Semisynthetic Macrolide Antibacterials Derived from Tylosin. Synthesis and Structure-Activity Relationships of Novel Desmycosin Analogues

J . Med. Chem. 2004, 47, 411-431

411

Sem isyn th etic Ma cr olid e An tiba cter ia ls Der ived fr om Tylosin . Syn th esis a n d

Str u ctu r e-Activity Rela tion sh ip s of Novel Desm ycosin An a logu es¹

Stjepan Mutak, Natasˇa Marsˇic´, Miroslava Dominis Kramaric´, and Drazˇen Pavlovic´*

PLIVA Pharmaceutical Industry Inc., Research Division, Prilaz baruna Filipovic´a 25, HR-10000 Zagreb, Croatia

Received May 15, 2003

A series of 20-O-substituted and 3,20-di-O-substituted derivatives of desmycosin were

synthesized and their biological properties were evaluated. In particular, we have synthesized

numerous side chain modified analogues of desmycosin as well as some analogues possessing

a combination of modified side chain and alternative C-3 substituents. Thus, R,â-unsaturated

analogues of desmycosin (2), tylosin (1), 10,11,12,13-tetrahydrotylosin (11), and 2,3-didehydro-

desmycosin (13) were prepared from the corresponding aldehydes by a Wittig reaction with

the stabilized ylides (a -d ), generating a trans-double bond, followed by modified Pfitzner-

Moffat oxidation of the C-3 hydroxyl group. To evaluate the importance of the C-3 position of

desmycosin for biological activity, the C-3 substituted derivatives were synthesized by a

standard sequence of protective group chemistry followed by Wittig reaction and esterification

as the key steps. For the attachment of the C-3 ester functionality, a mixed anhydride protocol

was adopted. Reaction proceeded smoothly to give corresponding esters in yields ranging from

70 to 80%. Base- and acid-catalyzed rearrangement products including desmycosin 8,20-aldols

(24a and 24b) and desmycosin 3,19-aldol (25) are also described. Parallel array synthesis and

purification techniques allowed for the rapid exploration of structure-activity relationships

within this class and for the improvement in potency. In vitro evaluation of these derivatives

demonstrated good antimicrobial activity against Gram-positive bacteria for most of the

compounds. The present derivatives of 16-membered macrolides were active against MLS_B-

resistant strains that were inducibly resistant, but not those constitutively resistant to

erythromycin.

In tr od u ction

concentrations of antibiotic activity in vivo. For instance,

the introduction of a 3,5-dimethylpiperidine moiety at

C-20 of desmycosin (2) via reductive amination has

culminated with the synthesis of tilmicosin (6), an

important drug developed exclusively for veterinary

medicine.⁸It has also been shown that derivatives of

desmycosin exhibit greater activity against Gram-

negative bacteria than do the analogous derivatives of

tylosin.⁹Consequently, C-20-modified derivatives of

desmycosin represent good starting materials for further

chemical modifications in the search for new 16-

membered macrolides possessing potentially useful

biological activities. Despite the relative maturity of the

field, research efforts have continued in order to discover

additional new semisynthetic derivatives that may

further expand the medicinal application of this class.

During the past 40 years, the structures of a number

of macrolide antibiotics have been elucidated. Of par-

ticular interest to us is the group of macrolides contain-

ing a 16-membered lactone ring, which include such

compounds as tylosin²(1) and demycarosyltylosine³

(desmycosin, 2) (Figure 1). The 16-membered ring

macrolide antibiotics⁴are an important series within

the macrolide class of antibiotics, since they offer some

advantages over 14-membered macrolides. These ad-

vantages include better gastrointestinal tolerance, lack

of drug-drug interactions, and activity against resis-

tance-expressing strains.⁵Tylosin is an important drug

used to treat veterinary Gram-positive and mycoplasma

infections as well as to promote livestock growth.⁶This

macrolide antibiotic is composed of a polyketide aglycon

(tylonolide) and three unusual sugars, D-mycaminose

(3), L-mycarose (4), and D-mycinose (5). On the other

hand, desmycosin obtained by the mild acidic hydrolysis

of tylosin has good antimicrobial activity in vitro against

Gram-positive bacteria and mycoplasma but almost no

activity in vivo when orally administered. Much of the

early efforts on structural modifications within the

desmycosin family of compounds have been directed

toward modification of the aldehyde group.⁷Derivatives

of desmycosin and related macrolides in which the

aldehyde function has been modified exhibit enhanced

oral bioavailability and higher and more prolonged

Ch em istr y

As part of a continuing synthetic program focused

upon synthesis of desmycosin analogues and related

products, we investigated the construction and screen-

ing of a small library of compounds with the goal of

identifying novel bacterial inhibitors. Access to a library

of desmycosin analogues required that we develop a

general synthetic strategy that would allow us to explore

chemical diversity at sites known to be linked to

biological activity. The complexity of the desmycosin

scaffold in combination with our desire to investigate

multiple structural variations posed a formidable syn-

thetic challenge.

* To whom correspondence should be addressed. Tel: +(385) 1 3781

585. Fax: +(385) 1 3722 932. E-mail: Drazen.Pavlovic@pliva.hr.

Published on Web 12/16/2003

412 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

F igu r e 1. Chemical structures of tylosin (1), desmycosin (2), and tilmicosin (6).

F igu r e 2. Library building blocks.

Ch a r t 1

Our basic synthetic approach envisioned constructing

appropriately functionalized and protected desmycosin

that would allow us to explore modifications at C-3,

C-20, and explore limited variation in the basic struc-

ture of the amino sugar D-mycaminose (3). A small

focused library was synthesized using various desmy-

cosin and tylosin-related scaffolds (Figure 2) in combi-

nation with a wide variety of carboxylic acids and

phosphorus ylides as building blocks. The search for new

valuable drug candidates not only demands that nu-

merous structural subunits (building blocks) are com-

bined on a particular backbone or template but also that

a rich variety of such scaffolds is provided. This takes

into account that the core structure of a compound class

contributes to the pharmacological profile in addition

to the effect it mediates by directing the spatial ar-

rangement of the pharmacophoric substituents. There-

fore, the following scaffolds were used for the construc-

tion of the library: 2′,4′,4′′-tri-O-acetyldesmycosin (7),^10-11

10,11,12,13-tetrahydrodesmycosin (8, THD),¹²4′-deoxy-

THD (9),¹³3-O-acetyldesmycosin (10),¹⁰tylosin (1, T),

THT (11),¹⁴2,3-anhydrodesmycosin (12),¹⁵2,3-didehy-

drodesmycosin (13),¹⁶and 2,3-didehydro-THD (14, Fig-

ure 2).¹⁷A simple straightforward structure such as 7

should allow optimization of potency, by parallel or

classical synthesis, for example, by formation of the

ester bond or double bond by classical carboxylic acid-

alcohol condensation methods or Wittig reaction, re-

spectively. Structural modifications considered for the

desmycosin 7 are outlined in Chart 1. Additionally, the

wide range of carboxylic acid and stabilized phosphorus

ylide libraries that are available to us made this

approach particularly attractive and also ensured that

a diverse set of compounds was synthesized.

Schemes 1 and 2. The desmycosin library was con-

structed by using a combination of classical and parallel

synthesis methods. Each library member was obtained

as a discrete product in ca. 10-50 mg scale and was

purified by silica gel chromatography (flash column or

thin layer), HPLC, or solid-phase extraction tech-

niques.¹⁸The synthetic strategy that we chose for the

synthesis of C-3 substituted analogues necessitated

regioselective protection of hydroxyl groups in the

positions C-2′, C-4′, and C-4′′ of desmycosin (see Figure

1 for numbering). After extensive experimentation, we

established an efficient synthesis of 13 (Scheme 1) by

sequentially protecting the various functional groups in

desmycosin according to their reactivities, with the

aldehyde (2) reacted first with trimethyl orthoformate

and a catalytic amount of p-toluenesulfonic acid followed

by acylation of the hydroxyl groups.^10,11Acetyl-derived

protecting groups were selected for all of these hydroxyl

groups, because they can be removed cleanly in one step

with aqueous ammonia in methanol. This process basi-

cally includes selective acetylation of the protected

aldehyde (15) via two-step sequence and starts with the

The solution-phase chemistry used to build initial

members of our desmycosin library is outlined in

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 413

Sch em e 1. Synthesis of 2,3-Didehydrodesmycosin (13)^a

a

Reagents and conditions: (a) Ac₂O, Et₃N, CH₂Cl₂, 25 °C, 1 h, 90%; (b) Ac₂O, DMAP, Et₃N, CH₂Cl₂, 25 °C, 2 h, 95%; (c) EDC, DMSO,

pyridinium trifluoroacetate, CH₂Cl₂, 0-25 °C, 4 h, 85%; (d) MeOH, reflux, 4 h, 85%; (e) aq NH₃, MeOH, 25 °C, 60 h, 74%; (f) 1% TFA,

MeCN, 25 °C, 2 h, 80%.

acetylation of the hydroxyl groups on amino sugar

D-mycaminose (3). Acetylation of the resulting 2′,4′-

diacetate (16) with acetic anhydride in the presence of

a catalytic amount of (dimethylamino)pyridine (DMAP)

and triethylamine proceeded selectively at the C-4′′

position of D-mycinose (5) to yield triacetate (17), the

substrate for the oxidation. The site of acetylation was

unambiguously assigned by one- and two-dimensional

¹H NMR and ¹³C NMR experiments and the usual

reactivity found in desmycosin analogues. With the rest

of the functionality suitably protected, we were now

ready to chemically manipulate the aglycon C-3 alcohol.

Oxidation of 2′,4′,4′′-tri-O-acetyldesmycosin 20-dimethyl-

acetal (17) was carried out using modified Pfitzner-

Moffat conditions: 1-(3-dimethylaminopropyl)-3-ethyl-

carbodiimide hydrochloride (EDC‚HCl)/DMSO/pyridin-

ium trifluoroacetate in methylene chloride at room

temperature (Scheme 1).¹⁹The reaction proceeded

smoothly to give virtually exclusively an enolic form of

desmycosin analogue (18) according to its ¹³C NMR

spectrum. Deprotection of 18 in methanol gave 4′′-

monoacetylated desmycosin 19, which was reacted

further with aqueous NH₃in methanol at room tem-

perature to afford 20 in 90% yield. Further deprotection

of 20 under acidic conditions (1% CF₃COOH, CH₃CN)

finally resulted in formation of 2,3-didehydrodesmycosin

(13) in 80% yield. The enol 13 was stable enough to be

purified by silica gel column chromatography. Recently,

a research group from Eli Lilly reported very similar

findings in the synthesis and evaluation of 16-membered

ketolide derivatives.¹⁶

aldehyde was used as starting material in the oxidation

reaction. Thus, acetylation of desmycosin (2) with acetic

anhydride and triethylamine led smoothly to diacetate

21, which was reacted further with acetic anhydride in

the presence of a catalytic amount of DMAP to furnish

2′,4′,4′′-tri-O-acetyldesmycosin (7) in 80% overall yield

after chromatographic purification.^10,11The Pfitzner-

Moffat oxidation of 7 provided 2′,4′,4′′-tri-O-acetyl-2,3-

didehydrodesmycosin (22), whose ¹³C NMR spectrum in

CDCl₃again exhibited a C-3 resonance at ca. 180 ppm,

unambiguously indicating that the enol form was present.

Deprotection carried out either with triethylamine in

methanol or with aqueous methanolic ammonia at 25

°C resulted in a formation of base-catalyzed aldol

reaction product as the principal product of the reaction.

Initial efforts to remove the protecting groups of enol

22 using triethylamine in methanol yielded the products

of intramolecular aldol condensation (24a and 24b) in

which cyclization occurred between C-8 and the alde-

hyde, forming a new five-membered ring. However,

hydrolysis of 22 in methanol afforded the product 23

derived from intramolecular cyclization between the

carbon alpha to the aldehyde and the C-3 keto group.

Removal of the remaining acetyl group of 23 with

aqueous ammonia or triethylamine in methanol finally

gave bicyclic aldehyde 25. Therefore, by subtle change

of reaction conditions used to deprotect hydroxyl groups

on both sugars, it was possible to obtain bicyclic alde-

hyde 23 substantially free of side products, such as the

aldol condensation products (24a and 24b) formed under

basic conditions (Scheme 2). According to LC/MS analy-

sis, less than 5% of the side products 24a and 24b were

actually observed.

The synthesis summarized in Scheme 2 followed the

same route as described for 13, except that the free

414 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Sch em e 2. Synthesis of Desmycosines (24a , 24b, and 25)^a

Pavlovic´ et al.

a

Reagents and conditions: (a) Ac₂O, Et₃N, CH₂Cl₂, 25 °C, 1 h, 90%; (b) Ac₂O, DMAP, Et₃N, CH₂Cl₂, 25 °C, 3 h, ca. 90%; (c) EDC,

DMSO, pyridinium trifluoroacetate, CH₂Cl₂, 0-25 °C, 3 h, 85%; (d) MeOH, 25 °, 80%, 6 h; (e) 2% Et₃N or aq NH₃, MeOH, 25 °C, 70%.

This reactivity indicates that the C3-position and the

methylene C19 are in close proximity within the lactone

ring. The aldehyde proton signal seen as a broad singlet

at δ 9.67 in 22 was observed as a doublet (J _19,20) 6.0

Hz) at δ 9.72 in 25. The signal changed to a singlet on

irradiation of the C19 methine proton at δ 2.60, indicat-

ing that the methine proton must be located at the

vicinal position with respect to the aldehyde. An un-

ambiguous NMR assignment of 25 was also made by

means of homonuclear ¹H-¹H and heteronuclear ¹H-

¹³C NMR spectroscopy. Observation of the molecular ion

peak at m/z 770, in addition to the ¹H NMR spectral

evidence described above, have led us to propose the

structure 3-hydroxybicyclo[12.2.1]desmycosin for 25

downfield shift of 3.8 ppm in 24a and 3.5 ppm in 24b

(δ 203.1 in 22, 206.9 in 24a , and 206.6 in 24b) based on

the substitution effect at the C-8 methine carbon. The

occurrence of C-9 at δ 206.9 and 206.6 suggested that

the C-20 hydroxyl group was hydrogen bonded to the

9-oxo group. These data clearly supported the presence

of hydrogen bonding between the 20-hydroxy and the

9-oxo group in the aldols 24a and 24b. This information

again indicated that only isomeric structures syn-24a

and anti-24b , could accommodate the data. Two-

dimensional NMR spectroscopy (DQF COSY, HSQC,

and HMBC) at 600 MHz enabled us to assign all of the

protons and carbons in 24a and 24b unambiguously and

to determine the coupling constants. Finally, the struc-

ture of 24a and 24b was assigned as 8R,20â- and

8â,20R-cyclo-20-hydroxydesmycosin, respectively.

Our next objective was to modify the aldehyde group

of desmycosin. Kirst and co-workers have demonstrated

that modification of the aldehyde group dramatically

enhances the oral efficacy against experimental infec-

tions caused by susceptible bacteria in laboratory

animals.²¹They also reported that derivatives of des-

mycosin combine the broadest spectrum of antimicrobial

activity with the best efficacy and bioavailability after

oral administration. In addition, it has been clearly

demonstrated that a C-3 keto group, particularly on the

14-membered ring macrolide erythromycin, can com-

pensate for the lack of R-L-cladinose, and this has given

rise to a very active, novel class of compounds, the

ketolides.²²As an extension of this line of thinking, we

felt that it would be of interest to study what influence

a combination of C-3 and C-20 substituents would have

1

(Scheme 2). On the other hand, in the H NMR spectra

of 24a and 24b, the aldehyde proton signal observed at

δ 9.67 in 22 was absent and the signal of the protons

attached to a newly formed oxycarbon was observed at

δ 4.02 and 3.99 as broad triplets. The other proton

signals on the aglycon moiety in 24a and 24b showed

almost the same chemical shift values as those of 22.

The methyl group substituted at the C8-position, which

is observed as a doublet at δ 1.16 in 22, appeared as a

singlet at δ 1.22 and 1.25 in 24a and 24b, respectively.

The ¹³C NMR spectra of 24a and 24b revealed the

conversion of the formyl carbon signal in 22 to the

oxycarbon signals at δ 81.1 and 78.6, respectively.

The C-8 methine carbon observed as a doublet in the

APT ¹³C NMR spectrum²⁰at δ 40.3 in 22 appeared as a

singlet at δ 61.8 and 60.3 in 24a and 24b, respectively.

Comparison of the chemical shift of the ketone carbonyl

at the 9-position in 22, 24a , and 24b revealed a

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 415

Sch em e 3. Wittig Reaction with Stabilized Phosphorus Ylides^a

a

Reagents and conditions: (a) Ph₃PCHCO₂CH₃(a 1), Ph₃PCHCO₂CH₂CH₃(a 2), Ph₃PCHCOCH₃(a 3), or Ph₃PCHCHO (a 4), benzene,

80 °C, 80-90%; (b) MeOH, 25 °C, 80%; (c) 2% Et₃N or aq NH₃, MeOH, 25 °C, 80%.

on these properties. However, structural variations at

these sites were never explored thoroughly. To expand

the structure-activity relationships (SARs) and to more

thoroughly define the scope of activity, optimize efficacy,

and select the most promising candidates for preclinical

development, a range of representative phosphorus

ylides (a 1-a 4) was reacted with the protected desmy-

cosin 7 in benzene to afford a series of C-20 substituted

alkenes (Scheme 3). Further extensions of this series

have also been made in which the C3-hydroxyl group

has been acylated with aromatic or heteroaromatic

carboxylic acids (Scheme 5) rather than oxidized to a

C3-ketone (Scheme 4). A stabilized Wittig reaction

between the ylides a 1-a 4 and the aldehyde 7 occurred

smoothly and stereoselectively, affording intermediates

26a -d in yields ranging from 80 to 90%. Wittig reac-

tions were both efficient and rapid, typically proceeding

to completion within 2 h at 80 °C. Even more encourag-

ing was the fact that products with the trans-geometry

of the double bond were formed virtually exclusively

using a wide variety of stabilized ylides. This was

proven unambiguously from the ¹H NMR spectra of the

products, which indicated clearly that trans-isomer had

formed, as shown by coupling constants for the vinyl

protons in the range 12-16 Hz.²³Deprotection of

2′,4′,4′′-tri-O-acetyl intermediates (26a -d ) were carried

out with methanol followed by either aqueous ammonia

or triethylamine in methanol to afford desmycosin

analogues 28a -d (Scheme 3). The E-R,â-unsaturated

derivatives (26a -d ) set the stage for further elaboration

as summarized in Scheme 4. The Pfitzner-Moffat

oxidation of 26a -d provided the corresponding enols

29a-d, which were sequentially hydrolyzed with metha-

nol followed by aqueous ammonia or triethylamine in

methanol to give fully deprotected enols 31a -d .

The other members of the library, particularly the

acylide family of compounds, were synthesized by the

same basic strategy, utilizing Wittig olefination for the

attachment of the unsaturated side chains.

Specifically, desmycosins 32-39a -d were synthe-

sized as outlined in Scheme 5. Thus, a number of

unsaturated side chains were introduced at C-6, and the

hydroxyl at C-3 was modified to include aromatic and

heteroaromatic acid side chains. Wittig reaction of the

ylides a 1-a 4 and the aldehyde 7 afforded the early

intermediates 26a -d . For the attachment of the C-3

ester functionality, a mixed anhydride protocol was

adapted. Attachment of the acid side chains (a 1-a 4)

onto the main framework of desmycosin was accom-

plished by reaction of alcohols (26a -d ) with mixed

anhydride in the presence of Et₃N and DMAP in CH₂-

Cl₂at room temperature, leading to esterified products

32-35a -d . Finally, exposure of 32-35a -d to methanol

and then to aqueous ammonia or triethylamine in

methanol resulted in the cleavage of the acetyl groups

and the liberation of desmycosin esters (36-39a -d ).

In addition, we realized some inherent flexibility was

present at the C-3 position, since the hydroxyl group

could be acylated or, alternatively, inverted by a Mit-

sunobu process to provide both epimers at this position.

We examined many variations of the classical Mit-

sunobu reaction for inverting the C-3 stereogenic center

of desmycosin (Scheme 6). Since the C-3 hydroxyl group

is in the middle of a large, highly branched aglycon,

steric hindrance was expected to impede the reaction.

It was decided that modified reaction conditions would

have to be applied to achieve the inversion. Therefore,

when 26b was treated successively with diisopropyl

azodicarboxylate (DIPAD), Ph₃P, and ClCH₂CO₂H²⁴in

THF and with aqueous ammonia in methanol at room

416 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Sch em e 4. Pfitzner-Moffat Oxidation^a

Pavlovic´ et al.

a

Reagents and conditions: (a) EDC‚HCl, DMSO, pyridinium trifluoroacetate, CH₂Cl₂, 0-25 °C, 80-90%; (b) MeOH, 25 °C, 80%; (c) 2%

Et₃N or aq NH₃, MeOH, 25 °C, 80%.

Sch em e 5. Synthesis of a Desmycosin Library in Solution Phase^a

a

Reagents and conditions: (a) p-nitrophenylacetic acid (a 1), p-nitrocinnamic acid (a 2), cinnamic acid (a 3), or pyridin-4-carboxylic acid

(a 4), t-BuCOCl, Et₃N, DMAP, CH₂Cl₂, 25 °C, 6 h, 60-80%; (b) MeOH, reflux, 3 h, 80%; (c) 2% Et₃N or aq NH₃, MeOH, 25 °C, 10 h, 85%,

temperature, the desired C-3-inverted product 41 was

obtained in 90% yield. However, treatment of 26b with

methanol as an acidic component did not give the

expected product, but instead, compound 42 formed by

addition of diethyl azodicarboxylate on the C-3 position

of desmycosin was obtained, as shown in Scheme 6.

Subsequent hydrolysis of 42 with aqueous ammonia in

methanol at room temperature afforded 43. Reaction of

26b with p-nitrophenylacetic acid in the presence of 1,1′-

azadicarbonylbispiperidine and Bu₃P resulted in forma-

tion of inverted acylide 44, which was hydrolyzed with

aqueous ammonia in methanol to give 45.

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 417

Sch em e 6. Mitsunobu Reaction-Inversion of Configuration at the C3 Position of Desmycosin^a

a

Reagents and conditions: (a) DIPAD, Ph₃P, ClCH₂CO₂H, THF, 25 °C, 1 h; (b) NH₃(g), MeOH, 25 °C, overnight, 81% for two steps; (c)

DEAD, Ph₃P, MeOH, THF, 25 °C, 3 h, 80%; (d) 1,1′-azadicarbonylbispiperidine, Bu₃P, p-nitrophenylacetic acid, THF, 25 °C, 3 h, 85%; (e)

aq NH₃, MeOH, 25 °C, 6 h, 70-80%.

Although several modifications of the C-3′-dimethyl-

amino group resulted in diminished antimicrobial activ-

ity,²⁵there were, to the best of our knowledge, no reports

published on the Polonovski reaction within the C-20-

substituted desmycosin class of 16-membered macro-

lides. Therefore, our interest was further focused on

chemical transformation of desmycosin derivatives into

neutral macrolides having a 3-keto group in order to

investigate the effect of this group on their antimicrobial

activity. Our synthetic strategy includes conversion of

the 3′-dimethylamino compound into the 3′-ketone by

utilizing the modified Polonovski rearrangement. Thus,

treatment of 15 with m-CPBA in CH₂Cl₂gave the

N-oxide 46, which was immediately used for the

Polonovski rearrangement. We have found that the

reaction of 46 with Ac₂O in CH₂Cl₂at room temperature

overnight yielded the 3′-ketone 47 as the major product.

Chromatographic separation allowed the isolation of 47

and the 3′-N-acetyl-3′-N-demethyl derivative 48 in 50

and 5% yield, respectively.

that 48 was a mixture of two rotational isomers around

the C-3′-N bond. Compounds 47 and 48 were depro-

tected in methanol to give intermediates 49 and 50,

respectively. Further deprotection of 49 and 50 under

acidic conditions finally afforded 51 and 52, respectively.

As shown in Table 1, compounds 51 and 52 showed no

antimicrobial activity. Therefore, the dimethylamino

group, which is a common structure of basic 16-

membered macrolides, is shown to play an important

role in their antimicrobial activity.

In continuation of our studies, we have used THD (8),

4′-deoxy-THD (9), tylosin (1), and THT (11) as sub-

strates for the Horner-Wadsworth-Emmons reaction

(Scheme 8). 4′-Deoxy-THD was prepared in six steps

according to literature procedure.¹³For a matter of

comparison we have prepared enol 14, a tetrahydro

analogue of 13, according to a published procedure.¹⁷

For comparisons of antimicrobial activity, we have also

prepared desmycosin carboxylic acid 28e, by base hy-

drolysis of methyl ester 28a .

The two doublet signals for H-2′ (δ 5.20, J ) 8.0 Hz)

and H-4′ (δ 4.98, J ) 10.0 Hz) of 47 supported the

absence of H-3′. The two N-methyl signals (δ 2.77 and

2.62 in a 1.5:1 ratio) for 48 indicated that it was a

mixture of two rotational isomers around the C-3′-N

bond in CDCl₃. In the phase-sensitive 2D ROESY

spectrum,^26,27the H-3′ signals of the major and minor

isomers at δ 4.63 and 3.70, respectively, showed a

distinct correlation peak having the same phase with

diagonal peaks. Although the respective pairs of the

H-1′, H-2′, and N-methyl signals of the two isomers

appeared close together, their correlation peaks were

also observed in the same phase. This type of signal

correlation due to saturation transfer occurs via a

conformational exchange process. Thus, it was proved

Resu lts a n d Discu ssion

Biologica l Eva lu a tion of Desm ycosin An a logu es.

All of the compounds were tested in vitro by standard

agar dilution method against both erythromycin-sus-

ceptible and erythromycin-resistant staphylococci, strep-

tococci, and Streptococcus pneumoniae, including con-

stitutive (Ery Rc) and inducible (Ery Ri) phenotype. In

addition, one strain each of Haemophilus influenzae and

Escherichia coli was also tested. A preliminary assess-

ment of the relative potency of the synthesized com-

pounds was achieved by rough IC₅₀and MIC determi-

nations. It was readily apparent from these experiments

that the conformationally constrained compounds such

as 24a , 24b, and 25 were significantly less active when

418 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

Ta ble 1. Antibacterial Activity of Selected Macrolides in Comparison with Tylosin (1) and Desmycosin (2)

MIC (µg/mL)

S. aureus

E. coli

H. influenzae

E. faecalis

S. pneumoniae

S. pyogenes

ATCC-

13709^a

PSCB-

0331^c

PSCB-

0330^d

ATCC-

125922

ATCC-

49247

ATCC-

29212

PSCB-

0541^e

PSCB-

0543^g

compd

0538^b

0545^f

8

9

1

2

32

8

4

16

8

4

32

0.5

2

0.5

2

1

32

8

32

128

>128

64

>128

128

>128

128

>128

128

>128

64

>128

128

>128

128

>128

128

64

32

64

4

32

8

16

8

2

4

2

8

2

8

64

4

8

32

2

1

16

2

1

4

1

16

32

0.5

1

0.5

128

4

0.5

16

1

2

64

2

32

8

64

<0.25

1

2

0.5

8

10

11

12

13

14

24a

24b

25

28a

28b

28c

28e

31a

37a

43

45

51

52

53

54

55

56

2

>128

128

64

>128

8

4

8

32

0.5

0.25

>128

2

<0.25

4

0.5

128

8

64

16

0.5

1

64

0.5

0.25

0.5

>128

2

16

4

0.5

>128

4

0.25

2

1

>128

128

8

128

4

>128

128

32

128

4

>128

32

4

2

0.25

4

2

0.5

32

2

32

64

8

32

4

16

128

32

8

>128

16

128

>128

128

32

128

1

128

64

128

64

128

1.0

0.5

128

>128

128

64

2

8

1

128

4

1

4

2

32

1

>128

128

>128

128

0.5

>128

1

0.5

1

64

8

1

a

b

S. aureus ATCC-13709: erythromycin-susceptible strain. S. aureus PSCB-0538: inducibly MLS_B-resistant strain. ^cS.aureus PSCB-

0331: efflux-resistant strain. S.aureus PSCB-0330: constitutively MLS_B-resistant strain encoded by an ermA gene. ^eS. pneumoniae

d

PSCB-0541: erythromycin-susceptible strain. ^fS. pyogenes PSCB-0545: efflux-resistant strain. ^gS. pyogenes PSCB-0543: inducibly MLS_B-

resistant strain.

Sch em e 7. Polonovski Rearrangement of 16^a

a

Reagents and conditions: (a) mCPBA, CHCl₃, 25 °C, 2 h, 90%; (b) Ac₂O, CH₂Cl₂, 25 °C, 18 h, 64%; (c) MeOH, 25 °C, 3 h, 80%;

(d) 1 M aq HCl, MeCN, 25 °C, 6 h, 60%.

compared to the unconstrained analogues 28a and 31a

(Scheme 3, Table 1). It is likely that the reduction of

activity caused by forming the bicyclic structure in

compounds 24a , 24b, and 25 is mainly due to the

change of orientation of the aldehyde function in the

molecule of 25 or to the change of conformation of the

aglycon ring. Compounds (13 and 14) displayed rela-

tively poor antibacterial activity compared to their

parent macrolides (2 and 8). The conversion of the 16-

membered ring macrolides to their ketolide analogues

(13 and 14) led to a decrease in antimicrobial activity

against macrolide-susceptible Gram-positive bacteria.

No improvement in activity was noted against macro-

lide-resistant or Gram-negative bacteria. The decrease

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 419

Sch em e 8. Horner-Wadsworth-Emmons Olefination^a

a

Reagents and conditions: (a) (MeO)₂P(O)CH₂CO₂Me, NaH, THF, 0-25 °C, 5 h.

in activity contrasted with results from the 14-mem-

bered ketolides, in which oxidation of the 3-hydroxyl

group to a 3-keto moiety resulted in improved activity.²²

In contrast, in vitro activity of desmycosin analogues

additionally substituted at the C-20 position (28a -28d )

was enhanced when compared to that of the parent

analogue (2). Compound 28c displayed the best activity

of all compounds tested from this group and exhibited

MIC values around 0.5 µg/mL against most of the

strains tested according to this analysis.

have identified a combination of structural factors that

contribute substantially to enhancement of antibacterial

activity. Figure 4 summarizes the SARs obtained within

the desmycosin family of compounds. These factors are

a conformationally restricted unsaturated side chain

and an aromatic or heteroaromatic moiety on the C-3

hydroxyl group. Moreover, hydrophilic para substituents

such as nitro are preferred for enhancing activity.

Modification of the aldehyde group of tylosin such as

in 55 (Table 1) resulted in general loss of activity against

all species of bacteria tested. These results are in accord

with previous studies reported by Kirst,^7bwhich indicate

that the exact pattern of substitution with the saccha-

rides mycarose and mycinose is very important for

activity and that the broadest spectrum of activity is

found with mycinose present and mycarose absent.

Compound 28c exhibited dramatically improved phar-

macokinetics in mice. As a result of Wittig olefination,

improvement in both serum and tissue concentrations

was achieved. Although compounds 28a , 28b, and 28c

displayed similar in vitro activities to desmycosin (2),

their activities against S. aureus were clearly enhanced

compared with that of 2. The activity of 28a , 28b, and

28c against S. pneumoniae, S. pyogenes, and H. influ-

enzae was comparable to that 2. Compound 28c also

exhibited good metabolic stability in rat plasma in vitro.

After 24 h of incubation, 85% of initial activity of 28c

was observed against Micrococcus luteus, while only

50% activity remained for 2. Thus, this analogue proved

to be more stable than 2 in vitro. Compound 28c, which

was the best compound in terms of potency and stability,

was finally examined in vivo. The serum concentration

of 28c following oral administration of 50 mg/kg to

Balb/c mice is shown in Figure 3. The serum concentra-

tion of 28c was dramatically higher and longer lasting

than that of desmycosin, which gave no detectable blood

levels in mice after 50 mg/kg oral dose. Its AUC was

also greater than that of desmycosin. The maximum

concentration of 28c in serum was comparable to that

of clarithromycin.²⁸The peak serum concentration

(C_max) was 5.01 µg/mL, and the time of peak concentra-

tion (T_max) was 2 h. The AUC_0-6was 0.5075 h µg/mL,

and the AUC_infwas 0.4495 h µg/mL. The serum con-

centrations of 28c after oral administration declined in

a monophasic manner, T_1/2being 0.28 h.

The importance of the C-6 unsaturated ester side

chain became apparent by a number of substitutions.

Thus, replacing the ester functionality (28a ) with car-

boxylic acid (28e) while maintaing the R,â-unsaturated

portion of the side chain resulted in complete loss of

activity, thereby suggesting that the ester functionality

is a requirement for activity. In contrast, modification

at the C-3 hydroxyl group appears much more tolerable

for biological activity. Thus, replacement of the OH

group of 28a with a p-nitrophenylacetic acid moiety

(37a ) resulted in enhanced biological activity against

most of the tested strains, whereas substitution with a

dicarbethoxyhydrazine moiety resulted in an overall

decrease of activity (43, Table 1). Modification of the

alcohol component of the C-20 ester group led to

negligible modulation of the biological activity of com-

pound 28a as compared to 28b. Thus, substitution of

the methyl (28a ) with an ethyl (28b) resulted in

negligible change of biological activity. Several of the

synthesized analogues were identified to be of equal or

superior biological activities (e.g. 28a -28c and 37a ) as

compared to tylosin (1) and desmycosin (2), setting the

stage for further improvement of antimicrobial activity.

In comparison with unsaturated analogues, the com-

pounds 53, 54, and 56 obtained by Horner-Wads-

worth-Emmons reaction of parent tetrahydro com-

pounds (8, 9, and 11, respectively) showed diminished

activity against the microorganisms tested.

St r u ct u r e-Act ivit y R ela t ion sh ip s of Desm y-

cosin An a logu es. The antibacterial activities in vitro

of novel derivatives of desmycosin compared with those

of the natural antibiotic tylosin (1) and semisynthetic

desmycosin (2) are shown in Table 1. All the compounds

tested were inactive against E. coli and erythromycin-

resistant (MLS_Bconstitutive type) strains of Staphylo-

coccus aureus (MIC g 128 µg/mL). In contrast, they were

very effective against inducibly erythromycin-resistant

staphylococci. In our study of desmycosin analogues, we

Following oral administration to mice, 28c was well-

absorbed and extensively distributed into tissues as

showed in Table 2.

420 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

F igu r e 3. Serum concentration of 28c in mice after a single oral dose of 50 mg/kg bw (n ) 3).

Con clu sion s

In summary, a series of 20-O-substituted and 3,20-

di-O-substituted derivatives of desmycosin and tylosin

were prepared and evaluated for in vitro antibacterial

activity. The application of high-throughput chemistry

and purification techniques facilitated the simultaneous

synthesis of arrays of desmycosin analogues and allowed

for the rapid elucidation of structure-activity relation-

ships. These compounds were generally better than or

equal to desmycosin in potency when tested against

macrolide-susceptible organisms. More importantly,

these compounds had increased activity against the

erythromycin-resistant strains (S. aureus PSCB-0538

and S. pyogenes PSCB-0543). These compounds, how-

ever, were not active against organisms with constitu-

tive MLS resistance. These studies demonstrated a

great sensitivity of the side chain domain toward

structural changes and thereby reveal a promising

potential for further systematic adjustments for fine-

tuning the biological properties of future analogues

within the same series. Whether the advantages noted

here are sufficient to warrant product development can

only be ascertained by further studies. We are currently

evaluating more compounds from this class in vitro and

in vivo, and the results will be reported in due time.

F igu r e 4. Structure-activity relationship (SARs) of desmy-

cosines: (a) replacement of side chain with carboxylic acid is

not tolerated; (b) replacement of the dimethylamino group by

a ketone or acetylmethylamino group (Polonovski rearrange-

ment) led to reduced activity; (c) esters at the C-3 position are

more active than the corresponding dicarbethoxyhydrazines;

(d) hydrophilic para substituents are preferred for enhance-

ment of antibacterial activity.

Ta ble 2. Tissue Pharmacokinetic Parameters for 28c after a

Single Oral 50 mg/kg Dose

b

tissue

C

_max(µg/g)

T_max(h)

C₂^a(µg/g)

T₂(h)

liver

33.34

14.28

0

7.97

10.41

2

0

0.5

2

24.43

4.58

0

7.00

10.24

4

0

2

kidney

brain

spleen

lungs

0.50

a

C₂, second peak concentration. ^bT₂, time when the second peak

was observed.

Exp er im en ta l Section

Peak tissue concentrations of 28c were reached

around 2 h after po application, with the exception of

spleen (0.5-1 h). Two peaks were observed in all organs.

The first peak in lungs and spleen was observed at 0.5

h, and another at 2 h after administration. For liver,

the first peak was observed at 2 h, the second at 4 h;

for kidney, the first peak was at 0.5 h and the second

at 2 h after administration. This could indicate the

formation of an active metabolite, but it can also be

explained by the high animal variability, which was

observed at each sampling time. C_maxfor liver was 33.34

µg/g, for kidney 14.28 µg/g, for spleen 7.97 µg/g, and for

lungs 10.41 µg/g.

The excellent pharmacokinetics of 28c could be mainly

explained by the increased bioavailability of antibiotic

after oral administration. These results demonstrate

the possibility to design and synthesize 16-membered

macrolide derivatives exhibiting similar efficacy to the

second-generation 14-membered macrolides, such as

clarithromycin. They also point the way for discovery

of highly potent and pharmacokinetically excellent

derivatives in the 16-membered macrolide series.

Gen er a l. Proton (¹H) and carbon (¹³C) nuclear magnetic

resonance spectra were recorded on either a Bruker 300 or a

Bruker 500 MHz spectrometer and on Varian Inova 600 MHz

spectrometer. Chemical shifts are recorded in parts per million

(δ) relative to tetramethylsilane (δ 0.00). Infrared (IR) spectra

were recorded on

a Perkin-Elmer Infracord 137 or 221

spectrometer or on a Pye Unicam 3-200 spectrometer. UV

spectra were run on a Cary 118 spectrometer. Low-resolution

electron impact mass spectra (MS) were recorded on a Varian

MAT CH5 spectrometer. Fast atom bombardment (FAB) mass

spectra were run on a Finnigan MAT 312 double-focusing mass

spectrometer, operating at an accelerating voltage of 3 kV. The

samples were ionized by bombardment with xenon atoms

produced by a saddle-field ion source from Ion Tech operating

with a tube current of 2 mA at an energy of 6 keV. Thin-layer

chromatography (TLC) was performed with Merck silica gel

60 F254 0.2-mm plates. The plates were visualized by using

an acid-based stain, prepared from p-anisaldehyde (5 mL),

concentrated sulfuric acid (5 mL), and glacial acetic acid (0.5

mL) in 95% ethanol (90 mL) and warming on a hot plate. Flash

chromatography was carried out using Merck silica gel 60

(230-400 mesh). Solvent systems are reported as volume

percent mixtures. Concentration in vacuo refers to the removal

of solvent using a Bu¨chi rotary evaporator and an aspirator

pump. All chromatography solvents were reagent grade.

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 421

Tetrahydrofuran (THF) was distilled from sodium benzophe-

none ketyl, and dichloromethane was distilled from calcium

hydride. All other reagents were purified by literature proce-

dures. All reactions were performed under an inert atmosphere

of dry argon. The course of the reaction is followed by

chromatography on a thin layer (TLC) of silica gel (Merck 60

interchangeable with D₂O), 6.99 (1H, d, H-11), 6.47 (1H, d,

H-10), 5.80, 5.68 (1H, d, H-13), 4.75 (1H, s, H-2, enol), 4.64

(1H, d, H-1′′), 4.41 (1H, dd, H-4′′), 4.38 (1H, d, H-1′), 3.39 (3H,

s, 3′′-OMe), 3.34 (3H, s, 2′′-OMe), 2.40 (6H, s, NMe₂), 2.08 (3H,

s, COMe), 1.81 (3H, s, H-22); ¹³C NMR (CDCl₃) δ 205.4 (s, C-9),

180.1 (s, C-3, enol), 172.5 (s, C-1), 170.4 (s, COMe), 147.6 (d,

C-11), 140.5 (d, C-13), 136.8 (s, C-12), 124.3 (d, C-10), 89.0 (d,

C-2, enol), 20.5 (q, COMe). Anal. (C₄₃H₇₁NO₁₆) C, H, N.

2,3-Dideh ydr odesm ycosin -20-dim eth ylacetal (20). Com-

pound 19 (3.2 g, 3.73 mmol) was dissolved in methanol (64

mL), 25% NH₄OH (32 mL) was added, and the mixture was

left to stand at 5 °C for 60 h. The reaction solution was

evaporated to an oily product, which was dissolved in chloro-

form (60 mL), washed with a saturated NaHCO₃solution, and

evaporated in vacuo to a dry residue. Following silica gel

chromatography (solvent system A) product 20 (2.25 g, 74%)

with the following characteristics was obtained: R_f(A) 0.38;

F

₂₅₄) in solvent systems methylene chloride-methanol-am-

monium hydroxide 25% (90:9:1.5, system A; 90:9:0.5, system

A1) or methylene chloride-acetone (8:2, system B; 7:3, system

C) unless otherwise stated. The separation of the reaction

products and the purification of the products for the purpose

of spectral analyses were performed on a silica gel column

(Merck 60, 230-400 mesh or 60-230 mesh in solvent system

A, B, or C unless otherwise stated.

The structure of all novel compounds was confirmed by IR,

MS, and NMR spectroscopic methods. Complete and unam-

biguous assignments for all ¹H and ¹³C resonances could be

achieved on the basis of chemical shift considerations, coupling

information (APT¹⁵and gated decoupled ¹³C NMR spectra),

and COSY-45,²⁹HMQC,³⁰and 1D-HETCOR³¹spectra as well

as on long-range INEPT experiments³²with selective DANTE

excitation.

Deter m in a tion of Min im u m In h ibitor y Con cen tr a tion

(MICs). The MICs of all antibiotics were determined by the

microdilution broth procedure as recommended by National

Committee of Clinical Laboratory Standards (NCCLS) guide-

lines.³³Peripheral plasma levels were determined by micro-

biological assay using M. luteus seeded in Difco Antibiotic

Media 1. Zone sizes were measured with a Fisher Zone Reader,

and antibiotic concentrations were calculated from the stan-

dard curve for the appropriate compound.

1

FAB-MS m/z 816 (MH⁺, 89%); H NMR (CDCl₃) δ 12.05 (1H,

s, 3-OH, interchangeable with D₂O), 7.16 (1H, d, H-11), 6.25

(1H, d, H-10), 5.81 (1H, d, H-13), 4.74 (1H, s, enol-H-2), 4.64

(1H, d, H-1′′), 4.38 (1H, d, H-1′), 3.53 (3H, s, 3′′-OMe), 3.47

(3H, s, 2′′-OMe), 3.29 (3H, s, 20-OMe), 3.22 (3H, s, 20-OMe),

2.34 (6H, s, NMe₂), 1.78 (3H, s, H-22). Anal. (C₄₁H₆₉NO₁₅) C,

H, N.

2,3-Did eh yd r od esm ycosin (13). Compound 20 (1.0 g, 1.22

mmol) was dissolved in acetonitrile (10 mL) and 10% trifluo-

roacetic acid (12 mL) and stirred for 2 h at room temperature,

chloroform (7 mL) was added thereto, and the mixture was

alkalized to a pH of 8.5. The organic layer was separated and

extracted once more with CHCl₃, and the combined extracts

were dried and evaporated to a dry residue. By chromatogra-

phy on a silica gel column (solvent system A), the product 13

(0.79 g, 84%) with the following characteristics was isolated:

2,3-Did eh yd r o-2′,4′,4′′-t r i-O-a cet yld esm ycosin -20-d i-

m et h yla cet a l (18). 2′,4′,4′′-Tri-O-acetyldesmycosin-20-di-

methylacetal (17, 10 g, 10 mmol), produced by literature

procedures,^10,11was dissolved in methylene chloride (230 mL),

dimethyl sulfoxide (16 mL, 0.22 moL) and, subsequently, 1-(3-

dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC‚

HCl, 20 g, 0.1 moL) were added thereto, and the reaction

mixture was cooled to 10 °C. A solution of pyridine trifluoro-

acetate (20.2 g, 0.1 moL) in methylene chloride (115 mL) was

added dropwise within 30 min. After 4 h of stirring at room

temperature the reaction solution was poured into 850 mL of

water and the organic layer was separated and extracted once

more with methylene chloride. The combined extracts were

washed with a saturated NaCl solution, dried over anhydrous

Na₂SO₄, and evaporated under vacuum. The crude product was

chromatographed on silica gel eluting with 10% acetone in

methylene chloride followed by 30% acetone in methylene

chloride (solvent system C) to give 18 (8.0 g, 85%) as pale

yellow solid: R_f(A) 0.95, R_f(C) 0.65; FAB-MS m/z 942 (MH⁺,

85%); UV λ_maxnm (ꢀ) 282 (18 900), 258 (17 900); IR (KBr) ν_max

1

R_f(A) 0.32; FAB-MS m/z 770 (MH⁺, 80%); H NMR (CDCl₃) δ

12.10 (1H, s, 3-OH, interchangeable with D₂O), 9.72 (1H, s,

H-20), 7.30 (1H, d, H-11), 6.04 (1H, d, H-10), 5.95 (1H, d, H-13),

4.74 (1H, s, enol-H-2), 4.54 (1H, d, H-1′′), 4.38 (1H, d, H-1′),

3.53 (3H, s, 3′′-OMe), 3.47 (3H, s, 2′′-OMe), 2.34 (6H, s, NMe₂),

1.78 (3H, s, H-22). Anal. (C₃₉H₆₃NO₁₄) C, H, N.

2,3-Did eh yd r o-2′,4′,4′′-t r i-O-a cet yld esm ycosin (22). A

solution of 7 prepared according to literature procedures^10,11

(1.24 g, 1.38 mmol), EDC‚HCl (3.17 g, 16.5 mmol), and DMSO

(1.76 mL, 24.8 mmol) in 20 mL of methylene chloride was

added dropwise at 0 °C to a solution of pyridinium trifluoro-

acetate (3.19 g, 16.5 mmol) in 5 mL of methylene chloride. The

reaction was stirred for 5 h at room temperature, and 10 mL

of water was added. After stirring for 10 min, the mixture was

taken up in 50 mL of methylene chloride, followed by washing

with water, drying over MgSO₄, and evaporation of the solvent.

The product was purified by column chromatography eluting

with 10% acetone in methylene chloride followed by solvent

system C to afford 0.374 g (90%) of enol 22 as pale yellow

solid: R_f(A) 0.90, R_f(C) 0.60; FAB-MS m/z 896 (MH⁺, 73%);

UV λ_maxnm (ꢀ) 279 (18 200), 256 (17 000); IR (KBr) ν_max2974,

2936, 1747, 1679, 1638, 1595, 1455, 1373, 1231, 1088, 1053

cm^-1; ¹H NMR (CDCl₃) δ 12.10 (1H, s, 3-OH, interchangeable

with D₂O), 9.70 (1H, s, H-20), 7.30 (1H, d, H-11), 6.05 (1H, d,

H-10), 5.92 (1H, d, H-13), 4.85 (1H, dd, H-2′), 4.72 (1H, dd,

H-4′), 4.70 (1H, s, H-2 enol), 4.65 (1H, d, H-1′′), 4.42 (1H, dd,

H-4′′), 4.36 (1H, d, H-1′), 3.52 (3H, s, 3′′-OMe), 3.45 (3H, s,

2′′-OMe), 2.35 (6H, s, NMe₂), 2.12 (3H, s, OCOMe), 2.05 (6H,

s, 2×OCOMe), 1.87 (3H, s, Me-22), 1.16 (3H, d, Me-21); ¹³C

NMR (CDCl₃) δ 203.1 (s, C-9), 202.9 (d, C-20), 180.0 (s, C-3,

enol), 172.7 (s, C-1), 170.2, 170.0, 169.3 (s, 3×COMe), 147.5

(d, C-11), 140.4 (d, C-13), 137.5 (s, C-12), 124.0 (d, C-10), 87.2

(d, C-2 enol), 40.3 (d, C-8), 20.8, 20.7, 20.6 (q, 3×OCOMe). Anal.

(C₄₅H₆₉NO₁₇) C, H, N.

1

2974, 2936, 1746, 1646, 1320, 1053 cm^-1; H NMR (CDCl₃) δ

12.04 (1H, s, 3-OH, interchangeable with D₂O), 7.14 (1H, d,

H-11), 6.25 (1H, d, H-10), 5.82 (1H, d, H-13), 4.89 (1H, dd,

H-2′), 4.74 (1H, dd, H-4′), 4.72 (1H, s, H-2, enol), 4.65 (1H, d,

H-1′′), 4.44 (1H, dd, H-4′′), 4.38 (1H, d, H-1′), 3.53 (3H, s, 3′′-

OMe), 3.47 (3H, s, 2′′-OMe), 3.34 (3H, s, 20-OMe), 3.29 (3H, s,

20-OMe), 2.34 (6H, s, NMe₂), 2.12 (3H, s, COMe), 2.06 (6H, s,

2×COMe), 1.88 (3H, s, H-22); ¹³C NMR (CDCl₃) δ 205.2 (s,

C-9), 180.2 (s, C-3, enol), 172.9 (s, C-1), 170.4, 170.1, 169.6 (s,

3×COMe), 147.6 (d, C-11), 140.5 (d, C-13), 137.6 (s, C-12),

124.2 (d, C-10), 88.9 (d, C-2, enol), 20.9, 20.8, 20.6 (q,

3×COMe). Anal. (C₄₇H₇₅NO₁₈) C, H, N.

2,3-Did eh yd r o-4′′-O-a cetyld esm ycosin -20-d im eth yla c-

eta l (19). Compound 18 (9 g, 9.6 mmol) was dissolved in

methanol (180 mL) and heated at reflux temperature for 4 h,

whereupon the reaction solution was evaporated to dryness

and the product was dissolved in chloroform (90 mL) and

washed with a saturated NaHCO₃solution. The chloroform

solution was dried over anhydrous K₂CO₃and evaporated

under vacuum. The crude product was chromatographed on

silica gel, eluting with solvent system A, to give the desired

product 19 (8.1 g, 98%) as a white solid: R_f(A) 0.45; FAB-MS

Syn th esis of 4′′-O-Acetyl Bicyclic Ald eh yd e (23). A

solution of 22 (130 mg, 0.15 mmol) in 1 mL of methanol was

heated to 60 °C for 6 h. After evaporation of the solvent, the

residue was taken up in water, the pH adjusted to 11 with

aqueous sodium hydroxide, and the mixture extracted with

ethyl acetate. The extracts were washed with water, dried over

K₂CO₃, and evaporated to dryness. The product was purified

1

m/z 858 (MH⁺, 85%); H NMR (CDCl₃) δ 12.00 (1H, s, 3-OH,

422 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

by column chromatography eluting with 90:10 methylene

chloride-methanol to afford 75.5 mg (93%) of 23 as a white

foam: FAB-MS m/z 812 (MH⁺, 78%); ¹H NMR (CDCl₃) δ 9.72

(1H, d, H-20), 7.30 (1H, d, H-11), 6.02 (1H, d, H-10), 5.95 (1H,

d, H-13), 5.11 (1H, dt, H-15, J _15,16a) 9.5 Hz, J _15,16b) 2.5 Hz),

18.2 (q, Me-C-5′), 17.7 (q, Me-C-5′′), 17.0 (q, Me-18), 12.6

(q, Me-22), 10.4 (q, Me-21), 9.4 (q, Me-17). Anal. (C₃₉H₆₃NO₁₄

C, H, N.

)

24b (minor isomer): FAB-MS m/z 770 (MH⁺, 63%); UV λ_max

nm (ꢀ) 278 (32 492); IR (KBr) ν_max3442, 2973, 2931, 1740, 1692,

1657, 1458, 1374, 1265, 1164, 1086, 1064 cm^-^{1 1}H NMR

;

4.64 (1H, d, H-1′′, J _{1′′,2′′}) 7.9 Hz), 4.46 (1H, dd, H-4′′, J _{3′′,4′′}

)

2.6 Hz, J _{4′′,5′′}) 9.9 Hz), 4.30 (1H, s, 3-OH, interchangeable

with D₂O), 4.29 (1H, d, H-1′, J _1′,2′) 9.5 Hz), 4.01 (1H, dd,

H-23b, J _23a,23b) 9.6 Hz, J _14,23b) 4.2 Hz), 3.95-3.89 (2H, m,

H-5′′ and H-3′′), 3.88-3.85 (1H, m, H-5), 3.58 (1H, dd, H-23a,

J _23a,23b) 9.6 Hz, J _14,23a) 4.2 Hz), 3.53 (3H, s, 3′′-OMe), 3.51-

3.49 (1H, m, H-2′), 3.48 (3H, s, 2′′-OMe), 3.30 (1H, dq, H-5′,

J _4′,5′) 8.8 Hz, J _5′,6′) 6.2 Hz), 3.21 (1H, br, H-8), 3.09-3.01

(3H, m, H-2′′, H-14, and H-4′), 2.80 (1H, dd, H-19, J _6,19) 7.7

Hz, J _19,20) 6.0 Hz), 2.61 (1H, d, H-2b, J _2a,2b) 17.2 Hz), 2.50

(6H, s, NMe₂), 2.37 (1H, t, H-3′, J _2′,3′) J _3′,4′ax) 10.2 Hz), 2.12

(3H, s, 4′′-OCOCH₃), 2.04 (1H, m, H-7b), 1.97 (1H, d, H-2a,

J _2a,2b) 17.2 Hz), 1.90 (1H, ddq, H-16b, J _15,16b) 3.0 Hz, J _16a,16b

) 14.5 Hz, J _16b,17) 7.3 Hz), 1.80 (3H, s, Me-22), 1.65-1.55

(3H, m, H-16a, H-6, and H-4), 1.35 (1H, m, H-7a), 1.31 (3H, d,

H-6′ (Me-C-5′), J _5′,6′) 6.1 Hz), 1.18 (3H, d, H-6′′ (Me-C-5′′),

J _{5′′,6′′}) 6.2 Hz), 1.14 (3H, d, Me-18, J _4,18) 6.0 Hz), 1.02 (3H,

(CDCl₃) δ 7.44 (1H, d, H-11, J _10,11) 16.5 Hz), 5.94 (1H, d, H-10,

J _10,11) 16.5 Hz), 5.90 (1H, d, H-13, J _13,14) 10.3 Hz), 5.10 (1H,

dt, H-15, J _14,15) 10.0 Hz, J _15,16b) 4.0 Hz), 4.78 (1H, d, H-5,

J _4,5) 6.9 Hz), 4.59 (1H, d, H-1′′, J _{1′′,2′′}) 7.7 Hz), 4.47 (1H, d,

H-1′, J _1′,2′) 7.4 Hz), 4.05-3.99 (2H, m, H-23b, H-20), 3.79-

3.73 (2H, m, H-3′′, H-2b), 3.61 (3H, s, 3′′-OMe), 3.60-3.50 (5H,

m, H-23a, H-5′′, H-5′, H-4, H-2′), 3.49 (3H, s, 2′′-OMe), 3.42

(1H, d, H-2a, J _2a,2b) 16.5 Hz), 3.18 (1H, dd, H-4′′, J _{3′′,4′′}) 3.2

Hz, J _{4′′,5′′}) 9.6 Hz), 3.10-3.04 (1H, dd, H-4′, J _3′,4′ax) J _4′,5′

)

10.0 Hz; 1H, dd, H-2′′, J _{1′′,2′′}) 7.9 Hz, J _{2′′,3′′}) 2.9 Hz), 2.99-

2.95 (1H, m, H-14), 2.51 (6H, s, NMe₂), 2.41 (1H, t, H-3′, J _2′,3′

) J _3′,4′ax) 10.1 Hz), 1.99 (1H, br, H-6), 1.86 (1H, m, H-19b),

1.83 (1H, m, H-7b), 1.80 (3H, s, Me-22), 1.76 (1H, m, H-16b),

1.61 (1H, m, H-16a), 1.35 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 5.9

Hz), 1.27 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.4 Hz), 1.25 (3H, s,

Me-21), 1.20 (1H, m, H-19a), 1.16 (1H, m, H-7a), 1.09 (3H, d,

Me-18, J _4,18) 6.5 Hz), 0.92 (3H, t, Me-17, J _16,17) 7.4 Hz); ¹³

C

d, Me-21, J _8,21) 6.4 Hz), 0.90 (3H, t, Me-17, J _16a,17) J _16b,17

)

7.3 Hz); ¹³C NMR (CDCl₃) δ 206.3 (s, C-9), 201.9 (d, C-20),

173.2 (s, C-1), 170.1 (s, 4′′-OCOMe), 147.8 (d, C-11), 140.6 (d,

C-13), 135.8 (s, C-12), 127.3 (d, C-10), 103.7 (d, C-1′), 101.0 (d,

C-1′′), 86.9 (d, C-5), 80.6 (d, C-2′′), 77.6 (d, C-3′′), 75.8 (s, C-3),

75.6 (d, C-15), 74.7 (d, C-4′′), 73.3 (d, C-5′), 70.6 (d, C-4′), 70.5

(d, C-3′), 69.9 (d, C-2′), 69.6 (t, C-23), 67.4 (d, C-5′′), 61.5 (q,

3′′-OMe), 59.4 (q, 2′′-OMe), 59.3 (d, C-19), 50.2 (d, C-4), 45.1

(t, C-2), 44.6 (d, C-14), 44.4 (d, C-6), 41.7 (q, NMe₂), 36.1 (d,

C-8), 33.9 (t, C-7), 25.9 (t, C-16), 20.9 (q, 4′′-OCOMe), 17.9 (q,

Me-21), 17.4 (q, Me-6′ (Me-C-5′)), 17.3 (q, Me-6′′ (Me-C-5′′)),

NMR (CDCl₃) δ 206.8 (s, C-3), 206.6 (s, C-9), 168.0 (s, C-1),

149.6 (d, C-11), 140.8 (d, C-13), 134.6 (s, C-12), 125.1 (d, C-10),

102.6 (d, C-1′), 100.9 (d, C-1′′), 81.8 (d, C-2′′), 81.3 (d, C-5),

79.7 (d, C-3′′), 78.6 (d, C-20), 76.4 (d, C-15), 73.3 (d, C-5′), 73.1

(d, C-4′′), 72.7 (d, C-5′), 70.9 (d, C-4′), 70.7 (d, C-3′), 70.6 (d,

C-2′), 70.1 (t, C-23), 70.0 (d, C-5′′), 62.9 (q, 3′′-OMe), 60.3 (s,

C-8), 59.6 (q, 2′′-OMe), 46.9 (t, C-2), 43.9 (d, C-14), 41.7 (q,

NMe₂), 41.3 (d, C-6), 37.1 (t, C-19), 37.0 (t, C-7), 35.7 (d, C-4),

26.1 (t, C-16), 18.2 (q, Me-C-5′), 17.7 (q, Me-C-5′′), 17.5 (q, Me-

21), 17.1 (q, Me-18), 12.4 (q, Me-22), 9.7 (q, Me-17). Anal.

(C₃₉H₆₃NO₁₄) C, H, N.

12.5 (q, Me-22), 11.7 (q, Me-18), 9.6 (q, Me-17). Anal. (C₄₁H₆₅

NO₁₅) C, H, N.

-

Bicyclic Ald eh yd e (25). To a solution of 23 (70.0 mg, 0.09

mmol) in 1 mL of methanol was added 1 mL of aqueous NH₃

(25%). The solution was stirred at room temperature for 16 h.

The solvent was removed in vacuo, water was added, and the

pH was allowed to reach 11 with concentrated ammonium

hydroxide. The solution was extracted with ethyl acetate, and

the organic extracts were dried over K₂CO₃to give 65.0 mg of

white foam. The product was purified by column chromatog-

raphy eluting with solvent system A, to afford 57.0 mg (85.8%)

of the bicyclic aldehyde 25 (R_f) 0.35) as a white foam: FAB-

MS m/z 770 (MH⁺, 73%); UV λ_maxnm (ꢀ) 278 (32 502); IR (KBr)

ν_max3444, 2970, 2929, 1716, 1659, 1628, 1455, 1377, 1199,

1168, 1082, 1065 cm^-1; ¹H NMR (CDCl₃) δ 9.72 (1H, d, H-20),

7.32 (1H, d, H-11), 6.03 (1H,d, H-10), 5.96 (1H, d, H-13), 5.11

(1H, dt, H-15, J _15,16a) 9.7 Hz, J _15,16b) 2.6 Hz), 4.58 (1H, d,

H-1′′, J _{1′′,2′′}) 8.0 Hz), 4.31 (1H, s, 3-OH, interchangeable with

D₂O), 4.30 (1H, d, H-1′, J _1′,2′) 9.5 Hz), 4.02 (1H, dd, H-23b,

J _23a,23b) 9.5 Hz), 3.86 (1H, t, H-5), 3.79-3.72 (1H, m, H-3′′),

3.62 (3H, s, 3′′-OMe), 3.60-3.50 (3H, m, H-23a, H-5′′, H-2′),

Desm ycosin 8r,20â- a n d 8â,20r-Ald ol (24a a n d 24b ).

Compound 22 (800.6 mg, 0.89 mmol) was dissolved in metha-

nol (30 mL), and aqueous ammonia (7.5 mL) was added. The

solution was stirred at 25 °C for 30 h, after which evaporation

in vacuo gave the title compound as a mixture of epimers at

C-8 and C-20. The mixture was chromatographed on a silica

gel flash column, using CH₂Cl_2-MeOH-aqueous NH₃(9:1:0.5)

as the eluent, to give 344.0 mg (50%) of the major 8R,20â-

epimer (24a ) and 54.8 mg (8%) of the minor 8â,20R-epimer

(24b).

24a (major isomer): FAB-MS m/z 770 (MH⁺, 52%); UV λ_max

nm (ꢀ) 278 (32 502); IR (KBr) ν_max3444, 2970, 2931, 1741, 1695,

1655, 1456, 1378, 1263, 1166, 1083, 1063 cm^-^{1 1}H NMR

;

(CDCl₃) δ 7.24(1H, d,H-11, J _10,11) 16.5 Hz), 5.97 (1H, d, H-10,

J _10,11) 16.5 Hz), 5.85 (1H, d, H-13, J _13,14) 10.2 Hz), 5.05 (1H,

dt, H-15, J _14,15) 10.2 Hz, J _15,16b) 4.3 Hz), 4.63 (1H, d, H-5,

J _4,5) 6.5 Hz), 4.58 (1H, d, H-1′′, J _{1′′,2′′}) 7.7 Hz), 4.49 (1H, d,

H-1′, J _1′,2′) 7.4 Hz), 4.05-3.99 (2H, m, H-23b, H-20), 3.88 (1H,

d, H-2b, H_2a,2b) 16.4 Hz), 3.79-3.73 (2H, m, H-4, H-3′′), 3.61

(3H, s, 3′′-OMe), 3.60-3.50 (4H, m, H-23a, H-5′′, H-5′, H-2′),

3.48 (3H, s, 2′′-OMe), 3.37 (1H, d, H-2a, J _2a,2b) 16.4 Hz), 3.19

(1H, dd, H-4′′, J _{3′′,4′′}) 3.0 Hz, J _{4′′,5′′}) 9.5 Hz), 3.10-3.04 (1H,

dd, H-4′, J _3′,4′ax) J _4′,5′) 10.0 Hz; 1H, dd, H-2′′, J _{1′′,2′′}) 7.9 Hz,

J _{2′′,3′′}) 3.0 Hz), 3.03-2.99 (1H, m, H-14), 2.51 (6H, s, NMe₂),

2.42 (1H, t, H-3′, J _2′,3′) J _3′,4′ax) 10.2 Hz), 2.28 (1H, br, H-6),

2.17 (1H, m, H-7b), 1.97 (1H, m, H-19b), 1.82 (3H, s, H-22),

1.78 (1H, m, H-16b), 1.66-1.57 (2H, m, H-7a, H-16a), 1.52 (1H,

m, H-19a), 1.34 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 6.1 Hz), 1.27

(3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.4 Hz), 1.22 (3H, s, Me-21),

3.48 (3H, s, 2′′-OMe), 3.30 (1H, dq, H-5′, J _4′,5′) 8.7 Hz, J _5′,6′

)

6.3 Hz), 3.24-3.14 (2H, m, H-8, H-4′′), 3.12-2.98 (3H, m, H-14,

H-4′, H-2′′), 2.78 (1H, dd, H-19, J _6,19) 7.7 Hz, J _19,20) 6.0 Hz),

2.62 (1H, d, H-2b, J _2a,2b) 17.1 Hz), 2.50 (6H, s, NMe₂), 2.37

(1H, dt, H-3′, J _2′,3′) 9.0 Hz, J _3′,4′ax) 10.0 Hz), 2.07 (1H, d,

H-7b, J _7a,7b) 15.0 Hz), 1.97 (1H, d, H-2a, J _2a,2b) 17.1 Hz),

1.92-1.85 (1H, m, H-16b), 1.80 (3H, s, Me-22), 1.68-1.52 (3H,

m, H-16a, H-6, and H-4), 1.31 (3H, d, H-6′ (Me-C-5′), J _5′,6′

)

6.2 Hz), 1.28 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.1 Hz), 1.14 (3H,

d, Me-18, J _4,18) 6.0 Hz), 1.02 (3H, d, Me-21, J _8,21) 6.3 Hz),

0.90 (3H, t, Me-17, J _16a,17) J _16b,17) 7.3 Hz); ¹³C NMR (CDCl₃)

δ 206.5 (s, C-9), 202.1 (d, C-20), 173.1 (s, C-1), 147.8 (d, C-11),

140.8 (d, C-13), 135.8 (s, C-12), 127.3 (d, C-10), 103.6 (d, C-1′),

101.0 (d, C-1′′), 86.8 (d, C-5), 81.8 (d, C-2′′), 79.6 (d, C-3′′), 75.7

(s, C-3), 75.4 (d, C-15), 73.1 (d, C-5′), 72.5 (d, C-4′′), 70.5 (d,

C-2′), 70.4 (d, C-4′), 70.3 (d, C-5′′), 69.8 (d, C-3′), 69.4 (t, C-23),

61.6 (q, 3′′-OMe), 59.4 (q, 2′′-OMe), 59.1 (d, C-19), 50.1 (d, C-4),

45.0 (t, C-2), 44.5 (d, C-14), 44.3 (d, C-6), 41.5 (q, NMe₂), 35.9

(d, C-8), 33.7 (t, C-7), 25.8 (t, C-16), 17.7 (q, Me-6′ (Me-C-5′)),

17.5 (q, Me-6′′ (Me-C-5′′), 17.2 (q, Me-21), 12.3 (q, Me-22), 11.5

(q, Me-18), 9.4 (q, Me-17). Anal. (C₃₉H₆₃NO₁₄) C, H, N.

1.10 (3H, d, Me-18, J _4,18) 6.5 Hz), 0.92 (3H, t, Me-17, J _16,17

)

7.4 Hz); ¹³C NMR (CDCl₃) δ 207.0 (s, C-3), 206.9 (s, C-9), 167.5

(s, C-1), 148.8 (d, C-11), 141.0 (d, C-13), 134.6 (s, C-12), 125.6

(d, C-10), 103.3 (d, C-1′), 100.9 (d, C-1′′), 81.8 (d, C-2′′), 81.4

(d, C-5), 81.1 (d, C-20), 79.7 (d, C-3′′), 76.5 (d, C-15), 73.2 (d,

C-4′′), 72.7 (d, C-5′), 70.8 (d, C-4′), 70.6 (d, C-3′, C-2′), 70.4 (t,

C-23), 70.1 (d, C-5′′), 62.9 (q, 3′′-OMe), 60.3 (s, C-8), 59.5 (q,

2′′-OMe), 44.2 (t, C-2), 43.5 (d, C-14), 41.7 (q, NMe₂), 39.1 (d,

C-6), 37.6 (t, C-19), 36.3 (t, C-7), 35.6 (d, C-4), 26.4 (t, C-16),

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 423

Gen er a l P r oced u r e for t h e Wit t ig R ea ct ion w it h

Sta bilized Ylid es. Syn th esis of Desm ycosin An a logu es

26a -d . To a solution of 2′,4′,4′′-tri-O-acetyldesmycosin 7^10,11

(898.0 mg, 1.0 mmol) in benzene (5 mL) was added stabilized

Wittig ylide a 1-a 4 (1.5 mmol, 1.5 equiv), and the reaction

mixture was heated at reflux temperature for 2 h. After the

end of the reaction was established (TLC), the solvent was

evaporated under reduced pressure, and the crude product was

chromatographed over silica gel to give following compounds.

(d, C-20), 147.5 (d, C-11), 141.6 (d, C-13), 134.9 (s, C-12), 121.9

(d, C-20′), 118.2 (d, C-10), 103.4 (d, C-1′), 100.9 (d, C-1′′), 80.4

(d, C-2′′), 80.2 (d, C-5), 77.6 (d, C-3′′), 75.2 (d, C-3), 75.1 (d,

C-15), 74.6 (d, C-4′′), 72.0 (d, C-3′), 70.9 (d, C-4′), 70.7 (d, C-2′),

68.9 (t, C-23), 67.2 (d, C-5′′), 67.0 (d, C-5′), 61.4 (q, 3′′-OMe),

59.8 (t, COOCH₂CH₃), 59.5 (q, 2′′-OMe), 44.8 (d, C-14, C-8, 2C),

41.2 (q, NMe₂), 40.3 (d, C-4), 39.2 (t, C-2), 35.7 (d, C-6), 32.4

(t, C-7), 30.9 (t, C-19), 25.2 (t, C-16), 21.3 (q, OCOCH₃), 21.2

(q, OCOCH₃), 20.9 (q, OCOCH₃), 17.4 (q, Me-21), 17.3 (q, Me-

C-5′), 17.1 (q, Me-C-5′′), 14.2 (q, COOCH₂CH₃), 13.0 (q, Me-

22), 9.5 (q, Me-17), 8.8 (q, Me-18). Anal. (C₄₉H₇₇NO₁₈) C, H,

N.

26c (88%): FAB-MS m/z 938 (MH⁺, 88%); UV λ_maxnm (ꢀ)

277 (30 569); ¹H NMR (CDCl₃) δ 7.30 (1H, d, H-11), 6.94 (1H,

dt, H-20), 6.25 (1H, d, H-10), 5.99 (1H, d, H-20′), 5.84 (1H, d,

H-13), 3.51 (3H, s, 3′′-OMe), 3.48 (3H, s, 2′′-OMe), 2.35 (6H, s,

NMe₂), 2.25 (3H, s, COCH₃), 2.11 (3H, s, OCOCH₃), 2.05 (6H,

s, 2×OCOCH₃), 1.78 (3H, s, Me-22); ¹³C NMR (CDCl₃) δ 203.1

(s, C-9), 199.0 (s, COCH₃), 174.1 (s, C-1), 170.2 (s, OCOCH₃),

169.6 (s, OCOCH₃), 169.1 (s, OCOCH₃), 149.2 (d, C-20), 146.8

(d, C-11), 140.8 (d, C-13), 134.5 (s, C-12), 120.8 (d, C-20′), 118.0

(d, C-10), 61.2 (q, 3′′-OMe), 59.2 (q, 2′′-OMe), 41.2 (q, NMe₂),

26.0 (q, COCH₃), 21.0 (q, OCOCH₃), 20.7 (q, OCOCH₃), 20.5

(q, OCOCH₃), 12.7 (q, Me-22). Anal. (C₄₈H₇₅NO₁₇) C, H, N.

26d (94%): FAB-MS m/z 924 (MH⁺, 92%); UV λ_maxnm (ꢀ)

279 (28 671); ¹H NMR (CDCl₃) δ 9.71 (1H, d, CHO), 7.28 (1H,

d, H-11), 6.72 (1H, dt, H-20), 6.23 (1H, d, H-10), 5.98 (1H, dd,

H-20′), 5.89 (1H, d, H-13), 3.50 (3H, s, 3′′-OMe), 3.48 (3H, s,

2′′-OMe), 2.40 (6H, s, NMe₂), 2.10 (3H, s, OCOCH₃), 2.02 (6H,

s, 2×OCOCH₃), 1.77 (3H, s, Me-22); ¹³C NMR (CDCl₃) δ 203.6

(s, C-9), 192.5 (d, CHO), 173.1 (s, C-1), 170.5 (s, OCOCH₃),

169.1 (s, OCOCH₃), 169.0 (s, OCOCH₃), 149.5 (d, C-20), 146.3

(d, C-11), 140.6 (d, C-13), 134.0 (s, C-12), 120.3 (d, C-20′), 117.8

(d, C-10), 61.2 (q, 3′′-OMe), 59.1 (q, 2′′-OMe), 41.0 (q, NMe₂),

21.1 (q, OCOCH₃), 20.9 (q, OCOCH₃), 20.7 (q, OCOCH₃), 12.8

(q, Me-22). Anal. (C₄₇H₇₃NO₁₇) C, H, N.

26a (85%): FAB-MS m/z 954 (MH⁺, 72%); UV λ_maxnm (ꢀ)

278 (30 722); ¹H NMR (CDCl₃) δ 7.33 (1H, d, H-11, J _10,11

)

15.3 Hz), 6.95 (1H, dt, H-20, J _20,20′) 15.7 Hz, J _19b,20) 2.7 Hz),

6.28 (1H, d, H-10, J _10,11) 15.3 Hz), 5.90 (1H, d, H-13, J _13,14

)

10.9 Hz), 5.86 (1H, d, H-20′, J _20,20′) 15.8 Hz), 4.97 (1H, dt,

H-15, J _14,15) 10.0 Hz, J _15,16b) 3.8 Hz), 4.90 (1H, dd, H-2′,

J _1′,2′) 9.3 Hz, J _2′,3′) 10.0 Hz), 4.75 (1H, t, H-4′, J _3′,4′ax) 9.7

Hz, J _4′,5′) 9.8 Hz), 4.63 (1H, d, H-1′′, J _{1′′,2′′}) 8.0 Hz), 4.40

(1H, dd, H-4′′, J _{3′′,4′′}) 2.1 Hz, J _{4′′,5′′}) 9.8 Hz), 4.37 (1H, d,

H-1′, J _1′,2′) 9.3 Hz), 4.00 (1H, dd, H-23b, J _23a,23b) 9.5 Hz,

J _14,23b) 4.3 Hz), 3.96-3.86 (2H, m, H-5′′, H-3′′), 3.73-3.60

(2H, m, H-5, H-3), 3.70 (3H, s, COOCH₃), 3.56 (1H, dd, H-23a,

J _23a,23b) 9.5 Hz, J _14,23a) 4.6 Hz), 3.53 (3H, s, 3′′-OMe), 3.49

(3H, s, 2′′-OMe), 3.39 (1H, dq, H-5′, J _4′,5′) 9.8 Hz, J _5′,6′) 6.0

Hz), 3.05 (1H, dd, H-2′′, J _{1′′,2′′}) 8.0 Hz, J _{2′′,3′′}) 2.7 Hz), 2.95

(1H, ddt, H-14, J _14,15) 10.0 Hz, J _14,23a) 6.5 Hz, J _14,23b) 4.0

Hz), 2.73 (1H, t, H-3′, J _2′,3′) 10.0 Hz), 2.68-2.50 (3H, m,

H-19b, H-8, H-7b), 2.44 (1H, dd, H-2b, J _2a,2b) 16.7 Hz, J _2b,3

)

10.8 Hz), 2.34 (6H, s, NMe₂), 2.29-2.16 (1H, m, H-19a), 2.12

(3H, s, OCOCH₃), 2.06 (6H, s, 2×OCOCH₃), 2.00 (1H, br, H-6),

1.90 (1H, d, H-2a, J _2a,2b) 16.7 Hz), 1.89-1.80 (1H, m, H-16b),

1.78 (3H, s, Me-22), 1.68-1.60 (1H, m, H-16a), 1.58-1.44 (3H,

m, H-7a, H-4), 1.21 (3H, d, Me-21, J _8,21) 6.7 Hz), 1.18 (3H, d,

H-6′ (Me-C-5′), J _5′,6′) 6.0 Hz), 1.17 (3H, d, H-6′′ (Me-C-5′′),

J _{5′′,6′′}) 6.1 Hz), 0.95 (3H, d, Me-18, J _4,18) 6.7 Hz), 0.93 (3H,

t, Me-17, J _16a,17) J _16b,17) 7.2 Hz); ¹³C NMR (CDCl₃) δ 203.4

(s, C-9), 174.2 (s, C-1), 170.1 (s, OCOCH₃), 169.8 (s, OCOCH₃),

169.3 (s, OCOCH₃), 167.2 (s, COOCH₃), 149.2 (d, C-20), 147.7

(d, C-11), 141.6 (d, C-13), 134.9 (s, C-12), 121.6 (d, C-20′), 118.3

(d, C-10), 101.9 (d, C-1′), 100.9 (d, C-1′′), 80.4 (d, C-2′′), 80.2

(d, C-5), 77.6 (d, C-3′′), 75.1 (d, C-15), 74.6 (d, C-4′′), 71.3 (d,

C-4′), 70.9 (d, C-5′), 70.5 (d, C-2′), 68.9 (t, C-23), 67.2 (d, C-5′′),

67.0 (d, C-3′), 66.7 (d, C-3), 61.4 (q, 3′′-OMe), 59.4 (q, 2′′-OMe),

51.0 (q, COOCH3), 44.8 (d, C-8), 44.7 (d, C-14), 41.0 (q, NMe₂),

40.3 (d, C-4), 39.1 (t, C-2), 35.6 (d, C-6), 32.4 (t, C-7), 30.8 (t,

C-19), 25.0 (t, C-16), 21.1 (q, OCOCH₃), 20.9 (q, OCOCH₃), 20.7

(q, OCOCH₃), 17.3 (q, Me-21), 17.1 (q, Me-C-5′), 17.0 (q, Me-

C-5′′), 12.8 (q, Me-22), 9.4 (q, Me-17), 8.6 (q, Me-18). Anal.

(C₄₈H₇₅NO₁₈) C, H, N.

Gen er a l P r oced u r e for Dep r otection of Desm ycosin

An a logu es 26a -d . Compounds 26a -d (3.0 g, 3.48 mmol)

were dissolved in methanol (40 mL) and the reaction mixture

was stirred at room temperature. The mixture was than

evaporated at room temperature under vacuum to give 27a -

d , which were purified by column chromatography (silica gel,

E1 solvent system). The following compounds were prepared.

27a (85%): FAB-MS m/z 870 (MH⁺, 58%). Anal. (C₄₄H₇₁

NO₁₆) C, H, N.

-

27b (92%): FAB-MS m/z 884 (MH⁺, 73%). Anal. (C₄₅H₇₃

NO₁₆) C, H, N.

27c (85%): FAB-MS m/z 854 (MH⁺, 91%). Anal. (C₄₄H₇₁

NO₁₅) C, H, N.

27d (89%): FAB-MS m/z 840 (MH⁺, 62%). Anal. (C₄₃H₆₉

NO₁₅) C, H, N.

26b (90%): FAB-MS m/z 968 (MH⁺, 58%); UV λ_maxnm (ꢀ)

276 (31 894); ¹H NMR (CDCl₃) δ 7.33 (1H, d, H-11, J _10,11

)

15.4 Hz), 6.93 (1H, dt, H-20, J _20,20′) 15.8 Hz, J _19,20) 7.8 Hz),

6.28 (1H, d, H-10, J _10,11) 15.4 Hz), 5.90 (1H, d, H-13, J _13,14

)

An aqueous solution of NH₃(25%) was added to 27a -d and

the mixture was stirred at 25 °C for 3 h. The crude residue

obtained by concentration of the reaction mixture was purified

by flash column chromatography (silica gel, E1 solvent system,

R_f) 0.30-0.50), furnishing the expected R,â-unsaturated

compounds 28a -d (60-90%). By using this procedure, the

following compounds were prepared.

10.9 Hz), 5.84 (1H, d, H-20′, J _20,20′) 15.8 Hz), 4.97 (1H, dt,

H-15, J _14,15) 10.0 Hz, J _15,16b) 3.9 Hz), 4.90 (1H, br, H-2′),

4.78 (1H, br, H-4′), 4.63 (1H, d, H-1′′, J _{1′′,2′′}) 8.0 Hz), 4.44

(1H, dd, H-4′′, J _{3′′,4′′}) 2.5 Hz, J _{4′′,5′′}) 9.9 Hz), 4.20-4.05 (3H,

m, COOCH₂CH₃, H-1′), 3.99 (1H, dd, H-23b, J _23a,23b) 9.5 Hz,

J _14,23b) 4.4 Hz), 3.94-3.84 (2H, m, H-5′′, H-3′′), 3.78-3.62

(2H, m, H-5, H-3), 3.55 (1H, dd, H-23a, J _23a,23b) 9.5 Hz, J _14,23a

) 4.7 Hz), 3.52 (3H, s, 3′′-OMe), 3.44 (3H, s, 2′′-OMe), 3.43-

3.28 (2H, m, H-6, H-5′), 3.05 (1H, dd, H-2′′, J _{1′′,2′′}) 8.0 Hz,

28a (90%): FAB-MS m/z 828 (MH⁺, 58%); UV λ_maxnm (ꢀ)

284 (28 634); ¹H NMR (CDCl₃) δ 7.29 (1H, d, H-11, J _10,11

)

16.5 Hz), 6.95 (1H, br, H-20), 6.25 (1H, d, H-10, J _10,11) 16.5

Hz), 5.90 (1H, d, H-13, J _13,14) 10.2 Hz), 5.85 (1H, d, H-20′,

J _{2′′,3′′}) 2.8 Hz), 2.94 (1H, ddt, H-14, J _14,15) 10.0 Hz, J _14,23a

)

6.5 Hz, J _14,23b) 4.1 Hz), 2.85 (1H, br, H-3′), 2.71-2.60 (1H,

m, H-8), 2.44 (1H, dd, H-2b, J _2a,2b) 16.1 Hz, J _2b,3) 9.8 Hz),

2.36 (7H, br, H-19b, NMe₂), 2.11 (9H, s, OCOCH₃), 1.99-1.83

(3H, m, H-19a, H-16b, H-2a), 1.79 (3H, s, Me-22), 1.63 (1H,

ddq, H-16a, J _15,16a) 10.5 Hz, J _16a,16b) 14.3 Hz, J _16a,17) 7.1

Hz), 1.52 (2H, br, H-7b, H-4), 1.27 (3H, t, COOCH₂CH₃, J _CH3,CH2

) 7.1 Hz), 1.21 (3H, d, Me-21, J _8,21) 6.7 Hz), 1.19 (3H, d, H-6′

J _20,20′) 15.7 Hz), 4.99 (1H, dt, H-15, J _14,15) 10.0 Hz, J _15,16a

)

11.1 Hz), 4.56 (1H, d, H-1′′, J _{1′′,2′′}) 7.8 Hz), 4.31 (1H, d, H-1′,

J _1′,2′) 7.4 Hz), 4.00 (1H, dd, H-23b, J _23a,23b) 9.6 Hz, J _14,23b

)

3.7 Hz), 3.80-3.73 (3H, m, H-5, H-3′′, H-3), 3.71 (3H, s,

COOCH₃), 3.62 (3H, s, 3′′-OMe), 3.60-3.51 (3H, m, H-23a,

H-5′′, H-2′), 3.50 (3H, s, 2′′-OMe), 3.33 (1H, br, H-5′), 3.20 (1H,

br, H-4′′), 3.09 (1H, t, H-4′, J _3′,4′ax) J _4′,5′) 10.0 Hz), 3.04 (1H,

dd, H-2′′, J _{1′′,2′′}) 7.7 Hz, J _{2′′,3′′}) 2.7 Hz), 2.98-2.90 (1H, m,

H-14), 2.80-2.68 (1H, m, H-8), 2.54 (6H, s, NMe₂), 2.52-2.45

(2H, m, H-19b, H-2b), 2.43 (1H, t, H-3′, J _2′,3′) J _3′,4′ax) 10.0

Hz), 2.33 (1H, br, H-19a), 2.05 (1H, br, H-6), 1.95 (1H, d, H-2a,

J _2a,2b) 16.2 Hz), 1.88 (1H, ddq, H-16b, J _15,16b) 3.0 Hz, J _16a,16b

(Me-C-5′), J _5′,6′) 6.0 Hz), 1.17 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}

6.2 Hz), 1.10-1.05 (1H, m, H-7a), 0.98 (3H, d, Me-18, J _4,18

)

6.9 Hz), 0.92 (3H, t, Me-17, J _16a,17) J _16b,17) 7.3 Hz); ¹³C NMR

(CDCl₃) δ203.2 (s, C-9), 174.0 (s, C-1), 170.0 (s, OCOCH₃), 169.8

(s, OCOCH₃), 169.2 (s, OCOCH₃), 166.7 (s, COOCH₂CH₃), 148.5

424 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

(Me-C-5′), J _5′,6′) 5.7 Hz), 1.26 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}

) 14.5 Hz, J _16b,17) 7.3 Hz), 1.79 (3H,s, Me-22), 1.70-1.46 (2H,

m, H-16a, H-4), 1.31 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 6.3 Hz),

1.27 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.0 Hz), 1.25 (1H, br, H-7b),

)

6.3 Hz), 1.20 (3H, d, Me-21, J _8,21) 6.6 Hz), 1.02 (3H, d, Me-

18, J _4,18) 6.6 Hz), 0.94 (3H, t, Me-17, J _16a,17) J _16b,17) 7.2

Hz); ¹³C NMR (CDCl₃) δ 203.6 (s, C-9), 199.2 (s, COCH₃), 174.4

(s, C-1), 148.9 (d, C-20), 147.9 (d, C-11), 141.9 (d, C-13), 134.9

(s, C-12), 132.3 (d, C-20′), 118.3 (d, C-10), 104.0 (d, C-1′), 100.9

(d, C-1′′), 81.6 (d, C-2′′), 80.8 (d, C-3′′), 79.6 (d, C-5), 75.1 (d,

C-15), 73.1 (d, C-5′), 72.5 (d, C-4′′), 70.7 (d, C-4′), 70.6 (d, C-5′′),

70.3 (d, C-2′), 70.0 (d, C-3′), 68.7 (t, C-23), 67.1 (d, C-3), 61.5

(q, 3′′-OMe), 59.4 (q, 2′′-OMe), 44.6 (d, C-14, C-8, 2C), 41.4 (q,

NMe₂), 39.9 (d, C-4), 39.1 (t, C-2), 36.2 (d, C-6), 33.2 (t, C-7),

31.9 (t, C-19), 26.2 (q, COCH₃), 25.1 (t, C-16), 17.7 (q, Me-C-

5′), 17.4 (q, Me-C-5′′), 17.1 (q, Me-21), 12.6 (q, Me-22), 9.3 (q,

Me-17), 8.9 (q, Me-18). Anal. (C₄₂H₆₉NO₁₄) C, H, N.

1.19 (3H, d, Me-21, J _8,21) 6.6 Hz), 1.00 (3H, d, Me-18, J _4,18

)

6.6 Hz), 0.94 (3H, t, Me-17, J _16a,17) J _16b,17) 7.2 Hz), 0.87 (1H,

d, H-7a, J _7a,7b) 6.9 Hz); ¹³C NMR (CDCl₃) δ 203.4 (s, C-9),

174.3 (s, C-1), 167.0 (s, COOCH₃), 148.9 (d, C-20), 147.6 (d,

C-11), 141.7 (d, C-13), 134.9 (s, C-12), 121.8 (d, C-20′), 118.6

(d, C-10), 104.1 (d, C-1′), 100.9 (d, C-1′′), 81.6 (d, C-5, C-2′′,

2C), 79.6 (d, C-3′′), 75.0 (d, C-15, C-3, 2C), 73.1 (d, C-4′′), 72.4

(d, C-4′), 70.7 (d, C-2′), 70.5 (d, C-5′′), 70.3 (d, C-3′), 69.9 (d,

C-5′), 68.8 (t, C-23), 61.5 (q, 3′′-OMe), 59.4 (q, 2′′-OMe), 51.0

(q, COOCH₃), 44.6 (d, C-14), 43.7 (d, C-8), 42.5 (d, C-4), 41.4

(q, NMe₂), 39.1 (t, C-2), 33.1 (d, C-6), 31.2 (t, C-7), 31.1 (t, C-19),

25.1 (t, C-16), 17.6 (q, Me-C-5′), 17.4 (q, Me-C-5′′), 17.0 (q, Me-

21), 12.6 (q, Me-22), 9.3 (q, Me-17), 8.9 (q, Me-18). Anal.

(C₄₂H₆₉NO₁₅) C, H, N.

28d (93%): FAB-MS m/z 798 (MH⁺, 58%); UV λ_maxnm (ꢀ)

1

282 (30 184); H NMR (CDCl₃) δ 9.73 (1H, d, CHO, J _CHO,20′

)

2.8 Hz), 7.28 (1H, d, H-11, J _10,11) 16.4 Hz), 6.70 (1H, dt, H-20,

J _20,20′) 15.8 Hz, J _19b,20) 2.6 Hz), 6.24 (1H, d, H-10, J _10,11

28b (85%): FAB-MS m/z 842 (MH⁺, 58%); UV λ_maxnm (ꢀ)

276 (31 894); IR (KBr) ν_max3445, 2971, 2932, 1714, 1681, 1651,

)

16.4 Hz), 6.00 (1H, dd, H-20′, J _20,20′) 15.8 Hz, J _CHO,20′) 2.8

Hz), 5.89 (1H, d, H-13, J _13,14) 10.3 Hz), 4.95 (1H, dt, H-15,

1

1593, 1455, 1372, 1169, 1081 cm^-1; H NMR (CDCl₃) δ 7.30

(1H, d, H-11, J _10,11) 16.6 Hz), 6.93 (1H, br, H-20), 6.24 (1H,

d, H-10, J _10,11) 16.6 Hz), 5.90 (1H, d, H-13, J _13,14) 10.3 Hz),

5.85 (1H, d, H-20′, J _20,20′) 15.8 Hz), 5.00 (1H, dt, H-15, J _14,15

) 10.0 Hz, J _15,16a) 11.1 Hz, J _15,16b) 3.8 Hz), 4.56 (1H, d, H-1′′,

J _{1′′,2′′}) 7.8 Hz), 4.35 (1H, d, H-1′, J _1′,2′) 7.3 Hz), 4.17 (2H, q,

J _14,15) 10.0 Hz, J _15,16b) 2.3 Hz), 4.52 (1H, d, H-1′′, J _{1′′,2′′})

7.5 Hz), 4.25 (1H, d, H-1′, J _1′,2′) 7.1 Hz), 3.99 (1H, dd, H-23b,

J _23a,23b) 9.6 Hz, J _14,23b) 3.7 Hz), 3.78-3.63 (3H, m, H-23a,

H-5′′, H-2′), 3.61 (3H, s, 3′′-OMe), 3.58-3.49 (3H, m, H-23a,

H-5′′, H-2′), 3.46 (3H, s, 2′′-OMe), 3.27 (1H, br, H-5′), 3.20-

3.15 (1H, m, H-4′′), 3.10-3.03 (1H, m, H-4′), 3.00 (1H, dd, H-2′′,

J _{1′′,2′′}) 7.5 Hz, J _{2′′,3′′}) 2.5 Hz), 2.96-2.88 (1H, m, H-14), 2.75-

2.58 (3H, m, H-19b, H-8, H-7b), 2.50 (6H, s, NMe₂), 2.46-2.40

(1H, m, H-2b), 2.38 (1H, t, H-3′, J _2′,3′) J _3′,4′ax) 10.1 Hz), 2.35-

2.30 (1H, m, H-19a), 2.15 (1H, br, H-6), 2.01-1.85 (2H, m,

H-16b, H-2a), 1.78 (3H, s, Me-22), 1.70-1.41 (2H, m, H-16a,

H-4), 1.30 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 6.2 Hz), 1.26 (3H, d,

H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.0 Hz), 1.24 (1H, br, H-7b), 1.18 (3H,

d, Me-21, J _8,21) 6.6 Hz), 1.02 (3H, d, Me-18, J _4,18) 6.5 Hz),

1.00 (1H, br, H-7a), 0.92 (3H, t, Me-17, J _16a,17) J _16b,17) 7.2

Hz); ¹³C NMR (CDCl₃) δ 203.4 (s, C-9), 192.4 (d, CHO), 173.8

(s, C-1), 148.2 (d, C-20), 147.1 (d, C-11), 140.7 (d, C-13), 133.1

(s, C-12), 132.0 (d, C-20′), 118.1 (d, C-10), 103.5 (d, C-1′), 100.7

(d, C-1′′), 82.0 (d, C-2′′), 80.5 (d, C-3′′), 78.9 (d, C-5), 74.9 (d,

C-15), 72.9 (d, C-5′), 72.1 (d, C-4′′), 70.5 (d, C-4′), 70.4 (d, C-5′′),

70.2 (d, C-2′), 69.8 (d, C-3′), 68.9 (t, C-23), 66.9 (d, C-3), 61.5

(q, 3′′-OMe), 59.8 (q, 2′′-OMe), 44.6 (d, C-14), 43.9 (d, C-8), 41.0

(q, NMe₂), 39.5 (d, C-4), 39.0 (t, C-2), 36.5 (d, C-6), 33.0 (t, C-7),

31.7 (t, C-19), 24.9 (t, C-16), 17.9 (q, Me-C-5′), 17.3 (q, Me-C-

5′′), 17.0 (q, Me-21), 12.4 (q, Me-22), 9.4 (q, Me-17), 8.8 (q, Me-

18). Anal. (C₄₁H₆₇NO₁₄) C, H, N.

COOCH_2bCH₃, J _{CH2b CH3}) 7.1 Hz), 4.00 (1H, dd, H-23b, J _23a,23b

,

) 9.6 Hz, J _14,23b) 3.8 Hz), 3.80-3.70 (3H, m, H-5, H-3′′, H-3),

3.62 (3H, s, 3′′-OMe), 3.58-3.51 (3H, m, H-23a, H-5′′, H-2′),

3.50 (3H, s, 2′′-OMe), 3.39 (1H, br, H-5′), 3.27-3.15 (3H, m,

H-6, H-4′′, H-4′), 3.04 (1H, dd, H-2′′, J _{1′′,2′′}) 7.8 Hz, J _{2′′,3′′}

2.9 Hz), 3.00-2.94 (1H, m, H-14), 2.80-2.65 (8H, m, NMe₂,

H-8, H-3′), 2.63 (1H, br, H-19b), 2.47 (1H, dd, H-2b, J _2a,2b

)

16.3 Hz, J _2b,3) 10.6 Hz), 2.35 (1H, br, H-19a), 1.96 (1H, d,

H-2a, J _2a,2b) 16.3 Hz), 1.89 (1H, ddq, H-16b, J _15,16b) 3.1 Hz,

J _16a,16b) 14.5 Hz, J _16b,17) 7.3 Hz), 1.80 (3H, s, Me-22), 1.70-

1.55 (2H, m, H-16a, H-4), 1.53-1.45 (1H, m, H-7b), 1.34 (1H,

d, H-7a, J _7a,8) 6.0 Hz), 1.29 (2H, q, COOCH_2aCH₃, J _CH2a,CH3

) 7.1 Hz), 1.28 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 7.1 Hz), 1.27

(3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.2 Hz), 1.19 (3H, d, Me-21,

J _8,21) 6.6 Hz), 1.00 (3H, d, Me-18, J _4,18) 6.2 Hz), 0.94 (3H, t,

Me-17, J _16a,17) J _16b,17) 7.3 Hz), 0.89 (3H, t, COOCH_2aCH₃,

J _CH3,CH2a) 7.1 Hz); ¹³C NMR (CDCl₃) δ 203.5 (s, C-9), 174.3

(s, C-1), 166.7 (s, COOCH₂CH₃), 148.6 (d, C-20), 147.8 (d, C-11),

140.5 (d, C-13), 135.1 (s, C-12), 122.4 (d, C-20′, C-10, 2C), 103.4

(d, C-1′), 101.0 (d, C-1′′), 81.9 (d, C-5, C-2′′, 2C), 79.8 (d, C-3′′),

75.3 (d, C-15, C-3, 2C), 73.3 (d, C-4′′), 72.7 (d, C-5′, C-4′, 2C),

70.6 (d, C-5′′, C-3′, C-2′, 3C), 69.1 (t, C-23), 61.8 (q, 3′′-OMe),

60.1 (t, COOCH₂CH₃), 59.7 (q, 2′′-OMe), 44.9 (d, C-14), 43.9

(d, C-8), 42.3 (d, C-4), 41.8 (q, NMe₂), 39.5 (t, C-2), 36.5 (d,

C-6), 31.6 (t, C-7), 29.0 (t, C-19), 25.5 (t, C-16), 17.9 (q, Me-

21), 17.8 (q, Me-C-5′′, Me-C-5′, 2C), 14.3 (q, COOCH₂CH₃), 13.0

P r ep a r a tion of Desm ycosin Ca r boxylic Acid (28e). The

methyl ester 28a (1.0 g, 1.2 mmol) was treated in THF:H₂O

(1:1, 30 mL) with LiOH (143.7 mg, 6.0 mmol, 5.0 equiv) at

ambient temperature for 3 h, after which time the end of the

reaction was established (TLC). The reaction mixture was

extracted with saturated aqueous NaHCO₃(3 × 20 mL), and

the combined aqueous extracts were acidified with 1 M HCl

to pH 4 and further extracted with EtOAc (4 × 20 mL).

Concentration of the combined organic solutions furnished, in

quantitative yield, essentially pure carboxylic acid 28e (976.8

mg, 100%): FAB-MS m/z 814 (MH⁺, 79%); UV λ_maxnm (ꢀ) 276

(q, Me-22), 10.4 (q, Me-18), 9.7 (q, Me-17). Anal. (C₄₃H₇₁NO₁₅

C, H, N.

)

28c (93%): FAB-MS m/z 812 (MH⁺, 58%); UV λ_maxnm (ꢀ)

282 (30 184); IR (KBr) ν_max3459, 2970, 2932, 1714, 1673, 1625,

1593, 1375, 1316, 1261, 1168, 1082, 1062 cm^-^{1 1}H NMR

;

(CDCl₃) δ 7.33 (1H, d, H-11, J _10,11) 16.5 Hz), 6.77 (1H, dt,

H-20, J _20,20′) 15.8 Hz, J _19b,20) 2.5 Hz), 6.26 (1H, d, H-10,

J _10,11) 16.5 Hz), 6.08 (1H, d, H-20′, J _20,20′) 15.8 Hz), 5.91

(1H, d, H-13, J _13,14) 10.3 Hz), 4.99 (1H, dt, H-15, J _14,15) 10.0

Hz), J _15,16b) 2.3 Hz), 4.56 (1H, d, H-1′′, J _{1′′,2′′}) 7.7 Hz), 4.30

(1H, d, H-1′, J _1′,2′) 7.2 Hz), 4.00 (1H, dd, H-23b, J _23a,23b) 9.7

Hz, J _14,23b) 3.8 Hz), 3.80-3.68 (3H, m, H-5, H-3′′, H-3′′), 3.62

(3H, s, 3′′-OMe), 3.60-3.52 (3H, m, H-23a, H-5′′, H-2′), 3.49

(3H, s, 2′′-OMe), 3.32 (1H, br, H-5′), 3.18 (1H, dd, H-4′′, J _{3′′,4′′}

1

(31 543); H NMR (CDCl₃) δ 12.0 (1H, br, COOH), 7.30 (1H,

d, H-11, J _10,11) 16.6 Hz), 6.97 (1H, br, H-20), 6.25 (1H, d, H-10,

J _10,11) 16.6 Hz), 6.97 (1H, br, H-20), 6.25 (1H, d, H-10, J _10,11

) 16.6 Hz), 5.91 (1H, d, H-13, J _13,14) 10.2 Hz), 5.81 (1H, d,

H-20′, J _20,20′) 15.6 Hz), 4.98 (1H, dt, H-15, J _14,15) 10.0 Hz,

J _15,16a) 11.0 Hz), 4.50 (1H, d, H-1′′, J _{1′′,2′′}) 7.8 Hz), 4.29 (1H,

d, H-1′, J _1′,2′) 7.4 Hz), 4.00 (1H, dd, H-23b, J _23a,23b) 9.6 Hz,

J _14,23b) 3.7 Hz), 3.85-3.69 (3H, m, H-5, H-3′′, H-3), 3.60 (3H,

s, 3′′-OMe), 3.58-3.50 (3H, m, H-23a, H-5′′, H-2′), 3.48 (3H, s,

2′′-OMe), 3.31 (1H, br, H-5′), 3.20-3.10 (1H, m, H-4′′), 3.08

(1H, t, H-4′, J _3′,4′ax) J _4′,5′) 10.0 Hz), 3.04 (1H, dd, H-2′′, J _{1′′,2′′}

) 7.8 Hz, J _{2′′,3′′}) 2.7 Hz), 2.98-2.90 (1H, m, H-14), 2.80-2.66

(1H, m, H-8), 2.53 (6H, s, NMe₂), 2.50-2.44 (2H, m, H-19b,

H-2b), 2.40 (1H, t, H-3′, J _2′,3′) J _3′,4′ax) 10.0 Hz), 2.33 (1H, br,

H-19a), 2.10 (1H, br, H-6), 1.94 (1H, d, H-2a, J _2a,2b) 16.1 Hz),

1.86 (1H, ddq, H-16b, J _15,16b) 3.0 Hz, J _16a,16b) 14.5 Hz, J _16b,17

) 7.2 Hz), 1.80 (3H, s, Me-22), 1.68-1.49 (2H, m, H-16a, H-4),

) 3.0 Hz, J _{4′′,5′′}) 9.6 Hz), 3.10 (1H, t, H-4′, J _3′,4′ax) J _4′,5′

)

10.0 Hz), 3.03 (1H, dd, H-2′′, J _{1′′,2′′}) 7.7 Hz, J _{2′′,3′′}) 2.6 Hz),

2.99-2.90 (1H, m, H-14), 2.78-2.56 (3H, m, H-19b, H-8, H-7b),

2.51 (6H, s, NMe₂), 2.47 (1H, dd, H-2b, J _2a,2b) 16.3 Hz, J _2b,3

) 5.7 Hz), 2.41 (1H, t, H-3′, J _2′,3′) J _3′,4′ax) 10.2 Hz), 2.34-

2.30 (1H, m, H-19a), 2.25 (3H, s, COCH₃), 2.05 (1H, br, H-6),

1.96 (1H, d, H-2a, J _2a,2b) 16.3 Hz), 1.86 (1H, ddq, H-16b, J _15,16b

) 3.0 Hz, J _16a,16b) 14.4 Hz, J _16b,17) 7.2 Hz), 1.79 (3H, s, Me-

22), 1.72-1.48 (4H, m, H-16a, H-7a, H-4), 1.31 (3H, d, H-6′

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 425

1.31 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 6.3 Hz), 1.26 (3H, d, H-6′′

(Me-C-5′′), J _{5′′,6′′}) 6.0 Hz), 1.25 (1H, br, H-7b), 1.18 (3H, d,

Me-21, J _8,21) 6.5 Hz), 0.98 (3H, d, Me-18, J _4,18) 6.6 Hz), 0.95

(3H,t, Me-17, J _16a,17) J _16b,17) 7.2 Hz), 0.87-0.82 (1H, m,

H-7a); ¹³C NMR (CDCl₃) δ 206.9 (s, C-9), 176.2 (s, C-1), 170.3

(s, COOH), 150.2 (d, C-20), 148.3 (d, C-11), 143.1 (d, C-13),

136.1 (s, C-12), 122.5 (d, C-20′), 119.2 (d, C-10), 103.8 (d, C-1′),

100.7 (d, C-1′′), 82.0 (d, C-5, C-2′′, 2C), 80.9 (d, C-3′′), 77.2 (d,

C-15, C-3, 2C), 74.5 (d, C-4′′), 73.1 (d, C-4′), 71.2 (d, C-2′), 70.8

(d, C-5′′), 70.6 (d, C-3′), 69.8 (d, C-5′), 68.9 (t, C-23), 61.5 (q,

3′′-OMe), 59.6 (q, 2′′-OMe), 44.8 (d, C-14), 43.9 (d, C-8), 43.0

(d, C-4), 41.0 (q, NMe₂), 39.8 (t, C-2), 34.6 (d, C-6), 31.0 (t, C-7),

30.8 (t, C-19), 26.2 (t, C-16), 17.8 (q, Me-C-5′), 17.6 (q, Me-C-

5′′), 17.0 (q, Me-21), 12.5 (q, Me-22), 9.8 (q, Me-17), 9.4 (q, Me-

18). Anal. (C₄₁H₆₇NO₁₅) C, H, N.

(6H, s, NMe₂), 2.12 (3H, s, 4′′-OCOCH₃), 2.03 (6H, s, 2′-

OCOCH₃, 4′-OCOCH₃), 1.80 (3H, s, Me-22), 1.29 (3H, t,

COOCH₂CH₃); ¹³C NMR (CDCl₃) δ 203.4 (s, C-9), 179.8 (s, C-3

enol), 170.1 (s, OCOCH₃), 169.6 (s, OCOCH₃), 169.1 (s,

OCOCH₃), 168.9 (s, C-1), 166.1 (s, COOCH₂CH₃), 148.3 (d,

C-20), 147.5 (d, C-11), 141.7 (d, C-13), 134.3 (s, C-12), 123.7

(d, C-10), 123.1 (d, C-20′), 88.9 (d, C-2 enol), 61.8 (q, 3′′-OMe),

59.5 (t, COOCH₂CH₃), 59.1 (q, 2′′-OMe), 41.4 (q, NMe₂), 21.4

(q, OCOCH₃), 20.9 (q, 2×OCOCH₃), 14.2 (q, COOCH₂CH₃), 12.3

(q, Me-22). Anal. (C₄₉H₇₅NO₁₈) C, H, N.

29c (85%): FAB-MS m/z 936 (MH⁺, 86%); UV λ_maxnm (ꢀ)

277 (28 823), 256 (17 653); ¹H NMR (CDCl₃) δ 11.90 (1H, s,

H-3 enol), 7.30 (1H, d, H-11), 6.90 (1H, dt, H-20), 6.12 (1H, d,

H-10), 5.81 (1H, d, H-20′), 5.75 (1H, d, H-13), 4.70 (1H, s, H-2

enol), 3.51 (3H, s, 3′′-OMe), 3.45 (3H, s, 2′′-OMe), 2.50 (6H, s,

NMe₂), 2.27 (3H, s, COCH₃), 2.05 (3H, s, 4′′-OCOCH₃), 1.98

(6H, s, 2′-OCOCH₃, 4′-OCOCH₃), 1.75 (3H, s, Me-22); ¹³C NMR

(CDCl₃) δ 203.5 (s, C-9), 199.2 (s, COCH₃), 179.1 (s, C-3 enol),

172.4 (s, C-1), 170.0 (s, OCOCH₃), 169.8 (s, OCOCH₃), 169.3

(s, OCOCH₃), 149.1 (d, C-20), 147.1 (d, C-11), 139.3 (d, C-13),

136.5 (s, C-12), 121.7 (d, C-20′), 118.3 (d, C-10), 89.1 (d, C-2

enol), 61.1 (q, 3′′-OMe), 59.3 (q, 2′′-OMe), 41.3 (q, NMe₂), 21.0

(q, OCOCH₃), 20.8 (q, OCOCH₃), 20.7 (q, OCOCH₃), 13.3 (q,

Me-22). Anal. (C₄₈H₇₃NO₁₇) C, H, N.

29d (92%): FAB-MS m/z 922 (MH⁺, 90%); UV λ_maxnm (ꢀ)

278 (29 128), 258 (16 953); ¹H NMR (CDCl₃) δ 11.82 (1H, s,

H-3 enol), 9.75 (1H, d, CHO), 7.25 (1H, d, H-11), 6.69 (1H, dt,

H-20), 6.20 (1H, d, H-10), 5.95 (1H, dd, H-20′), 5.87 (1H, d,

H-13), 4.75 (1H, s, H-2 enol), 3.52 (3H, s, 3′′-OMe), 3.46 (3H,

s, 2′′-OMe), 2.37 (6H, s, NMe₂), 2.12 (3H, s, 4′′-OCOCH₃), 2.01

(6H, s, 2′-OCOCH₃, 4′-OCOCH₃), 1.78 (3H, s, Me-22); ¹³C NMR

(CDCl₃) δ 203.1 (s, C-9), 193.0 (d, CHO), 180.1 (s, C-3 enol),

173.0 (s, C-1), 170.2 (s, OCOCH₃), 169.7 (s, OCOCH₃), 169.1

(s, OCOCH₃), 149.4 (d, C-20), 146.2 (d, C-11), 140.1 (d, C-13),

135.1 (s, C-12), 120.9 (d, C-20′), 118.0 (d, C-10), 89.0 (d, C-2

enol), 61.0 (q, 3′′-OMe), 59.4 (q, 2′′-OMe), 41.0 (q, NMe₂), 21.3

(q, OCOCH₃), 21.0 (q, OCOCH₃), 20.8 (q, OCOCH₃), 12.9 (q,

Me-22). Anal. (C₄₇H₇₁NO₁₇) C, H, N.

Gen er a l P r oced u r e for Dep r otection of Desm ycosin

An a logu es 29a -d . Compounds 29a -d (3.48 mmol) were

dissolved in methanol (40 mL) and the solution was heated

under reflux for 1 h. The residue obtained after evaporation

in vacuo was chromatographed on silica gel (8:2, hexane-

acetone) to give 30a -d . Compounds 30a -d (2.0 mmol) were

dissolved in methanol, then an aqueous solution of NH₃(25%)

was added and the mixture was stirred for 3 h at 25 °C. The

crude product obtained by concentration of the reaction

mixture was chromatographed on silica gel (E1 solvent system,

R_f) 0.30-0.50), furnishing the expected R,â-unsaturated

compounds 31a -d (60-90%). By using these procedures, the

following compounds were prepared.

P fitzn er -Moffa t Oxid a tion of Desm ycosin An a logu es

26a -d . Compounds 26a -d (1.4 mmol) were dissolved in

anhydrous CH₂Cl₂(5 mL). To this solution were added 1-(3-

dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC‚

HCl, 3.2 g, 16.8 mmol, 12 equiv) and dimethyl sulfoxide (1.8

mL, 25 mmol, 18 equiv) followed by pyridine trifluoroacetate

(3.2 g, 16.8 mmol, 12 equiv). After stirring at room temperature

for 18 h, CH₂Cl₂(15 mL) was added and the mixture was

filtered. The precipitate was washed with fresh CH₂Cl₂. The

filtrates were combined and washed with water and then

brine. The organic solution was dried over anhydrous Na₂SO₄

and evaporated at room temperature under vacuum. The

residue was chromatographed on silica gel, eluting with system

B, to give derivatives 29a -d .

29a (84%): FAB-MS m/z 952 (MH⁺, 71%); UV λ_maxnm (ꢀ)

276 (32 413), 255 (17 807); ¹H NMR (CDCl₃) δ 11.88 (1H, s,

H-3 enol), 7.20 (1H, d, H-11, J _10,11) 15.5 Hz), 6.85 (1H, dt,

H-20, J _20,20′) 16.0 Hz, J _19b,20) 2.5 Hz), 6.17 (1H, d, H-10,

J _10,11) 15.5 Hz), 5.75 (1H, d, H-20′, J _20,20′) 16.0 Hz), 5.71

(1H, d, H-13, J _13,14) 9.5 Hz), 4.88-4.76 (2H, m, H-15, H-2′),

4.68 (1H, t, H-4′, J _3′,4′ax) J _4′,5′) 10.0 Hz), 4.64 (1H, s, H-2

enol), 4.56 (1H, d, H-1′′, J _{1′′,2′′}) 8.0 Hz), 4.54 (1H, t, H-3′′, J _{2′′,3′′}

) J _{3′′,4′′}) 3.0 Hz), 4.37 (1H, d, H-4′′, J _{4′′,5′′}) 9.5 Hz), 4.32 (1H,

d, H-1′, J _1′,2′) 7.5 Hz), 3.96-3.88 (1H, dd, H-23b, J _23a,23b

)

9.6 Hz, J _14,23b) 4.5 Hz), 3.87-3.80 (1H, m, H-5′′), 3.69 (1H, d,

H-5, J _4,5) 10.5 Hz), 3.65 (3H, s, COOCH₃), 3.52 (1H, dd,

H-23a, J _23a,23b) 9.6 Hz, J _14,23a) 4.0 Hz), 3.45 (3H, s, 3′′-OMe),

3.42 (3H, s, 2′′-OMe), 3.34 (1H, dq, H-5′, J _4′,5′) 9.5 Hz, J _5′,6′

)

6.3 Hz), 2.99 (1H, dd, H-2′′, J _{1′′,2′′}) 8.0 Hz, J _{2′′,3′′}) 3.0 Hz),

2.93-2.84 (1H, m, H-14), 2.67 (1H, t, H-3′, J _2′,3′) J _3′,4′ax) 10.0

Hz), 2.54 (1H, br, H-8), 2.40-2.31 (3H, m, H-19, H-4), 2.27

(6H, s, NMe₂), 2.06 (3H, s, 4′′-OCOCH₃), 2.03 (1H, br, H-6),

1.97 (6H, s, 2′-OCOCH₃, 4′-OCOCH₃), 1.82 (1H, ddq, H-16b,

J _15,15b) 2.7 Hz, J _16a,16b) 14.0 Hz, J _16b,17) 7.0 Hz), 1.72 (3H,

s, Me-22), 1.64-1.48 (2H, m, H-16a, H-7b), 1.43-1.34 (1H, m,

H-7a), 1.22 (3H, m, H-16a, H-7b), 1.18 (3H, d, Me-21, J _8,21

)

30a (86%): FAB-MS m/z 868 (MH⁺, 79%); UV λ_maxnm (ꢀ)

6.7 Hz), 1.13 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 6.3 Hz), 1.10 (3H,

d, H-6′′, (Me-C-5′′), J _{5′′,6′′}) 6.1 Hz), 0.88 (3H, t, Me-17, J _16a,17

) J _16b,17) 7.0 Hz); ¹³C NMR (CDCl₃) δ 203.4 (s, C-9), 179.6 (s,

C-3 enol), 172.1 (s, C-1), 170.1 (s, OCOCH₃), 169.7 (s, OCOCH₃),

169.1 (s, OCOCH₃), 167.1 (s, COOCH₃), 149.2 (d, C-20), 147.2

(d, C-11), 139.5 (d, C-13), 136.8 (s, C-12), 121.9 (d, C-20′), 118.6

(d, C-10), 102.1 (d, C-1′), 100.9 (d, C-1′′), 89.1 (d, C-2 enol),

80.4 (d, C-2′′), 79.5 (d, C-5), 77.6 (d, C-3′′), 74.7 (d, C-15), 74.5

(d, C-4′′), 71.2 (d, C-4′), 71.0 (d, C-5′), 70.3 (d, C-2′), 69.3 (t,

C-23), 67.2 (d, C-5′′), 66.9 (d, C-3′), 61.4 (q, 3′′-OMe), 59.4 (q,

2′′-OMe), 51.1 (q, COOCH₃), 44.5 (d, C-14, C-8, 2C), 43.2 (d,

C-4), 41.0 (q, NMe₂), 37.9 (d, C-6), 31.6 (t, C-7), 30.4 (t, C-19),

25.6 (t, C-16), 21.0 (q, OCOCH₃), 20.9 (q, OCOCH₃), 20.7 (q,

OCOCH₃), 17.7 (q, Me-18), 17.4 (q, Me-21), 17.1 (q, Me-C-5′),

1

276 (31 543), 256 (17 326); H NMR (CDCl₃) δ 11.67 (1H, br,

H-3 enol), 7.22 (1H, d, H-11, J _10,11) 15.1 Hz), 6.96 (1H, dt,

H-20, J _20,20′) 15.5 Hz, J _19b,20) 2.3 Hz), 6.24 (1H, d, H-13,

J _13,14) 10.0 Hz), 5.86 (1H, d, H-20′, J _20,20′) 15.5 Hz), 5.80

(1H, d, H-13, J _13,14) 10.0 Hz), 4.92 (1H, dt, H-15, J _14,15) 9.8

Hz, J _15,16b) 2.1 Hz), 4.74 (1H, s, H-2 enol), 4.64 (1H, d, H-1′′,

J _{1′′,2′′}) 7.8 Hz), 4.44 (1H, dd, H-4′′, J _{3′′,4′′}) 3.0 Hz, J _{4′′,5′′}) 9.2

Hz), 4.32 (1H, d, H-1′, J _1′,2′) 7.5 Hz), 4.00 (1H, dd, H-23b,

J _23a,23b) 9.6 Hz, J _14,23b) 4.1 Hz), 3.94-3.92 (1H, m, H-5′′),

3.90 (1H, t, H-3′′, J _{2′′,3′′}) J _{3′′,4′′}) 3.0 Hz), 3.86 (1H, d, H-5, J _4,5

) 10.0 Hz), 3.73 (3H, s, COOCH₃), 3.58 (1H, dd, H-23a, J _23a,23b

) 9.6 Hz, J _14,23a) 4.0 Hz), 3.56-3.51 (1H, m, H-2′), 3.53 (3H,

s, 3′′-OMe), 3.50 (3H, s, 2′′-OMe), 3.32 (1H, dq, H-5′, J _4′,5′

)

17.0 (q, Me-C-5′′), 13.4 (q, Me-22), 9.6 (q, Me-17). Anal. (C₄₈H₇₃

-

9.5 Hz, J _5′,6′) 6.3 Hz), 3.11 (1H, t, H-4′, J _3′4′ax) J _4′,5′) 9.5

Hz), 3.06 (1H, dd, H-2′′, J _{1′′,2′′}) 7.8 Hz, J _{2′′,3′′}) 3.0 Hz), 3.00-

2.93 (1H, m, H-14), 2.70 (1H, dd, H-19b, J _19a,19b) 16.3 Hz,

J _19b,20) 2.3 Hz), 2.63 (1H, br, H-8), 2.52 (6H, s, NMe₂), 2.44-

2.36 (3H, m, H-19a, H-4, H-3′), 2.11 (3H, s, 4′′-OCOCH₃), 2.02

NO₁₈) C, H, N.

29b (75%): FAB-MS m/z 966 (MH⁺, 71%); UV λ_maxnm (ꢀ)

278 (29 236), 257 (17 896); IR (KBr) ν_max2971, 2925, 1749,

1716, 1681, 1643, 1596, 1455, 1374, 1232, 1171, 1089, 1051

1

cm^-1; H NMR (CDCl₃) δ 11.70 (1H, s, H-3 enol), 7.31 (1H, d,

(1H, br, H-6), 1.90 (1H, ddq, H-16b, J _15,15b) 2.8 Hz, J _16a,16b)

H-11), 6.83 (1H, dt, H-20), 6.21 (1H, d, H-10), 5.84 (1H, d,

H-13), 5.81 (1H, d, H-20′), 4.71 (1H, s, H-2 enol), 4.20 (3H, q,

COOCH₂CH₃), 3.64 (3H, s, 3′′-OMe), 3.43 (3H, s, 2′′-OMe), 2.58

14.0 Hz, J _16b,17) 7.1 Hz), 1.80 (3H, s, Me-22), 1.71-1.57 (2H,

m, H-16a, H-7b), 1.56-1.48 (1H, m, H-7a), 1.34 (3H, d, H-6′.

(Me-C-5′), J 5′,6′ ) 6.3 Hz), 1.33 (3H, d, Me-18, J _4,18) 6.3 Hz),

426 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

1.21 (3H, d, Me-21, J _8,21) 6.7 Hz), 1.18 (3H, d, H-6′′ (Me-C-

5′′), J _{5′′,6′′}) 6.1 Hz), 0.95 (3H, t, Me-17, J _16a,17) J _16b,17) 7.1

Hz); ¹³C NMR (CDCl₃) δ 203.2 (s, C-9), 180.8 (s, C-3 enol),

171.3 (s, C-1), 170.1 (s, 4′′-OCOCH₃), 167.1 (s, COOCH₃),

149.0 (d, C-20), 147.4 (d, C-11), 139.7 (d, C-13), 136.8 (s, C-12),

122.1 (d, C-20′), 118.5 (d, C-10), 104.1 (d, C-1′), 101.0 (d, C-1′′),

89.2 (d, C-2 enol), 80.5 (d, C-2′′), 79.3 (d, C-5), 77.7 (d, C-3′′),

74.7 (d, C-15, C-4′′, 2C), 73.5 (d, C-5′), 71.0 (d, C-2′), 70.7

(d, C-4′), 70.1 (d, C-3′), 69.5 (t, C-23), 67.3 (d, C-5′′), 61.5 (q,

3′′-OMe), 59.6 (q, 2′′-OMe), 51.3 (q, COOCH₃), 44.8 (d, C-14),

44.0 (d, C-8), 43.7 (d, C-4), 41.7 (q, NMe₂), 38.0 (d, C-6), 32.5

(t, C-7), 30.7 (t, C-19), 25.9 (t, C-16), 20.9 (q, 4′′-OCOCH₃),

17.8 (q, Me-18), 17.6 (q, Me-C-5′), 17.4 (q, Me-21), 17.1 (q,

C-11), 140.0 (d, C-13), 135.3 (s, C-12), 121.0 (d, C-20′), 118.3

(d, C-10), 89.2 (d, C-2 enol), 61.0 (q, 3′′-OMe), 59.6 (q, 2′′-OMe),

41.0 (q, NMe₂), 21.6 (q, 4′′-OCOCH₃), 12.8 (q, Me-22). Anal.

(C₄₃H₆₇NO₁₅) C, H, N.

31a (89%): FAB-MS m/z 826 (MH⁺, 57%); UV λ_maxnm (ꢀ)

1

288 (33 666), 256 (17 345); H NMR (CDCl₃) δ 11.67 (1H, d,

H-11, J _10,11) 15.2 Hz), 6.95 (1H, dt, H-20, J _20,20′) 15.6 Hz,

J _19b,20) 2.5 Hz), 6.23 (1H, d, H-10, J _10,11) 15.2 Hz), 5.86 (1H,

d, H-20′, J _20,20′) 15.6 Hz), 5.82 (1H, d, H-13, J _13,14) 10.2 Hz),

4.92 (1H, dt, H-15, J _14,15) 9.8 Hz, J _15,16b) 2.1 Hz), 4.74 (1H,

s, H-2 enol), 4.57 (1H, d, H-1′′, J _{1′′,2′′}) 7.8 Hz), 4.32 (1H, d,

H-1′, J _1′,2′) 7.5 Hz), 4.00 (1H, dd, H-23b, J _23a,23b) 9.6 Hz,

J _14,23b) 4.1 Hz), 3.85 (1H, d, H-5, J _4,5) 10.1 Hz), 3.76 (1H, t,

H-3′′, J _{2′′,3′′}) J _{3′′,4′′}) 3.1 Hz), 3.73 (3H, s, COOCH₃), 3.62 (3H,

s, 3′′-OMe), 3.61-3.52 (3H, m, H-23a, H-5′′, H-2′), 3.34-3.30

(1H, m, H-5′), 3.19 (1H, dd, H-4′′, J _{3′′,4′′}) 3.1 Hz, J _{4′′,5′′}) 9.3

Hz), 3.11 (1H, t, H-4′, J _3′,4′ax) J _4′,5′) 9.6 Hz), 3.05 (1H, dd,

H-2′′, J _{1′′,2′′}) 7.8 Hz, J _{2′′,3′′}) 2.8 Hz), 3.05-2.93 (1H, m, H-14),

2.82 (1H, br, H-8), 2.72-2.56 (1H, m, H-19b), 2.52 (6H, s,

NMe₂), 2.46-2.37 (3H, m, H-19a, H-4, H-3′), 2.03 (1H, br, H-6),

1.89 (1H, ddq, H-16b, J _15,16b) 2.1 Hz, J _16a,16b) 14.1 Hz, J _16b,17

) 7.3 Hz), 1.80 (3H, s, Me-22), 1.70-1.57 (2H, m, H-16a, H-7b),

Me-C-5′′), 13.7 (q, Me-22), 9.9 (q, Me-17). Anal. (C₄₄H₆₉NO₁₆

)

C, H, N.

30b (91%): FAB-MS m/z 882 (MH⁺, 79%); UV λ_maxnm (ꢀ)

1

281 (27 443), 257 (18 108); H NMR (CDCl₃) δ 11.95 (1H, br,

H-3 enol), 7.22 (1H, d, H-11, J _10,11) 15.6 Hz), 6.93 (1H, dt,

H-20, J _20,20′) 15.6 Hz, J _19b,20) 2.3 Hz), 6.24 (1H, d, H-10,

J _10,11) 15.6 Hz), 5.84 (1H, d, H-20′, J _20,20′) 15.6 Hz), 5.78

(1H, d, H-13, J _13,14) 10.1 Hz), 4.91 (1H, dt, H-15, J _14,15) 9.9

Hz, J _15,16b) 2.5 Hz), 4.73 (1H, s, H-2 enol), 4.64 (1H, d, H-1′′,

J _{1′′,2′′}) 7.7 Hz), 4.44 (1H, dd, H-4′′, J _{3′′,4′′}) 3.0 Hz, J _{4′′,5′′}) 9.1

Hz), 4.33 (1H, d, H-1′, J _1′,2′) 7.5 Hz), 4.18 (2H, q, COOCH₂-

CH₃, J _CH2,CH3) 7.1 Hz), 4.01 (1H, dd, H-23b, J _23a,23b) 9.5 Hz,

J _14,23b) 4.1 Hz), 3.95-3.92 (1H, m, H-5′′), 3.90 (1H, t, H-3′′,

J _{2′′,3′′}) J _{3′′,4′′}) 3.0 Hz), 3.86 (1H, d, H-5, J _4,5) 10.0 Hz), 3.58

(1H, dd, H-23a, J _23a,23b) 9.5 Hz, J _14,23a) 4.0 Hz), 3.55-3.50

(1H, m, H-2′), 3.53 (3H, s, 3′′-OMe), 3.50 (3H, s, 2′′-OMe), 3.37-

3.30 (1H, m, H-5′), 3.15 (1H, t, H-4′, J _3′,4′ax) J _4′,5′) 9.5 Hz),

3.06 (1H, dd, H-2′′, J _{1′′,2′′}) 7.7 Hz, J _{2′′,3′′}) 3.0 Hz), 3.01-2.92

1.55-1.47 (1H, m, H-7a), 1.33 (3H, d, H-6′ (Me-C-5′), J _5′,6′

)

6.3 Hz), 1.27 (3H, d, Me-18, J _4,18) 6.3 Hz), 1.26 (3H, d, H-6′′

(Me-C-5′′), J _{5′′,6′′}) 6.1 Hz), 1.21 (3H, d, Me-21, J _8,21) 6.7 Hz),

0.96 (3H, t, Me-17, J _16a,17) J _16b,17) 7.3 Hz); ¹³C NMR (CDCl₃)

δ 203.3 (s, C-9), 179.8 (s, C-3 enol), 172.2 (s, C-1), 167.1 (s,

COOCH₃), 149.0 (d, C-20), 147.5 (d, C-11), 139.9 (d, C-13),

136.7 (s, C-12), 122.1 (d, C-20′), 118.6 (d, C-10), 104.2 (d, C-1′),

101.1 (d, C-1′′), 89.2 (d, C-2 enol), 81.9 (d, C-2′′), 79.8 (d, C-3′′),

79.3 (d, C-5), 74.8 (d, C-15), 73.5 (d, C-5′), 72.6 (d, C-4′′), 71.0

(d, C-2′), 70.6 (d, C-2′′), 70.3 (d, C-4′), 70.1 (d, C-3′), 70.0 (d,

C-5′′), 69.4 (t, C-23), 61.7 (q, 3′′-OMe), 59.8 (q, 2′′-OMe), 51.3

(q, COOCH₃), 44.9 (d, C-14), 44.5 (d, C-8), 43.5 (d, C-4), 41.7

(q, NMe₂), 38.3 (d, C-6), 32.5 (t, C-7), 30.7 (t, C-19), 25.9 (t,

C-16), 18.1 (q, Me-18), 17.9 (q, Me-C-5′), 17.8 (q, Me-21), 17.6

(1H, m, H-14), 2.65 (1H, dd, H-19b, J _19a,19b) 16.2 Hz, J _19b,20

)

2.3 Hz), 2.60 (1H, br, H-8), 2.55 (6H, s, NMe₂), 2.48-2.37 (3H,

m, H-19a, H-4, H-3′), 2.12 (3H, s, 4′′-OCOCH₃), 1.99 (1H, br,

H-6), 1.90 (1H, ddq, H-16b, J _15,16b) 2.5 Hz, J _16a,16b) 14.0 Hz,

J _16b,17) 7.1 Hz), 1.80 (3H, s, Me-22), 1.72-1.56 (2H, m, H-16a,

H-7b), 1.57-1.49 (1H, m, H-7a), 1.36 (3H, d, H-6′ (Me-C-5′),

J _5′,6′) 6.3 Hz), 1.34 (3H, d, Me-18, J _4,18) 6.3 Hz), 1.29 (3H, t,

(q, Me-C-5′′), 13.7 (q, Me-22), 9.9 (q, Me-17). Anal. (C₄₂H₆₇

-

NO₁₅) C, H, N.

COOCH₂CH₃, J _CH2,CH3) 7.1 Hz), 1.21 (3H, d, Me-21, J _8,21

)

31b (89%): FAB-MS m/z 840 (MH⁺, 57%); UV λ_maxnm (ꢀ)

6.7 Hz), 1.18 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.1 Hz), 0.95 (3H,

t, Me-17, J _16a,17) J _16b,17) 7.1 Hz); ¹³C NMR (CDCl₃) δ 203.3

(s, C-9), 179.8 (s, C-3 enol), 172.3 (s, C-1), 170.2 (s, 4′′-

OCOCH₃), 166.4 (s, COOCH₂CH₃), 148.6 (d, C-20), 147.5 (d,

C-11), 139.8 (d, C-13), 136.8 (s, C-12), 123.7 (d, C-20′), 118.6

(d, C-10), 104.1 (d, C-1′), 101.1 (d, C-1′′), 89.2 (d, C-2 enol),

80.6 (d, C-2′′), 79.4 (d, C-5), 77.7 (d, C-2′), 70.7 (d, C-4′), 70.4

(d,C-3′), 69.5 (t, C-23), 67.4 (d, C-5′′), 61.6 (q, 3′′-OMe), 60.0

(t, COOCH₂CH₃), 59.6 (q, 2′′-OMe), 44.9 (d, C-14), 44.6 (d, C-8),

43.5 (d, C-4), 41.8 (q, NMe₂), 38.2 (d, C-6), 32.3 (t, C-7), 30.8

(t, C-19), 26.0 (t, C-16), 21.0 (q, 4′′-OCOCH₃), 18.1 (q, Me-18),

17.9 (q, Me-C-5′), 17.8 (q, Me-21), 17.4 (q, Me-C-5′′), 14.3 (q,

1

289 (28 696), 256 (17 864); H NMR (CDCl₃) δ 11.97 (1H, br,

H-3 enol), 7.25 (1H, d, H-11, J _10,11) 15.5 Hz), 6.93 (1H, dt,

H-20, J _20,20′) 15.6 Hz, J _19b,20) 2.3 Hz), 6.25 (1H, d, H-10,

J _10,11) 15.5 Hz), 5.87 (1H, d, H-20′, J _20,20′) 15.6 Hz), 5.81

(1H, d, H-13, J _13,14) 10.1 Hz), 4.94 (1H, dt, H-15, J _14,15) 9.8

Hz, J _15,16b) 2.5 Hz), 4.76 (1H, s, H-2 enol), 4.61 (1H, d, H-1′′,

J _{1′′,2′′}) 7.7 Hz), 4.34 (1H, d, H-1′, J _1′,2′) 7.5 Hz), 4.20 (2H, q,

COOCH₂CH₃, J _CH2,CH3) 7.1 Hz), 4.02 (1H, dd, H-23b, J _23a,23b

) 9.6 Hz, J _14,23b) 4.0 Hz), 3.88 (1H, d, H-5, J _4,5) 10.1 Hz),

3.77 (1H, t, H-3′′, J _{2′′,3′′}) J _{3′′,4′′}) 2.9 Hz), 3.64 (3H, s, 3′′-OMe),

3.61-3.54 (3H, m, H-23a, H-5′′, H-2′), 3.52 (3H, s, 2′′-OMe),

3.40-3.33 (1H, m, H-5′), 3.20 (1H, br, H-4′′), 3.15 (1H, t, H-4′,

J _3′,4′ax) J _4′,5′) 9.5 Hz), 3.05 (1H, dd, H-2′′, J _{1′′,2′′}) 7.7 Hz,

J _{2′′,3′′}) 2.8 Hz), 3.03-2.91 (1H, m, H-14), 2.84 (1H, br, H-8),

2.73-2.59 (1H, m, H-19b), 2.57 (6H, s, NMe₂), 2.50-2.38 (3H,

m, H-19a, H-4, H-3′), 2.00 (1H, br, H-6), 1.88 (1H, ddq, H-16b,

J _15,16b) 2.5 Hz, J _16a,16b) 14.5 Hz, J _16b,17) 7.2 Hz), 1.82 (3H,

s, Me-22), 1.72-1.60 (2H, m, H-16a, H-7b), 1.58-1.48 (1H, m,

H-7a), 1.37 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 6.3 Hz), 1.35 (3H, d,

COOCH₂CH₃), 13.7 (q, Me-22), 9.9 (q, Me-17). Anal. (C₄₅H₇₁

-

NO₁₆) C, H, N.

30c (88%): FAB-MS m/z 852 (MH⁺, 79%); UV λ_maxnm (ꢀ)

1

288 (32 135), 255 (17 684); H NMR (CDCl₃) δ 11.65 (1H, br,

H-3 enol), 7.20 (1H, d, H-11), 6.94 (1H, dt, H-20), 6.24 (1H, d,

H-10), 5.83 (1H, d, H-20′), 5.78 (1H, d, H-13), 4.76 (1H, s, H-2

enol), 3.51 (3H, s, 3′′-OMe), 3.48 (3H, s, 2′′-OMe), 2.50 (6H, s,

NMe₂), 2.25 (3H, s, COCH₃), 2.10 (3H, s, 4′′-OCOCH₃), 1.81

(3H, s, Me-22); ¹³C NMR (CDCl₃) δ 203.1 (s, C-9), 199.1 (s,

COCH₃), 180.5 (s, C-3 enol), 171.3 (s, C-1), 170.0 (s, 4′′-

OCOCH₃), 149.2 (d, C-20), 147.1 (d, C-11), 139.4 (d, C-13),

136.7 (s, C-12), 122.0 (d, C-20′), 118.1 (d, C-10), 89.4 (d, C-2

enol), 59.8 (q, 3′′-OMe), 58.8 (q, 2′′-OMe), 41.3 (q, NMe₂), 26.2

(q, COCH₃), 20.9 (q, 4′′-OCOCH₃), 13.7 (q, Me-22). Anal.

(C₄₄H₆₉NO₁₅) C, H, N.

Me-18, J _4,18) 6.3 Hz), 1.32 (3H, t, COOCH₂CH₃, J _CH2CH3

7.1 Hz), 1.29 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.1 Hz), 1.23 (3H,

d, Me-21, J _8,21) 6.7 Hz), 0.97 (3H, t, Me-17, J _16a,17) J _16b,17

)

7.2 Hz); ¹³C NMR (CDCl₃) δ 203.3 (s, C-9), 179.8 (s, C-3 enol),

172.3 (s, C-1), 166.7 (s, COOCH₂CH₃), 149.3 (d, C-20), 147.5

(d, C-11), 140.0 (d, C-13), 136.8 (s, C-12), 122.6 (d, C-20′), 118.6

(d, C-10), 104.0 (d, C-1′), 101.1 (d, C-1′′), 89.2 (d, C-2 enol),

81.9 (d, C-2′′), 79.9 (d, C-3′′), 79.4 (d, C-5), 74.8 (d, C-15), 73.5

(d, C-5′), 72.7 (d, C-4′′), 70.9 (d, C-2′), 70.7 (d, C-2′′), 70.6

(d, C-4′), 70.3 (d, C-3′), 70.1 (d, C-5′′), 69.4 (t, C-23), 61.8

(q, 3′′-OMe), 60.0 (t, COOCH₂CH₃), 59.8 (q, 2′′-OMe), 44.9

(d, C-14), 44.6 (d, C-8), 43.6 (d, C-4), 41.8 (q, NMe₂), 38.2

(d, C-6), 32.9 (t, C-7), 30.8 (t, C-19), 26.0 (t, C-16), 18.7

(q, Me-18), 18.1 (q, Me-C-5′), 17.9 (q, Me-21), 17.8 (q, Me-C-

5′′), 14.3 (q, COOCH₂CH₃), 13.7 (q, Me-22), 9.9 (q, Me-17). Anal.

(C₄₃H₆₉NO₁₅) C, H, N.

30d (94%): FAB-MS m/z 838 (MH⁺, 84%); UV λ_maxnm (ꢀ)

286 (29 754), 256 (17 274); ¹H NMR (CDCl₃) δ11.80 (1H, s, H-3

enol), 9.74 (1H, d, CHO), 7.23 (1H, d, H-11), 6.63 (1H, dt, H-20),

6.25 (1H, d, H-10), 5.91 (1H, dd, H-20′), 5.80 (1H, d, H-13),

4.81 (1H, s, H-2 enol), 3.50 (3H, s, 3′′-OMe), 3.45 (3H, s, 2′′-

OMe), 2.11 (3H, s, 4′′-OCOCH₃), 1.78 (3H, s, Me-22); ¹³C NMR

(CDCl₃) δ 203.0 (s, C-9), 193.2 (d, CHO), 180.3 (s, C-3 enol),

173.2 (s, C-1), 170.4 (s, 4′′-OCOCH₃), 149.2 (d, C-20), 146.1 (d,

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 427

31c (89%): FAB-MS m/z 810 (MH⁺, 84%); UV λ_maxnm (ꢀ)

289 (29 476), 256 (17 453); ¹H NMR (CDCl₃) δ 11.98 (1H, s,

H-3 enol), 7.23 (1H, d, H-11), 6.93 (1H, dt, H-20), 6.24 (1H, d,

H-10), 5.83 (1H, d, H-20′), 5.75 (1H, d, H-13), 4.78 (1H, s, H-2

enol), 3.68 (3H, s, 3′′-OMe), 3.50 (3H, s, 2′′-OMe), 2.51 (6H, s,

NMe₂), 2.24 (3H, s, COCH₃), 1.81 (3H, s, Me-22); ¹³C NMR

(CDCl₃) δ 203.1 (s, C-9), 199.0 (s, COCH₃), 179.6 (s, C-3 enol),

172.1 (s, C-1), 149.1 (d, C-20), 147.8 (d, C-11), 140.5 (d, C-13),

136.9 (s, C-12), 122.0 (d, C-20′), 118.1 (d, C-10), 89.0 (d, C-2

enol), 61.8 (q, 3′′-OMe), 59.7 (q, 2′′-OMe), 41.5 (q, NMe₂), 26.1

(q, COCH₃), 13.6 (q, Me-22). Anal. (C₄₂H₆₇NO₁₄) C, H, N.

31d (96%): FAB-MS m/z 796 (MH⁺, 100%); UV λ_maxnm (ꢀ)

286 (29 864), 256 (17 356); ¹H NMR (CDCl₃) δ 11.78 (1H, s,

H-3 enol), 9.77 (1H, d, CHO), 7.21 (1H, d, H-11), 6.61 (1H, dt,

H-20), 6.30 (1H, d, H-10), 5.92 (1H, dd, H-20′), 5.79 (1H, d,

H-13), 4.84 (1H, s, H-2 enol), 3.52 (3H, s, 3′′-OMe), 3.46 (3H,

s, 2′′-OMe), 1.79 (3H, s, Me-22); ¹³C NMR (CDCl₃) δ 203.2 (s,

C-9), 192.0 (d, CHO), 180.1 (s, C-3 enol), 173.1 (s, C-1), 149.7

(d, C-20), 146.5 (d, C-11), 140.8 (d, C-13), 135.1 (s, C-12), 121.3

(d, C-20′), 118.7 (d, C-10), 89.1 (d, C-2 enol), 59.9 (q, 3′′-OMe),

Hz, J _16a,17) 7.3 Hz), 1.45 (1H, br, H-7b), 1.28 (3H, t,

COOCH₂CH₃, J _CH3,CH2) 7.1 Hz), 1.23 (3H, s, OCOCH₃), 1.19

(3H, d, Me-21, J _8,21) 6.7 Hz), 1.18 (3H, d, H-6′ (Me-C-5′), J _5′,6′

)

6.0 Hz), 1.17 (3H, d, H-6′′(Me-C-5′′), J _{5′′,6′′}) 6.3 Hz), 1.08-

1.01 (1H, m, H-7a), 0.93-0.87 (3H, t, Me-17, J _16a,17) J _16b,17

)

C

7.3 Hz; 1H, m, H-3a′′), 0.85 (3H, d, Me-18, J _4,18) 6.9 Hz); ¹³

NMR (CDCl₃) δ 203.3 (s, C-9), 183.4 (s, OCOCH₃), 170.2 (s,

OCOCH₃, 2C), 169.9 (s, C-1), 166.8 (s, COOCH₂CH₃), 166.4

(s, OCOCH₂C₆H₄NO₂), 147.9 (d, C-20), 147.7 (d, C-11), 147.1

(s, Ar-D), 142.0 (s, Ar-A), 141.9 (d, C-13), 135.0 (s, C-12), 130.7

(d, Ar-B, 2C), 123.0 (d, C-20′), 103.5 (d, C-1′), 101.0 (d, C-1′′),

80.6 (d, C-2′′), 79.6 (d, C-5), 77.7 (d, C-3′′), 75.6 (d, C-3), 75.3

(d, C-15), 74.7 (d, C-4′′), 71.8 (d, C-3′), 71.8 (d, C-3′), 71.2 (d,

C-4′), 71.0 (d, C-2′), 69.6 (t, C-23), 67.4 (d, C-5′′), 67.1 (d, C-5′),

61. 6 (q, 3′′-OMe), 60.1 (t, COOCH₂CH₃), 59.4 (q, 2′′-OMe), 44.6

(d, C-14, C-8, 2C), 41.2 (q, NMe₂), 40.9 (t, C-3′′; d, C-4; 2C),

37.7 (t, C-2), 36.9 (d, C-6), 33.3 (t, C-7), 31.5 (t, C-19), 27.1 (q,

OCOCH₃), 21.0 (q, OCOCH₃), 17.4 (q, Me-C-5′, Me-C-5′′, 2C),

17.2 (q, Me-21), 14.3 (q, COOCH₂CH₃), 13.2 (q, Me-22), 10.0

(q, Me-18), 9.5 (q, Me-17, J _16a,17) J _16b,17) 7.3 Hz). Anal.

(C₅₇H₈₂N₂O₂₁) C, H, N.

59.3 (q, 2′′-OMe), 41.0 (q, NMe₂), 12.7 (q, Me-22). Anal. (C₄₁H₆₅

-

33b (85%): FAB-MS m/z 1143 (MH⁺, 51%); ¹H NMR (CDCl₃)

δ 8.19 (2H, d, Ar-C), 7.91 (1H, d, H-3′′), 7.59 (2H, d, Ar-B),

7.30 (1H, d, H-11), 6.90 (1H, dt, H-20), 6.25 (1H, d, H-2′′), 6.22

(1H, d, H-10), 5.89 (1H, d, H-13), 5.81 (1H, d, H-20′), 4.21 (2H,

q, COOCH₂CH₃), 3.50 (3H, s, 3′′-OMe), 3.40 (3H, s, 2′′-OMe),

2.15 (3H, s, OCOCH₃), 2.10 (6H, s, OCOCH₃), 1.27 (3H, t,

COOCH₂CH₃); ¹³C NMR (CDCl₃) δ 202.5 (s, C-9), 182.4 (s,

C-1′′), 173.0 (s, C-1), 171.2 (s, OCOCH3), 169.5 (s, OCOCH3),

169.1 (s, OCOCH3), 165.8 (s, COOCH₂CH₃), 148.3 (d, C-20),

146.8 (d, C-11), 144.7 (d, C-3′′), 144.6 (s, Ar-D), 142.1 (s, Ar-

A), 141.3 (d, C-13), 134.3 (s, C-12), 127.5 (d, Ar-B, 2C), 121.5

(d, C-20′), 121.4 (d, Ar-C, 2C), 117.9 (d, C-10), 116.5 (d, C-2′′),

75.3 (d, C-3), 61.2 (q, 3′′-OMe), 59.4 (t, COOCH₂CH₃), 59.2 (q,

2′′-OMe), 41.0 (q, NMe₂), 21.1 (q, OCOCH₃), 21.0 (q, OCOCH₃),

NO₁₄) C, H, N.

Syn th esis of Mixed An h yd r id es of th e Ca r boxylic

Acid s. To a solution of acids a 1-a 4 (4.16 mmol, 1.0 equiv) in

THF (40 mL) at room temperature (25 °C) was added pivaloyl

chloride (0.54 mL, 4.58 mmol, 1.1 equiv), and the reaction

mixture was stirred at the same temperature for 12 h. Once

complete by TLC, the reaction mixture was filtered, and the

filtrate was concentrated under reduced pressure and dried

under high vacuum to give the corresponding anhydrides. The

anhydrides were stored as a 0.2 M solution in CH₂Cl₂and used

in this form for the esterification.

Syn th esis of a Desm ycosin Libr a r y (32-39a -d ) in

Solu tion P h a se. A mixture of the corresponding alcohol

26a -d (0.120 mmol, 1.0 equiv), DMAP (14.7 mg, 0.120 mmol,

1.0 equiv), triethylamine (0.3 mL, 2.15 mmol, 17.9 equiv), and

the mixed anhydride of the corresponding acid (6.0 mL of 0.2

M solution in methylene chloride, 1.22 mmol, 10.0 equiv) was

stirred at room temperature for 22 h. The reaction mixture

was then concentrated and purified by flash chromatography

(silica gel, 10% acetone in methylene chloride followed by 30%

acetone in methylene chloride) to yield esters 32-39a -d . By

using this procedure, the following compounds were prepared

as discrete compounds.

20.6 (q, OCOCH₃), 14.0 (q, COOCH₂CH₃). Anal. (C₅₈H₈₂N₂O₂₁

)

C, H, N.

33c (92%): FAB-MS m/z 1098 (MH⁺, 74%); ¹H NMR (CDCl₃)

δ 7.91 (1H, d, H-3′′), 7.33 (2H, d, Ar-B), 7.32 (1H, d, H-11),

7.24 (2H, d, Ar-C), 7.17 (1H, dd, Ar-D), 6.94 (1H, dt, H-20),

6.25 (1H, d, H-2′′), 6.20 (1H, d, H-10), 5.83 (1H, d, H-13), 5.79

(1H, d, H-20′), 4.18 (2H, q, COOCH₂CH₃), 3.46 (3H, s, 3′′-OMe),

3.27 (3H, s, 2′′-OMe), 2.12 (3H, s, OCOCH₃), 2.06 (6H, s,

OCOCH₃), 1.22 (3H, t, COOCH₂CH₃); ¹³C NMR (CDCl₃) δ 201.8

(s, C-9), 181.8 (s, C-1′′), 173.6 (s, C-1), 171.9 (s, OCOCH3),

168.7 (s, OCOCH3), 168.9 (s, OCOCH3), 164.3 (s, COOCH₂-

CH₃), 147.6 (d, C-20), 145.3 (d, C-11), 144.0 (d, C-3′′), 141.1

(d, C-13) 136.0 (s, Ar-A), 134.8 (s, C-12), 126.5 (d, Ar-B, Ar-

C, 4C), 125.5 (d, Ar-D), 121.2 (d, C-20′), 116.8 (d, C-10), 116.2

(d, C-2′′), 75.0 (d, C-3), 61.0 (q, 3′′-OMe), 59.2 (t, COOCH₂-

CH₃), 59.1 (q, 2′′-OMe), 39.8 (q, NMe₂), 21.4 (q, OCOCH₃), 21.3

(q, OCOCH₃), 20.2 (q, OCOCH₃), 14.1 (q, COOCH₂CH₃). Anal.

(C₅₈H₈₃NO₁₉) C, H, N.

32a (81%): FAB-MS m/z1117 (MH⁺,63%).Anal.(C₅₆H₈₀N₂O₂₁)

C, H, N.

32b (77%): FAB-MS m/z1129 (MH⁺,74%).Anal.(C₅₇H₈₀N₂O₂₁)

C, H, N.

32c (59%): FAB-MS m/z 1084 (MH⁺, 86%). Anal. (C₅₇H₈₁

-

NO₁₉) C, H, N.

32d (90%): FAB-MS m/z1059 (MH⁺,43%).Anal.(C₅₄H₇₈N₂O₁₉)

C, H, N.

33a (78%): FAB-MS m/z 1131 (MH⁺, 58%); UV λ_maxnm (ꢀ)

276 (31 894), 250 (13 300); ¹H NMR (CDCl₃) δ 8.17 (2H, d, Ar-

C, J _B,C) 8.7 Hz), 7.54 (2H, d, Ar-B, J _B,C) 8.7 Hz), 7.35 (1H,

d, H-11, J _10,11) 15.5 Hz), 6.84 (1H, dt, H-20, J _20,20′) 15.8 Hz,

J _19,20) 7.8 Hz), 6.26 (1H, d, H-10, J _10,11) 15.5 Hz), 5.85 (1H,

d, H-13, J _13,14) 10.3 Hz), 5.83 (1H, d, H-20′, J _20,20′) 15.8 Hz),

5.12 (1H, br, H-2′), 5.05 (1H, d, H-3, J _2b,3) 9.8 Hz), 4.92 (1H,

br, H-4′), 4.78 (1H, dt, H-15, J _14,15) 10.0 Hz, J _15,16b) 3.9 Hz),

33d (90%): FAB-MS m/z 1073 (MH⁺, 91%); UV λ_maxnm (ꢀ)

275 (32 985), 250 (12 985); ¹H NMR (CDCl₃) δ 8.76 (2H, s, Ar-

C), 7.81 (2H, s, Ar-B), 7.45 (1H, d, H-11, J _10,11) 15.5 Hz),

6.85 (1H, dt, H-20, J _20,20′) 15.8 Hz, J _19,20) 7.8 Hz), 6.31 (1H,

d, H-10, J _10,11) 15.5 Hz), 5.90 (1H, d, H-13, J _13,14) 10.4 Hz),

5.75 (1H, d, H-20′, J _20,20′) 15.8 Hz), 5.33 (1H, d, H-3, J _2b,3

9.3 Hz), 4.92 (1H, br, H-2′), 4.81 (1H, dt, H-15, J _14,15) 10.0

Hz, J _15,16b) 3.8 Hz; 1H, br, H-4′), 4.59 (1H, d, H-1′′, J _{1′′,2′′}

)

4.60 (1H, d, H-1′′, J _{1′′,2′′}) 8.0 Hz), 4.43 (1H, dd, H-4′′, J _{3′′,4′′}

)

8.0 Hz), 4.42 (1H, dd, H-4′′, J _{3′′,4′′}) 2.5 Hz, J _{4′′,5′′}) 9.9 Hz),

4.34 (1H, br, H-1′), 4.08-3.97 (2H, m, COOCH₂CH₃), 3.94 (1H,

dd, H-23b, J _23a,23b) 9.5 Hz, J _14,23b) 4.3 Hz), 3.92-3.86 (3H,

m, H-5′′, H-5, H-3′′), 3.51 (3H, s, 3′′-OMe), 3.41 (3H, s, 2′′-OMe),

3.37 (1H, dd, H-2′′, J _{1′′,2′′}) 8.0 Hz, J _{2′′,3′′}) 2.8 Hz), 2.97-2.93

(1H, m, H-14), 2.76 (1H, dd, H-2b, J _2a,2b) 16.1 Hz, J _2b,3) 9.3

Hz), 2.70 (5H, br, H-8, H-3′, NMea), 2.37 (4H, br, H-19b,

NMeb), 2.11 (6H, s, OCOCH₃), 2.05-1.98 (1H, m, H-2a), 1.87-

1.83 (2H, m, H-16b, H-4), 1.82 (3H, s, Me-22), 1.77-1.65 (1H,

2.5 Hz, J _{4′′,5′′}) 9.9 Hz), 4.21-4.09 (3H, m, COOCH₂CH₃, H-1′),

3.96 (1H, dd, H-23b, J _23a,23b) 9.5 Hz, J _14,23b) 4.4 Hz), 3.94-

3.87 (2H, m, H-5′′, H-3′′), 3.77-3.66 (2H, m, H-5, H-3b′′), 3.52

(3H, s, 3′′-OMe), 3.51-3.47 (1H, m, H-23a), 3.43 (3H, s, 2′′-

OMe), 3.28-3.20 (1H, m, H-5′), 3.13 (1H, br, H-6), 3.02 (1H,

dd, H-2′′, J _{1′′,2′′}) 8.0 Hz, J _{2′′,3′′}) 2.8 Hz), 2.96 (1H, ddt, H-14,

J _14,15) 10.0 Hz, J _14,23a) 6.5 Hz, J _14,23b) 4.1 Hz), 2.93-2.89

(1H, m, H-3′), 2.70-2.61 (4H, m, H-8, NMea), 2.57 (1H, dd,

H-2b, J _2a,2b) 16.2 Hz, J _2b,3) 9.8 Hz), 2.35 (4H, br, H-19b,

NMeb), 2.12 (6H, s, OCOCH₃), 1.93 (1H, d, H-2a, J _2a,2b) 16.2

Hz), 1.86 (1H, ddq, H-16b, J _15,16a) 10.5 Hz, J _16a,16b) 14.4 Hz,

J _16a,17) 7.3 Hz), 1.78 (3H, s, Me-22), 1.74-1.65 (2H, m, H-19a,

H-4), 1.59 (1H, ddq, H-16a, J _15,16a) 10.5 Hz, J _16a,16b) 14.4

m, H-19a), 1.60 (1H, ddq, H-16a, J _15,16a) 10.5 Hz, J _16,16b

)

14.4 Hz, J _16a,17) 7.3 Hz), 1.51 (3H, br, OCOCH₃), 1.29 (3H, d,

Me-21, J _8,21) 6.7 Hz), 1.28-1.21 (3H, t, COOCH₂CH₃, J _CH3,CH2

) 7.1 Hz; 1H, m, H-7b), 1.16 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}

)

428 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

6.2 Hz), 1.10-1.03 (6H, m, Me-18, Me-C-5′), 0.96-0.91 (1H,

m, H-7a), 0.88 (3H, t, Me-17, J _16a,17) J _16b,17) 7.2 Hz); ¹³C

NMR (CDCl₃) δ 203.3 (s, C-9), 170.2 (s, OCOCH₃, 3C), 169.9

(s, C-1), 166.4 (s, OCOPy), 166.3 (s, COOCH₂CH₃), 150.5 (d,

Ar-C, 2C), 147.9 (d, C-20), 147.6 (d, C-11), 141.4 (d, C-13),

137.3 (s, Ar-A), 134.8 (s, C-12), 123.1 (d, C-20′, Ar-B, 3C),

123.0 (d, C-10), 103.5 (d, C-1′), 101.0 (d, C-1′′), 80.5 (d, C-2′′),

79.4 (d, C-5), 77.6 (d, C-3′′), 75.6 (d, C-3), 75.4 (d, C-15), 74.7

(d, C-4′′), 71.7 (d, C-3′), 71.2 (d, C-4′), 71.0 (d, C-2′), 69.5 (t,

C-23), 67.3 (d, C-5′′), 67.0 (d, C-5′), 61.6 (q, 3′′-OMe), 59.9 (t,

COOCH₂CH₃), 59.4 (q, 2′′-OMe), 44.7 (d, C-14, C-8, 2C), 41.2

(q, NMe₂; d, C-4), 37.6 (t, C-2), 35.9 (d, C-6), 31.6 (t, C-19, C-7,

2C), 25.6 (t, C-16), 22.0 (q, OCOCH₃), 21.6 (q, OCOCH₃), 21.4

(q, OCOCH₃), 17.4 (q, Me-C-5′, Me-C-5′′, 2C), 17.1 (q, Me-21),

14.3 (q, COOCH₂CH₃), 13.1 (q, Me-22), 10.1 (q, Me-18), 9.5 (q,

Me-17). Anal. (C₅₅H₈₀N₂O₁₉) C, H, N.

(q, 2′′-OMe), 44.4 (d, C-14, C-8, 2C), 41.7 (q, NMe₂), 40.6 (t,

C-3′′; d, C-4; 2C), 37.6 (t, C-2), 37.0 (d, C-6), 33.3 (t, C-7), 31.8

(t, C-19), 25.6 (t, C-16), 17.6 (q, Me-C-5′, Me-C-5′′, 2C), 17.3

(q, Me-21), 14.2 (q, COOCH₂CH₃), 12.9 (q, Me-22), 10.2 (q, Me-

18), 9.4 (q, Me-17). Anal. (C₅₁H₇₆N₂O₁₈) C, H, N.

37b (79%): FAB-MS m/z 1017 (MH⁺, 79%); ¹H NMR (CDCl₃)

δ 8.14 (2H, d, Ar-C), 7.87 (1H, d, H-3′′), 7.47 (2H, d, Ar-B),

7.25 (1H, d, H-11), 6.73 (1H, dt, H-20), 6.21 (1H, d, H-2′′), 6.18

(1H, d, H-10), 5.80 (1H, d, H-13), 5.75 (1H, d, H-20′), 4.20 (2H,

q, COOCH₂CH₃), 3.48 (3H, s, 3′′-OMe), 3.30 (3H, s, 2′′-OMe),

1.22 (3H, t, COOCH₂CH₃); ¹³C NMR (CDCl₃) δ 202.2 (s, C-9),

181.8 (s, C-1′′), 173.5 (s, C-1), 165.9 (s, COOCH₂CH₃), 148.8

(d, C-20), 147.2 (d, C-11), 144.3 (d, C-3′′), 144.0 (s, Ar-D), 141.8

(s, Ar-A), 141.1 (d, C-13), 133.8 (s, C-12), 127.9 (d, Ar-B, 2C),

121.2 (d, C-20′), 120.8 (d, Ar-C, 2C), 117.3 (d, C-10), 116.2 (d,

C-2′′), 75.2 (d, C-3), 61.1 (q, 3′′-OMe), 59.6 (t, COOCH₂CH₃),

59.4 (q, 2′′-OMe), 41.1 (q, NMe₂), 14.0 (q, COOCH₂CH₃). Anal.

(C₅₂H₇₆N₂O₁₈) C, H, N.

37c (81%): FAB-MS m/z 972 (MH⁺, 64%); ¹H NMR (CDCl₃)

δ 7.87 (1H, d, H-3′′), 7.30 (2H, d, Ar-B), 7.24 (1H, d, H-11),

7.20 (2H, d, Ar-C), 7.11 (1H, dd, Ar-D), 6.91 (1H, dt, H-20),

6.15 (1H, d, H-2′′), 6.10 (1H, d, H-10), 5.81 (1H, d, H-13), 5.71

(1H, d, H-20′), 4.15 (2H, q, COOCH₂CH₃), 3.43 (3H, s, 3′′-OMe),

3.24 (3H, s, 2′′-OMe), 1.21 (3H, t, COOCH₂CH₃); ¹³C NMR

(CDCl₃) δ 202.5 (s, C-9), 182.1 (s, C-1′′), 173.8 (s, C-1), 164.9

(s, COOCH₂CH₃), 147.4 (d, C-20), 145.0 (d, C-11), 144.6 (d,

C-3′′), 141.4 (d, C-13) 136.8 (s, Ar-A), 135.4 (s, C-12), 126.9 (d,

Ar-B, Ar-C, 4C), 125.3 (d, Ar-D), 121.5 (d, C-20′), 117.6 (d,

C-10), 116.6 (d, C-2′′), 75.5 (d, C-3), 61.4 (q, 3′′-OMe), 59.8 (t,

COOCH₂CH₃), 59.6 (q, 2′′-OMe), 40.1 (q, NMe₂), 14.3 (q,

COOCH₂CH₃). Anal. (C₅₂H₇₇NO₁₆) C, H, N.

37d (71%): FAB-MS m/z 947 (MH⁺, 48%); ¹H NMR (CDCl₃)

δ 8.69 (2H, s, Ar-C), 7.72 (2H, s, Ar-B), 7.42 (1H, d, H-11),

6.89 (1H, dt, H-20), 6.38 (1H, d, H-10), 5.95 (1H, d, H-13), 5.70

(1H, d, H-20′), 5.31 (1H, d, H-3), 4.87 (1H, br, H-2′), 4.76 (1H,

dt, H-15; 1H, br, H-4′), 4.63 (1H, d, H-1′′), 4.45 (1H, dd, H-4′′),

4.39 (1H, br, H-1′), 4.03-3.95 (2H, m, COOCH₂CH₃), 3.90 (1H,

dd, H-23b), 3.88-3.81 (3H, m, H-5′′, H-5, H-3′′), 3.50 (3H, s,

3′′-OMe), 3.44 (3H, s, 2′′-OMe), 3.33 (1H, dd, H-2′′), 2.96-2.90

(1H, m, H-14), 2.71 (1H, dd, H-2b), 2.67 (5H, br, H-8, H-3′,

NMea), 2.30 (4H, br, H-19b, NMeb), 2.05-1.92 (1H, m, H-2a),

1.85-1.81 (2H, m, H-16b, H-4), 1.78 (3H, s, Me-22), 1.75-1.62

(1H, m, H-19a), 1.60 (1H, ddq, H-16a), 1.27 (3H, d, Me-21),

1.25-1.19 (3H, t, COOCH₂CH₃, 1H, m, H-7b), 1.14 (3H, d, H-6′′

(Me-C-5′′)), 1.11-1.01 (6H, m, Me-18, Me-C-5′), 0.96-0.90 (1H,

m, H-7a), 0.85 (3H, t, Me-17); ¹³C NMR (CDCl₃) δ 202.8 (s,

C-9), 169.7 (s, C-1), 166.2 (s, OCOPy), 166.0 (s, COOCH₂CH₃),

150.1 (d, Ar-C, 2C), 147.4 (d, C-20), 147.2 (d, C-11), 141.8 (d,

C-13), 137.6 (s, Ar-A), 134.1 (s, C-12), 123.0 (d, C-20′, Ar-B,

3C), 122.7 (d, C-10), 103.9 (d, C-1′), 101.2 (d, C-1′′), 80.4 (d,

C-2′′), 79.8 (d, C-5), 77.4 (d, C-3′′), 75.5 (d, C-3), 75.1 (d, C-15),

74.4 (d, C-4′′), 71.9 (d, C-3′), 71.4 (d, C-4′), 71.1 (d, C-2′), 69.4

(t, C-23), 67.2 (d, C-5′′), 67.5 (d, C-5′), 61.2 (q, 3′′-OMe), 59.7

(t, COOCH₂CH₃), 59.2 (q, 2′′-OMe), 44.5 (d, C-14, C-8, 2C), 41.7

(q, NMe₂; d, C-4), 37.8 (t, C-2), 35.5 (d, C-6), 31.8 (t, C-19, C-7,

2C), 25.0 (t, C-16), 17.2 (q, Me-C-5′, Me-C-5′′, 2C), 17.0 (q, Me-

21), 14.2 (q, COOCH₂CH₃), 12.8 (q, Me-22), 10.4 (q, Me-18),

9.2 (q, Me-17). Anal. (C₅₅H₈₀N₂O₁₉) C, H, N. Anal. (C₄₉H₇₄N₂O₁₆)

C, H, N.

34a (65%): FAB-MS m/z1101 (MH⁺,64%).Anal.(C₅₆H₈₀N₂O₂₀)

C, H, N.

34b (75%): FAB-MS m/z1113 (MH⁺,58%).Anal.(C₅₇H₈₀N₂O₂₀)

C, H, N.

34c (84%): FAB-MS m/z 1068 (MH⁺, 92%). Anal. (C₅₇H₈₁

-

NO₁₈) C, H, N.

34d (85%): FAB-MS m/z1043 (MH⁺,84%).Anal.(C₅₄H₇₈N₂O₁₈)

C, H, N.

35a (76%): FAB-MS m/z1087 (MH⁺,49%).Anal.(C₅₅H₇₈N₂O₂₀)

C, H, N.

35b (84%): FAB-MS m/z1099 (MH⁺,65%).Anal.(C₅₆H₇₈N₂O₂₀)

C, H, N.

35c (69%): FAB-MS m/z 1054 (MH⁺, 59%). Anal. (C₅₆H₇₉

NO₁₈) C, H, N.

35d (75%): FAB-MS m/z1029 (MH⁺,63%).Anal.(C₅₃H₇₆N₂O₁₈)

C, H, N.

36a (91%): FAB-MS m/z 991 (MH⁺, 32%). Anal. (C₅₀H₇₄N₂O₁₈)

C, H, N.

36b (86%): FAB-MS m/z1003 (MH⁺,59%).Anal.(C₅₁H₇₄N₂O₁₈)

C, H, N.

36c (83%): FAB-MS m/z 958 (MH⁺, 53%). Anal. (C₅₁H₇₅

-

)

NO₁₆) C, H, N.

36d (75%): FAB-MS m/z933 (MH⁺, 39%). Anal. (C₄₈H₇₂N₂O₁₆

C, H, N.

37a (88%): FAB-MS m/z 1005 (MH⁺, 79%); UV λ_maxnm (ꢀ)

276 (31 543), 250 (13 336); IR (KBr) ν_max3459, 2972, 2933,

1742, 1594, 1523, 1455, 1347, 1167, 1082 cm^-^{1 1}H NMR

;

(CDCl₃) δ 8.17 (2H, d, Ar-C, J _B,C) 8.7 Hz), 7.52 (2H, d, Ar-B,

J _B,C) 8.7 Hz), 7.36 (1H, d, H-11, J _10,11) 16.5 Hz), 6.89 (1H,

dt, H-20, J _20,20′) 15.8 Hz, J _19,20) 7.8 Hz), 6.24 (1H, d, H-10,

J _10,11) 16.5 Hz), 5.87 (1H, d, H-13, J _13,14) 10.4 Hz), 5.86 (1H,

d, H-20′, J _20,20′) 15.8 Hz), 5.13 (1H, d, H-3, J _2b,3) 9.8 Hz),

4.81 (1H, dt, H-15, J _14,15) 10.0 Hz, J _15,16a) 11.0 Hz, J _15,16b

)

3.7 Hz), 4.55 (1H, d, H-1′′, J _{1′′,2′′}) 7.8 Hz), 4.23-4.09 (3H, m,

COOCH₂CH₃, H-1′), 3.97 (1H, dd, H-23b, J _23a,23b) 9.4 Hz,

J _14,23b) 4.2 Hz), 3.82-3.71 (3H, m, H-5, H-3b′′, H-3′′), 3.62

(3H, s, 3′′-OMe), 3.57-3.46 (3H, m, H-23a, H-5′′, H-2′), 3.44

(3H, s, 2′′-OMe), 3.35-3.24 (2H, m, H-6, H-5′), 3.22-3.12 (2H,

m, H-4′′, H-4′), 3.00 (1H, dd, H-2′′, J _{1′′,2′′}) 7.8 Hz, J _{2′′,3′′}) 2.9

Hz), 2.97-2.92 (1H, m, H-14), 2.80-2.67 (1H, m, H-8), 2.61

(6H, s, NMe₂), 2.54-2.40 (2H, m, H-3′, H-2b), 2.36-2.26

(1H, m, H-19b), 1.98 (1H, d, H-2a, J _2a,2b) 16.1 Hz), 1.93-

1.87 (1H, m, H-16b), 1.85-1.71 (2H, m, H-19a, H-4), 1.79 (3H,

38a (69%): FAB-MS m/z 975 (MH⁺, 48%). Anal. (C₅₀H₇₄N₂O₁₇)

C, H, N.

s, Me-22), 1.59 (1H, ddq, H-16a, J _15,16a) 10.5 Hz, J _16a,16b

)

14.4 Hz, J _16a,17) 7.3 Hz), 1.51-1.44 (1H, m, H-7b), 1.34 (3H,

d, H-6′ (Me-C-5′), J _5′,6′) 5.9 Hz), 1.28 (3H, t, COOCH₂CH₃,

J _CH3,CH2) 7.2 Hz), 1.27 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.9

Hz), 1.19 (3H, d, Me-21, J _8,21) 6.7 Hz), 1.14-1.09 (1H, m,

H-7a), 1.02-0.96 (3H, d, Me-18, J _4,18) 6.9 Hz; 1H, m, H-3a′′),

0.91 (3H, t, Me-17, J _16a,17) J _16b,17) 7.3 Hz); ¹³C NMR (CDCl₃)

δ 203.2 (s, C-9), 169.9 (s, C-1), 166.6 (s, COOCH₂CH₃,

OCOCH₂C₆H₄NO₂; 2C), 148.0 (d, C-20), 147.8 (d, C-11), 146.9

(s, Ar-D), 141.7 (s, Ar-A; d, C-13; 2C), 134.7 (s, C-12), 130.6

(d, Ar-B), 123.5 (d, C-10), 123.3 (d, Ar-C), 122.8 (d, C-20′),

103.5 (d, C-1′), 100.9 (d, C-1′′), 81.7 (d, C-2′′), 80.4 (d, C-5),

79.6 (d, C-3′′), 75.4 (d, C-3), 75.0 (d, C-15), 73.3 (d, C-5′),

72.5 (d, C-4′′), 70.7 (d, C-4′, C-3′, 2C), 70.2 (d, C-5′′, C-2′, 2C),

69.4 (t, C-23), 61.6 (q, 3′′-OMe), 59.9 (t, COOCH₂CH₃), 59.5

38b (59%): FAB-MS m/z987 (MH⁺, 64%). Anal. (C₅₁H₇₄N₂O₁₇

)

-

)

C, H, N.

38c (68%): FAB-MS m/z 942 (MH⁺, 81%). Anal. (C₅₁H₇₅

NO₁₅) C, H, N.

38d (72%): FAB-MS m/z917 (MH⁺, 64%). Anal. (C₄₈H₇₂N₂O₁₅

C, H, N.

39a (75%): FAB-MS m/z 961 (MH⁺, 56%). Anal. (C₄₉H₇₂N₂O₁₇)

C, H, N.

39b (63%): FAB-MS m/z973 (MH⁺, 64%). Anal. (C₅₀H₇₂N₂O₁₇

C, H, N.

39c (85%): FAB-MS m/z 928 (MH⁺, 63%). Anal. (C₅₀H₇₃

NO₁₅) C, H, N.

)

-

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 429

39d (59%): FAB-MS m/z903 (MH⁺, 69%). Anal. (C₄₇H₇₀N₂O₁₅

C, H, N.

)

3.29-3.11 (3H, m, H-6, H-4′′, H-4′), 3.07 (1H, dd, H-2′′), 3.03-

2.93 (1H, m, H-14), 2.83-2.65 (8H, m, NMe₂, H-8, H-3′), 2.60

(1H, br, H-19b), 2.44 (1H, dd, H-2b), 2.35 (1H, br, H-19a), 1.95

(1H, d, H-2a), 1.90 (1H, ddq, H-16b), 1.82 (3H, s, Me-22), 1.75-

1.50 (2H, m, H-16a, H-4), 1.52-1.42 (1H, m, H-7b), 1.32 (1H,

d, H-7a), 1.31 (1H, q, COOCH_2aCH₃, J _CH2a,CH3) 7.1 Hz), 1.28

(3H, d, H-6′ (Me-C-5′)), 1.27 (3H, d, H-6′′ (Me-C-5′′)), 1.25 (3H,

t, NHCOOCH₂CH₃, J _CH3,CH2) 7.2 Hz) 1.18 (3H, d, Me-21), 1.00

(3H, d, Me-18), 0.92 (3H, t, Me-17), 0.88 (3H, t, COOCH_2aCH₃,

J _CH3,CH2a) 7.1 Hz). δ Anal. (C₄₉H₈₁N₃O₁₈) C, H, N.

Mit su n ob u R ea ct ion w it h 1,1′-Aza d ica r b on ylb is-

p ip er id in e. P r ep a r a t ion of 44 a n d 45. A solution of

1,1′-(azadicarbonyl)bispiperidine (516 mg, 2.05 mmol) and

Bu₃P (85%; 500 µL, 1.73 mmol) in anhydrous THF (15 mL)

was added dropwise to a stirred solution of p-nitrophenylacetic

acid (445.3 mg, 2.46 mmol) in anhydrous THF (15 mL) at room

temperature. After stirring at room temperature for 15 min,

the mixture was cooled to 0 °C and 26b (1.98 g, 2.05 mmol) in

anhydrous THF (8 mL) was added and the mixture stirred at

0 °C for 3 h and then at room temperature for 3 h. The solvent

was evaporated and the residue was chromatographed on silica

gel, eluting with 20% acetone in hexane, to give 44 (1.97 g,

85%) as a white solid: FAB-MS m/z 1131 (MH⁺, 94%). Anal.

(C₅₇H₈₂N₂O₂₁) C, H, N.

Mitsu n obu Rea ction w ith Diisop r op yl Azod ica r box-

yla te. P r ep a r a tion of 40 a n d 41. Diisopropyl azodicarbox-

ylate (514 µL, 2.61 mmol) was added to a mixture of 26b (842.2

mg, 0.87 mmol), Ph₃P (686 mg, 2.61 mmol), and ClCH₂CO₂H

(247 mg, 2.61 mmol) in THF (18 mL) at 0 °C, and the mixture

was stirred for 50 min at room temperature. The reaction was

quenched by addition of ice, and the mixture was partitioned

between AcOEt and saturated aqueous NaHCO₃. The organic

layer was washed with water and brine, dried (Na₂SO₄), and

concentrated in vacuo. The crude product was chromato-

graphed on silica gel, eluting with 20% acetone in hexane, to

give 40 (816.7 mg, 90%) as a pale yellow solid: FAB-MS m/z

1044 (MH⁺, 66%). Anal. (C₅₁H₇₈ClNO₁₉) C, H, N.

Compound 40 (805.0 mg, 0.77 mmol) was dissolved in NH₃/

MeOH (20 mL, saturated at 0 °C) and kept at room temper-

ature overnight. The solvent was removed in vacuo, and the

residue was purified on a silica gel column with EtOH in

CHCl₃(0-16%) to give 41 (659.3 mg, 90%) as a white solid.

An analytical sample was crystallized from AcOEt-hexane to

1

give white crystals: FAB-MS m/z 842 (MH⁺, 66%); H NMR

(CDCl₃) δ 7.30 (1H, d, H-11), 6.96 (1H, br, H-20), 6.27 (1H, d,

H-10), 5.93 (1H, d, H-13), 5.87 (1H, d, H-20′), 4.99 (1H, dt,

H-15), 4.43 (1H, d, H-1′′, J _{1′′,2′′}) 7.8 Hz), 4.31 (1H, d, H-1′,

J _1′,2′) 7.3 Hz), 4.19 (2H, q, COOCH₂CH₃), 4.07 (1H, dd, H-23b,

J _23a,23b) 9.6 Hz, J _14,23b) 3.8 Hz), 3.90-3.80 (2H, m, H-5, H-3′′),

3.70 (1H, br, H-3), 3.61 (3H, s, 3′′-OMe), 3.58-3.53 (3H, m,

H-23a, H-5′′, H-2′), 3.46 (3H, s, 2′′-OMe), 3.40 (1H, br, H-5′),

3.34-3.10 (3H, m, H-6, H-4′′, H-4′), 3.05 (1H, dd, H-2′′), 3.00-

2.92 (1H, m, H-14), 2.82-2.63 (8H, m, NMe₂, H-8, H-3′), 2.60

(1H, br, H-19b), 2.42 (1H, dd, H-2b), 2.31 (1H, br, H-19a), 2.15

(1H, d, H-2a), 1.85 (1H, ddq, H-16b), 1.82 (3H, s, Me-22), 1.73-

1.56 (2H, m, H-16a, H-4), 1.53-1.40 (1H, m, H-7b), 1.35 (1H,

d, H-7a), 1.29 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 7.0 Hz), 1.25 (3H,

Compound 44 (1.95 g, 1.72 mmol) was dissolved in methanol

(5 mL). To this solution was added aqueous ammonia (25%,

2.5 mL) and the mixture was stirred at room temperature for

4 h. The residue obtained after evaporation in vacuo was

purified by flash chromatography (silica gel, solvent system

A1) to furnish 1.38 g (80%) of inverted acylide 45 as a nearly

colorless solid: FAB-MS m/z 1005 (MH⁺, 52%); UV λ_maxnm

(ꢀ) 275 (30 769), 250 (13 345); IR (KBr) ν_max3448, 2978, 2937,

1

1748, 1597, 1524, 1373, 1348, 1051 cm^-1; H NMR (CDCl₃) δ

8.20 (2H, d, Ar-C), 7.50 (2H, d, Ar-B), 7.30 (1H, d, H-11),

6.85 (1H, dt, H-20), 6.22 (1H, d, H-10), 5.85 (1H, d, H-13), 5.83

(1H, d, H-20′), 5.20-5.10 (1H, m, H-3), 4.80 (1H, dt, H-15),

4.51 (1H, d, H-1′′), 4.25-4.12 (3H, m, COOCH₂CH₃, H-1′), 3.95

(1H, dd, H-23b), 3.90-3.68 (3H, m, H-5, H-3b′′, H-3′′), 3.65

(3H, s, 3′′-OMe), 3.62-3.49 (3H, m, H-23a, H-5′′, H-2′), 3.44

(3H, s, 2′′-OMe), 3.35-3.22 (2H, m, H-6, H-5′), 3.20-3.10 (2H,

m, H-4′′, H-4′), 3.00 (1H, dd, H-2′′), 2.96-2.92 (1H, m, H-14),

2.80-2.67 (1H, m, H-8), 2.59 (6H, s, NMe₂), 2.55-2.42 (2H,

m, H-3′, H-2b), 2.38 (1H, br, H-19b), 1.99 (1H, d, H-2a), 1.95-

1.88 (1H, m, H-16b), 1.84-1.69 (2H, m, H-19a, H-4), 1.80 (3H,

s, Me-22), 1.60 (1H, ddq, H-16a), 1.51-1.44 (1H, m, H-7b), 1.35

(3H, d, Me-C-5′), 1.29 (3H, t, COOCH₂CH₃), 1.27 (3H, d, Me-

C-5′′), 1.20 (3H, d, Me-21), 1.15-1.10 (1H, m, H-7a), 1.03-

0.98 (3H, d, Me-18; 1H, m, H-3′′a), 0.91 (3H, t, Me-17).¹³C NMR

(CDCl₃) δ 203.5 (s, C-9), 169.0 (s, C-1), 166.2 (s, COOCH₂CH₃),

166.1 (s, OCOCH₂C₆H₄NO₂), 148.3 (d, C-20), 147.5 (d, C-11),

146.5 (s, Ar-D), 142.0 (s, Ar-A), 141.8 (d, C-13), 134.5 (s, C-12),

130.8 (d, Ar-B), 123.8 (d, C-10), 123.5 (d, Ar-C), 123.0 (d,

C-20′), 103.9 (d, C-1′), 100.9 (d, C-1′′), 82.0 (d, C-2′′), 80.9 (d,

C-5), 79.8 (d, C-3′′), 78.0 (d, C-3), 75.3 (d, C-15), 73.1 (d, C-5′),

72.8 (d, C-4′′), 70.1 (d, C-4′, C-3′, 2C), 70.0 (d, C-5′′), 69.9 (d,

C-2′), 69.0 (t, C-23), 61.9 (q, 3′′-OMe), 59.4 (t, COOCH₂CH₃),

59.2 (q, 2′′-OMe), 44.8 (d, C-14), 44.6 (d, C-8), 41.5 (q, NMe₂),

40.9 (t, C-3′′), 40.1 (d, C-4), 37.3 (t, C-2), 36.9 (d, C-6), 33.0 (t,

C-7), 31.6 (t, C-19), 25.8 (t, C-16), 17.5 (q, Me-C-5′, Me-C-5′′,

2C), 17.5 (q, Me-21), 14.3 (q, COOCH₂CH₃), 12.5 (q, Me-22),

10.2 (q, Me-18), 9.1 (q, Me-17). Anal. (C₅₁H₇₆N₂O₁₈) C, H, N.

d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.3 Hz), 1.18 (3H, d, Me-21, J _8,21

)

6.6 Hz), 1.05 (3H, d, Me-18, J _4,18) 6.0 Hz), 0.92 (3H, t, Me-

17, J _16a,17) J _16b,17) 7.1 Hz), 0.88 (3H, t, COOCH₂CH₃); ¹³C

NMR (CDCl₃) δ 203.6 (s, C-9), 176.8 (s, C-1), 169.1 (s, COOCH₂-

CH₃), 148.0 (d, C-20), 146.4 (d, C-11), 139.8 (d, C-13), 133.5

(s, C-12), 124.1 (d, C-20′), 123.7 (d, C-10), 103.9 (d, C-1′), 101.5

(d, C-1′′), 82.1 (d, C-5, C-2′′, 2C), 80.5 (d, C-3′′), 74.3 (d, C-15),

73.7 (d, C-3), 73.0 (d, C-4′′), 72.9 (d, C-5′, C-4′, 2C), 71.3 (d,

C-5′′, C-3′, 2C), 70.6 (d, C-2′), 66.9 (t, C-23), 61.5 (q, 3′′-OMe),

60.6 (t, COOCH₂CH₃), 58.1 (q, 2′′-OMe), 43.7 (d, C-14), 43.1

(d, C-8), 42.9 (d, C-4), 41.5 (q, NMe₂), 39.3 (t, C-2), 34.9 (d,

C-6), 32.8 (t, C-7), 29.9 (t, C-19), 25.7 (t, C-16), 16.6 (q, Me-

21), 15.4 (q, Me-C-5′′, Me-C-5′, 2C), 14.3 (q, COOCH₂CH₃), 13.5

(q, Me-22), 10.8 (q, Me-18), 9.1 (q, Me-17). Anal. (C₄₃H₇₁NO₁₅

C, H, N.

)

Mitsu n obu Rea ction w ith Dieth yl Azod ica r boxyla te.

P r ep a r a tion of 42 a n d 43. Compound 26b (968.0 mg, 1.0

mmol) in anhydrous THF (10 mL) under argon at 0 °C was

sequentialy treated with triphenyl phosphine (525.0 mg, 2.0

mmol) and diethyl azodicarboxylate (330.7 µL, 2.1 mmol) over

a 10 min period. After 10 min, the reaction was treated with

methanol (405.0 µL, 10.0 mmol) and stirred for an additional

2 h. The solvent was evaporated and the residue was chro-

matographed on silica gel, eluting with 20% acetone in hexane,

to give 42 (1.01 g, 90%) as a white solid: FAB-MS m/z 1126

(MH⁺, 64%). Anal. (C₅₅H₈₇N₃O₂₁) C, H, N.

3′-De(d im eth yla m in o)-3′-oxod esm ycosin (51) a n d 3′-N-

Acetyl-3′-N-d em eth yld esm ycosin (52). To a solution of bis-

(methylacetal) 15 (574.0 mg, 0.70 mmol), produced analogously

to the literature procedure,³⁴in dry CHCl₃(9.2 mL) was added

m-CPBA (133.3 mg, 0.89 mmol), and the mixture was stirred

at room temperature for 2 h, after which TLC (CH₂Cl₂-CH₃-

OH-aq NH₃90:9:1.5; R_f) 0.28) indicated that the reaction

was complete. The mixture was washed with saturated aque-

ous Na₂SO₃and saturated aqueous NaHCO₃, dried, and

filtered. To the resulting solution of 46 was added Ac₂O (333.5

µL, 3.5 mmol) and the mixture was kept at room temperature

overnight. After washing with saturated aqueous NaHCO₃, the

organic solution was dried and concentrated. The residue

Compound 42 (1.0 g, 0.88 mmol) was dissolved in NH₃/

MeOH (10 mL, saturated at 0 °C) and kept at room-temper-

ature overnight. The solvent was removed in vacuo, and the

residue was purified on a silica gel column with EtOH in

CHCl₃(0-16%) to give 43 (792 mg, 90%) as a white solid:

1

FAB-MS m/z 1000 (MH⁺, 47%); H NMR (CDCl₃) δ 7.28 (1H,

d, H-11), 6.87 (1H, br, H-20), 6.59 (1H, br, NH), 6.22 (1H, d,

H-10), 5.94 (1H, d, H-13), 5.81 (1H, d, H-20′), 4.95 (1H, dt,

H-15), 4.60 (1H, d, H-1′′), 4.32 (1H, d, H-1′), 4.22 (2H, q,

NHCOOCH₂CH₃, J

) 7.2 Hz), 4.15 (1H, q, COOCH_2b-

CH2,CH3

CH₃, J _CH2b,_CH3) 7.1 Hz), 4.00 (1H, dd, H-23b), 3.80-3.70 (3H,

m, H-5, H-3′′, H-3), 3.60 (3H, s, 3′′-OMe), 3.54-3.51 (3H, m,

H-23a, H-5′′, H-2′), 3.50 (3H, s, 2′′-OMe), 3.36 (1H, br, H-5′),

430 J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2

Pavlovic´ et al.

obtained was submitted to column chromatography (8:2 hex-

ane-acetone, then 6:2 hexane-acetone). The fraction having

R_f) 0.51 (8:2 hexane-acetone) gave, on concentration, 47

(113.0 mg, 60%) as a colorless solid: FAB-MS m/z 873 (MH⁺,

89%); IR (KBr)ν_max3459, 2966, 2934, 1746, 1681, 1593, 1455,

Hz), 3.02 (1H, dd, H-2′′, J _{1′′,2′′}) 7.9 Hz, J _{2′′,3′′}) 2.8 Hz), 2.80-

2.66 (2H, m, H-19b, H-8), 2.55 (6H, s, NMe₂), 2.53-2.46 (2H,

m, H-3′, H-2b), 2.45-2.36 (2H, m, H-12, H-10), 2.10-1.94 (3H,

m, H-14, H-6, H-2a), 1.92-1.84 (1H, m, H-19a), 1.82-1.76 (1H,

m, H-16b), 1.70-1.62 (2H, m, H-11, H-4), 1.60-1.48 (2H, m,

H-16a, H-7b), 1.40-1.33 (2H, m, H-13, H-7a), 1.31 (3H, d, H-6′-

(Me-C-5′), J 5′,6′ ) 5.8 Hz), 1.24 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}

) 5.9 Hz), 1.05 (3H, d, Me-21, J _8,21) 6.6 Hz), 0.99 (3H, d, Me-

18, J _4,18) 7.0 Hz), 0.88 (3H, d, Me-22, J _12,22) 7.0 Hz), 0.86

(3H, t, Me-17, J _16a,17) J _16b,17) 7.5 Hz); ¹³C NMR (CDCl₃) δ

214.9 (s, C-9), 172.8 (s, C-1), 167.2 (s, COOCH₃), 149.4 (d,

C-20), 122.2 (d, C-20′), 105.5 (d, C-1′), 100.9 (d, C-1′′), 82.1 8d,

C-5, C-2′′, 2C), 79.8 (d, C-3′′), 76.5 (d, C-15), 73.8 (d, C-4′′, C-3,

2C), 72.9 (d, C-4′), 70.8 (d, C-5′′, C-5′, 2C), 70.4 (d, C-2′), 69.9

(d, C-3′), 61.9 (q, 3′′-OMe), 59.6 (q, 2′′-OMe), 51.6 (q, COOCH₃),

43.2 (d, C-8), 42.0 (q, NMe₂), 40.7 (d, C-14), 39.7 (t, C-10), 39.3

(t, C-2; d, C-4; 2C), 37.8 (d, C-6), 34.9 (t, C-23), 33.0 (t, C-7),

32.7 (t, C-19), 31.8 (t, C-11), 30.7 (d, C-12), 29.8 (t, C-16), 23.6

(t, C-13), 20.5 (q, Me-22), 18.2 (q, Me-C-5′), 18.0 (q, Me-C-5′′),

1

1374, 1216, 1168, 1082, 1062 cm^-1; H NMR (CDCl₃) δ 7.33

(1H, d, H-11, J _10,11) 16.5 Hz), 6.29 (1H, d, H-10, J _10,11) 16.5

Hz), 5.91 (1H, d, H-13, J _13,14) 10.2 Hz), 5.20 (1H, d, H-2′, J _1′,2′

) 8.0 Hz), 4.98 (1H, d, H-4′, J _4′,5′) 10.0 Hz), 4.95 (1H, dt, H-15,

J _14,15) 10.1 Hz, J _15,16b) 4.3 Hz), 4.66 (1H, d, H-1′, J _1′,2′) 8.0

Hz), 4.55 (1H, d, H-1′′, J _{1′′,2′′}) 7.8 Hz), 4.54-4.51 (1H, m,

H-20), 4.00 (1H, dd, H-23b, J _23a,23b) 9.5 Hz, J _14,23b) 4.1 Hz),

3.78-3.71 (3H, m, H-5, H-3′′, H-3), 3.64 (1H, dq, H-5′, J _4′,5′

)

8.7 Hz, J _5′,6′) 6.1 Hz), 3.61 (3H, s, 3′′-OMe), 3.57-3.49 (2H,

m, H-23a, H-5′′), 3.48 (3H, s, 2′′-OMe), 3.31 (3H, s, MeO-C-

20), 3.25 (3H, s, MeO-C-20), 3.22-3.15 (1H, m, H-4′′), 3.03

(1H, dd, H-2′′, J _{1′′,2′′}) 7.8 Hz, J _{2′′,3′′}) 2.7 Hz), 2.98-2.92 (1H,

m, H-14), 2.69 (1H, br, H-8), 2.47 (1H, dd, H-2b, J _2a,2b) 16.0

Hz, J _2b,3) 10.5 Hz), 2.30 (1H, d, 4′′-OH, J _{4′′,4′′-OH}) 10.0 Hz),

2.17 (6H, s, 2′-OCOCH₃, 4′-OCOCH₃), 2.02-1.92 (2H, m,

H-19b, H-7b), 1.93 (1H, d, H-2a, J _2a,2b) 16.0 Hz), 1.90-1.82

(2H, m, H-19a, H-16b), 1.79 (3H, s, Me-22), 1.66-1.50 (3H,

m, H-16a, H-7a, H-4), 1.39 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 6.2

Hz), 1.26 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.1 Hz), 1.22 (3H, d,

Me-21, J _8,21) 6.7 Hz), 0.94 (3H, d, Me-18, J _4,18) 6.3 Hz), 0.91

(3H, t, Me-17, J _16a,17) J _16b,17) 7.1 Hz); ¹³C NMR (CDCl₃) δ

203.7, 194.6, 174.0, 169.5, 169.3, 148.0, 142.6, 135.0, 118.6,

103.0, 102.2, 101.4, 83.3, 82.1, 80.1, 78.3, 78.0, 75.4, 72.9, 70.9,

70.0, 69.3, 67.1, 62.0, 59.9, 53.9, 50.8, 45.4, 41.4, 40.0, 33.6,

33.1, 31.8, 31.6, 25.6, 22.9, 20.7, 20.6, 18.4, 18.0, 14.4, 13.3,

9.9, 8.9. Anal. (C₄₃H₆₈O₁₈) C, H.

14.3 (q, Me-21), 10.6 (q, Me-17), 8.3 (q, Me-18). Anal. (C₄₂H₇₃

-

NO₁₅) C, H, N.

54 (78%): FAB-MS m/z 816 (MH⁺, 74%); H NMR (CDCl₃)

1

δ 6.89 (1H, dt, H-20, J _20,20′) 15.8 Hz, J _19b,20) 2.3 Hz), 5.82

(1H, d, H-20′, J _20,20′) 15.8 Hz), 4.99 (1H, dt, H-15, J _14,15

)

10.0 Hz, J _15,16b) 3.5 Hz), 4.53 (1H, d, H-1′′, J _{1′′,2′′}) 7.9 Hz),

4.37 (1H, d, H-1′, J _1′,2′) 7.2 Hz), 4.20 (1H, t, H-3, J _2b,3) 6.9

Hz), 3.97 (1H, dd, H-23b, J _23a,23b) 9.0 Hz, J _14,23b) 4.4 Hz),

3.90-3.80 (1H, m, H-5), 3.76 (1H, t, J _{2′′,3′′}) J _{3′′,4′′}) 3.0 Hz),

3.71 (3H, s, COOCH₃), 3.61 (3H, s, 3′′-OMe), 3.59-3.52 (2H,

m, H-5′′, H-5′), 3.50 (3H, s, 2′′-OMe), 3.34-3.24 (2H, m, H-23a,

H-2′), 3.17 (1H, dd, H-4′′, J _{4′′,5′′}) 9.3 Hz, J _{3′′,4′′}) 3.0 Hz), 3.01

(1H, dd, H-2′′, J _{1′′,2′′}) 7.9 Hz, J _{2′′,3′′}) 2.8 Hz), 2.91-2.62 (3H,

m, H-19b, H-8, H-3′), 2.60-2.52 (1H, m, H-2b), 2.48-2.40 (2H,

m, H-12, H-10), 2.17 (1H, br, H-6), 2.05-1.82 (2H, m, H-19a,

H-14), 1.80-1.58 (3H, m, H-16b, H-4′b, H-4), 1.56-1.47 (1H,

m, H-11), 1.45-1.35 (2H, m, H-16a, H-7b), 1.34-1.27 (4H, m,

H-13, H-7a, H-4′a), 1.26 (3H, d, H-6′ (Me-C-5′), J _5′,6′) 5.8 Hz),

1.24 (3H, d, H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.0 Hz), 1.04 (3H, d, Me-

21, J _8,21) 6.8 Hz), 0.99 (3H, d, Me-18, J _4,18) 7.0 Hz), 0.88

The fraction having R_f) 0.35 (8:2 hexane-acetone) gave,

on concentration, 48 (7.5 mg, 4%) as a colorless solid: FAB-

MS m/z 930 (MH⁺, 63%). Anal. (C₄₆H₇₅NO₁₈) C, H, N.

The latter compounds 47 and 48 were sequentially hydro-

lyzed with methanol to give intermediates 49 and 50, respec-

tively.

49: FAB-MS m/z 789 (MH⁺, 63%). Anal. (C₃₉H₆₄O₁₆) C, H.

50: FAB-MS m/z 846 (MH⁺, 58%). Anal. (C₄₂H₇₁NO₁₆) C,

H, N.

(3H, d, Me-22, J _12,22) 7.1 Hz), 0.87 (3H, t, Me-17, J _16a,17

)

J _16b,17) 7.5 Hz); ¹³C NMR (CDCl₃) δ 214.9 (s, C-9), 172.4 (s,

C-1), 166.9 (s, COOCH₃), 149.6 (d, C-20), 121.6 (d, C-20′), 105.9

(d, C-1′), 100.7 (d, C-1′′), 85.4 (d, C-5), 81.9 (d, C-2′′), 79.4 (d,

C-3′′), 75.6 (d, C-15), 72.6 (d, C-4′′, C-3, 2C), 70.4 (d, C-5′′, C-5′,

2C), 69.5 (d, C-2′), 65.4 (d, C-3′), 61.6 (q, 3′′-OMe), 59.3 (q, 2′′-

OMe), 51.2 (q, COOCH₃), 41.8 (d, C-8), 40.2 (q, NMe₂), 39.9

(d, C-14), 39.6 (t, C-2), 39.4 (t, C-10), 39.3 (d, C-4), 37.5 (d,

C-6), 35.4 (t, C-23), 32.9 (t, C-7), 32.5 (t, C-19), 30.2 (t, C-11),

29.5 (d, C-12), 28.9 (t, C-16), 22.1 (t, C-13), 21.1 (q, Me-C-5′),

20.6 (q, Me-22), 17.6 (q, Me-C-5′′), 16.2 (q, Me-21), 10.6 (q, Me-

17), 7.6 (q, Me-18). Anal. (C₄₂H₇₃NO₁₄) C, H, N.

Further deprotection of 49 and 50 by aqueous 1 M HCl in

acetonitrile finally afforded 51 and 52, respectively.

51: FAB-MS m/z 743 (MH⁺, 75%). Anal. (C₃₇H₅₈O₁₅) C, H.

52: FAB-MS m/z 800 (MH⁺, 91%). Anal. (C₄₀H₆₅NO₁₅) C,

H, N.

Syn th esis of r,â-Un sa tu r a ted Ester s (53-56) via Hor -

n er -Wa d sw or th -Em m on s Rea ction . To a THF suspension

of sodium hydride (60% w/w in mineral oil, 542 mg, 13.55

mmol, 2.0 equiv) was gradually added a solution of trimeth-

ylphosphonoacetate (2.7 mL, 13.55 mmol, 2.0 equiv) in THF

(10 mL) via cannula at 0 °C. A solution of the corresponding

aldehyde (8, 9, 1, and 11; 6.78 mmol, 1.0 equiv) in THF (15

mL) was slowly added to the reaction mixture via cannula at

0 °C, and the reaction mixture was stirred at the same

temperature for 1 h and at 25 °C for 4 h. After the end of the

reaction was established by TLC, the reaction was quenched

by the addition of saturated NH₄Cl solution (50 mL), extracted

with EtOAc (2 × 100 mL), dried over Na₂SO₄, and concen-

trated. The crude product obtained after evaporation of solvent

was purified by flash chromatography (silica gel, 2% EtOAc

in hexane) to furnish the corresponding R,â-unsaturated esters

53-56. By using this procedure, the following compounds were

prepared.

55 (92%): FAB-MS m/z 972 (MH⁺, 71%); H NMR (CDCl₃)

1

δ 7.30 (1H, d, H-11, J _10,11) 16.6 Hz), 6.93 (1H, br, H-20), 6.25

(1H, d, H-10, J _10,11) 16.6 Hz), 5.90 (1H, d, H-13, J _13,14) 10.1

Hz), 5.86 (1H, d, H-20′, J _20,20′) 15.7 Hz), 5.12 (1H, br, H-1′′),

4.99 (1H, dt, H-15, J _14,15) 10.0 Hz, J _15,16a) 11.1 Hz), 4.56

(1H, d, H-1′′, J _{1′′,2′′}) 7.7 Hz), 4.39 (1H, br, H-1′), 4.00 (1H, dd,

H-23b, J _23a,23b) 9.5 Hz, J _14,23b) 3.7 Hz), 3.82-3.72 (3H, m,

H-5, H-3′′, H-3), 3.71 (3H, s, COOCH₃), 3.62 (3H, s, 3′′-OMe),

3.60-3.51 (3H, m, H-23a, H-5′′, H-2′), 3.50 (3H, s, 2′′-OMe),

3.35 (1H, br, H-5′), 3.23-3.12 (2H, m, H-4′′, H-4′), 3.03 (1H,

dd, H-2′′, J _{1′′,2′′}) 7.7 Hz, J _{2′′,3′′}) 2.6 Hz), 2.99-2.89 (2H, m,

H-14, H-4′′), 2.75-2.60 (2H, m, H-19b,H-8), 2.57-2.49 (1H,

m, H-19a; 6H, s, NMe₂), 2.46 (1H, dd, H-2b, J _2a,2b) 16.7 Hz,

J _2b,3) 10.8 Hz), 2.33 (1H, d, H-3′, J _3′,4′) 11.1 Hz), 2.05 (1H,

br, H-6), 2.03 (1H, d, H-2′′b, J _{2′′a,2′′b}) 14.2 Hz), 1.95 (1H, d,

H-2a, J _2a,2b) 16.7 Hz), 1.91-1.80 (1H, m, H-16b), 1.79 (3H, s,

Me-22), 1.75 (1H, dd, H-2′′a, J _{2′′a,2′′b}) 14.2 Hz, J _{1′′,2′′a}) 4.0

Hz), 1.70-1.54 (2H, m, H-16a, H-4), 1.53-1.45 (1H, m, H-7b),

1.40-1.28 (9H, m, Me-C-5′′, Me-C-5′, Me-C-3′′), 1.26 (3H, d,

H-6′′ (Me-C-5′′), J _{5′′,6′′}) 6.2 Hz), 1.23 (1H, br, H-7a), 1.19 (3H,

d, Me-21, J _8,21) 6.4 Hz), 1.00 (3H, d, Me-18, J _4,18) 6.2 Hz),

53 (78%): FAB-MS m/z 832 (MH⁺, 69%); IR (KBr) ν_max3444,

2970, 2932, 1716, 1652, 1439, 1382, 1273, 1169, 1083, 1063

cm^-1; ¹H NMR (CDCl₃) δ 6.89 (1H, dt, H-20, J _20,20′) 15.7 Hz,

J _19b,20) 2.3 Hz), 5.83 (1H, d, H-20′, J _20,20′) 15.7 Hz), 5.02

(1H, dt, H-15, J _14,15) 9.9 Hz, J _15,16b) 3.4 Hz), 4.53 (1H, d,

H-1′′, J _{1′′,2′′}) 7.9 Hz), 4.37 (1H, d, H-1′, J _1′,2′) 7.2 Hz), 4.09

(1H, t, H-3, J _2b,3) 6.7 Hz), 3.86 (1H, dd, H-23b, J _23a,23b) 9.0

Hz, J _14,23b) 4.2 Hz), 3.84-3.80 (1H, m, H-5), 3.76 (1H, t, J _{2′′,3′′}

) J _{3′′,4′′}) 3.0 Hz), 3.71 (3H, s, COOCH₃), 3.61 (3H, s, 3′′-OMe),

3.56-3.51 (2H, m, H-23a, H-5′), 3.18 (1H, dd, H-4′′, J _{3′′,4′′}

)

0.94 (3H, t, Me-17, J _16a,17) J _16b,17) 7.3 Hz). Anal. (C₄₉H₈₁-

NO₁₈) C, H, N.

3.0 Hz, J _{4′′,5′′}) 9.3 Hz), 3.15 (1H, t, H-4′, J _3′,4′ax) J _4′,5′) 10.0

J ournal of Medicinal Chemistry, 2004, Vol. 47, No. 2 431

56 (74%): FAB-MS m/z 976 (MH⁺, 86%). Anal. (C₄₉H₈₅NO₁₈

C, H, N.

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J M0308951

Article Doi

Semisynthetic Macrolide Antibacterials Derived from Tylosin. Synthesis and Structure-Activity Relationships of Novel Desmycosin Analogues

DOI: 10.1021/jm0308951

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