Total Synthesis of 34-Hydroxyasimicin and Its Photoactive Derivative for Affinity Labeling of the Mitochondrial Complex I

Article abstract of DOI:10.1002/chem.200305557

The asymmetric total synthesis of the 34-hydroxyasimicin and its 3-(4-benzoylphenyl)propionate ester was achieved by means of a convergent synthetic strategy. This ester, which contains eight asymmetric centers, represents the first photoaffinity-labeling

Full text of DOI:10.1002/chem.200305557

FULL PAPER
Total Synthesis of 34-Hydroxyasimicin and Its Photoactive Derivative for
Affinity Labeling of the Mitochondrial Complex I
Hongna Han,[a] Mantosh K. Sinha,[a, b] Lawrence J. D×Souza,[a] Ehud Keinan,*[a, b, c] and
Subhash C. Sinha*[a]
Abstract: The asymmetric total synthe-
sis of the 34-hydroxyasimicin and its 3-
(4-benzoylphenyl)propionate ester was
achieved by means of a convergent
synthetic strategy. This ester, which
contains eight asymmetric centers, rep-
resents the first photoaffinity-labeling
agent that is derived from an Annona-
ceous acetogenin. The key transforma-
tions in the synthesis include the
Sharpless asymmetric dihydroxylation
reaction, the Wittigolefination reac-
tion, an oxidative cyclization reaction
with rhenium(vii) oxide, the William-
son etherification reaction, and a palla-
dium-catalyzed cross-couplingreaction.
Use of the target molecule for photoaf-
finity-labelingstudies of bovine mito-
chondrial NADH-ubiquinone oxidore-
ductase (Complex I) may shed light on
the structure/function of this intricate
enzyme and on the origin of the high
antitumor activity exhibited by the An-
nonaceous acetogenins.
Keywords:
dihydroxylation
acetogenins
¥ mitochondria
¥
¥
photoaffinity labeling ¥ rhenium
Introduction
tein subunits, seven of which are encoded in the mitochon-
drial genome, while the others originate from the nuclear
DNA.[2,3] The complex spans the inner-mitochondrial mem-
brane, generating a proton gradient across the membrane by
translocation of protons from the matrix side of the mem-
brane to the cytoplasm. Since structural and functional de-
fects of Complex I are reported to be a primary cause in
many diseases, includinga wide variety of degenerative dis-
eases, aging, and cancer, the structure and catalytic mecha-
nism of this enzyme complex have attracted an ever growing
attention.[4]. The three-dimensional images of Complex I
from N. Crassa and E. Coli were achieved by electron mi-
croscopy.[5]
NADH-ubiquinone oxidoreductase, also known as Com-
plex I, is one of four multisubunit enzyme complexes of the
respiratory chain in the mammalian mitochondria that form
the electron-transport chain from NADH to oxygen and
generate the energy source ATP.[1] Complex I, which bears
one noncovalently bound flavin mononucleotide (FMN) and
eight iron sulfur clusters with a total molecular mass of ap-
proximately 1000000 Da, is one of the most intricate
enzyme complexes known, consistingof more than 46 pro-
Due to the lack of detailed structural information about
Complex I (and about its bacterial analogue, NDH-1), very
little is known about the electron pathways from matrix
NADH to membrane ubiquinone. The clues linkingthis
process with the translocation of protons are highly contro-
versial.[6] Different types of inhibitors (Scheme 1) have been
used in an effort to dissect the electron and proton pathways
of this complicated enzyme system.[7] For example, the use
of two rotenone-derived photoaffinity probes have located a
single inhibitor-binding site in the ND1 subunit.[8] Likewise,
[a] Dr. H. Han, M. K. Sinha, Dr. L. J. D×Souza, Prof. E. Keinan,
Prof. S. C. Sinha
Department of Molecular Biology and
The Skaggs Institute for Chemical Biology
The Scripps Research Institute, 10550 N. Torrey Pines Road
La Jolla, California 92037 (USA)
Fax : (+858)784-8735
E-mail: Hanhn@scripps.edu
Subhash@scripps.edu
Mantosh@scripps.edu
Keinan@scripps.edu
[9]
photoaffinity labelingwith a fenpyroximate derivative spe-
[b] M. K. Sinha, Prof. E. Keinan
cifically labeled the ND5 subunit of Complex I.[10] Other
subunits were specifically labeled with a 14C-tagged N,N’-di-
cyclohexylcarbodiimide,[11] a ubiquinone derivative,[12] and
pyridaben derivative.[13,14] Consequently, the subunits IP49 K,
PSST, ND1, ND3, and ND5 were proposed to comprise an
Department of Chemistry
and Institute of Catalysis Science and Technology
Technion-Israel Institute of Technology
Technion City, Haifa 32000 (Israel)
[c] Prof. E. Keinan
Incumbent of the Benno Gitter &
Ilana Ben-Ami chair of Biotechnology, Technion
[15]
inhibitor-bindingpocket in either Complex I or in NDH-1.
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FULL PAPER
Scheme 1. Reported inhibitors of Complex I.
Of particular interest are the Annonaceous acetogenins,
which were found to be the most powerful inhibitors of the
mammalian Complex I and of the insect mitochondrial elec-
tron-transport systems.[16] These natural products are known
not only for their antitumor activity, but also for being
potent antimalarial, immunosuppressive, pesticidal, and anti-
feedant agents.[17] More than 350 acetogenins have already
been isolated from 37 species in the Annonaceae, a family
of tropical trees and shrubs that accommodates over
2300 species.[18] While most of these fatty acid derivatives ex-
hibit remarkable structural diversity, they share very similar
carbon skeletons, with the main variations beingthe relative
and absolute configuration of the various stereogenic
oxygen functions. For example, a dominant structural fea-
ture that appears in more than 40% of the Annonaceous
acetogenins is a ten-carbon fragment that contains two adja-
cent tetrahydrofuran rings flanked by either one or two hy-
droxyl groups. A long alkyl chain tethers this fragment to a
butenolide group, which represents the conserved part of
almost all acetogenins.
The stronginhibitory potency of these compounds and
their structural diversity make them interestingtools to in-
vestigate the structure function problems of Complex I. Fur-
thermore, previous reports have suggested that the various
acetogenins inhibit Complex I in different ways,[16c,19]
rather surprisingobservation on grounds of the very close
a
chemical resemblance amongthem. For example, the closely
related rolliniastatin-1, rolliniastatin-2 (bullatacin), and co-
rossolin were found to inhibit Complex I with different ki-
[20]
netic features reflectingdifferential bindingmodes.
These
observations offer interestingopportunities in both mecha-
nistic investigations and drug discovery, particularly since
few of these compounds have shown in vitro antitumor po-
tency 108 times greater than that of adriamycin.[21] Neverthe-
less, attempts to photolabel Complex I with an acetogenin
derivative have not yet been reported, probably because the
synthesis of such derivatives is much more difficult than that
of the other inhibitors.
Here we report on the first synthesis of a photoaffinity-la-
belingagent for Complex I that is derived from the Annona-
ceous acetogenins. Our design is based on the skeleton of
asimicin (1a, Scheme 2), the synthesis of which was reported
earlier.[22] Asimicin was first isolated from extracts of the
bark and seeds of the pawpaw tree, Asimina triloba Dunal,
by usingbrine shrimp lethality for activity-directed fractio-
nation.[23] It was found to be extremely cytotoxic in the 9KB
(human nasophyraneal carcinoma, ED50 <10À5 mgmLÀ1) and
Abstract in Hebrew:
the 9BS (murine lymphocyte leukemia, ED50 <10À7 mgmLÀ1
)
system. Bullatacin, which is an epimer of asimicin at posi-
tion 24, has also shown antitumor potential in vitro against
HL-60 cells that are resistant to adriamycin,[24] and in vivo
with mice bearingL1210 murine leukemia and with mice
[25]
bearingA2780 conventional ovarian cancer xenorgafts.
Both asimicin and bullatacin were found to be potent inhibi-
tors of Complex I.[16]
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Chem. Eur. J. 2004, 10, 2149 2158

Total Synthesis of 34-Hydroxyasimicin
2149 2158
ically in the range of 5 10%,
whereas they are much higher
for benzophenyl radical.
Results and Discussion
In our previous studies on the
total synthesis of adjacent bis-
THF acetogenins as well as
other natural and non-natural
acetogenins, including solamin,
reticulatacin, asimicin, bullata-
cin, trilobin, trilobacin, squa-
motacin, rolliniastatin, uvari-
cin, rollidecins C and D, muco-
cin, goniocin, 17,18-bis-epigo-
niocin, and cyclogoniodenin
T,[22,28] we met the synthetic
challenges by examining three
general synthetic strategies:
the ™naked∫ carbon-skeleton
strategy,[29] the convergent ap-
proach, and a hybrid strategy
that combines the advantages
of the first two.[30] In principle,
all three approaches can be
generally used for the synthesis
Scheme 2. Retrosynthetic analysis of 34-hydroxyasimicin.
of 1b and 1c as well as their
The decision concerningthe attachment point of the pho-
toactive device was nontrivial, because the detailed mode of
action and the bindingorientation of the Annonaceous ace-
togenins are yet unknown. Since the butenolide fragment is
highly conserved in most of the acetogenins, one could
assume that in order to retain the inhibitory activity the bu-
tenolide fragment should remain intact. Furthermore, stud-
ies on acetogenin analogues in which the butenolide frag-
ment was replaced by a ubiquinone ringhave indicated that
the butenolide moiety of natural acetogenins binds to the
ubiquinone reduction site of the enzyme.[26] Similar argu-
ments also hold true for the bis-THF fragment of the mole-
cule, because small variations in the stereogenic centers of
this fragment are known to cause significant changes in the
biological activity. Furthermore, the length of the poly-
methylene chain that links both functional fragments was
also found to be essential for activity. Consequently, the
only part of the molecule that could suffer the required
modification with minimal loss of activity seemed to be the
end of the alkyl chain. Accordingly, our target molecule
(1c) was designed to contain a benzophenone group attach-
ed by a flexible linkage to position 34 of the molecule. We
decided to use the benzophenone label, because it offers the
advantage of being more reactive than other photolabeling
diastereomers. In this work we have chosen the convergent
strategy, which is outlined in the retrosynthetic analysis
(Scheme 2). The analysis dissects the target molecule into
two major fragments, the bis-THF fragment (2) and the bu-
tenolide moiety (3). Assembly of these buildingblocks
could be achieved by a palladium-catalyzed cross-coupling
reaction.[31] The butenolide intermediate (3) was obtained
by previously described methods,[22] and alkyne 2 was pre-
pared from the correspondingtricyclic intermediate 4. The
synthesis of 4 represents the most significant component of
the entire synthesis, not only because it contains as many as
six asymmetric centers, but also because the potential ster-
eomeric variability of this fragment represents the origin of
diversity in the bis-THF subgroup of the Annonaceous ace-
togenins. We envisioned the preparation of 4 from alkene 5,
which, in turn, could be obtained by Wittigcouplingfrom
phosphonium salt 6 and aldehyde 7. This last compound was
prepared previously in seven steps from 1,4-dihydroxybu-
tane.[22]
The synthesis of intermediate 2 (Scheme 3) started with
undec-10-enal (8), which was treated with vinyl magnenium
bromide. Treatment of the resultant allylic alcohol with
triethyl orthoacetate in the presence of a catalytic amount
of propionic acid produced the g,d-unsaturated ester 9 by
means of the Claisen-Johnson rearrangement. The Sharpless
asymmetric dihydroxylation (AD) reaction of 9 with AD-
mix-b, followed by base and acid treatment afforded hydrox-
ylactone 10 with >95% ee, which was increased to essen-
tially 100% ee in one crystallization step. Lithium aluminum
hydride (LAH) reduction afforded the correspondingtriol,
devices, such as diazo and azide groups, with preferential re-
[27]
À
À
activity towards C H over X H bonds. In addition, diazo
and azide compounds are activated irreversibly at 245 nm,
while benzophenone is activated reversibly at 350 365 nm,
and is also more chemically and room light stable. Further-
more, labelingefficiencies for nitrenes and carbenes are typ-
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E. Keinan, S. C. Sinha et al.
FULL PAPER
single diastereomer in 76%
yield. Activation of the free
hydroxyl group in 14 in the
form of a mesylate (15), fol-
lowed by acid-catalyzed hy-
drolysis of the acetonide group
produced the free diol (16).
Heatingcompound 16 in pyri-
dine affected the Williamson-
type etherification to produce
the tricyclic intermediate 4.
LAH reduction afforded triol
17, in which the primary alco-
hol was protected in the form
of
a
tert-butyldimethylsilyl
ether, while the two secondary
alcohols were converted to
methoxymethyl
ethers
to
afford 18. Hydroboration of
the terminal double bond of 18
afforded alcohol 19, which was
protected in the form of 4-me-
thoxybenzyloxymethyl ether to
give 20. The tert-butyldi-
methylsilyl ether was then
cleaved to afford alcohol 21,
which was oxidized to give the
correspondingaldehyde. The
aldehyde was immediately
treated with PPh3-CBr4 in the
presence of triethylamine to
Scheme 3. Synthesis of intermediate 2. Key: a) i) Vinylmagnesium bromide, THF, 08C, 0.5 h; ii) (EtO)3CCH3,
propionic acid, xylene, reflux, 2 h; b) i) AD-mix-b, MeSO2NH2, tBuOH/water (1:1), 08C, 12 h; ii) Aqueous
KOH (3 n), MeOH, 608C, 2 h, then HCl (3n); iii) TsOH (5%), CH2Cl2, RT, 1 h; c) i) LiAlH4, diethyl ether/
THF, 08C, then reflux, 2 h; ii) acetone/hexane (1:2), TsOH (cat); d) I2, imidazole, PPh3, CH2Cl2, RT, 2 h; e) I2,
PPh3, NaHCO3, CH3CN, reflux, 16 h; f) NaHMDS, THF, HMPA, À788C, 2 h, then 7, À788C to RT, 16 h;
g) TBAF, THF, 08C to RT, 2 h; h) Re2O7, lutidine, CH2Cl2, 12 h; i) MsCl, Et3N, CH2Cl2, À308C, 0.5 h;
j) TsOH, MeOH-H2O (4:1), RT, 16 h; k) pyridine, reflux, 3 h; l) LiAlH4, diethyl ether/THF, 08C, then reflux,
2 h; m) TBSCl, iPr2NEt, DMAP, CH2Cl2, 08C to RT, 12 h, then ClCH2OMe, iPr2NEt, 08C to RT, 16 h; n) 9-
BBN, THF, 08C to RT, 4 h, then H2O2 (35%), aq NaOH (3n), 08C, 1 h; o) p-MeOC6H4CH2OCH2Cl, iPr2NEt,
CH2Cl2, 08C to RT, 3 h; p) TBAF, THF, 08C to RT, 2 h; q) i) (COCl)2, DMSO, CH2Cl2, À788C, 1 h, then Et3N,
À788C to 08C; ii) Ph3P, CBr4, Et3N, CH2Cl2, 08C, 16 h; r) EtMgBr, THF, 08C, 0.5 h.
produce
the
1,1-dibromo-
alkene 22. Finally, treatment
of 22 with EtMgBr pro-
vided the desired key inter-
in which the vicinal diol was protected in the form of an
acetonide derivative, 11. The unprotected primary alcohol in
11 was converted to the correspondingiodide, 12, which was
then treated with triphenylphosphine to produce the phos-
phonium salt 6. Wittigreaction between 6 and aldehyde 7[22]
was carried out in the presence of sodium hexamethyldisila-
zide to afford the cis-alkene 13. Cleavage of the tert-butyldi-
phenylsilyl group in 13 with tetrabutyl ammonium fluoride
(TBAF) produced alcohol 5, one of the key intermediates of
this synthetic scheme. Oxidative cyclization with CF3CO3-
ReO3 and lutidine provided the trans-THF ringin 14[32] as a
mediate 2.[33]
The synthesis of the butenolide fragment 3 (Scheme 4)
started from octa-1,7-diene (23) by usingour previously de-
scribed methods for the preparation of homologous com-
pounds.[22] Thus, dihydroxylation with AD-mix-b usingpyri-
midine ligand afforded diol 24. The primary hydroxyl was
selectively converted to the correspondingtosylate 25, and
the secondary hydroxyl was protected in the form of a silyl
ether (26) by usingTBSOTf at low temperature. The tosyl-
ate group was then converted to iodide 27 by usingNaI in
refluxingacetone. Lactone 28[34] was alkylated with iodide
Scheme 4. Synthesis of the butenolide fragment, 3. a) i) AD-mix-b, tBuOH/water (2:1), 08C, 18 h; b) TsCl, collidine, 08C, 16 h; c) TBSOTf, lutidine,
CH2Cl2, À788C, 3 h; d) NaI, NaHCO3 acetone, reflux, 36 h; e) LDA, THF, HMPA, compound 28, À788C, then compound 27, RT, 24 h; f) i) m-CPBA,
CH2Cl2, 08C, 10 min; ii) toluene, 908C, 2 h; g) OsO4, THF/H2O, then NaIO4, 2.5 h; h) CHI3, CrCl2, THF, 08C, 4 h.
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Total Synthesis of 34-Hydroxyasimicin
2149 2158
27 with LDA in THF-HMPA to produce sulfide 29, which in
turn was oxidized with m-CPBA; the resultant sulfoxide was
heated in toluene at 908C to produce the butenolide 30. Se-
lective dihydroxylation of the monosubstituted double bond
in 30 with OsO4 followed by oxidative cleavage with NaIO4
produced aldehyde 31. Finally, olefination with iodoform
and chromium dichloride afforded the desired vinyl iodide 3
in the form of a mixture of the E/Z isomers.[35]
Experimental Section
General methods: 1H and 13C NMR spectra were measured in CDCl3.
Optical rotations were measured in a one-decimeter (1.3 mL) cell by
usingan Autopol III automatic polarimeter. TLC was performed on glass
sheets precoated with silica gel (Merck, Kieselgel 60, F254, Art. 5715).
Column chromatographic separations were performed on silica gel
(Merck, Kieselgel 60, 230 400 mesh, Art. 9385) under pressure. All com-
mercially available reagents were used without further purification. Sol-
vents were either used as purchased or distilled usingcommon practices
where appropriate. All reactions were carried out under dry Argon.
The target molecules 1b and 1c were assembled from in-
termediates 2 and 3 (Scheme 5) by a PdII-catalyzed cross-
(trans)-Ethyl pentadec-4,14-dienoate
(9): Vinylmagnesium bromide (1m,
96 mL, 96 mmol) was added to a sol-
ution of undecylenic aldehyde
(13.46 g, 80 mmol) in THF (140 mL)
at 08C. The mixture was stirred for
0.5 h and then worked up with dieth-
yl ether and saturated aqueous
NH4Cl. Removal of solvents followed
by filtration over silica gel (hexanes/
ethyl acetate, 4:1) afforded tridec-1,
12-dien-3-ol (16.1 g), which was taken
to next step without further purifica-
tion.
The above-mentioned allylic alcohol
(16.1 g),
triethyl
orthoacetate
(24.3 mL, 160 mmol), and propionic
acid (0.08 g, 0.017 mmol) were dis-
solved in xylene (25 mL), and the
mixture was refluxed for 2 h. Solvents
were removed under reduced pres-
sure, and the residue was distilled to
give 9 (15.49 g, 73%) in the form of a
light yellow oil. 1H NMR (500 MHz):
d=5.85 5.79 (m, 1H), 5.48 5.38 (m,
2H), 5.01 4.92 (m, 2H), 4.13 (q, J=
7.3 Hz, 2H), 2.43 2.30 (m, 2H), 2.28
(t, J=4.4 Hz, 2H), 2.07 2.02 (m,
2H), 1.99 1.95 (m, 2H), 1.39
1.16 ppm (m and brs, 15H);
13C NMR (75 MHz): d=173.1, 139.1,
131.7, 127.8, 114.0, 60.2, 34.5, 33.9,
Scheme 5. Synthesis of 34-hydroxyasimicin, 1b and its photolabelingderivative, 1c. a) [Pd(Ph3P)2Cl2], CuI,
Et3N, RT, 2 h; b) [Rh(Ph3P)3Cl], H2, benzene/MeOH (6:1), RT, 16 h; c) DDQ, CH2Cl2/H2O, RT, 1 h; d) 3-(4-
benzoylphenyl)propionate, EDCI, DMAP, CH2Cl2, RT, 16 h; e) BF3¥OEt2, Me2S, 0 8C, 1 h.
couplingreaction in the presence of CuI and Et N to pro-
3
32.6, 29.5, 29.2 (î2), 29.0, 28.0, 14.3 ppm; ESIMS: m/z calcd for
duce the eneyne intermediate 32.[31] Hydrogenation over
Wilkinson×s catalyst afforded the protected acetogenin 33.
Oxidative cleavage of the 4-methoxybenzyloxymethyl ether
with DDQ afforded alcohol 34.[36] Treatment of 34 with
BF3¥Et2O in dimethyl sulfide afforded the fully deprotected
acetogenin 1b. Alternatively, alcohol 34 was acylated with
3-(4-benzoylphenyl)propionate[37] in the presence of EDCI
and DMAP to produce the correspondingester 35, which
was then deprotected usingBF 3¥Et2O in methyl sulfide to
afford the photoaffinity label 1c.
C17H30O2: 266; found: 265 [MÀH]À.
(4R,5R)-5-Hydroxypentadec-14-en-1,4-olide (10): Compound 9 (15.19 g,
57.11 mmol) was added to a cold (08C) solution of AD-mix-b (85.61 g)
and MeSO2NH2 (5.49 g, 57.11 mmol) in tert-BuOH/water (1:1, 560 mL),
and the mixture was stirred at 08C for 12 h and then quenched by the ad-
dition of sodium metabisulfite (85.67 g). The mixture was worked-up
with ethyl acetate and water, solvents were removed under reduced pres-
sure, and the residue was dissolved in methanol (84 mL). Aqueous KOH
(3n, 56 mL) was added, and the mixture was stirred at 608C for 2 h, then
cooled to 08C, acidified with 3n HCl, and extracted with ethyl acetate.
Solvents were removed under reduced pressure, and the residue was dis-
solved in CH2Cl2. p-Toluenesulfonic acid (TsOH, 1.57 g) was added, and
the mixture was stirred at room temperature for 1 h, worked up with sa-
turated aqueous NaHCO3 and CH2Cl2, and purified by column chroma-
tography (silica gel, hexanes/ethyl acetate, 1:1) to give lactone 10 (4.52 g,
31%) in the form of a white solid. [a]D =À23.0 (c=0.98 in CHCl3);
1H NMR (300 MHz): d=5.82 5.71 (m, 1H), 5.00 4.87 (m, 2H), 4.40 (td,
J=6.9, 4.5 Hz, 1H), 3.57 3.51 (m, 1H), 2.66 2.44 (m, 4H), 2.24 2.09 (m,
2H), 2.05 1.98 (m, 2H), 1.55 1.21 ppm (m and brs, 12H); 13C NMR
(75 MHz): d=177.4, 138.9, 113.9, 83.0, 73.3, 33.7, 32.9, 29.4, 29.4 (î2),
29.0, 28.8, 28.7, 25.5, 23.0 ppm; ESIMS: m/z calcd for C15H26O3: 254.19;
found: 255 [M+H+], 277 [M+Na]À), 289 [M+Cl]À.
In conclusion, the synthesis of the target molecule 1c was
achieved through a convergent strategy in a total of 35 steps,
startingwith octa-1,7-diene, 1,4-dihydroxybutane, undec-10-
enal, and (S)-(À)-propylene oxide. While the commercially
available (S)-(À)-propylene oxide provided the asymmetric
center of the butenolide ring, all other stereogenic centers
in the target molecule were achieved either by the Sharpless
AD reaction (C15, C16, C23, and C24) or by the oxidative
cyclization reaction with rhenium(vii) oxide (C19, and C20).
Photolabelingstudies of bovine mitochondrial Complex I
with 1c are currently underway and the results will be re-
ported shortly.
(4R,5R)-4,5-Isopropylidenedioxy-14-en-pentadecanol
(11):
LiAlH4
(2.13 g, 53.28 mmol) was added in portion to a solution of 10 (4.52 g,
17.8 mmol) in dry diethyl ether (35 mL) at 08C. The mixture was stirred
at 08C, then refluxed for another 2 h, cooled, diluted with diethyl ether,
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E. Keinan, S. C. Sinha et al.
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and worked up by dropwise addition of water. After all inorganic materi-
al was precipitated, the solid was filtered to give crude corresponding
triol (3.7 g).
1H NMR (500 MHz): d=5.84 5.79 (m, 1H), 5.43 5.38 (m, 2H), 5.01 4.92
(m, 2H), 4.41 (dt, J=7.3, 4.8 Hz, 1H), 3.60 3.59 (m and brs, 3H), 2.61
2.52 (m, 2H), 2.28 2.03 (m, 8H), 1.50 1.27 (m and brs, 18H), 1.36 ppm
(s, 6H); 13C NMR (100 MHz): d=177.3, 139.0, 130.0, 129.0, 113.4, 107.7,
83.0, 80.7, 80.2, 72.5, 33.6, 32.8, 32.4, 29.6, 29.3, 29.2, 28.9, 28.7, 28.5, 27.2,
26.0 (î2), 23.9, 23.8, 23.0 ppm; ESIMS: m/z calcd for C26H44O5: 436;
found: 459 [M+Na]À, 435 [MÀH]À, 471 [M+Cl]À.
The above-mentioned triol (3.7 g) and TsOH (0.38 g 2.02 mmol) were
dissolved in a mixture of acetone/hexane (116 mL, acetone/hexane=1:2)
and the solution was refluxed for 6 h with Dean-Stark apparatus. The re-
action mixture was worked up by addition of diethyl ether, removal of
the solvent, and purification of the residue by column chromatography
(silica gel, hexane/ethyl acetate, 7:3) to give 11 (3.34 g, 63%) in the form
of a colorless oil. [a]D =+20.8 (c=1.3 in CHCl3); 1H NMR (500 MHz):
d=5.81 5.78 (m, 1H), 5.00 4.93 (m, 2H), 3.68 3.60 (m, 2H), 3.61 3.60
(m, 2H), 2.17 (s, 1H), 2.04 2.03 (m, 2H), 1.72 1.71 (m, 3H), 1.52 1.45
(m, 3H), 1.37 (s, 6H), 1.37 1.28 ppm (m and brs, 12H).
(4R,5R,8R,9S,12R,13R)-9-Hydroxy-12,13-isopropylidenedioxy-5,8-oxido-
tricos-22-en-1,4-olide (14): Re2O7 (3.06 g, 6.33 mmol) was added in por-
tions to a solution of compound 5 (0.92 g, 2.11 mmol) and 2,6-lutidine
(2.11 mL, 19.0 mmol) in dry CH2Cl2 (20 mL). The mixture was stirred
overnight at RT and then quenched by dropwise addition of saturated
solution of NaHCO3 (8 mL) and H2O2 (35% in water, 8 mL). After stir-
ringwas continued for 20 min, the mixture was extracted with CH 2Cl2.
The organic layer was washed with water and dried over MgSO4. Sol-
vents were removed under reduced pressure, and the residue was purified
by column chromatography (silica gel, hexanes/ethyl acetate, 3:1) to give
14 (0.72 g, 76%) in the form of a colorless oil. [a]D =++7.44 (c=1.08 in
CHCl3); 1H NMR (500 MHz): d=5.85 5.77 (m, 1H), 5.00 4.91 (m, 2H),
4.47 4.44 (m, 1H), 4.09 4.06 (m, 1H), 3.91 3.87 (m, 1H), 3.78 3.76 (m,
1H), 3.61 3.55 (m, 2H), 2.70 2.63 (m, 1H), 2.50 2.43 (m, 2H), 2.32 2.25
(m, 1H), 2.21 2.14 (m, 1H), 2.07 2.00 (m, 3H), 1.96 1.86 (m, 3H), 1.83
1.78 (m, 1H), 1.68 1.61 (m, 1H), 1.53 1.28 (m and brs, 15H), 1.37 ppm
(s, 6H); 13C NMR (75 MHz): d=177.4, 139.2, 114.1, 108.0, 83.2, 81.4,
81.1, 81.0 (î2), 71.7, 33.8, 32.7, 29.7, 29.6, 29.4, 29.2, 29.0, 28.9, 28.2, 28.0,
27.3, 27.2, 26.1, 25.4, 24.6 ppm; ESIMS: m/z calcd for C26H44O6: 452;
found: 453 [M+H]À, 451 [MÀH]À, 487 [M+Cl]À.
(4R,5R,8R,9S,12R,13R)-12,13-Isopropylidinedioxy-9-mesyloxy-5,8-oxido-
tricos-22-en-1,4-olide (15): MsCl (0.25 mL, 3.18 mmol) was added to a
solution of 14 (0.72 g, 1.59 mmol) and Et3N (0.89 mL, 6.36 mmol) in
CH2Cl2 (17 mL) at À308C. The mixture was stirred at this temperature
for 0.5 h, was quenched with water, and extracted with CH2Cl2. The or-
ganic layer was washed with water and dried over MgSO4. Solvents were
removed under reduced pressure, and the residue was purified by column
chromatography (silica gel, hexanes/ethyl acetate, 7:3) to yield 15 (0.77 g,
91%) in the form of a colorless oil. [a]D =+12.4 (c=1.39 in CHCl3);
1H NMR (500 MHz): d=5.82 5.77 (m, 1H), 4.98 4.88 (m, 2H), 4.80 4.77
(m, 1H), 4.46 4.42 (m, 1H), 4.07 4.03 (m, 2H), 3.60 3.55 (m, 1H), 3.51
(dt, J=8.8, 2.6 Hz, 1H), 3.02 (s, 3H), 2.61 2.59 (m, 1H), 2.48 2.42 (m,
1H), 2.30 2.23 (m, 1H), 2.14 1.75 (m, 9H), 1.69 1.61 (m, 1H), 1.52 1.44
(m, 4H), 1.33 (s, 6H), 1.33 1.22 ppm (m, 11H); 13C NMR (75 MHz): d=
177.2, 139.1, 114.0, 107.9, 83.6, 81.0, 80.9, 80.8, 80.7, 80.5, 38.5, 33.7, 33.7,
32.6, 31.4, 29.6 (î2), 29.3 (î3), 29.0, 28.8 (î2), 28.4, 28.1, 27.7, 27.2 (î4),
26.0 (î3), 24.5 ppm; ESIMS: m/z calcd for C27H46O8S: 530; found: 531
[M+H]À, 553 [M+Na]À, 529 [MÀH]À, 565 [M+Cl]À.
(4R,5R)-1-Iodo-4,5-isopropylidenedioxy-14-pentadecene (12): Iodine
(3.42 g, 13.44 mmol) was added to a solution of 11 (3.34 g, 11.2 mmol),
PhP3 (4.42 g, 16.8 mmol), and imidazole (1.15 g, 16.8 mmol) in CH2Cl2
(26 mL) at 08C. The mixture was stirred at RT for 2 h and a saturated
solution of NaHCO3 was added, followed by I2 until the color started ap-
pearing. The reaction mixture was worked up with hexanes and water
and the organic phase washed with a 10% aqueous Na2S2O3 solution.
Solvents were removed under vacuum and the residue was purified by
column chromatography (silica gel, hexane/ethyl acetate, 19:1) to give 12
(4.07 g, 89%) as a colorless oil. 1H NMR (300 MHz): d=5.89 5.75 (m,
1H), 5.04 4.91 (m, 2H), 3.62 3.60 (m, 2H), 3.25 (t, J=6.6 Hz, 2H), 2.09
2.01 (m, 4H), 1.71 1.44 (m, 4H), 1.39 (s, 6H), 1.39 1.31 ppm (m and brs,
12H); 13C NMR (75 MHz): d=139.0, 114.0, 107.9, 80.8, 79.9, 33.9, 33.8,
33.0, 30.2, 29.9, 29.6, 29.5, 29.2, 29.0, 27.5, 27.4, 26.2, 7.1 ppm; ESIMS:
m/z calcd for C18H33IO2: 408; found: 409 [M+H]À, 431 [M+Na]À, 407
[MÀH]À, 443 [M+Cl]À.
(4R,5R)-4,5-Isopropylidenedioxy-14-pentadecen-1-yl-triphenylphosphoni-
um iodide (6): A mixture of 12 (4.05, 10 mmol), PPh3 (5.24 g, 20 mmol),
and NaHCO3 (1.68 g, 20 mmol) in CH3CN (120 mL) was heated at reflux
for 16 h. Solvents were removed and the residue was redissolved in
CH2Cl2. Inorganic material was removed by filtration, the solvents were
also removed, and the residue was triturated with diethyl ether to afford
6 (5.25 g, 78%) in the form of a thick syrup. 1H NMR (300 MHz): d=
7.77 7.72 (m, 9H), 7.68 7.62 (m, 6H), 5.79 5.66 (m, 1H), 4.94 4.81 (m,
2H), 3.75 3.62 (m, 2H), 3.58 3.47 (m, 2H), 2.02 1.93 (m, 2H), 1.86 1.65
(m, 2H), 1.45 1.38 (m, 2H), 1.29 (s, 6H), 1.29 1.20 ppm (m, 14H);
13C NMR (75 MHz): d=138.8, 134.8, 134.7, 133.3, 133.2, 130.2, 130.1,
118.1, 117.0, 113.7, 107.7, 80.8, 79.9, 32.6, 32.4, 29.5, 29.3 (î2), 28.9, 28.8,
27.3, 27.2, 26.1 ppm; ESIMS: m/z calcd for C36H48IO2P: 670; found: 705
[M+Cl]À.
(cis,4R,5R,12R,13R)-5-tert-Butyldiphenylsilyloxytricos-12,13-isopropyl-
idenedioxy-8,22-dien-1,4-olide (13): NaHMDS (1.0m in THF, 4.45 mL)
was added to a stirred solution of Wittigsalt 6 (2.98 g, 4.45 mmol) in dry
THF (5 mL) at À788C and the mixture was stirred at the same tempera-
ture for 2 h. HMPA (1.38 mL, 7.94 mmol) and aldehyde 7[22] in THF was
added dropwise, and the mixture was stirred for 16 h at À788C to RT. Sa-
turated aqueous NH4Cl was added and the mixture was extracted with
Et2O. The combined organic layer was washed with brine and dried over
MgSO4. The crude residue was purified by column chromatography
(silica gel, hexanes/ethyl acetate, 10:1) affording compound 13 (2.37 g,
73%) in the form of a light yellow oil. [a]D =À13.4 (c=1.1 in CHCl3);
1H NMR (500 MHz): d=7.71 7.69 (m, 4H), 7.46 7.38 (m, 6H), 5.84 5.77
(m, 1H), 5.26 5.21 (m, 1H), 5.04 4.97 (m, 2H), 4.94 4.92 (m, 1H), 4.53
(dt, J=6.6, 3.7 Hz, 1H), 3.76 3.73 (m, 1H), 3.59 3.51 (m, 2H), 2.58 2.43
(m, 2H), 2.18 2.12 (m, 2H), 2.07 1.88 (m, 6H), 1.71 1.29 (m and brs,
18H), 1.37 (s, 6H), 1.06 ppm (s, 9H); 13C NMR (100 MHz): d=177.1,
139.0, 135.8, 135.7, 133.6, 133.0, 129.8, 129.6, 129.4, 129.0, 127.6, 127.5,
114.1, 107.7, 80.7, 80.6, 80.1, 74.4, 33.7, 32.8, 32.7, 32.2, 29.6, 29.4, 29.3,
29.0, 28.8, 28.4, 27.2, 26.9, 26.0, 23.7, 23.2, 22.8, 19.4 ppm; ESIMS: m/z
calcd for C42H62SiO5: 674; found: 697 [M+Na]À, 673 [MÀH]À, 709
[M+Cl]À.
(4R,5R,8R,9S,12R,13R)-12,13-Dihydroxy-9-mesyloxy-5,8-oxidotricos-22-
en-1,4-olide (16): TsOH (0.415 g, 2.18 mmol) was added to a solution of
15 (0.77 g, 1.45 mmol) in MeOH/water (4:1, 8 mL). The mixture was stir-
red at RT for 16 h, diluted with a saturated solution of NaHCO3, and ex-
tracted with EtOAc. The organic layer was washed with brine and dried
over MgSO4. Solvents were removed under reduced pressure, and the
residue was purified by column chromatography (silica gel, hexanes/ethyl
acetate, 1:1) to give the corresponding triol derivative, 16 (0.55 g, 77%)
as
a
light yellow oil. [a]D =+7.43 (c=1.74 in CHCl3); 1H NMR
(500 MHz): d=5.84 5.76 (m, 1H), 4.99 4.90 (m, 2H), 4.83 4.81 (m, 1H),
4.47 4.44 (m, 1H), 4.09 4.04 (m, 2H), 3.38 3.37 (m, 2H), 3.05 (s, 3H),
2.66 2.61 (m, 1H), 2.43 (m, 4H), 2.29 2.26 (m, 1H), 2.08 2.00 (m, 6H),
1.95 1.90 (m, 3H), 1.70 1.68 (m, 2H), 1.49 1.43 (m, 4H), 1.36 1.25 ppm
(m and brs, 7H); 13C NMR (75 MHz): d=177.3, 139.0, 113.9, 83.9, 81.1,
80.5, 74.3, 38.5, 33.7, 33.5, 29.6, 29.5, 29.4, 29.3, 29.1, 28.9, 28.2, 28.1, 27.8,
26.2, 25.7, 24.6 ppm; ESIMS: m/z calcd for C24H42O8S: 490; found: 491
[M+H]À, 513 [M+Na]À, 525 [M+Cl]À.
(4R,5R,8R,9R,12R,13R)-13-Hydroxy-5,8,9,12-dioxidotricos-22-en-1,4-
olide (4): Compound 16 (0.55 g, 1.12 mmol) was dissolved in pyridine
(15.5 mL), and the mixture was heated at reflux for 3 h, cooled to RT, di-
luted with water, and extracted with EtOAc. The organic layer was first
washed with a cold 3n HCl and then with brine, and dried over MgSO4.
Solvents were removed under reduced pressure, and the residue was pu-
rified by column chromatography (silica gel, hexanes/ethyl acetate, 1:1)
to give 4 (0.40 g, 90%) as a colorless oil. [a]D =++2.04 (c=0.83 in
CHCl3); 1H NMR (500 MHz): d=5.85 5.77 (m, 1H), 5.00 4.91 (m, 2H),
(cis,4R,5R,12R,13R)-5-Hydroxytricos-12,13-isopropylidenedioxy-8,22-
dien-1,4-olide (5): TBAF (1m in THF, 5.3 mL, 5.3 mmol) was added to a
solution of compound 13 (2.36 g, 3.5 mmol) in dry THF (35 mL) at 08C,
and the mixture was stirred for 2 h at RT. Workup usingdiethyl ether/
water followed by purification (silica gel, hexanes/ethyl acetate, 1:1) af-
forded 5 (1.14 g, 81%) as a colorless oil. [a]D =À1.2 (c=1.16 in CHCl3);
2154
¹ 2004 Wiley-VCH VerlagGmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 2149 2158

Total Synthesis of 34-Hydroxyasimicin
2149 2158
4.49 4.45 (m, 1H), 4.09 (dt, J=7.1, 2.3, 1H), 3.91 3.84 (m, 2H), 3.81
3.77 (m, 1H), 3.39 3.36 (m, 1H), 2.70 2.66 (m, 1H), 2.48 2.42 (m, 1H),
2.29 2.24 (m, 2H), 2.05 1.93 (m, 7H), 1.76 1.71 (m, 3H), 1.41 1.35 ppm
(m and brs, 14H); 13C NMR (75 MHz): d=177.3, 138.8, 113.8, 82.6, 82.1,
81.2, 81.1, 80.7, 73.6, 33.5, 33.1, 29.4, 29.2, 29.1, 28.8, 28.6, 28.5, 28.1, 28.0
(x2), 27.5, 25.3, 24.3 ppm; ESIMS: m/z calcd for C23H38O5: 394; found:
395 [M+H]À, 417 [M+Na]À, 393 [MÀH]À, 429 [M+Cl]À.
reaction mixture was washed with saturated aqueous NH4Cl and brine,
and dried over Na2SO4. Solvents were removed, and residue was purified
by column Chromatography (silica gel, hexane/ethyl acetate, 4:1) to
afford 20 (0.186 g, 90%) as a light yellow oil. [a]D =+26.9 (c=1.79 in
CHCl3); 1H NMR (500 MHz): d=7.28 (d, J=8.8 Hz, 2H), 6.88 (d, J=
8.8 Hz, 2H), 4.83 (d, J=7.0 Hz, 2H), 4.73 (s, 2H), 4.67 (dd, J=7.0 Hz,
2.2, 2H), 4.53 (s, 2H), 4.02 3.98 (m, 2H), 3.93 3.90 (m, 2H), 3.80 (s,
3H), 3.63 3.61 (m, 2H), 3.57 (t, J=6.6 Hz, 2H), 3.51 3.48 (m, 2H), 3.39
(s, 3H), 3.39 (s, 3H), 1.94 1.92 (m, 4H), 1.80 1.79 (m, 2H), 1.63 1.58 (m,
8H), 1.47 1.28 (m, 16H), 0.89 (s, 9H), 0.04 ppm (s, 6H); 13C NMR
(100 MHz): d=159.2, 130.0, 129.5, 113.8, 96.6, 94.3, 81.8, 81.7, 81.1, 81.1,
79.5, 79.3, 68.8, 68.0, 63.1, 55.7, 55.2, 33.5, 31.1, 29.8, 29.7, 29.6, 29.4, 28.9,
28.3, 28.2, 27.4, 26.2, 25.9, 25.6, 18.3, À5.3 ppm.
(4R,5R,8R,9R,12R,13R)-5,8,9,12-Dioxidotricos-22-en-1,4,13-triol
(17):
LiAlH4 (77 mg, 2.03 mmol) was added in portions to a stirred solution of
4 (0.40 g, 1.01 mmol) in dry diethyl ether at 08C, and the mixture was al-
lowed to warm to RT, then refluxed for 2 h, cooled back to RT, diluted
with diethyl ether, and worked up by dropwise addition of water. The in-
organic material was filtered off and washed with EtOAc, and the com-
bined organic solution was collected. Solvents were removed under re-
duced pressure, and the residue was purified by column chromatography
(silica gel, ethyl acetate/MeOH, 1:0 19:1) to give 17 (0.34 g, 85%) in the
(4R,5R,8R,9R,12R,13R)-4,13-Di(methoxymethoxy)-23-(p-methoxyben-
zyloxy)methoxy-5,8,9,12-dioxidotricosan-1-ol (21): TBAF (1m in THF,
0.22 mL, 0.22 mmol) was added to a solution of 20 (0.17 g, 0.22 mmol) in
dry THF (2 mL) at 08C. After the mixture was stirred for 2 h at RT, it
was worked up by usingdiethyl ether and water. The crude product was
purified (silica gel, hexane/ethyl acetate, 1:1) affording 21 (138 mg, 95%)
form of
a
colorless oil. [a]D =+7.15 (c=1.57 in CHCl3); 1H NMR
(500 MHz): d=5.84 5.78 (m, 1H), 5.00 4.92 (m, 2H), 3.90 3.83 (m, 4H),
3.69 3.64 (m, 2H), 3.47 3.43 (m, 1H), 3.41 3.37 (m, 1H), 2.60 (brs, 3H),
2.04 1.97 (m, 6H), 1.75 1.26 ppm (m and brs, 22H); 13C NMR
(100 MHz): d=139.1, 114.0, 83.1, 82.9, 81.8, 81.7, 73.8, 73.7, 62.5, 33.7,
33.2, 30.0, 29.6, 29.5, 29.3, 29.1 (î2), 28.9 (î2), 28.8, 28.2 (î2), 25.5;
ESIMS: m/z calcd for C23H42O5: 398.3; found: 421 [M+Na]À, 397
[MÀH]À.
1
as a colorless oil. [a]D =+26.89 (c=1.79 in CHCl3); H NMR (500 MHz):
d=7.28 7.26 (m, 2H), 6.89 6.86 (m, 2H), 4.83 (dd, J=6.6, 2.9 Hz, 2H),
4.72 (s, 2H), 4.68 (t, J=6.6 Hz, 2H), 4.53 (s, 2H), 4.05 3.98 (m, 2H),
3.92 3.90 (m, 2H), 3.80 (s, 3H), 3.67 3.64 (m, 2H), 3.57 3.53 (m, 3H),
3.49 3.46 (m, 1H), 3.40 (s, 3H), 3.39 (s, 3H), 1.96 1.91 (m, 5H), 1.79
1.27 ppm (m, 26H); 13C NMR (100 MHz): d=159.3, 129.8, 129.3, 113.7,
96.7, 96.6, 94.2, 81.7, 81.5, 81.2, 81.2, 79.5, 79.3, 68.8, 68.0, 62.9, 55.8, 55.7,
55.3, 31.2, 29.9, 29.8, 29.7, 29.6, 28.9, 28.4, 28.3, 27.6, 26.4, 25.8 ppm;
ESIMS: m/z calcd for C36H62O10: 654; found: 655 [M+H]À.
(4R,5R,8R,9R,12R,13R)-1-tert-Butyldimethylsilyloxy-4,13-di(methoxy-
methoxy)-5,8,9,12-dioxidotricos-22-ene (18): TBSCl (193 mg, 1.28 mmol)
was added to a stirred solution of 17 (0.34 g, 0.85 mmol), diisopropyle-
thylamine (0.45 mL, 2.56 mmol), and DMAP (42 mg, 0.34 mmol) in dry
CH2Cl2 (15 mL), and the solution was stirred for 6 h at RT. Upon com-
pletion of the reaction (by TLC), the mixture was cooled to 08C, and di-
isopropylethylamine (1.78 mL, 10.2 mmol) and MOMCl (0.87 mL,
11.44 mmol) were added sequentially. The mixture was stirred for anoth-
er 12 h, worked up with water and CH2Cl2, the combined organic layer
was washed with water and dried over MgSO4, and the solvents were re-
moved under reduced pressure. The residue was purified by column chro-
matography (silica gel, hexane/ethyl acetate, 4:1) to give 18 (0.511 g,
96%) in the form of a colorless oil. [a]D =+29.5 (c=7.29 in CHCl3);
1H NMR (500 MHz): d=5.79 5.73 (m, 1H), 4.97 4.88 (m, 2H), 4.79 (dd,
J=7.0, 1.5, 2H), 4.64 (dd, J=6.8, 2.4 Hz, 2H), 3.99 3.94 (m, 2H), 3.89 (t,
J=6.1 Hz, 2H), 3.61 3.57 (m, 2H), 3.48 3.42 (m, 2H), 3.36 (s, 6H), 2.02
1.87 (m, 6H), 1.80 1.72 (m, 2H), 1.67 1.54 (m, 6H), 1.47 1.23 (m and
brs, 14H), 0.86 (s, 9H), 0.01 ppm (s, 6H); 13C NMR (100 MHz): d=
139.1, 114.0, 96.5, 81.7, 81.6, 81.1 (x2), 79.4, 79.2, 63.0, 55.6, 33.7, 31.1,
29.7, 29.5, 29.4, 29.0, 28.8 (î2), 28.2, 28.1, 27.4, 25.9, 25.5, 18.2, À5.4 ppm;
ESIMS: m/z calcd for C33H64O7Si: 600; found: 623 [M+Na]À, 635
[M+Cl]À.
(5R,6R,9R,10R,13R,14R)-1,1-Dibromo-5,14-di(methoxymethoxy)-24-(p-
methoxybenzyloxy) methoxy-6,9,10,13-dioxidotricos-1-ene (22): A solu-
tion of DMSO (0.04 mL, 0.53 mmol) in CH2Cl2 (0.3 mL) was added drop-
wise to a stirred solution of oxalyl chloride (0.15 mL, 0.30 mmol) in
CH2Cl2 (1.5 mL) at À788C under Ar. After the mixture was stirred for
30 min at À788C, a solution of 21 (0.10 g, 0.15 mmol) in CH2Cl2 (0.6 mL)
was added dropwise, and the mixture was stirred at the same temperature
for 1 h. Triethylamine (0.15 mL, 1.07 mmol) was added, and the resulting
mixture was gradually warmed to 08C with stirringand poured into ice-
water. The mixture was extracted with diethyl ether. The extracts were
sequentially washed with cold HCl solution, sat. NaHCO3 solution,
water, and brine. The organic layer was dried over MgSO4 and concen-
trated to give aldehyde (0.10 g). This compound was employed to the
next step without further purification.
Triphenyl phosphine (0.168 g, 0.64 mmol) in CH2Cl2 (0.4 mL) was added
to a stirried solution of CBr4 (0.106 g, 0.32 mmol) in CH2Cl2 (1.3 mL) at
08C. After 10 min, triethylamine (0.17 mL, 1.26 mmol) was added. After
another 10 min, a solution of the aldehyde (99.69 mg) in CH2Cl2 (0.8 mL)
was added dropwise at 08C. The mixture was stirred at 08C for 16 h,
poured into sat. NaHCO3 solution, and then extracted with CH2Cl2. The
extracts were washed with water and brine, dried on Na2SO4, and concen-
trated. The residue was purified by chromatography (silica gel, hexane/
ethyl acetate, 10:1) to afford the dibromide 22 (90.0 mg, 73% from 21).
[a]D =+25.07 (c=4.5 in CHCl3); 1H NMR (500 MHz): d=7.21 7.20 (m,
2H), 6.82 6.80 (m, 2H), 6.36 (t, J=7.15 Hz, 1H), 4.75 (dd, J=6.6,
1.1 Hz, 2H), 4.66 (s, 2H), 4.59 (dd, J=7.0, 3.0 Hz, 2H), 4.46 (s, 2H),
3.95 3.91 (m, 2H), 3.86 3.82 (m, 2H), 3.73 (s, 3H), 3.50 (t, J=6.6 Hz,
2H), 3.45 3.39 (m, 2H), 3.33 (s, 3H), 3.32 (s, 3H), 2.20 2.07 (m, 2H),
1.97 1.83 (m, 4H), 1.75 1.68 (m, 2H), 1.61 1.21 ppm (m, 22H);
13C NMR (100 MHz): d=159.2, 138.3, 130.0, 129.5, 113.8, 96.8, 96.6, 94.3,
88.9, 81.7, 81.3, 81.2, 79.4, 78.8, 68.8, 68.0, 55.8, 55.7, 55.2, 31.1, 29.8, 29.7,
29.6, 29.4, 29.3, 29.0, 28.2, 28.0, 26.2, 25.6 ppm; ESIMS: m/z calcd for
C37H60O9Br2: 806; found: 829 [M+Na]À, 805 [MÀH]À, 841 [M+Cl]À.
(5R,6R,9R,10R,13R,14R)-5,14-Di(methoxymethoxy)-24-(p-methoxyben-
zyloxy)methoxy-6,9,10,13-dioxidotricosan-1-yne (2): A solution of ethyl-
magnesium bromide in THF (1.0m, 0.22 mL, 0.22 mmol) was added drop-
wise to a stirred solution of 22 (90 mg, 0.11 mmol) in THF (1.0 mL) at
08C, and then the mixture was stirred at the same temperature for 0.5 h.
A saturated solution of NH4Cl (1.0 mL) was added and the resultingmix-
ture was extracted with diethyl ether. The extracts were washed with
water and brine, dried, and concentrated. The residue was purified by
column chromatography (silica gel, hexane/ethyl acetate, 4:1) to afford 2
(71 mg, 98%) in the form of a light yellow oil. 1H NMR (500 MHz): d=
(4R,5R,8R,9R,12R,13R)-1-tert-Butyldimethylsilyloxy-4,13-di(methoxy-
methoxy)-5,8,9,12-dioxidotricosan-23-ol (19):
A solution of olefin 18
(0.228 g, 0.38 mmol) in THF (4 mL) was treated with 9-BBN (0.5m in
THF, 1.36 mL, 0.68 mmol) at 08C, and the resultingsolution was stirred
at RT for 4 h. NaOH (3m, 0.3 mL, 0.94 mmol) and 30% H2O2 (0.07 mL,
0.86 mmol) were added to this solution at 08C, and stirringwas continued
for 1 h at RT. The reaction mixture was extracted with diethyl ether,
washed with water and brine, dried, and concentrated. The residue was
purified by column chromatography (silica gel, hexane/ethyl acetate, 1:1)
to give 19 (0.20 g, 87%) in the form of a colorless oil. [a]D =+30.0 (c=
1.47 in CHCl3); 1H NMR (500 MHz): d=4.82 (d, J=7.0 Hz, 2H), 4.67(d,
J=7.0 Hz, 2H), 3.99 3.98 (m, 2H), 3.91 (m and brs, 2H), 3.64 3.61 (m,
4H), 3.47 (m and brs, 2H), 3.39 (s, 6H), 1.93 1.92 (m, 4H), 1.80 1.78 (m,
2H), 1.67 1.53 (m, 8H), 1.45 1.43 (m, 5H), 1.27 (m and brs, 11H), 0.88
(s, 9H), 0.04 ppm (s, 6H); 13C NMR (75 MHz): d=96.9, 81.8, 81.7, 81.2,
81.1, 79.4, 79.3, 63.0, 55.7, 32.8, 31.1, 29.8, 29.5, 29.5, 29.4, 28.9, 28.3, 28.2,
27.4, 25.9, 25.7, 25.6, 18.3, À5.3 ppm; ESIMS: m/z calcd for C33H66O8Si:
618.4; found: 641 [M+Na], 653 [M+Cl]À.
(4R,5R,8R,9R,12R,13R)-1-tert-Butyldimethylsilyloxy-4,13-di(methoxy-
methoxy)-23-(p-methoxybenzyloxy)methoxy-5,8,9,12-dioxidotricosane
(20): A solution of crude p-methoxybenzyloxy-methyl chloride (0.137 mg,
0.74 mmol) in 3.5 mL of CH2Cl2 was added dropwise to a cooled (08C)
solution of 19 (0.152 g, 0.245 mmol) and diiospropylethylamine (0.21 mL,
1.23 mmol) in CH2Cl2 (14 mL). After the addition was complete, the re-
action mixture was allowed to warm to RT and was stirred for 3 h. The
2155
Chem. Eur. J. 2004, 10, 2149 2158
www.chemeurj.org
¹ 2004 Wiley-VCH VerlagGmbH & Co. KGaA, Weinheim

E. Keinan, S. C. Sinha et al.
FULL PAPER
7.28 (d, J=8.5 Hz, 2H), 6.89 (d, J=8.5 Hz, 2H), 4.83 (dd, J=6.6, 2.0 Hz,
2H), 4.73 (s, 2H), 4.69 (dd, J=15.5, 6.6 Hz, 2H), 4.54 (s, 2H), 4.04 3.98
(m, 2H), 3.95 3.90 (m, 2H), 3.81 (s, 3H), 3.64 3.60 (m, 1H), 3.58 (t, J=
6.6 Hz, 2H), 3.49 3.46 (m, 1H), 3.41 (s, 3H), 3.40 (s, 3H), 2.37 2.32 (m,
2H), 1.99 1.92 (m, 5H), 1.81 1.57 (m, 10H), 1.46 1.26 ppm (m, 14H);
13C NMR (100 MHz): d=159.2, 130.0, 129.5, 113.8, 97.0, 96.7, 94.3, 84.2,
83.3, 81.8, 81.5, 81.3, 81.1, 79.5, 78.2, 68.8, 68.5, 68.0, 55.9, 55.7, 55.3, 31.1,
30.2, 29.8, 29.7, 29.6, 29.5, 28.3, 26.2, 25.6, 14.8 ppm; ESIMS: m/z calcd
for C37H60O9: 648; found: 671 [M+Na]À.
5.8 mmol) and HMPA (2.9 g, 2.8 mL, 16 mmol) in THF (5 mL) were
added and the mixture was stirred at RT for 20 h. The mixture was
worked up with saturated aqueous NH4Cl and diethyl ether, the organic
layer was dried over MgSO4 and concentrated under reduced pressure,
and the residue was purified by column chromatography (silica gel, hex-
anes/diethyl ether, 1:0 9:1) to give 29 (1.2 g, 50%) in the form of a color-
less oil (mixture of two diastereomers). 1H NMR of the major product
(300 MHz): d=7.54, À7.49 (m, 2H), 7.34 7.27 (m, 3H), 5.78 5.66 (m,
1H), 4.98 4.88 (m, 2H), 4.50 4.40 (m, 1H), 4.25 4.21 (m, 1H), 3.02 (dd,
J=14.1, 7.5 Hz, 1H), 2.05 1.76 (m, 5H), 1.45 1.19 (m and brs, 9H), 0.89
(d, J=6.4 Hz, 3H), 0.88 (s, 9H), 0.13 (s, 3H), 0.10 ppm (s, 3H); ESIMS:
m/z calcd for C25H40O3SSi: 448.73; found: 471 [M+Na]À, 483 [M+Cl]À.
(2R)-Oct-7-en-1,2-diol (24): AD-mix-b (141 g) was added to a mixture of
1,7-octadiene (11.1 g, 100 mmol) in tBuOH/water (2:1, 570 mL) at 08C
and the mixture was stirred at this temperature for 18 h. The mixture was
worked up by the slow addition of Na2S2O5 (47 g), diluted with water and
extracted with EtOAc. Solvents were removed under reduced pressure
and the residue was purified by column chromatography (silica gel, hex-
anes/EtOAc, 1:1) to give 24 (4.85 g, 34%) in the form of a colorless oil.
1H NMR (300 MHz): d=5.90 5.85 (m, 1H), 5.02 4.91 (m, 2H), 3.67 3.62
(m, 1H), 3.62 (d, J=11.3 Hz, 1H), 3.39 (dd, J=10.6, 8.1 Hz, 1H), 2.76
(brs, 2H), 2.02 (q, J=6.7 Hz, 2H), 1.45 1.25 ppm (m and brs, 6H);
13C NMR (75 MHz): d=138.6, 114.4, 72.2, 66.8, 33.7, 33.1, 28.9, 25.1 ppm;
ESIMS: m/z calcd for C8H16O2: 144.12; found: 145 [M+H]À, 167
[M+Na]À, 143 [MÀH]À.
(2R)-1-Tosyloxyoct-7-en-2-ol (25): TsCl (2.76 g, 14.5 mmol) was added to
a solution of 24 (1.5 g, 10.4 mmol), 2,4,6-collidine (11.88 g, 93.6 mmol),
and DMAP (1.26 g, 10.4 mmol) in dry CH2Cl2 (20 mL) at 08C. The mix-
ture was stirred between 08C and RT for 16 h, and then diluted with
water and extracted with CH2Cl2. The combined organic layer was
washed with dilute HCl and then with water, and dried over anhydrous
MgSO4. Solvents were evaporated under vacuum and the resultant resi-
due was purified by column chromatography (silica gel, benzene/EtOAc,
9:1) affording 25 (2.1 g, 65%) in the form of a colorless oil. [a]D =À4.1
(c=0.35 in CHCl3); 1H NMR (300 MHz): d=7.79 (d, J=8.1 Hz, 2H),
7.35 (d, J=8.1 Hz, 2H), 5.82 5.71 (m, 1H), 5.02 4.92 (m, 2H), 4.05 (dd,
J=9.6, 2.7 Hz, 1H), 3.92 3.84 (m, 2H), 2.47 (s, 3H), 2.04 2.0 (m,3H),
1.47 1.31 ppm (m and brs, 6H); ESIMS: m/z calcd for C15H22O4S: 298;
found: 297 [MÀH]À, 333 [M+Cl]À.
(4S,2’R)-2-(2’-tert-Butyldimethylsilyloxy-oct-7’-en-1’-yl)pent-2-en-1,4-
olide (30): m-CPBA (0.77 g, 75%, 3.35 mmol) was added in portions to a
solution of 29 (1.0 g, 2.23 mmol) in dry CH2Cl2 (15 mL) at 08C. The mix-
ture was stirred at this temperature for 20 min, then worked up with a sa-
turated solution of NaHCO3 and CH2Cl2; the combined organic layers
were dried over MgSO4 and the solvents were removed under reduced
pressure. The residue was dissolved in toluene (30 mL) and heated at the
reflux temperature for 2 h; solvents were removed under reduced pres-
sure and the residue was purified by column chromatography (silica gel,
hexanes/diethyl ether, 9:1 7:3) to give 30 (0.56 g, 75%) in the form of a
colorless oil. [a]D =+16.0 (c=0.9 in CHCl3); 1H NMR (300 MHz): d=
7.10 (s, 1H), 5.82 5.68 (m, 1H), 4.99 4.87 (m, 2H), 3.94 À388 (m, 1H),
2.41 (d, J=5.6 Hz, 2H), 2.02 (q, J=7.5 Hz, 2H), 1.42 1.22 (m and brs,
9H), 0.85 (s, 9H), 0.23 (s, 3H), 0.08 ppm (s, 3H); 13C NMR (75 MHz):
d=173.5, 151.2, 138.4, 130.4, 114.1, 69.9, 36.6, 33.5, 32.6, 28.8, 25.7, 24.5,
18.9, 17.9, À4.5 ppm; ESIMS: m/z calcd for C19H34O3Si: 338; found: 361
[M+Na]À, 337 [MÀH]À.
(4S,2’R)-2-(2’-tert-Butyldimethylsilyloxyhept-7’-al-1’-yl)pent-2-en-1,4-
olide (31): OsO4 (0.25 g, 1 mmol) was added to a solution of 30 (0.26 g,
0.77 mmol) in THF/water (4:1, 16 mL) under argon. The mixture was stir-
red for 5 min, and sodium periodate (0.83 g, 3.9 mmol) was added over a
10 min in three portions. The mixture was stirred for 3 h and then diluted
with diethyl ether (30 mL) and water (25 mL). The aqueous phase was
extracted with additional diethyl ether and the combined organic layers
were washed with brine, dried over MgSO4, and concentrated under re-
duced pressure. The residue was purified by column chromatography
(silica gel, hexanes/diethyl ether, 7:3 3:7) to provide 31 (0.185 g, 71%) in
the form of a colorless oil. 1H NMR (300 MHz): d=9.71 (t, J=1.8 Hz,
1H), 7.07 (s, 1H), 4.99 (q, J=6.8 Hz, 1H), 3.95 3.88 (m, 1H), 2.42 À2.36
(m, 4H), 1.61 À1.17 (m, brs, 9H), 0.84 (s, 9H), 0.12 (s, 3H), 0.04 ppm (s,
3H); ESIMS: m/z calcd for C18H32O4Si: 340.56; found: 339 [MÀH]À.
(2R)-1-Tosyloxy-2-tert-butyldimethylsilyloxyoct-7-ene (26): TBSOTf
(2.12 g, 8.0 mmol) was added to a solution of 25 (2 g, 6.7 mmol) and 2,6-
lutidine (1.07 g, 10.1 mmol) in dry CH2Cl2 (25 mL) at À788C. The mix-
ture was stirred at the same temperature for 1.5 h, then worked up with
water and CH2Cl2. The organic layer was dried over MgSO4 and concen-
trated under reduced pressure. The residue was purified by column chro-
matography (silica gel, hexanes/EtOAc) to give 26 (2.65 g, 96%) in the
form of colorless oil. [a]D =+3.0 (c=0.45 in CHCl3); 1H NMR
(300 MHz): d=7.76 (d, J=8.1 Hz, 2H), 7.31 (d, J=8.1 Hz, 2H), 5.82
5.66 (m, 1H), 4.99 4.83 (m, 2H), 3.88 3.79 (m, 3H), 2.44 (s, 3H), 2.05
(4S,2’R)-2-(2’-tert-Butyldimethylsilyloxy-8’-iodooct-7’-en-1-yl)pent-2-en-
1,4-olide (3): A mixture of aldehyde 31 (110 mg, 0.32 mmol) and iodo-
form (260 mg, 0.66 mmol) in dry THF (5 mL) was added dropwise to a
solution of CrCl2 (240 mg, 1.94 mmol) in dry THF (3 mL) at 08C and stir-
red for 4 h at the same temperature. The reaction was quenched by addi-
tion of water and extracted with diethyl ether. The combined diethyl
ether layer was washed with brine, dried over MgSO4, and evaporated to
a residue which was chromatographed over (silica gel, hexanes/EtOAc,
9:1) to yield iodide 3 (90 mg, 60%) as a mixture of trans and cis isomers
1.95 (m, 2H), 1.45 1.22 (m and brs, 6H), 0.82 (s, 9H), 0.11 (s, 3H),
13
0.04 ppm (s, 3H);
C NMR (75 MHz): d=144.6, 138.4, 132.8, 129.6,
127.7, 114.4, 73.0, 69.9, 33.9, 33.6, 28.8, 25.7, 24.3, 21.6, 18, À4.5
À4.7 ppm; ESIMS: m/z calcd for C21H36O4SSi: 412; found: 435 [M+Na]À,
447 [M+Cl]À.
1
(2R)-2-tert-Butyldimethylsilyloxy-1-iodooct-7-ene (27): A mixture of 26
(2.62 g, 6.26 mmol), NaI (9.54 g, 63.6 mmol) and NaHCO3 (0.53 g,
6.36 mmol) in dry acetone (80 mL) was stirred at reflux temperature for
38 h. Solvent was removed under reduced pressure and the residue was
dissolved in water and extracted with EtOAc. The organic layer was
washed with aqueous Na2S2O3 and brine, dried over MgSO4, and concen-
trated under reduced pressure. The residue was purified by column chro-
matography (silica gel, hexanes/EtOAc) to afford 27 (2.2 g, 95%) in the
(5:4) in the form of an oil. H NMR (300 MHz): d=7.10 (d, J=1.5, 1H),
6.53 6.44(m, 1H), 5.82 5.68 (m, 1H), 4.99 4.87 (m, 2H), 3.94 388 (m,
1H), 2.41 (d, J=5.6 Hz, 2H), 2.02 (q, J=7.5 Hz, 2H), 1.42 1.22 (m and
brs, 9H), 0.85 (s, 9H), 0.28 (s, 3H), 0.11 ppm (s, 3H); ESIMS: m/z calcd
for C19H33IO3Si: 464.95; found: 487 [M+Na]À, 463 [MÀH]À, 499
[M+Cl]À.
{9(E,Z)}-4-tert-Butyldimethylsilyloxy-15,24-di(methoxymethoxy)-34-(p-
methoxybenzyloxy)methyoxyasimicin-9-en-11-yne (32): To a stirred solu-
tion of 2 (54.3 mg, 83 mmol) and vinyl iodide 3 (65.3 mg, 141 mmol) in
Et3N (1.6 mL) were added (Ph3P)2PdCl2 (5.9 mg, 8.4 mmol) and CuI
(5.1 mg, 26.8 mmol) at room temperature, and the reaction mixture was
stirred at room temperature for 2 h and poured into ice-water. The re-
sultingmixture was extracted with ethyl acetate. The extracts were
washed sequentially with cold HCl (10%) solution, water, saturated
NaHCO3 solution, water, and brine. Organic layer was dried and concen-
trated, and the residue was purified by column chromatography (silica
gel, hexane/ethyl acetate, 2:1) to give compound 32 (89.5 mg, 83%) as a
form of
a
colorless oil. [a]D =+7.0 (c=0.85 in CHCl3); 1H NMR
(300 MHz): d=5.78 5.66 (m, 1H), 4.96 4.84 (m, 2H), 3.49 3.44 (m, 1H),
3.11 (d, J=5.4 Hz, 2H), 1.98 (q, J=7.2 Hz, 2H), 1.55 1.16 (m, 6H), 0.83
(s, 9H), 0.09 (s, 3H), 0.02 ppm (s, 3H); 13C NMR (75 MHz): d=138.6,
114.4, 71.4, 36.8, 33.7, 28.9, 25.9, 24.5, 18.2, 14.1, À4.2, À4.5 ppm; ESIMS:
m/z calcd for C14H29IOSi: 368.33; found: 369 [M+H]À, 403 [M+Cl]À.
(2RS,4S,2’R)-2-(2’-tert-Butyldimethylsilyloxyoct-7’-en-1’-yl)-2-(phenylsul-
fanyl)pentan-1,4-olide (29): Lactone 28[34] (1.1 g, 5.29 mmol) in dry THF
(5 mL) was added dropwise to an ice-cold solution of LDA (5.8 mmol,
prepared from 5.8 mmol nBuLi and 6.3 mmol diisopropylamine in 20 mL
dry THF). The mixture was stirred for 30 min, iodide 27 (2.12 g,
1
stereoisomeric mixture. H NMR (500 MHz): d=7.28 (d, J=8.8 Hz, 2H),
7.12 (brs, 1H), 6.88 (d, J=8.8 Hz, 2H), 6.05 5.99 (m, 1H), 5.43 (d, J=
2156
¹ 2004 Wiley-VCH VerlagGmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2004, 10, 2149 2158

Total Synthesis of 34-Hydroxyasimicin
2149 2158
15.8 Hz, 1H), 5.01 (dd, J=13.0, 6.0 Hz, 1H), 4.83 (d, J=6.6 Hz, 2H),
4.73 (s, 2H), 4.69 (dd, J=16.3, 6.8 Hz, 2H), 4.53 (s, 2H), 4.03 3.89 (m,
5H), 3.81 (s, 3H), 3.62 3.60 (m, 1H), 3.57 (t, J=6.6, 2H), 3.48 3.46 (m,
1H), 3.40 (s, 3H), 3.40 (s, 3H), 2.46 2.40 (m, 4H), 2.07 2.05 (m, 2H),
1.97 1.92 (m, 4H), 1.77 1.72 (m, 4H), 1.69 1.57 (m, 6H), 1.42 1.25 (m,
23H), 0.88 (s, 9H), 0.05 (s, 3H), 0.02 ppm (s, 3H); 13C NMR (100 MHz):
d=173.9, 159.1, 151.5, 143.1, 142.3, 130.6, 129.9, 129.4, 113.7, 109.9, 96.8,
96.6, 94.2, 88.0, 81.7, 81.5, 81.2, 81.1, 79.4, 78.4, 77.4, 69.9, 68.8, 67.9, 55.8,
55.6, 55.2, 36.6, 32.8, 32.6, 31.1, 30.4, 29.9, 29.7, 29.6, 29.5, 29.4, 28.8, 28.2,
26.2, 25.8, 25.5, 24.5, 18.9, 17.9, 15.7, À4.5 ppm; ESIMS: m/z calcd for
C56H92O12Si: 984.6; found: 1007.6 [M+Na]À, 983.4 [MÀH]À, 1019.4
[M+Cl]À.
in CHCl3); 1H NMR (500 MHz): d=7.80 7.75 (m, 4H),7.61 7.57 (m,
1H), 7.50 7.47 (m, 2H), 7.34 7.32 (m, 2H), 7.13 (d, J=1.1 Hz, 1H),
5.02 5.00 (m, 1H), 4.83 (dd, J=7.0, 1.5 Hz, 2H), 4.68 (d, J=6.6 Hz, 2H),
4.08 (t, J=6.8 Hz, 2H), 4.02 3.90 (m, 5H), 3.49 3.48 (m, 2H), 3.40 (s,
6H), 3.05 (t, J=7.7 Hz, 2H), 2.68 (t, J=6.6 Hz, 2H), 2.43 2.42 (m, 2H),
1.95 1.92 (m, 3H), 1.78 1.75 (m, 2H), 1.65 1.60 (m, 12H), 1.46 1.41 (m,
10H), 1.26 (m, 22H), 0.88 (s, 9H), 0.06 (s, 3H), 0.03 ppm (s, 3H);
13C NMR(100 MHz): d=200.8, 178.5, 177.1, 155.9, 150.1, 142.2, 140.1,
136.7, 135.3, 134.9, 134.4, 132.7 (î2), 101.1, 86.2, 85.7, 84.0, 81.8, 74.6,
69.3, 60.2, 41.4, 39.8, 37.2, 36.4, 35.6, 35.4, 34.3, 34.2, 34.0 (x3), 33.7, 33.5,
33.1, 32.7, 30.4, 30.3, 30.1, 29.6, 23.4, 22.5, À4.5 ppm; ESIMS: m/z calcd
for C63H100O12Si: 1076.7; found: 1100 [M+Na]À, 1076 [MÀH]À, 1112
[M+Cl].
4-tert-Butyldimethylsilyloxy-15,24-di(methoxymethoxy)-34-(p-methoxy-
benzyloxymethoxy)asimicin (33): A mixture of 32 (89.5 mg, 91 mmol) and
tris(triphenylphosphine)rhodium chloride (65 mg, 70 mmol) in benzene/
methanol (1:1, 14 mL) was stirred at room temperature for 16 h under
hydrogen atmosphere and concentrated, The residue was purified by
column chromatography (silica gel, hexane/ethyl acetate, 1:1) to give 33
(81.2 mg, 90%) as a colorless oil. [a]D =+29.47 (c=0.57 in CHCl3);
1H NMR (500 MHz): d=7.28 (d, J=8.45 Hz, 2H), 7.13 (brs, 1H), 6.89
(d, J=8.45 Hz, 2H), 5.01 5.00 (m, 1H), 4.83 (d, J=6.95 Hz, 2H), 4.73 (s,
2H), 4.68 (d, J=6.6 Hz, 2H), 4.54 (s, 2H), 4.03 3.98 (m, 2H), 3.97 3.91
(m, 3H), 3.81 (s, 3H), 3.58 (t, J=6.6 Hz, 2H), 3.48 (m, 2H), 3.40 (s, 6H),
2.43 (d, J=5.5 Hz, 2H), 1.93 1.92 (m, 4H), 1.78 (m, 2H), 1.68 1.57 (m,
6H), 1.47 1.26 (m, 37H), 0.88 (s, 9H), 0.05 (s, 3H), 0.03 ppm (s, 3H);
13C NMR (100 MHz): d=174.0, 159.1, 151.4, 130.7, 129.9, 129.4, 113.7,
96.6, 94.2, 81.6, 81.1, 79.4, 77.4, 70.1, 68.8, 68.0, 55.6, 55.2, 36.9, 32.6, 31.1,
29.7, 29.6, 29.5, 29.4, 28.2, 26.2, 25.8, 25.5, 25.0, 18.9, 18.0, À4.5 ppm;
ESIMS: m/z calcd for C56H98O12Si: 990.68; found: 1014 [M+Na]À, 990
[MÀH]À, 1026 [M+Cl]À.
BF3¥Et2O (58 mL) was added to a solution of 35 (8.4 mg, 7.7 mmol) in
methylsulfide (0.45 mL) at 08C, and the mixture was stirred at this tem-
perature for 1 h. After addition of saturated NaHCO3 solution, the result-
ingmixture was extracted with EtOAc. The organic phase was washed
with water and brine and dried in Na2SO4. This crude residue was puri-
fied by column chromatography (silica gel, ethyl acetate/MeOH, 10:1) to
give 1c (5.0 mg, 74%) as a colorless oil. [a]D =+8.9 (c=0.27 in CHCl3);
1H NMR (500 MHz): d=7.80 7.75 (m, 4H), 7.60 7.58 (m, 1H), 7.50 7.47
(m, 2H), 7.33 7.32 (m, 2H), 7.19 (d, J=1.1 Hz, 1H), 5.08 5.04 (m, 1H),
4.07 (t, J=6.7 Hz, 2H), 3.89 3.82 (m, 5H), 3.39 (brs, 2H), 3.05 (t, J=
7.7 Hz, 2H), 2.70 (t, J=7.7 Hz, 2H), 2.55 2.51(m, 1H), 2.45 (brs, 2H),
2.43 2.38 (m, 1H), 2.30 (brs, 1H), 2.00 1.98 (m, 4H), 1.71 1.59 (m,
12H), 1.44 1.27 ppm (m, 33H); 13C NMR (125 MHz): d=196.4, 174.6,
172.6, 151.8, 145.6, 137.7, 135.7, 132.3, 131.2, 130.5, 130.0, 128.3, 83.2,
81.8, 78.0, 74.1, 70.0, 64.8, 37.4, 35.4, 33.4, 33.3, 30.9, 29.7 (î2), 29.6, 29.5,
29.2, 30.0, 28.6, 28.4, 25.9, 25.6 (î3), 19.1 ppm; HRMS calcd for
C53H78O10Na: 897.5487; found: 897.5457 [M+Na]À.
4-tert-Butyldimethylsilyloxy-15,24-di(methoxymethoxy)-34-hydroxyasimi-
cin (34): DDQ (24 mg, 106 mmol) was added to a solution of ether 33
(69.8 mg, 70.5 mmol) in H2O/CH2Cl2 (1:10, 1.3 mL). Saturated NaHCO3
was added after 1 h, and the aqueous phase was extracted with CH2Cl2.
The combined organic phases were dried and concentrated. The residue
was purified by column chromatography (silica gel, hexane/ethyl acetate,
1:1 0:1) to give 34 (54.7 mg, 92%) as a colorless oil. [a]D =+29.7 (c=2.7
in CHCl3); 1H NMR (500 MHz): d=7.13 (d, J=1.1 Hz, 1H), 5.03 5.00
(m, 1H), 4.83 (dd, J=6.8, 2.0 Hz, 2H), 4.68 (d, J=6.6 Hz, 2H), 4.02 3.91
(m, 5H), 3.64 (t, J=6.6 Hz, 2H), 3.49 3.46 (m, 2H), 3.40 (s, 6H), 2.43 (d,
J=5.5 Hz, 2H), 1.95 1.91 (m, 4H), 1.81 1.74 (m, 2H), 1.66 1.55 (m,
10H), 1.47 1.26 (m, 33H), 0.88 (s, 9H), 0.06 (s, 3H), 0.03 ppm (s, 3H);
13C NMR (100 MHz): d=174.0, 151.5, 130.8, 96.6, 81.7, 81.6, 81.2, 79.4,
77.4, 70.1, 63.0, 55.7, 36.9, 32.7 (î2), 31.1, 29.8, 29.7 (î2), 29.6, 29.5 (î2),
29.4, 28.2, 25.8, 25.7, 25.6, 25.5, 25.1, 18.9, 18.0, À4.5 ppm; ESIMS: m/z
calcd for C47H88O10Si: 840.6; found: 842 [M+H]À, 864 [M+Na]À, 840
[MÀH]À, 876 [M+Cl]À.
34-Hydroxyasimicin (1b): BF3¥Et2O (0.08 mL, 0.654 mmol) was added
dropwise to a solution of 34 (9.2 mg, 10.9 mmol) in dimethyl sulfide
(0.5 mL) at 08C, the mixture as stirred for 1 h, quenched with saturated
NaHCO3, and then diluted with EtOAc. The mixture was then washed
with water and brine, dried over MgSO4, and concentrated. The residue
was purified by column chromatography (silica gel, ethyl acetate/metha-
nol, 20:1 10:1) to give 1b (4.7 mg, 68%) as a colorless oil. [a]D =+15.2
(c=0.33 in CH3OH); 1H NMR (500 MHz, [D4]methanol): d=7.35 (dd,
J=2.8, 1.3 Hz, 1H), 5.11 5.07 (m, 1H), 3.87 3.83 (m, 4H), 3.79 3.77 (m,
1H), 3.54 (t, J=6.6 Hz, 2H), 3.41 3.3.37 (m, 2H), 2.43 2.39 (m, 1H),
2.35 2.31(m, 1H), 1.99 1.95 (m, 4H), 1.74 1.63 (m, 4H), 1.54 1.42(m,
10H), 1.41 1.39 (m, 3H), 1.36 1.29 ppm (m, 28H); 13C NMR (125 MHz,
[D4]methanol): d=176.6, 154.5, 131.7, 84.4, 83.6, 79.9, 75.0, 70.6, 63.2,
38.5, 34.5, 34.1, 33.8, 31.0, 30.9, 30.8, 29.9, 29.4, 27.1 (î2), 26.9, 19.3 ppm;
HRMS: m/z: calcd for C37H66O8Na: 661.4655; found: 661.4629 [M+Na]À.
Acknowledgement
We thank the Israel US binational Science Foundation, the CapCure
Foundation, and the German Israeli Project Cooperation (DIP) for fi-
nancial support. H.H. and L.J.D.S. thank the Skaggs Institute for Chemi-
cal Biology for postdoctoral fellowships.
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Received: September 20, 2003 [F5557]
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