, 9H, J=6.9 Hz).

Benzoic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-13-

acetoxy - 7,15 - dihydroxy - 6,8,14,16 - tetramethyleicosa -

4,9,17,19-tetraenyl ester (78). A mixture of the alcohol

73 (1.9 mg, 2.8 mmol), pyridine and benzoyl chloride

was stirred for 24 h. Following the general procedure,

benzoic acid, (Z,Z,Z)-(6S,7S,8S,13R,14S,15S,16S)-13-

acetoxy-7,15-bis(4-methoxybenzyloxy)-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester was obtained.

¹H NMR (300 MHz, CDCl₃) 8.04 (dd, 2H, J=8.6, 1.5

Hz), 7.57–7.53 (m, 1H), 7.48–7.40 (m, 2H), 7.28–7.25

(m, 4H), 6.87 (d, 2H, J=8.5 Hz), 6.85 (d, 2H, J=8.5

Hz), 6.68 (ddd, 1H, J=18.5, 11.0, 10.0 Hz), 6.01 (dd,

1H, J=11.0, 11.0 Hz), 5.54–5.45 (m, 2H), 5.40–5.20 (m,

To the esterabove obtained (2.0 mg, 2.7 mmol) was

added NaHCO₃and DDQ. Chromatography of the

crude product using CH₂Cl₂to CH₂Cl₂/EtOAc 1:1 gave

1 mg (77%) of the analogue 76 as a colorless oil.

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3355

3H), 5.19 (d, 1H, J=18.5 Hz), 5.12 (d, 1H, J=10.0 Hz),

4.94 (dt, 1H, J=8.3, 5.2 Hz), 4.58–4.50 (m, 3H), 4.48 (d,

1H, J=9.2 Hz), 4.25–4.19 (m, 2H), 3.80 (s, 3H), 3.79 (s,

3H), 3.16–3.07 (m, 2H), 3.03 (dd, 1H, J=7.4, 4.2 Hz),

2.75–2.68 (m, 1H), 2.59–2.49 (m, 1H), 2.36–2.18 (m, 2H),

2.04 (s, 3H), 2.05–1.96 (m, 1H), 1.84–1.74 (m, 4H), 1.64–

1.55 (m, 2H), 1.07 (d, 3H, J=6.7 Hz), 1.01–0.97 (m, 9H).

eicosa-4,9,17,19-tetraenyl ester (90). The above proce-

dure was repeated starting from 87 (3.0 mg, 4.4 mmol) to

give 90 (2.0 mg, 4.1 mmol, 93%). H NMR (300 MHz,

1

CDCl₃) 6.66 (td, 1H, J=16.5, 10.6 Hz), 6.15 (t, 1H,

J=10.9 Hz), 5.49–5.15 (m, 7H), 4.91–4.85 (m, 1H), 4.62

(bs, 2H), 3.72 (t, 2H, J=6.4 Hz), 3.40 (dd, 1H, J=7.4,

3.6 Hz), 3.19 (t, 1H, J=5.8 Hz), 2.91–2.83 (m, 1H),

2.64–2.50 (m, 3H), 2.17–1.99 (m, 4H), 1.86–1.61 (m,

7H), 1.18 (d, 6H, J=6.7 Hz), 0.98 (d, 6H, J=6.7 Hz),

0.97 (d, 6H, J=6.5 Hz); MS (EI, m/z) 476, 410, 386,

368, 121.

The esterabove obtained (1.6 mg, 2.0 mmol) was treated

with NaHCO₃and DDQ according to the general

method. Chromatography of the crude product using

CH₂Cl₂to CH₂Cl₂/EtOAc 17:3 provided 0.7 mg (70%)

of the corresponding analogue 78.

2,2-Dimethylpropionic acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,

15S,16S)-13-carbamoyloxy-7,15-dihydroxy-6,8,14,16-tet-

ramethyleicosa-4,9,17,19-tetraenyl ester (91). Following

the general procedure, starting from 3.0 mg (4.4 mmol)

¹H NMR (300 MHz, CDCl₃) 8.05 (d, 2H, J=7.5 Hz),

7.58–7.54 (m, 1H), 7.47–7.43 (m, 2H), 6.65 (ddd, 1H,

J=16.5, 11.0, 10.6 Hz), 6.16 (dd, 1H, J=11.0, 11.0 Hz),

5.57–5.49 (m, 1H), 5.41–5.23 (m, 5H), 5.18 (d, 1H,

J=10.6 Hz), 5.04–5.00 (m, 1H), 4.34–4.30 (m, 2H),

3.37–3.33 (m, 1H), 3.20 (dd, 1H, J=5.5, 5.5 Hz), 2.87–

2.79 (m, 1H), 2.67–2.59 (m, 2H), 2.21–2.11 (m, 2H), 2.06

(s, 3H), 1.90–1.79 (m, 4H), 1.66–1.58 (m, 3H), 0.98–0.95

(m, 12H); MS (FAB in glycerol, m/z) 541 (M+H)⁺,

492, 477, 409, 371, 208, 105; HRMS (FAB in glycerol)

calcd forC ₃₃H₄₉O₆(M+H)⁺541.3529, found

541.3531; [a]²_D⁰+36.6 (c 0.03, CHCl₃).

1

of 87 was obtained 1.6 mg (3.1 mmol, 70%) of 91. H

NMR (300 MHz, CDCl₃) 6.66 (td, 1H, J=16.9, 10.6

Hz), 6.15 (t, 1H, J=11.0 Hz), 5.49–5.15 (m, 7H), 4.91–

4.85 (m, 1H), 4.61 (bs, 2H), 4.06 (t, 2H, J=6.3 Hz), 3.40

(dd, 1H, J=7.3, 3.6 Hz), 3.19 (t, 1H, J=5.7 Hz), 2.93–

2.82 (m, 1H), 2.65–2.55 (m, 2H), 2.19–2.01 (m, 4H),

1.84–1.59 (m, 7H), 1.20 (s, 9H), 0.98 (d, 6H, J=6.8 Hz),

0.97 (d, 6H, J=7.0 Hz); MS (APCI, m/z) 521 (M)⁺,

520, 504, 443, 425, 341.

Benzoic acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,16S)-13-

carbamoyloxy-7,15-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (92). The above procedure was

repeated starting from 3.0 mg (4.4 mmol) of 87 to yield

General procedure for the (11R,17R)-carbamoyloxy or

(11R,17R)-acetoxy analogues of discodermolide

1

Acetic acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,16S)-13-

carbamoyloxy-7,15-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (89). To a solution of 87 (3.2

mg, 4.7 mmol) in 500 mL of dichloromethane was added

pyridine (2.0 mL, 24 mmol) followed by acetyl chloride

(1.0 mL, 13 mmol). After3 h, the solution was con-

centrated and chromatographed (hexane/ether 2:3) to

aﬀord 3.3 mg (98%) of the acetate. The acetate obtained

above was dissolved in dichloromethane (1.0 mL) and

NaHCO₃(120 mg) was added to the solution followed

by DDQ (4.0 mg, 18 mmol). After 1 h of stirring at

ambient temperature, the mixture was concentrated

undera stream of nitrogen and chromatographed (hexane/

EtOAc 1:2) to give 2.2 mg (99%) of the analogue 89.

92 (1.7 g, 3.2 mmol, 73%). H NMR (300 MHz, CDCl₃)

8.05 (d, 2H, J=7.4 Hz), 7.56 (d, 1H, J=7.4 Hz), 7.45 (t,

2H, J=7.4 Hz), 6.67 (td, 1H, J=16.9, 10.8 Hz), 6.14 (t,

1H, J=11.0 Hz), 5.48–5.15 (m, 7H), 4.90–4.84 (m, 1H),

4.60 (bs, 2H), 4.33 (t, 2H, J=6.3 Hz), 3.39 (dd, 1H,

J=7.0, 3.3 Hz), 3.19 (t, 1H, J=5.2 Hz), 2.90–2.82 (m,

1H), 2.66–2.54 (m, 2H), 2.29–1.98 (m, 4H), 1.93–1.58

(m, 7H), 0.98–0.92 (m, 12H); MS (APCI, m/z) 540

(MꢀH)⁺, 524, 463, 445, 323; HRMS (EI) calcd for

C₂₆H₃₈NO₆(MꢀC₆H₉)⁺460.2699, found 460.2696.

Methoxyacetic acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,

16S)-13-carbamoyloxy-7,15-dihydroxy-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester (93). The general

procedure was repeated starting from 3.0 mg (4.4 mmol)

1

IR (thin ﬁlm, NaCl) 3445, 2961, 1718, 1602, 1251 cm^ꢀ1

;

of 87 to aﬀord 2.0 mg (4.1 mmol, 93%) of 93. H NMR

¹H NMR (500 MHz, CDCl₃) 6.79–6.66 (td, 1H,

J=16.6, 10.4 Hz), 6.03 (dd, 1H, J=11.1, 11.1 Hz), 5.56–

5.46 (m, 2H), 5.38–5.12 (m, 5H), 4.87–4.83 (m, 1H), 4.71

(bs, 2H), 3.61 (t, 2H, J=6.5 Hz), 3.22–3.11 (m, 2H),

3.06 (dd, 1H, J=7.7, 3.2 Hz), 2.71–2.60 (m, 2H), 2.11–

1.76 (m, 6H), 2.03 (s, 3H), 1.65–1.50 (m, 3H), 1.10 (d,

3H, J=6.6 Hz), 1.04–1.00 (m, 9H); ¹³C NMR

(125 MHz, CDCl₃) 159.2, 159.2, 157.2, 140.8, 134.4,

134.1, 132.7, 132.4, 131.4, 131.2, 129.6, 129.3, 128.6,

125.7, 117.7, 113.9, 88.2, 84.3, 75.6, 75.1, 75.0, 62.7,

55.5, 40.3, 36.3, 35.6, 35.5, 32.9, 30.5, 29.9, 24.1, 23.8,

19.3, 18.9, 17.8, 10.3; MS (APCI, m/z) 478 (MꢀH)⁺,

462, 401, 383, 323, 282. HRMS (EI) calcd for

C₂₁H₃₆NO₆(MꢀC₆H₉)⁺398.2543, found 398.2544.

(300 MHz, CDCl₃) 6.67 (td, 1H, J=16.9, 10.6 Hz), 6.15

(t, 1H, J=10.9 Hz), 5.49–5.15 (m, 7H), 4.88 (td, 1H,

J=7.9, 4.6 Hz), 4.62 (bs, 2H), 4.18 (t, 2H, J=6.6 Hz),

4.04 (s, 2H), 3.46 (s, 3H), 3.40 (dd, 1H, J=7.5, 3.4 Hz),

3.19 (t, 1H, J=5.7 Hz), 2.91–2.83 (m, 1H), 2.63–2.54

(m, 2H), 2.16–2.01 (m, 4H), 1.85–1.63 (m, 7H), 0.98 (d,

6H, J=6.7 Hz), 0.97 (d, 6H, J=6.4 Hz); MS (APCI, m/

z) 508 (MꢀH)⁺, 492, 431, 413, 341.

Acetic acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,16S)-13-

acetoxy - 7,15 - dihydroxy - 6,8,14,16 - tetramethyleicosa -

4,9,17,19-tetraenyl ester (94). Following the general

method starting from 88 (3.0 mg, 4.5 mmol) was

obtained 94 (1.5 mg, 3.1 mmol, 69%). ¹H NMR

(300 MHz, CDCl₃) 6.65 (td, 1H, J=16.9, 10.8 Hz), 6.16

(t, 1H, J=10.9 Hz), 5.50–5.16 (m, 7H), 5.10–5.00 (m,

1H), 4.06 (t, 2H, J=6.5 Hz), 3.36 (dd, 1H, J=7.6, 3.5

Isobutyric acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,16S)-

13-carbamoyloxy-7,15-dihydroxy-6,8,14,16-tetramethyl-

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3356

Hz), 3.19 (t, 1H, J=5.4 Hz), 2.88–2.80 (m, 1H), 2.71–

2.53 (m, 2H), 2.06 (s, 3H), 2.05 (s, 3H), 2.18–2.00 (m,

4H), 1.88–1.80 (m, 1H), 1.75–1.60 (m, 6H), 1.10–0.95

(m, 12H); MS (EI, m/z) 478 (M)⁺, 418, 346, 185, 121,

95; HRMS (EI) calcd forC ₂₂H₃₇O₆(MꢀC₆H₉)⁺

397.2590, found 397.2591.

J=6.3 Hz), 0.97 (d, 6H, J=6.5 Hz), 0.96 (d, 3H, J=6.2

Hz); MS (APCI, m/z) 509 (MꢀH)⁺, 491, 431, 413, 341,

323.

Biological evaluation

Electrophoretically homogenous tubulin free from

microtubule associated proteins was isolated as descri-

bed.²³

Isobutyric acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,16S)-

13-acetoxy-7,15-dihydroxy-6,8,14,16-tetramethyleicosa-

4,9,17,19-tetraenyl ester (95). The above reaction was

repeated from 5.0 mg (7.5 mmol) of 88 to give 2.6 mg

(5.3 mmol, 71%) of the analogue 95. ¹H NMR

(300 MHz, CDCl₃) 6.66 (td, 1H, J=16.8, 10.5 Hz), 6.16

(t, 1H, J=11.0 Hz), 5.49–5.16 (m, 7H), 5.03 (q, 1H,

J=5.7 Hz), 4.07 (t, 2H, J=6.5 Hz), 3.35 (dd, 1H,

J=7.5, 3.2 Hz), 3.19 (t, 1H, J=5.5 Hz), 2.88–2.80 (m,

1H), 2.65–2.50 (m, 3H), 2.06 (s, 3H), 2.20–1.98 (m, 4H),

1.87–1.60 (m, 7H), 1.18 (d, 6H, J=6.7 Hz), 0.99–0.96

(m, 12H); MS (EI, m/z) 440, 368, 284, 95.

Microtubule assembly assay.^4a,8Assembly of tubulin

into polymer was followed by turbidity measurement at

350 nm with a temperature-controlled, six-cuvette

Beckman-Coulter7400 specotrphotomete.r Reaction

mixtures (0.25 mL ﬁnal volume) contained tubulin (ﬁnal

concentration 10 mM; 1 mg/mL), monosodium gluta-

mate (0.8 M from a stock solution adjusted to pH 6.6

with HCl), DMSO (ﬁnal volume 4% v/v), and test agent

(10 mM). Reaction mixtures without test agent were

cooled to 0 ^ꢁC and added to cuvettes held at 0.25–0.5 ^ꢁC

in the spectrophotometer. Test agent in DMSO was

then rapidly mixed in the reaction mixture. Each run

contained one positive control (paclitaxel, 10 mM ﬁnal

concentration) and one negative control (DMSO only).

Baselines were established at 0.25–2.5 ^ꢁC and tempera-

ture was rapidly raised to 30 ^ꢁC (in approximately 1

min) and held there for 20 min. The temperature was

then rapidly lowered back to 0.25–2.5 ^ꢁC. The change in

absorbance 20 min after samples reached 30 ^ꢁC was

used to calculate the extent of polymerization. The

change in absorbance at this time point for the addition

of vehicle plus paclitaxel was considered 100% assembly

(positive control), while the change in absorbance for

addition of vehicle alone (negative control) was taken as

0% assembly.

2,2-Dimethylpropionic acid, (Z,Z,Z)-(6S,7R,8S,13R,

14S,15S,16S)-13-acetoxy-7,15-dihydroxy-6,8,14,16-tetra-

methyleicosa-4,9,17,19-tetraenyl ester (96). The above

procedure was repeated with 88 (3.0 mg, 4.5 mmol) to

1

give 96 (0.8 mg, 1.5 mmol, 33%). H NMR (300 MHz,

CDCl₃) 6.66 (td, 1H, J=16.6, 10.5 Hz), 6.16 (t, 1H,

J=11.0 Hz); 5.49–5.16 (m, 7H), 5.04 (q, 1H, J=5.9 Hz),

4.07 (t, 2H, J=6.4 Hz), 3.36 (dd, 1H, J=7.6, 3.5 Hz),

3.19 (t, 1H, J=5.8 Hz), 2.88–2.80 (m, 1H), 2.68–2.53

(m, 2H), 2.06 (s, 3H), 2.18–1.99 (m, 4H), 1.89–1.80 (m,

1H), 1.75–1.55 (m, 6H), 1.21 (s, 9H), 0.99 (d, 3H, J=6.5

Hz), 0.97 (d, 6H, J=6.8 Hz), 0.96 (d, 3H, J=6.5 Hz);

MS (APCI, m/z) 519 (MꢀH)⁺, 503, 443, 425, 251;

HRMS (EI) calcd forC ₂₅H₄₃O₆(MꢀC₆H₉)⁺439.3060,

found 439.3063.

Benzoic acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,16S)-13-

acetoxy - 7,15 - dihydroxy - 6,8,14,16 - tetramethyleicosa -

4,9,17,19-tetraenyl ester (97). Following the general

protocol starting from 88 (5.0 mg, 7.5 mmol) 2.7 mg (5.0

Paclitaxel binding site inhibition assay.²⁴A stock solu-

tion of [³H]paclitaxel (26.8 mM, 16.2 Ci/mmol),

obtained from the NCI, was prepared in 37% (v/v)

DMSO. The test agents were prepared in 25% (v/v)

DMSO–0.75 M monosodium glutamate (prepared from

a 2 M stock solution adjusted to pH 6.6 with HCl). The

radiolabeled paclitaxel and test agents, as indicated in

terms of ﬁnal concentrations, were mixed in equal

volumes and warmed to 37 ^ꢁC. A reaction mixture (50

mL) containing 0.75 M monosodium glutamate, 4.0 mM

tubulin, and 40 mM ddGTP (a non-hydrolyzable analo-

gue of GTP) was prepared and incubated at 37 ^ꢁC for30

min to preform microtubules. An equivalent volume of

drug mixture with [³H]paclitaxel was added to pre-

formed polymer and incubated for 30 min at 37 ^ꢁC.

Bound [³H]paclitaxel was separated from free drug by

centrifugation of the reaction mixtures at 14,000 rpm

for 20 min at room temperature. Radioactive counts

from the supernatant (50 mL) were determined by scin-

tillation spectrometry. Bound [³H]paclitaxel was calcu-

lated from the following: total paclitaxel added to each

reaction mixture minus the paclitaxel present in the

supernatant (free drug). The % bound values were nor-

malized to the control values with no inhibitor added.

1

mmol, 67%) of 97 was obtained. H NMR (300 MHz,

CDCl₃) 8.05 (d, 2H, J=7.3 Hz), 7.58 (d, 1H, J=7.3

Hz), 7.45 (t, 2H, J=7.3 Hz), 6.65 (td, 1H, J=16.9, 10.7

Hz), 6.15 (t, 1H, J=10.9 Hz), 5.50–5.12 (m, 7H), 5.03

(q, 1H, J=5.8 Hz), 4.34–4.30 (m, 2H), 3.35 (dd, 1H,

J=7.6, 3.4 Hz), 3.18 (t, 1H, J=5.3 Hz), 2.89–2.78 (m,

1H), 2.66–2.53 (m, 2H), 2.30–2.02 (m, 4H), 2.05 (s, 3H),

1.89–1.81 (m, 3H), 1.70–1.60 (m, 4H), 0.98 (d, 3H,

J=6.5 Hz), 0.95 (d, 6H, J=6.5 Hz), 0.93 (d, 3H, J=6.9

Hz); MS (APCI, m/z) 523 (MꢀOH)⁺, 463, 445, 341,

323.

Methoxyacetic acid, (Z,Z,Z)-(6S,7R,8S,13R,14S,15S,

16S)-13-acetoxy-7,15-dihydroxy-6,8,14,16-tetramethylei-

cosa-4,9,17,19-tetraenyl ester (98). The above reaction

was repeated with 3.0 mg (4.5 mmol) of 88 to aﬀord 2.0

mg (3.9 mmol, 87%) of the analogue 98. ¹H NMR

(300 MHz, CDCl₃) 6.65 (td, 1H, J=16.9, 10.6 Hz), 6.16

(t, 1H, J=10.9 Hz), 5.50–5.18 (m, 7H), 5.03 (q, 1H,

J=5.8 Hz), 4.18 (t, 2H, J=6.6 Hz), 4.04 (s, 2H), 3.46 (s,

3H), 3.36 (dd, 1H, J=7.6, 3.5 Hz), 3.19 (t, 1H, J=5.9

Hz), 2.90–2.81 (m, 1H), 2.66–2.54 (m, 2H), 2.06 (s, 3H),

2.18–1.95 (m, 4H), 1.85–1.62 (m, 7H), 0.98 (d, 3H,

Antiproliferative activity.^8,25,26Cells were plated (500–

2000 cells/well depending on the cell line) in 96-well

´

J.M. Mınguez et al. / Bioorg. Med. Chem. 11 (2003) 3335–3357

3357

microplates, allowed to attach and grow for 48 h, then

treated with vehicle (4% DMSO, a concentration that

allowed doubling times of 24 h orless) ortest agent (50,

10, 2, 0.4 and 0.08 mM forthe new agents; 0.01, 0.05,

0.010, 0.020 and 0.100 mM forpaclitaxel and dis-

codermolide) for the given times. One plate consisted of

cells from each line used for a time zero cell number

determination. The other plates in a given determina-

tion contained eight wells of control cells, eight wells of

medium and each agent concentration tested in quad-

ruplicate. Cell numbers were obtained spectro-

photometrically (absorbance at 490 nm minus that at

630 nm) in a Dynamax plate reader after treatment with

3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-

2-(4-sulfophenyl)-2H-tetrazolium (MTS) using phena-

zine methanesulfonate as the electron acceptor. After

initial screening with the above 5-fold dilutions, 50%

growth inhibitory concentration (GI₅₀) values were

determined for each agent by repeating the screen using

2-fold dilutions (ﬁve concentrations) centered on the

initial estimated GI₅₀concentration, again in quad-

ruplicate.

6. Martello, L. A.; McDaid, H. M.; Regl, D. L.; Yang, C. P.;

Meng, D.; Pettus, T. R.; Kaufman, M. D.; Arimoto, H.;

Danishefsky, S. J.; Smith, A. B. Clin. Cancer Res. 2000, 6, 1978.

7. (a) Hung, D. T.; Nerenberg, J. B.; Schreiber, S. L. J. Am.

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8. The ﬁnal steps in the synthesis of analogues 38–43 and

some of their biological activities have been reported: Min-

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Acknowledgements

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Financial support was provided by the National Cancer

Institute through grant CA78039 and by the Ministerio

˜

de Educacion y Cultura de Espana (Postdoctoral Fel-

lowship to J.M.M.). The authors thank Dr. Kenneth

Bair at Novartis Corp. for the gift of 1.

11. Mancuso, A. J.; Swern, D. Synthesis 1981, 165.

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B. W. Biochemistry 1996, 35, 243. (b) Hung, D. T.; Chen, J.;

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Cancer Drugs 1998, 9, 67.

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Synthesis and biological assessment of simplified analogues of the potent microtubule stabilizer (+)-discodermolide

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