Total synthesis of (+)-batzelladine A and (-)-batzelladine D, and identification of their target protein

Article abstract of DOI:10.1002/chem.200500852

Asymmetric total synthesis of batzelladine A (1) and batzelladine D (2) has been achieved. Our synthesis of batzelladines features 1) stereoselective construction of the cyclic guanidine system by means of successive 1,3-dipolar cycloaddition reaction and

Full text of DOI:10.1002/chem.200500852

DOI: 10.1002/chem.200500852
Total Synthesis of (+)-Batzelladine A and (À)-Batzelladine D, and
Identification of Their Target Protein
Jun Shimokawa,[b] Takanori Ishiwata,[c] Koji Shirai,[a] Hiroyuki Koshino,[c] Aya Tanatani,[b]
[a]
Tadashi Nakata,[c, d] Yuichi Hashimoto,[b] andKazuo Nagasawa*
Abstract: Asymmetric total synthesis
of batzelladine A (1) and batzella-
dine D (2) has been achieved. Our syn-
thesis of batzelladines features 1) ste-
reoselective construction of the cyclic
guanidine system by means of succes-
sive 1,3-dipolar cycloaddition reaction
and subsequent cyclization, 2) direct
esterification of the bicyclic carboxylic
acid 35 with the guanidine alcohol 8 or
59 to construct the whole carbon skele-
ton of batzelladines, and 3) one-step
formation of the a,b-unsaturated alde-
hyde 53 from the primary alcohol 47
ruthenate (TPAP), providing an effi-
cient route to the left-hand bicyclic
guanidine alcohol of batzelladine A
(1). With the synthetic compounds 1
and 2 in hand, their target protein was
examined by using immobilized CD4
and gp120 affinity gels. The results in-
dicated that batzelladines A (1) and D
(2) bind specifically to CD4.
with
tetra-n-propylammoniumper-
Keywords: batzelladine · guanidine ·
inhibitors · natural products · total
synthesis
Introduction
Batzelladines A–I are a novel class of polycyclic guanidine
alkaloids isolated from Bahamian (batzelladines A (1), B, C,
D (2), E) and Jamaican sponge (batzelladines F (3), G, H, I)
by a SmithKline Beecham group in 1995 and 1997, respec-
tively.[1,2] The structural feature of this family is a bicyclic
and/or tricyclic guanidine structure, which is tethered by an
alkyl ester unit. The unique structures of batzelladines have
inspired considerable synthetic attention. Murphy et al. and
Snider et al. independently reported the synthesis of a tricy-
[a] K. Shirai, Prof. K. Nagasawa
Department of Biotechnology and Life Science
Faculty of Technology
Tokyo University of Agriculture and Technology
2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)
Fax : (+81)42-388-7295
E-mail: knaga@cc.tuat.ac.jp
[b] J. Shimokawa, Dr. A. Tanatani, Prof. Y. Hashimoto
Institute of Molecular and Cellular Biosciences
The University of Tokyo
1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)
[c] T. Ishiwata, Dr. H. Koshino, Prof. T. Nakata
RIKEN (The Institute of Physical and Chemical Research)
2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan)
clic guanidine moiety corresponding to the left-hand tricy-
clic guanidine portion of batzelladine F (3) by a biomimetic
[d] Prof. T. Nakata
route.[3,4] In 1996 Snider et al. reported a total synthesis of
Department of Chemistry, Faculty of Science
Tokyo University of Science
[3b]
batzelladine Ethrough a biomimetic synthetic route.
Sub-
1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)
sequently, Overman et al. reported the total synthesis of bat-
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FULL PAPER
zelladines D (2)[5] and F (3)[6] by applying a tethered Biginel-
li reaction. Quite recently, Gin et al. reported the total syn-
thesis of 2 by using [4+2] annulation of vinyl carbodiimides
with N-alkylimines.[7] These synthetic successes, together
with synthetic studies from other groups,[8–13] greatly contrib-
uted to structure revisions of batzelladines.
by successive 1,3-dipolar cycloaddition reaction[13] between
the nitrone 7 and olefins. In this sequential process, hydroxyl
groups on the side chains of pyrrolidine are introduced, and
the newly generated stereochemistry at the C2- and C5-posi-
tions of pyrrolidine and at the hydroxyl groups on the side
chains of 6 can be controlled simultaneously (Scheme 1).
Moreover various substituents can be installed simply by
changing the olefins. So it should be possible to synthesize
stereoselectively various types of cyclic guanidines, as seen
in batzelladines.
Batzelladines have been reported to disrupt protein–pro-
tein interactions. For example, batzelladines A–Eblock in-
teraction between the surface of the HIV envelope glyco-
protein gp120 and the extracellular domains of human CD4
receptor protein.[1a] Batzelladines F (3) and G induce disso-
ciation of the complex between the protein kinase p56lck and
CD4,[1b] and synthetic derivatives of batzelladines were re-
ported to disrupt Nef–p53, Nef–actin, and Nef–p56lck inter-
actions.[14] Elucidation of the mechanism by which protein–
protein interactions are modulated by these small molecules
is of great interest, since protein–protein associations are
important in all aspects of cell biochemistry. Moreover,
small molecules that influence protein–protein association
would be new biological tools and potential therapeutic
agents.[15] In particular, batzelladines or their derivatives
may prove to be applicable for AIDS treatment. Because of
our interest in the control of protein–protein interactions
with small molecules, we have started the synthetic studies
on batzelladines, and we recently have accomplished the
total synthesis of (Æ)-batzelladine D (2)[16] and (+)-batzella-
dine A (1).[17] In this article, we describe the asymmetric
total synthesis of (À)-batzelladine D (2) and, full detail of
our synthetic studies on (+)-batzelladine A (1). We also de-
scribe the identification of target protein of batzelladines as
the CD4 cell-surface receptor protein on T-cells by using the
synthetic batzelladines.
Results andDiscussion
Total synthesis of (À)-batzelladine D (2): Batzelladine D (2)
is a structurally relatively simple member of the batzelladine
alkaloids, with five asymmetric carbon centers in the tricy-
clic guanidine moiety. As depicted in Scheme 2, batzella-
Synthetic plan: Stereoselective construction of the character-
istic tricyclic guanidine structure in batzelladines is a key
issue for the total synthesis of these natural products. Our
synthetic concept of the tricyclic guanidine 4 is illustrated in
Scheme 1. The tricyclic guanidine 4 could be constructed
from the guanidine-substituted, 2,5-disubstituted pyrrolidine
5, which has hydroxyl groups on its side chain at the b-posi-
tions. The 2,5-disubstituted pyrrolidine 6 could be prepared
Scheme 2. Retrosynthetic analysis of 2.
dine D (2) can be synthesized by esterification with the alco-
hol 8 and cyclic guanidine carboxylic acid 9, which can in
turn be prepared based upon the strategy illustrated in
Scheme 1, specifically by using the nitrone 7 and two olefins,
methyl crotonate (10) and 1-undecene (11). At the begin-
ning of our synthetic studies on 2, we examined the synthe-
sis of the cyclic guanidine 9 as a racemic form.
1,3-Dipolar cycloaddition of the nitrone 7 and methyl
crotonate (10) in toluene gave the isoxazolidine 12 in 82%
yield (Scheme 3). The ester group of 12 was reduced with
LiAlH4 and subsequent protection of the hydroxyl group as
the tert-butyldimethylsilyl (TBS) ether gave 13 in 95%
yield. The oxidation of the isoxazolidine 13 with m-chloro-
peroxybenzoic acid (mCPBA)[18] effected regioselective ring
cleavage to give the nitrone 14, which was subsequently sub-
Scheme 1. Synthetic plan for the tricyclic guanidine 4.
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K. Nagasawa et al.
With the tricyclic guanidine carboxylic acid 9 in hand, es-
terification with the side chain alcohol 8 was examined
(Scheme 4). Although various conditions, such as 1-ethyl-3-
Scheme 3. Synthesis of the tricyclic guanidine carboxylic acid 9. Reagents
and conditions: a) methyl crotonate (10), toluene, 1008C, 82%; b) 1)
LiAlH4, E tO, 0 8C; 2) TBSCl, imidazole, CH2Cl2, RT, 95% (2 steps);
2
Scheme 4. Esterification of 9, 21, and 25 with 8. Reagents and conditions:
c) mCPBA, CH2Cl2, 08C; d) 1-undecene (11), toluene, 1108C, 76% (2
a) Pd(OH)2/C, H2, EtOH, RT, 97%; b) bis-Cbz-2-methyl-2-thiopseudo-
steps); e) 1) Ac2O, pyridine, RT; 2) Pd/C, H2, EtOH, RT, 98% (2 steps);
urea, HgCl2, E tN, DMF, 08C to RT, 60%; c) DEAD, PPh3, toluene, RT,
f) bis-Cbz-2-methyl-2-thiopseudourea, HgCl2, E tN, DMF, 08C to RT,
3
3
88%; d) TBAF, THF, RT, 70%; e) Jones reagent, acetone, 08C; f) 8,
EDCI, DMAP, CH2Cl2, RT, 40% (2 steps).
52%; g) DEAD, PPh3, THF, RT, 58%; h) NaH, THF/MeOH (1:1), RT,
80%; i) MsCl, Et3N, CH2Cl2, 08C, 82%; j) Jones reagent, acetone, 08C;
k) TMSCHN2, PhH/MeOH (7:2), RT, 47% (2 steps); l) Pd/C, H2, EtOH,
RT, 85 %.
jected to a second 1,3-dipolar cycloaddition with 1-undecene
(11) to give 15 in 76% yield (2 steps). In this cycloaddition,
1-undecene (11) approached from the less-hindered side of
14 (b-face) in the exo-mode, and the newly generated ste-
reochemistries of 15 at C8 and C11 were well controlled.[13]
After protection of the hydroxyl group of 15 with acetic an-
(3-dimethylaminopropyl)carbodiimide (EDCI)/4-dimethyl-
amino pyridine (DMAP), bis(2-oxo-3-oxazolidinyl)phos-
phinic chloride (BOPCl)/triethylamine, or tosylchloride
(TsCl)/pyridine, were examined, the ester 23 was not pro-
duced at all and the carboxylic acid 9 was decomposed.
Thus, we next examined trans-esterification using the ester
21 and alcohol 8 in the presence of the Otera reagent,[24] but
we failed to obtain the desired product 23. These results
might have been due to the low reactivity of the axially ori-
entated carboxylic acid or ester group of 9 or 21 at C7, as
Snider and Chen had suggested.[3b] To relax the rigidity of
the axial orientation of the carboxylic acid of 9, bicyclic gua-
nidine carboxylic acid 25 was prepared from 13 (Scheme 4)
and its esterification with 8 was examined. In this reaction,
we found that the coupling reaction proceeded in the pres-
ence of EDCI and DMAP, giving the ester 26 in 40% yield.
Thus, we decided to introduce the side chain 8 prior to the
tricyclic guanidine formation in the total synthesis of natural
product.
The optically active bicyclic guanidine carboxylic acid 35
was synthesized from the nitrone 27[25] derived from malic
acid, as shown in Scheme 5. In short, 1,3-dipolar cycloaddi-
tion reaction of the nitrone 27 and 1-undecene (11) gave the
isoxazolidine 28, and deoxygenation using the Barton–
McCombie method[26] gave 29. Treatment of 29 with
mCPBA effected regioselective regeneration of the nitrone,
and a second 1,3-dipolar reaction with methyl crotonate (10)
gave the isoxazolidine 30, the ester group of which was re-
À
hydride in pyridine, the N O bond was reduced with hydro-
gen in the presence of 10% Pd/C to give the trans-2,5-disub-
stituted-b-hydroxypyrrolidine 16 in 98% yield. Treatment of
16 with bis-Cbz-2-methyl-2-thiopseudourea (Cbz=benzyl-
oxycarbonyl) in the presence of mercury(ii) chloride[19] gener-
ated the guanylated pyrrolidine 17 in 52% yield. Treatment
of 17 under the Mitsunobu reaction conditions[20] effected
cyclization with inversion of the stereochemistry at C13 to
give the bicyclic guanidine 18 in 58% yield. Deprotection of
one of the Cbz groups and the acetyl group of 18 took place
simultaneously with sodium hydride in MeOH/THF (1:1)[21]
to give 19 in 80% yield. The tricyclic guanidine was formed
on treatment of 19 with methanesulfonyl chloride in the
presence of triethylamine to give 20 in 82% yield. The TBS
group of 20 was removed and oxidation of the resulting pri-
mary alcohol was performed with Jones reagent to give the
carboxylic acid 9.[22] The structure of 9 was confirmed by fur-
ther conversion into the known ester 22, reported by Over-
man,[23] through treatment of 9 with (trimethylsilyl)diazome-
thane and subsequent deprotection of the Cbz group with
hydrogen over 10% Pd/C.
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Total Synthesis
FULL PAPER
TBS and Cbz groups of 36 with HF/pyridine and hydrogen
in the presence of 10% Pd/C, respectively, the tricyclic gua-
nidine was formed under the Mitsunobu reaction conditions
to give fully stereocontrolled 37. Finally, deprotection of
Boc groups was conducted with trifluoroacetic acid (TFA),
and (À)-batzelladine D (2) was obtained in 66% yield. The
spectral data (1H NMR, 13C NMR, and high-resolution mass
spectra and optical rotation data) of the synthetic 2 were
consistent with those of natural batzelladine D (2) reported
by Patil et al.[1a]
Total synthesis of (+)-batzelladine A (1): Batzelladine A (1)
has been reported to show the most potent biological activi-
ty among the batzelladine alkaloids.[1a] It has a characteristic
left-hand bicyclic guanidine in addition to the right-hand tri-
cyclic guanidine, a common structural features of these alka-
loids. In the left-hand bicyclic guanidine, a chiral center is
present at C13. In 2002, Duron and Gin synthetically deter-
mined this stereochemistry to be R.[10] We started our syn-
thesis of (+)-1 from this particular left-hand bicyclic guani-
dine.
Scheme 5. Synthesis of the bicyclic guanidine carboxylic acid 35. Re-
agents and conditions: a) 1-undecene (11), toluene, 908C, 75%; b) 1)
CsF, EtOH, 908C, 98%; 2) PhOC(S)Cl, DMAP, pyridine, RT,; 3)
nBu3SnH, AIBN, toluene, 1008C, 51% (2 steps); c) 1) mCPBA, CH2Cl2,
08C; 2) methyl crotonate (10), toluene, 1108C, 75% (2 steps); d) 1)
LiAlH4, E tO, 0 8C; 2) TBSCl, imidazole, CH2Cl2, RT, 88% (2 steps);
2
e) Pd/C, H2, EtOH, RT; f) bis-Cbz-2-methyl-2-thiopseudourea, HgCl2,
Et3N, DMF, 08C to RT, 84% (2 steps); g) DEAD, PPh3, toluene, RT,
64%; h) 1) TBAF, THF, RT, 97%; 2) Jones reagent, acetone, 08C.
Application of the 1,3-dipolar cycloaddition reaction was
planned for the synthesis of the bicyclic guanidine alcohol
38, which corresponds to the left-hand bicyclic guanidine of
1 (Scheme 7). In this strategy, introduction of the double
duced with LiAlH4. Subsequent protection of the two hy-
droxyl groups with TBSCl furnished 31. Reduction of the
À
N O bond of 31 afforded the 2,5-disubstituted pyrrolidine
32, which was treated with bis-Cbz-2-methyl-2-thiopseudo-
urea to give 33. The formation of the bicyclic guanidine was
performed under the Mitsunobu reaction conditions and the
bicyclic guanidine 34 was obtained. Selective deprotection
of the primary silyl ether of 34 followed by Jones oxidation
gave the bicyclic guanidine carboxylic acid 35.
Then, esterification of the carboxylic acid 35 with the side
chain alcohol 8 was conducted in the presence of EDCI and
DMAP at 08C, and the ester 36 was obtained in 66% yield
from 34 (Scheme 6). After sequential deprotection of the
Scheme 7. Retrosynthetic analysis of 1.
bond at C7=C8 of 38 is addressed by means of oxidation of
39.
The synthesis of the bicyclic guanidine 49 is illustrated in
Scheme 8; it involves reaction of the optically active nitrone
Scheme 6. Total synthesis of (À)-batzelladine D (2). Reagents and condi-
tions: a) 8, EDCI, DMAP, CH2Cl2, 08C, 66% (from 34); b) 1) HF/pyri-
dine, THF, 08C, 81%; 2) Pd/C, H2, EtOH, RT; 3) DEAD, PPh3, toluene,
RT; c) TFA, CH2Cl2, RT, 66% (3 steps).
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K. Nagasawa et al.
Table 1. Investigation of oxidation of 47 to 53.
Reagents
Solvent
T [8C]
53 [%]
54 [%]
TPAP(5 mol%)–NMO (4 equiv)
PCC (4 equiv)
PDC (4 equiv)
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
RT
RT
RT
À78
47
6
36
0
0
0
0
Swern oxidation
94
47% yield with complete regioselectivity. Interestingly, oxi-
dation of the aldehyde 54, obtained through Swern oxida-
tion, with TPAP did not proceed. This TPAP direct oxida-
tion of 47 presumably occurs via the iminium–ruthenium–
alkoxide complex 55 as an intermediate, as proposed by
Murahashi et al.[31] (Scheme 10).
Scheme 8. Synthesis of the bicyclic guanidine 49. Reagents and condi-
tions: a) 40, toluene, 908C; b) 1) LiAlH4, E tO, 0 8C; 2) CsF, EtOH, 908C
2
(59% from 27); c) 1) TBSCl, pyridine, RT; 2) PhOC(S)Cl, DMAP, pyri-
dine, RT; 3) nBu3SnH, AIBN, toluene, 1008C, 44% (3 steps);
d) Pd(OH)2/C, H2, EtOH, RT; e) bis-Boc-2-methyl-2-thiopseudourea,
HgCl2, E tN, DMF, RT, 71% (2 steps); f) DEAD, PPh3, toluene, RT;
3
g) TBAF, THF, RT, 81% (from 45); h) 1) (COCl)2, DMSO, Et3N,
CH2Cl2, À788C to RT; 2) NaClO2, NaH2PO4, 2-methyl-2-butene, tBuOH/
H2O, RT; i) TMSCHN2, benzene/MeOH, RT, 71% (from 47).
27 and olefin 40 through 1,3-dipolar cycloaddition (27 into
41), guanylation with bis-Boc-2-methyl-2-thiopseudourea
(44 into 45; Boc=tert-butoxycarbonyl), and bicyclic guani-
dine construction under the Mitsunobu conditions (45 into
46).
Then, conversion of 49 into the a,b-unsaturated carbonyl
compound 50 was investigated (Scheme 9). We firstly exam-
ined the oxidation of 49 by Sharpless’ method utilizing orga-
noselenium reagents[27] or the Saegusa–Tsuji method,[28] but
neither the reaction with phenylselenyl bromide in the pres-
ence of lithium diisopropylamide (LDA) nor the ketenesilyl
acetal formation proceeded. Thus, we tried direct formation
of the a,b-unsaturated aldehyde 53 from the primary alco-
hol 47 with o-iodoxybenzoic acid (IBX), as developed by
Nicolaou et al.,[29] and obtained 53 in 13% yield. Several ox-
idation reagents for this conversion were further investigat-
ed, and the results are summarized in Table 1. Among them,
tetra-n-propylammoniumperruthenate (TPAP)[30] gave 53 in
Scheme 10. Proposed mechanism of TPAP oxidation of 47.
The resulting aldehyde 53 was further oxidized with
sodium chlorite[32] to the carboxylic acid, and then treatment
with (trimethylsilyl)diazomethane gave the methyl ester 56
in 86% yield. Demethylation of the methyl ester 56 with
nPrSLi and subsequent condensation with the guanidine al-
cohol 8 provided the ester in 54% yield from 58. Finally, the
p-methoxybenzyl (MPM) group was deprotected with 2,3-di-
chloro-5,6-dicyano-1,4-benzoquinone (DDQ) to give the al-
cohol 59 in 66% yield (Scheme 11).
Total synthesis of batzelladine A (1) was achieved with
the alcohol 59 and bicyclic guanidine carboxylic acid 35
(Scheme 12). The reaction of the carboxylic acid 35 and bi-
cyclic guanidine alcohol 59 in the presence of EDCI and
DMAP at 08C gave the ester 60 in 60% yield. The TBS
group of 60 was deprotected with HF/pyridine to give 61 in
89% yield. After deprotection of the Cbz group with hydro-
gen in the presence of 10% Pd/C, cyclization was performed
under the Mitsunobu conditions to give tricyclic guanidine
62. Finally, deprotection of the four Boc groups with TFA
and subsequent purification with HPLC (PEGASIL-ODS,
Scheme 9. Synthetic approaches of 50 from 49.
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Total Synthesis
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The proteins gp120 and CD4, and ethanolamine (as a con-
trol) were treated with agarose gel activated with hydroxy-
succinimide to obtain affinity gels bearing gp120, CD4, and
ethanolamine, respectively. These affinity gels were each
mixed with various concentrations of synthetic batzella-
dine D (2) from 0.1 to 0.5 mgmLÀ1. After one hour at 48C,
the mixture was centrifuged, and the amount of free batzel-
ladine D (2) in the supernatant was quantified by HPLC.
With the gp120- or ethanolamine-immobilized affinity gel, 2
was recovered almost quantitatively at every concentration
tested. In contrast, the amount of free 2 in the supernatant
decreased when the CD4 affinity gel was used. These results
indicate that the target protein of 2 is CD4 rather than
gp120; this result is inconsistent with the result of the com-
puter-assisted docking studies performed by Bewley et al.
Using the above-mentioned affinity gel method, we conduct-
ed a Scatchard plot analysis of the binding of CD4 with syn-
thetic batzelladines A (1) and D (2). As shown in Figure 1,
Scheme 11. Synthesis of bisguanidine alcohol 59. Reagents and condi-
tions: a) NaClO2, NaH2PO4, 2-methyl-2-butene, tBuOH/H2O, RT;
TMSCHN2, RT, 65% (23% SM recovery); b) nPrSLi, HMPA, RT, c) 8,
BOPCl, Et3N, CH2Cl2, 54% (from 56); d) DDQ, CH2Cl2/H2O, RT, 66 %.
Figure 1. Scatchard plot analysis of batzelladine A (1) and batzelladine D
(2) with CD4 affinity gel. (Cb: Concentration of CD4 bounded batzella-
dines of 1 and 2. Cf: Concentration of free batzelladines of 1 and 2.).
Scheme 12. Total synthesis of (+)-batzelladine A (1). Reagents and con-
ditions: a) 35, EDCI, DMAP, CH2Cl2, 08C, 60%; b) HF/pyridine, THF,
08C, 89%; c) 1) Pd/C, H2, EtOAc, RT; 2) DEAD, PPh3, toluene, RT;
d) TFA/CH2Cl2, RT, 24% (from 61).
the plots showed good linearity (r=0.97 (1) and 0.91 (2)),
suggesting that CD4 protein has a specific binding site for 1
and 2. The association constants (Ka values) of 1 and 2 were
calculated from the slope of the lines to be 3.0”105 mÀ1 and
1.8”105 mÀ1, respectively. This order of the values is consis-
tent with the order of inhibitory activities of 1 and 2 against
gp120–CD4 binding (IC50 values of 26 mm and 72 mm, respec-
tively).[1a] Moreover, the Scatchard plot analysis suggested
that the binding of 1 and 2 is specific and that their binding
sites on CD4 are the same, since the Scatchard plot lines of
1 and 2 crossed the x axis at almost the same positions.
These results indicate that the target protein of batzelladines
A (1) and D (2) is CD4.
eluted with 50% MeCN/H2O 0.1% TFA) gave (+)-batzella-
dine A (1) in 24% yield from 61.[17] All of the data for syn-
thetic (+)-batzelladine A (1) were in good agreement with
reported values.[1a] Thus, the structure of 1, including the ab-
solute stereochemistry, was confirmed.
Evaluation of the target protein of batzelladine A (1) and D
(2): Batzelladines inhibit the binding of the HIV envelope
glycoprotein gp120 and cellular CD4 receptor, which is the
initial step of HIV infection into T-cells. To establish the
mechanism of this interesting action of small molecules,
identification of the target protein is fundamental. Recently,
Bewley et al. conducted computer-assisted docking studies
of gp120 with batzelladine F-type polycyclic guanidine com-
pounds,[33] and suggested that the target protein of batzella-
dines is gp120. Intrigued with these results, we decided to
test their hypothesis using synthetic batzelladines A (1) and
D (2) and an affinity gel bearing gp120 and CD4.
Conclusion
In summary, asymmetric total synthesis of the guanidine al-
kaloids (+)-batzelladine A (1) and (À)-batzelladine D (2)
has been accomplished, by using a successive 1,3-dipolar cy-
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K. Nagasawa et al.
57.0, 42.5, 33.9, 31.8, 31.7, 29.62, 29.57, 29.5, 29.2, 26.4, 24.3, 22.6,
14.0 ppm; IR (neat): n˜ =2926, 2855, 1465 cmÀ1; HRMS (FAB): calcd for
C15H30NO [M++H]: 240.2327; found: 240.2383.
cloaddition reaction protocol for the stereoselective con-
struction of the tricyclic guanidine skeleton. A novel oxida-
tion reaction from the primary alcohol 47 to a,b-unsaturated
aldehyde 53 under TPAP–NMO (NMO=4-methylmorpho-
line N-oxide) conditions was also developed and applied to
the synthesis of the left-hand bicyclic guanidine of 1. This
also established the absolute stereochemistry. Furthermore,
the target protein of 1 and 2 was examined using immobi-
lized CD4 and/or gp120 affinity gel. The results indicated
that batzelladines A (1) and D (2) bind to CD4, in contrast
to the results of computer-assisted docking studies obtained
using batzelladine F type polycyclic guanidine compounds.
Further experiments to identify the binding site of batzella-
dines on CD4 are planned.
Ester 30: mCPBA (1.81 g, 7.6 mmol) was added to a solution of isoxazoli-
dine 29 (1.52 g, 6.35 mmol) in CH2Cl2 (30 mL) at 08C. After stirring for
5 min, a large excess of Ca(OH)2 was added, the resulting mixture was
filtered through a pad of Celite, and the filtrates were concentrated in
vacuo to give nitrone as a clear oil. The mixture of the nitrone and 10
(3.4 mL, 32 mmol) in toluene (60 mL) was stirred at 1008C for 1 h. After
cooling, the reaction mixture was concentrated under reduced pressure,
and the residue was purified by silica gel column chromatography
(hexane/EtOAc; 2:1) to give methyl ester 30 (1.68 g, 75% overall) as a
clear oil. [a]2D3 =À86.2 (c=1.01 in CHCl3); 1H NMR (500 MHz, CDCl3):
d=4.30 (m, 1H), 4.08 (q, J=6.8 Hz, 1H), 3.92 (m, 1H), 3.70 (s, 3H), 3.37
(m, 1H), 3.04 (t, J=9.8 Hz, 1H), 1.96–1.84 (m, 2H), 1.74 (ddd, J=4.6,
10.1, 10.1 Hz, 1H), 1.59–1.24 (m, 19H), 1.32 (d, J=6.8 Hz, 3H), 0.86 ppm
(t, J=7.0 Hz, 3H); 13C NMR (125 MHz, CDCl3): d=170.3, 72.1, 69.1,
65.43, 65.35, 57.3, 51.8, 39.2, 37.6, 31.9, 29.7, 29.6, 29.5, 29.3, 28.9, 27.3,
25.7, 22.6, 16.6, 14.1 ppm; IR (neat): n˜ =3361, 2925, 2853, 1736,
1437 cmÀ1 HRMS (FAB): calcd for C20H38NO4 [M++H]: 355.2801;
;
found: 355.2840.
Experimental Section
Silyl ether 31: A solution of methyl ester 30 (2.00 g, 5.63 mmol) in Et2O
General: Flash chromatography was performed on Silica gel 60 (spheri-
cal, particle size 0.040–0.100 mm; Kanto). Optical rotations were mea-
sured on a JASCO DIP polarimeter 370, using the sodium D line. IR
spectra were measured with a JASCO VALOR-III FT-IR spectropho-
(30 mL) was added slowly to
a suspension of LiAlH4 (320 mg,
8.43 mmol) in Et2O (40 mL) at 08C. After stirring for 2 h at this tempera-
ture, the reaction was quenched by sequential addition of H2O (500 mL),
2.0m NaOH aq. (500 mL), and H2O (1 mL). MgSO4 was added, the result-
ing mixture was stirred for 20 min and filtered through a pad of Celite,
and the filtrates were concentrated in vacuo to give an alcohol (2.26 g)
which was used without further purification. TBSCl (3.12 g) was added to
a solution of the alcohol and imidazole (2.82 g) in CH2Cl2 (70 mL) and
the mixture was stirred at room temperature for 20 min. The reaction
was quenched by the addition of H2O and extracted with ethyl acetate.
The organic layer was washed with brine, dried over MgSO4, and concen-
trated in vacuo. The residue was purified by silica gel column chromatog-
raphy (hexane/EtOAc; 15:1) to give bis-TBS ether 31 (3.24 g, 85%) as a
colorless oil. [a]2D4 =À57.2 (c=1.40 in CHCl3); 1H NMR (500 MHz,
CDCl3): d=3.91 (ddd, J=12.4, 5.1, 4.7 Hz, 1H), 3.83–3.63 (m, 4H), 3.13
(ddd, J=16.2, 6.0, 6.0 Hz, 1H), 2.33 (m, 1H), 1.95 (m, 1H), 1.76–1.61 (m,
4H), 1.53 (ddd, J=13.7, 7.3, 6.4 Hz, 1H), 1.46–1.20 (m, 19H), 0.883 (s,
9H), 0.88 (s, 9H), 0.86 (t, J=6.8 Hz, 3H), 0.06 (s, 6H), 0.05 ppm (s, 6H);
13C NMR (125 MHz, CDCl3): d=73.0, 70.6, 66.8, 65.2, 60.5, 54.3, 43.0,
38.1, 31.9, 31.1, 29.9, 29.6, 29.5, 29.3, 26.0, 25.8, 25.5, 24.7, 22.7, 18.1, 17.7,
14.1, À4.3, À4.4, À5.5, À5.6 ppm; IR (neat): n˜ =2955, 2928, 2856, 1471,
1463, 1387, 1361, 1254 cmÀ1; HRMS (FAB): calcd for C31H66NO3Si2 [M+
+H]: 556.4581; found: 556.4576.
1
tometer. H and 13C NMR spectra were recorded on JEOL JNM-ECP500
instrument. Mass spectra were recorded on JEOL JMS-HX110 spectrom-
eter with m-nitrobenzyl alcohol.
Isoxazolidine 28: A mixture of nitrone 27 (9.0 g, 35.0 mmol) and 11
(27.0 g, 175.0 mmol) in toluene (200 mL) was heated at 908C for 9 h.
After cooling, the reaction mixture was concentrated in vacuo and puri-
fied by silica gel column chromatography (hexane/EtOAc; 16: 1 to 8:1)
to give isoxazolidine 28 (10.8 g, 75%) as a clear oil. [a]2D2 =3.6 (c=0.9 in
CHCl3); 1H NMR (500 MHz, CDCl3): d=4.12 (ddd, J=5.6, 3.0, 3.0 Hz,
1H), 3.90 (m, 1H), 3.60 (ddd, J=8.1, 3.0, 3.0 Hz, 1H), 3.37 (ddd, J=12.4,
8.1, 6.4 Hz, 1H), 3.18 (ddd, J=12.4, 6.4, 4.7 Hz, 1H), 2.15–2.02 (m, 3H),
1.72 (m, 1H), 1.62 (m, 1H), 1.43–1.20 (m, 15H), 1.13–0.95 (m, 21H),
0.87 ppm (t, J=6.8 Hz, 3H); 13C NMR (125 MHz, CDCl3): d=78.7, 76.6,
73.9, 55.2, 40.1, 34.2, 33.7, 31.5, 29.2, 29.14, 29.1, 28.9, 26.0, 22.3, 17.5,
13.7, 11.6 ppm; IR (neat): n˜ =2927, 2865, 1465, 1381, 1368 cmÀ1; HRMS
(FAB): calcd for C24H50NO2Si [M++H]: 412.3611; found: 412.3622.
Isoxazolidine 29: A mixture of isoxazolidine 28 (10.7 g, 10.0 mmol) and
CsF (11.9 g) in EtOH (20 mL) was refluxed at 908C for 9 h. After cool-
ing, the solution was poured into H2O and extracted with ethyl acetate.
The solution was dried over MgSO4 and concentrated in vacuo. The resi-
due was purified by silica gel column chromatography (CHCl3/MeOH;
9:1) to give an alcohol (6.71 g, q.y.) as a clear oil. [a]2D2 =À18.7 (c=0.69
in CHCl3); 1H NMR (500 MHz, CDCl3): d=4.08 (m, 1H), 3.91 (m, 1H),
3.56 (m, 1H), 3.39 (m, 1H), 3.12 (m, 1H), 2.15–2.00 (m, 3H), 1.72 (m,
1H), 1.60 (m, 1H), 1.47–1.20 (m, 15H), 0.86 ppm (t, J=6.9 Hz, 3H);
13C NMR (125 MHz, CDCl3): d=76.7, 72.7, 55.0, 40.0, 33.3, 33.26, 31.5,
29.3, 29.2, 29.17, 29.0, 26.0, 22.3, 13.7 ppm; IR (neat): n˜ =3362, 2926,
2855, 1466 cmÀ1; HRMS (FAB): calcd for C15H30NO2 [M++H]: 256.2277;
found: 256.2288. Phenyl chlorothionoformate (5.8 mL) was added to a so-
lution of the alcohol (5.40 g, 21.1 mmol) and DMAP (180 mg) in pyridine
(100 mL) at room temperature. After stirring for 5 h, the reaction mix-
ture was concentrated in vacuo and diluted with ethyl acetate. The solu-
tion was washed with H2O twice, and the organic layer was dried over
MgSO4 and concentrated in vacuo. The residue was purified by silica gel
column chromatography (hexane-EtOAc; 12:1) to give xanthate as a
yellow oil. To a solution of xanthate in toluene (100 mL), nBu3SnH
(17 mL) and azobisisobutyronitrile (AIBN; 345 mg) was added and re-
fluxed at 1108C for 20 min. The solution was concentrated in vacuo and
the residue was purified by silica gel column chromatography (hexane/
Guanidine 33: Pd/C (400 mg) was added to a solution of bis-TBS ether
31 (992 mg, 1.78 mmol) in EtOH (6.0 mL), and the reaction mixture was
stirred at room temperature under a hydrogen atmosphere (balloon).
After 20 h, the reaction mixture was filtered through a pad of Celite, and
the filtrates were concentrated in vacuo to give pyrrolidine 32. HgCl2
(570 mg, 2.1 mmol) was added to a solution of 32 (978 mg, 1.75 mmol),
1,3-bis(benzyloxycarbonyl)-2-methyl-2-thiopseudourea
(753 mg,
2.1 mmol), and triethylamine (850 mL, 6.1 mmol) in DMF (18 mL), and
the resulting mixture was stirred for 30 min. The reaction mixture was di-
luted with EtOAc, and filtered through a pad of Celite. The filtrate was
concentrated in vacuo, and the residue was purified by silica gel column
chromatography (hexane/EtOAc; 8:1) to give the bis-Cbz-protected gua-
nidine 33 (902 mg, 58% overall).
Guanidine 34: Diethylazodicarboxylate (DEAD; 995 mL, 6.32 mmol) was
added to a solution of guanidine 33 (3.66 g, 4.21 mmol) and PPh3 (1.66 g,
6.32 mmol) in toluene (40 mL). After stirring for 5 min, the reaction was
quenched with H2O (10 mL) and concentrated in vacuo. Purification of
the residue by flash chromatography (hexane/EtOAc; 9:1) gave bicyclic
guanidine 34 (2.31 g, 65%) as a clear oil. [a]2D4 =À160.0 (c=1.68 in
1
EtOAc 6:1 to 1:2) to give isoxazolidine 29 (2.56 g, 51% overall). [a]D23
À34.1 (c=1.19 in CHCl3); H NMR (500 MHz, CDCl3): d=4.01 (m, 1H),
3.73 (m, 1H), 3.13 (m, 2H), 2.08–1.82 (m, 4H), 1.72–1.20 (m, 18H),
0.88 ppm (t, J=6.8 Hz, 3H); 13C NMR (125 MHz, CDCl3): d=76.4, 64.8,
=
CHCl3); H NMR (500 MHz, CDCl3): d=7.36–7.20 (m, 10H), 5.17 (d, J=
1
12.4 Hz, 1H), 4.97 (d, J=12.4 Hz, 1H), 4.92 (d, J=12.4 Hz, 1H), 4.90 (d,
J=12.4 Hz, 1H), 4.63 (m, 1H), 4.05 (m, 1H), 3.82 (m, 1H), 3.65 (m,
3H), 2.65–2.52 (m, 2H), 2.17 (m, 1H), 1.97 (m, 1H), 1.73–1.53 (m, 2H),
6884
www.chemeurj.org
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2005, 11, 6878 – 6888

Total Synthesis
FULL PAPER
1.52–1.15 (m, 17H), 1.18 (d, J=7.3 Hz, 3H), 0.87 (t, J=0.9 Hz, 3H), 0.87
(s, 18H), 0.04 (s, 6H), 0.04 ppm (s, 6H); 13C NMR (125 MHz, CDCl3):
d=160.3, 153.1, 150.5, 137.3, 135.6, 128.3, 128.2, 128.0, 128.0, 127.3, 70.6,
68.2, 66.7, 60.7, 57.7, 56.3, 49.8, 43.0, 41.8, 37.0, 31.9, 29.8, 29.6, 29.3, 28.4,
25.9, 25.7, 24.4, 22.6, 18.0, 14.4, 14.0, À4.4, À4.43, À5.6 ppm; IR (neat):
(125 MHz, CDCl3): d=169.8, 163.5, 159.3, 156.1, 153.6, 153.3, 152.6,
136.9, 135.1, 128.4, 128.1 ,127.9, 127.6, 127.4, 83.1, 79.2, 68.2, 66.4, 65.0,
56.9, 56.4, 53.1, 50.7, 44.4, 40.1, 36.9, 31.9, 29.9, 29.7, 29.6, 29.3, 28.7, 28.3,
28.0, 27.0, 26.3, 25.7, 25.6, 22.7, 16.5, 14.1 ppm; IR (neat): n˜ =3333, 2927,
2855, 1728, 1690, 1639, 1616, 1576, 1497, 1456, 1416, 1367, 1328 cmÀ1
;
n˜ =2953, 2928, 2856, 1727, 1677, 1581, 1470, 1387, 1287, 1244 cmÀ1
;
HRMS (FAB): calcd for C51H77N6O11 [M++H]: 949.5650; found:
949.5657. A catalytic amount of Pd/C was added to a solution of the alco-
hol (57.0 mg, 0.060 mmol) in EtOH (1.0 mL). The reaction mixture was
stirred at room temperature under a hydrogen atmosphere (balloon) for
3 h, and the reaction mixture was filtered though a pad of Celite. The fil-
trates were concentrated in vacuo to give guanidine alcohol. DEAD
(132 mL, 40% in toluene) was added to a solution of guanidine alcohol
and PPh3 (76.0 mg) in toluene (100 mL). After stirring for 6 h, the reac-
tion was quenched with one drop of H2O and concentrated in vacuo. The
residue was purified by silica gel column chromatography (CHCl3/
MeOH; 9:1) to give tricyclic guanidine 37. The tricyclic guanidine 37 was
dissolved in 50% TFA in CH2Cl2 (500 mL). After 30 min, the solution
was concentrated under reduced pressure and the residue was purified by
HPLC (PEGASIL-ODS 45% MeCN aq. 0.1% TFA) to give (À)-batzel-
HRMS (FAB): calcd for C48H80N3O6Si2 [M++H]: 850.5586; found:
850.5580.
Ester 36: TBAF hydrate (44 mg) was added to a solution of bicyclic gua-
nidine 34 (44 mg, 0.052 mmol) in THF (1.0 mL) at 08C and stirred at the
temperature for 100 min. The reaction mixture was poured into saturated
NaHCO3 aq. and extracted with ethyl acetate. The combined organic
layers were washed with saturated NH4Cl aq., H2O, and brine. The solu-
tion was concentrated in vacuo and purified by silica gel column chroma-
tography (hexane/EtOAc; 2:1) to give mono-TBS ether protected alcohol
(37.7 mg, 0.051 mmol, 99%) as a clear oil. [a]2D9 =À186.0 (c=1.16 in
1
CHCl3); H NMR (500 MHz, CDCl3): d=7.36–7.20 (m, 10H), 5.19 (d, J=
12.2 Hz, 1H), 4.97 (d, J=12.5 Hz, 1H), 4.92 (d, J=12.5 Hz, 1H), 4.87 (d,
J=12.2 Hz, 1H), 4.64 (m, 1H), 4.06 (m, 1H), 3.84–3.67 (m, 4H), 2.62 (m,
1H), 2.55 (ddd, J=12.8, 7.3, 3.1 Hz, 1H), 2.19 (m, 1H), 2.05 (m, 1H),
1.73–1.19 (m, 19H), 1.21 (d, J=7.3 Hz, 3H), 0.88 (t, J=7.0 Hz, 3H), 0.87
(s, 9H), 0.04 (s, 3H), 0.04 ppm (s, 3H); 13C NMR (125 MHz, CDCl3): d=
160.4, 153.2, 150.6, 137.2, 135.6, 128.4, 128.2, 128.11, 128.1, 128.0, 127.4,
70.6, 68.3, 66.9, 60.3, 57.8, 56.3, 50.0, 42.8, 41.8, 37.0, 31.9, 29.9, 29.7, 29.6,
29.3, 28.5, 25.9, 24.5, 22.7, 18.0, 14.5, 14.1, À4.3, À4.4 ppm; IR (neat): n˜ =
3430, 2953, 2927, 2855, 1725, 1574, 1471 cmÀ1; HRMS (FAB): calcd for
C42H66N3O6Si [M++H]: 735.4721; found: 735.4724. Jones reagent
(10 drops) was added to a solution of the alcohol (80.3 mg, 0.109 mmol)
in acetone (2.0 mL) and stirred at 08C for 30 min. The mixture was
added excess of 2-propanol and poured into ethyl acetate. The solution
was washed with brine and the aqueous layer was re-extracted with ethyl
acetate. The combined organic layer was dried over MgSO4 and concen-
trated in vacuo to give the carboxylic acid 35. EDCI (62.7 mg) and
DMAP (6.7 mg) were added to a mixture of the carboxylic acid 35 and
alcohol 8 (72.2 mg, 0.218 mmol) in CH2Cl2 (1.0 mL) at 08C. After stirring
at the temperature for 3 h, the reaction mixture was poured into H2O
and extracted with diethyl ether. The extracts were washed with saturat-
ed NaHCO3 aq., brine, and H2O and dried over MgSO4. The solution
was evaporated and the residue was purified by silica gel column chroma-
tography (CH2Cl2/hexane/EtOAc; 16:8:3) to give ester 36 (78.5 mg,
0.074 mmol, 68%) as a clear oil. [a]2D5 =À137.3 (c=0.88 in CHCl3);
1H NMR (500 MHz, CDCl3): d=11.49 (br, 1H), 8.31 (br, 1H), 7.25–7.12
(m, 10H), 5.15 (d, J=12.4 Hz, 1H), 4.97 (d, J=12.4 Hz, 1H), 4.90 (d, J=
12.7 Hz, 1H), 4.87 (d, J=12.7 Hz, 1H), 4.49 (m, 1H), 4.09 (m, 3H), 3.86
(m, 2H), 3.41 (d, J=12.4, 6.8 Hz, 2H), 3.22 (dd, J=7.7, 4.7 Hz, 1H), 2.27
(m, 2H), 1.90–1.19 (m, 24H), 1.50 (s, 9H), 1.49 (s, 9H), 1.37 (d, J=
6.7 Hz, 3H), 0.88 (t, J=7.0 Hz, 3H), 0.87 (s, 9H), 0.04 (s, 3H), 0.04 ppm
(s, 3H); 13C NMR (125 MHz, CDCl3): d=169.8, 163.6, 160.0, 156.1, 153.3,
152.9, 150.0, 137.2, 135.6, 128.3–128.0 (12 carbons), 127.4, 83.1, 79.2, 71.1,
68.1, 66.8, 64.8, 58.5, 56.2, 52.2, 50.1, 40.7, 40.5, 40.4, 40.2, 37.4, 31.9, 29.9,
29.6, 29.3, 28.8, 28.3, 28.02, 27.98, 27.5, 25.9, 25.8, 25.6, 24.4, 22.7, 18.0,
16.4, 14.1, À4.32, À4.40 ppm; IR (neat): n˜ =3332, 2929, 2856, 1724, 1614,
ladine D (2; 27.4 mg, 0.040 mmol, 66% overall) as a viscous oil. [a]D23
=
À19.4 (c=1.04 in MeOH); 1H NMR (500 MHz, CD3OD): d=4.17 (t, J=
6.4 Hz, 2H), 3.95 (m, 1H), 3.85 (m, 1H), 3.53 (m, 2H), 3.21 (t, J=7.0 Hz,
2H), 3.13 (dd, J=4.0, 3.7 Hz, 1H), 2.34 (m, 1H), 2.22 (m, 2H), 1.76–1.50
(m, 7H), 1.50–1.20 (m, 19H), 0.89 ppm (t, J=6.7 Hz, 3H); 13C NMR
(125 MHz, CD3OD): d=170.6, 158.7, 151.5, 65.4, 57.8, 57.3, 53.2, 49.9,
42.0, 36.9, 34.2, 33.0, 31.4, 30.7, 30.6, 30.4, 29.3, 26.9, 26.6, 26.2, 23.7, 18.4,
14.4 ppm; IR (neat): n˜ =3353, 3203, 2928, 2857, 1730, 1651, 1644, 1326,
1205 cmÀ1 HRMS (FAB): calcd for C25H47N6O2 [M++H]: 463.3761;
;
found: 463.3800.
Diol 42: A mixture of nitrone 27 (15.2 g, 59.0 mmol) and a,b-unsaturated
ester 40 (25.9 g, 68.9 mmol) in toluene (100 mL) was heated at 908C for
19 h. After cooling, the reaction mixture was concentrated in vacuo to
give isoxazolidine (42.0 g). A solution of the crude isoxazolidine (16.6 g,
40% of the above product) in Et2O (30 mL) was added slowly to a sus-
pension of LiAlH4 (1.53 g, 40.3 mmol) in Et2O (220 mL) at 08C. After
stirring for 3 h, the reaction was quenched by sequential addition of H2O
(500 mL), 2.0m NaOH aq. (500 mL), and H2O (1 mL). MgSO4 was added,
the resulting mixture was stirred for 20 min and filtered through a pad of
Celite, and the filtrates were concentrated in vacuo to afford a residue
(16.4 g), which was used without further purification. A solution of the
crude alcohol and CsF (11.4 g, 75.0 mmol) in EtOH (90.0 mL) was re-
fluxed at 908C for 13 h. The reaction was concentrated and the residue
was filtered through a Florisil column. The filtrates were concentrated
and purified on silica gel (CHCl3/MeOH; 20:1) to give diol 42 (6.63 g,
59% overall) as a clear viscous oil. [a]2D3 =À65.3 (c=0.63 in CHCl3);
1H NMR (500 MHz, CDCl3): d=7.25 (d, J=8.6 Hz, 2H), 6.87 (d, J=
8.6 Hz, 2H), 4.44–4.38 (m, 1H), 4.42 (s, 2H), 3.85 (d, J=8.1 Hz, 2H),
3.80 (s, 3H), 3.58–3.51 (m, 2H), 3.48 (ddd, J=12.4, 7.7, 4.3 Hz, 1H), 3.42
(t, J=6.6 Hz, 2H), 3.09 (ddd, J=12.4, 9.0, 6.8 Hz, 1H), 2.73 (m, 1H),
2.27 (m, 1H), 1.78 (m, 1H), 1.62–1.45 (m, 4H), 1.45–1.20 ppm (m, 12H);
13C NMR (125 MHz, CDCl3): d=158.8, 130.3, 129.0, 113.4, 77.8, 74.7,
72.2, 70.5, 69.9, 59.8, 54.93, 54.9, 52.4, 33.1, 29.4, 29.35, 29.2, 29.15, 26.0,
25.9 ppm; IR (neat): n˜ =3392, 2929, 2854, 1613, 1586, 1513, 1464, 1361,
1302, 1248 cmÀ1; HRMS (FAB): calcd for C24H40NO5 [M++H]: 422.2906;
found: 422.2928.
1455, 1416 cmÀ1
;
HRMS (FAB): calcd for C57H91N6O11Si [M++H]:
1063.6515; found: 1063.6475.
(À)-Batzelladine D (2): HF/pyridine (200 mL) was added to a solution of
36 (78.5 mg 0.074 mmol) in THF (2.0 mL) in a polypropylene tube at
08C. After stirring for 4 h, saturated NaHCO3 aq. (500 mL) and solid
NaHCO3 (100 mg) was added. The mixture was dried over MgSO4, fil-
tered through a pad of Celite, and washed with ethyl acetate. The filtrates
were concentrated in vacuo, and the residue was purified by silica gel
column chromatography (hexane/EtOAc; 2:1) to give an alcohol
(57.0 mg, 0.060 mmol, 81%) as a clear oil. [a]2D5 =À147.0 (c=1.17 in
CHCl3); 1H NMR (500 MHz, CDCl3): d=11.47 (br, 1H), 8.30 (br, 1H),
7.30–7.17 (m, 10H), 6.22 (d, J=3.8 Hz, 1H), 5.16 (d, J=12.4 Hz, 1H),
5.01 (d, J=12.8 Hz, 1H), 4.84 (d, J=12.4 Hz, 1H), 4.78 (d, J=12.4 Hz,
1H), 4.58 (m, 1H), 4.40 (m, 1H), 4.12 (dt, J=11.1, 5.1 Hz, 2H), 3.95 (m,
1H), 3.52 (br, 1H), 3.39 (dt, J=6.6, 6.0 Hz, 2H), 3.21 (dd, J=7.7, 3.8 Hz,
1H), 2.33 (m, 1H), 1.97 (m, 1H), 1.86 (m, 1H), 1.76–1.10 (m, 23H), 1.49
(s, 18H), 1.47 (d, J=6.4 Hz, 3H), 0.88 ppm (t, J=6.8 Hz, 3H); 13C NMR
Isoxazolidine 43: TBSCl (361 mg, 2.40 mmol) was added to the solution
of diol 42 (774 mg, 1.84 mmol) in pyridine (20 mL) at room temperature.
After 19 h, the mixture was concentrated and purified on silica gel
(CHCl3/MeOH; 30:1) to give the mono-TBS ether (799.4 mg, 81%) as a
colorless oil. [a]2D2 =À16.4 (c=1.18 in CHCl3); 1H NMR (500 MHz,
CDCl3): d=7.25 (d, J=8.6 Hz, 2H), 6.86 (d, J=8.6 Hz, 2H), 4.72 (br,
1H), 4.67 (d, J=9.4 Hz, 1H), 4.41 (s, 2H), 4.30 (dt, J=8.1, 4.3 Hz, 1H),
4.07 (m, 1H), 3.93 (dd, J=11.1, 4.7 Hz, 1H), 3.83 (dd, J=11.1, 4.7 Hz,
1H), 3.79 (s, 3H), 3.55–3.48 (m, 1H), 3.42 (t, J=6.8 Hz, 2H), 2.73 (m,
1H), 2.28 (m, 2H), 1.69 (m, 2H), 1.57 (tt, J=6.8, 6.8 Hz, 2H), 1.48–1.16
(m, 12H), 0.87 (s, 9H), 0.09 (s, 3H), 0.07 ppm (s, 3H); 13C NMR
(125 MHz, CDCl3): d=158.9, 130.6, 129.0, 113.5, 85.9, 77.9, 77.2, 72.3,
70.0, 58.8, 55.3, 55.1, 49.6, 32.9, 32.6, 29.6, 29.2, 29.1, 29.0, 26.0, 17.9, À5.7,
À5.8 ppm; IR (neat): n˜ =3288, 2929, 2856, 2416, 2349, 2285, 1613, 1586,
Chem. Eur. J. 2005, 11, 6878 – 6888
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6885

K. Nagasawa et al.
1513, 1464, 1361, 1302, 1249 cmÀ1; HRMS (FAB): calcd for C48H81N2O10Si
[M++H]: 536.3771; found: 536.3767. Phenyl chlorothionoformate
(3.3 mL) was added to a solution of the mono-TBS alcohol (6.35 g,
11.9 mmol) and DMAP (145 mg) in pyridine (120 mL) at 08C. After stir-
ring for 20 h at room temperature, the reaction mixture was diluted with
Et2O and washed with H2O and brine. The organic layer was dried over
MgSO4, filtered, and concentrated in vacuo. The residue was purified by
flash chromatography on silica gel (hexane/EtOAc; 10:1) to give a xan-
thate (4.64 g, 58%) as a yellow oil. The xanthate (4.64 g) was dissolved in
toluene (35 mL), and nBu3SnH (3.7 mL) and AIBN (113 mg) were
added. The resulting mixture was heated at 1108C for 30 min. After cool-
ing, the reaction mixture was concentrated in vacuo and purified on silica
gel (hexane/EtOAc; 3:1) to afford isoxazolidine 43 (3.36 g, 94%) as a
clear oil. [a]2D2 =À46.3 (c=1.21 in CHCl3); 1H NMR (500 MHz, CDCl3):
d=7.24 (d, J=8.6 Hz, 2H), 6.86 (d, J=8.6 Hz, 2H), 4.41 (s, 2H), 3.78 (s,
3H), 3.72–3.62 (m, 4H), 3.42 (t, J=13.8 Hz, 2H), 3.20 (m, 1H), 3.10 (m,
1H), 2.63 (m, 1H), 1.94 (m, 1H), 1.71 (m, 2H), 1.61–1.52 (m, 5H), 1.45
(m, 1H), 1.35–1.20 (m, 11H), 0.88 (s, 9H), 0.04 ppm (s, 6H); 13C NMR
(125 MHz, CDCl3): d=158.9, 130.6, 129.0, 113.5, 78.6, 72.3, 70.0, 68.3,
61.5, 56.7, 55.0, 53.6, 34.5, 29.6, 29.5, 29.4, 29.3, 26.2, 26.0, 25.7, 24.9, 24.6,
18.0, À5.6, À5.7 ppm; IR (neat): n˜ =2929, 2855, 1613, 1513, 1464, 1361,
1366, 1325, 1301, 1249 cmÀ1; HRMS (FAB): calcd for C35H58N3O7 [M+
+H]: 632.4275; found: 632.4274.
Aldehyde 53: TPAP (8.4 mg) was added in one portion to a stirred mix-
ture of alcohol 47 (301 mg, 0.48 mmmol), NMO (225 mg, 1.92 mmol) and
powdered 4 Š molecular sieves (240 mg) in CH2Cl2 (2.0 mL) at room
temperature. After stirring for 30 min, the reaction mixture was concen-
trated in vacuo and the resulting black residue was purified on silica gel
(hexane/EtOAc; 3:1) to give a,b-unsaturated aldehyde 53 (143 mg, 47%)
as a yellow oil. [a]2D4 =À34.3 (c=1.01 in CHCl3); 1H NMR (500 MHz,
CDCl3): d=9.51 (s, 1H), 7.26 (d, J=8.5 Hz, 2H), 6.87 (d, J=8.5 Hz,
2H), 5.26 (dd, J=8.5, 4.5 Hz, 1H), 4.42 (s, 2H), 3.97 (ddd, J=12.1, 7.7,
7.7 Hz, 1H), 3.85 (ddd, J=12.1, 8.5, 4.5 Hz, 1H), 3.80 (s, 3H), 3.42 (t, J=
6.8 Hz, 2H), 3.15 (ddd, J=16.5, 8.5, 4.5 Hz, 1H), 2.98 (ddd, J=16.5, 8.5,
8.5 Hz, 1H), 2.22–2.13 (m, 1H), 2.13–2.03 (m, 1H), 1.63–1.55 (m, 2H),
1.52 (s, 9H), 1.49 (s, 9H), 1.40–1.20 ppm (m, 14H); 13C NMR (125 MHz,
CDCl3): d=158.9, 158.8, 151.9, 150.5, 130.5, 129.0, 113.5, 81.8, 77.6, 72.3,
70.0, 59.9, 57.2, 55.0, 54.2, 46.8, 43.4, 29.5, 29.3, 29.2, 29.0, 28.4, 28.3, 27.9,
26.1, 25.9, 21.9 ppm; IR (neat): n˜ =2977, 2930, 2855, 1739, 1695, 1651,
1613, 1514, 1457, 1416, 1392, 1368, 1335, 1304 cmÀ1; HRMS (FAB): calcd
for C35H54N3O7 [M++H]: 628.3962; found: 628.3959.
Methyl ester 56: NaClO2 (63.0 mg) and NaH2PO4·2H2O (63.0 mg) in
1302, 1249, cmÀ1 HRMS (FAB): calcd for C48H81N2O9Si [M++H]:
;
water (190 mL) were added to
a mixture of aldehyde 53 (36.1 mg,
520.3822; found: 520.3820.
0.058 mmol) and 2-methyl-2-butene (300 mL) in tBuOH (520 mL) at room
temperature, and the mixture was stirred vigorously for 14 h. An excess
of TMSCHN2 (40% in hexane) was added to the reaction mixture and
the mixture was diluted with EtOAc. The mixture was extracted with
ethyl acetate and the extracts were dried over MgSO4, filtered, and con-
centrated in vacuo. The residue was purified by flash chromatography on
silica gel (hexane/EtOAc; 4:1) to give methyl ester 56 (24.6 mg,
0.037 mmol, 65%, 86% from recovered aldehyde) and the starting alde-
hyde 53 (8.3 mg, 0.013 mmol, 23%). [a]2D4 =18.7 (c=1.08 in CHCl3);
1H NMR (500 MHz, CDCl3): d=7.26 (d, J=8.5 Hz, 2H), 6.87 (d, J=
8.5 Hz, 2H), 5.21 (dd, J=8.5, 4.5 Hz, 1H), 4.43 (s, 2H), 3.80 (s, 3H),
3.76–3.69 (m, 1H), 3.74 (s, 3H), 3.48 (ddd, J=11.5, 8.0, 8.0 Hz, 1H), 3.42
(t, J=6.8 Hz, 2H), 3.23 (ddd, J=17.8, 8.2, 4.2 Hz, 1H), 2.92 (ddd, J=
17.8, 9.0, 9.0 Hz, 1H), 2.10–1.90 (m, 2H), 1.60–1.00 (m, 16H), 1.51 (s,
9H), 1.49 ppm (s, 9H); 13C NMR (125 MHz, CDCl3): d=165.7, 158.8,
152.0, 150.8, 144.8, 131.5, 130.7, 129.2, 113.7, 102.9, 83.1, 79.6, 72.4, 70.2,
55.2, 53.0, 51.2, 48.8, 33.6, 31.2, 29.7, 29.6, 29.4, 29.37, 29.1, 28.7, 28.3,
28.2, 28.1, 26.2, 24.7, 21.3 ppm; IR (neat): n˜ =2979, 2931, 2855, 1740,
1698, 1655, 1612, 1513, 1457, 1438, 1416, 1390, 1368, 1346 cmÀ1; HRMS
(FAB): calcd for C36H56N3O8 [M++H]: 658.4067; found: 658.4064.
Guanidine 45: Pd(OH)2/C (400 mg) was added to a solution of isoxazoli-
dine 43 (797 mg, 1.53 mmol) in EtOH (5.0 mL), and the reaction mixture
was stirred at room temperature under a hydrogen (balloon). After 3 h,
the reaction mixture was filtered through a pad of Celite. The filtrates
were concentrated in vacuo to give pyrrolidine 44. HgCl2 (500 mg,
1.85 mmol) was added to a solution of pyrrolidine 44, 1,3-bis(tert-butoxy-
carbonyl)-2-methyl-2-thiopseudourea (537 mg, 1.85 mmol) and triethyl-
amine (640 mL, 4.62 mmol) in DMF (10.0 mL), and the resulting mixture
was stirred for 30 min. The reaction mixture was diluted with ethyl ace-
tate, and filtered through a pad of Celite. The filtrates were concentrated
in vacuo, and the residue was purified by silica gel column chromatogra-
phy (hexane/EtOAc; 5:1) to give the bis-Boc-protected guanidine 45
(830 mg, 71% overall).
Bicyclic guanidine 46: DEAD (750 mL, 1.65 mmol, 40% in toluene) was
added to a solution of guanidine 45 (830 mg, 1.09 mmol) and PPh3
(433 mg, 1.65 mmol) in toluene (10.0 mL). After stirring for 30 min, the
reaction mixture was quenched with H2O (50 mL) and concentrated in
vacuo. The residue was purified by flash chromatography on silica gel
(hexane/EtOAc; 3:2) to give bicyclic guanidine 46 (860 mg, q.y.) as a
clear oil. [a]2D4 =À128.9 (c=1.68 in CHCl3); 1H NMR (500 MHz, CDCl3):
d=7.25 (d, J=8.6 Hz, 2H), 6.87 (d, J=8.6 Hz, 2H), 4.45 (m, 1H), 4.42
(s, 2H), 3.79 (s, 3H), 3.70–3.47 (m, 5H), 3.42 (t, J=6.8 Hz, 2H), 2.60 (m,
1H), 2.00–1.85 (m, 2H), 1.81–1.54 (m, 6H), 1.54–1.18 (m, 12H), 1.48 (s,
9H), 1.47 (s, 9H), 0.89 (s, 9H), 0.06 (s, 3H), 0.06 ppm (s, 3H); 13C NMR
(125 MHz, CDCl3): d=159.2, 159.1, 151.9, 150.0, 130.8, 129.2, 113.7, 81.8,
77.8, 72.5, 70.3, 60.5, 56.7, 55.2, 54.0, 46.7, 43.8, 29.8, 29.6, 29.5, 29.4, 29.3,
28.5, 28.4, 28.2, 28.16, 26.3, 26.2, 25.8, 22.1, 18.0, À5.5, À5.6 ppm; IR
(neat): n˜ =2929, 2856, 1732, 1678, 1586, 1513, 1471, 1390, 1365, 1326,
1301, 1249 cmÀ1; HRMS (FAB): calcd for C41H72N3O7 [M++H]: 746.5140;
found: 746.5143.
Ester 58: nPrSLi (71.9 mg) was added to a solution of methyl ester 56
(57.6 mg, 0.088 mmol) in HMPA (2.1 mL) at room temperature, and the
mixture was stirred for 80 min. The reaction mixture was poured into ice/
Et2O, and washed with water. The aqueous layer was acidified to pH 3
with 0.1m HCl aq. and extracted with Et2O. After washing with HCl aq.
(pH 3), the combined organic layer was dried over MgSO4 and concen-
trated in vacuo to give carboxylic acid 57. Triethylamine (37 mL) was
added to a mixture of the crude carboxylic acid 57, guanidine alcohol 8
(117 mg, 0.35 mmol), and BOPCl (56.0 mg) in CH2Cl2 (2 mL) at room
temperature. After stirring for 12 h, the reaction mixture was diluted
with ethyl acetate and washed with brine. The organic layer was dried
over MgSO4, filtered, and concentrated in vacuo. The residue was puri-
fied by flash chromatography on silica gel (hexane/EtOAc; 4:1) to give
ester 58 (45.3 mg, 0.047 mmol, 54% overall) as a yellow oil. [a]2D4 =28.3
Alcohol 47: TBAF (590 mg, 2.26 mmol) was added to a solution of TBS
ether 46 (860 mg, 1.13 mmol) in THF (15 mL). After 2 h, the solution
was diluted with ethyl acetate and washed with H2O and saturated
NH4Cl aq. The organic layer was dried over MgSO4 and concentrated in
vacuo. The residue was purified on silica gel (hexane/EtOAc; 1:2) to give
alcohol 47 (580 mg, 81%) as a colorless oil. [a]2D4 =À133.4 (c=1.30 in
CHCl3); 1H NMR (500 MHz, CDCl3): d=7.26 (d, J=8.6 Hz, 2H), 6.87
(d, J=8.6 Hz, 2H), 4.42 (s, 2H), 4.41 (m, 1H), 3.80 (s, 3H), 3.73 (m,
2H), 3.63 (m, 2H), 3.52 (m, 1H), 3.43 (t, J=6.6 Hz, 2H), 2.62 (m, 1H),
1.98 (m, 2H), 1.78 (m, 1H), 1.70–1.53 (m, 3H), 1.48 (s, 9H), 1.48 (s, 9H),
1.42–1.20 ppm (m, 14H); 13C NMR (125 MHz, CDCl3): d=158.9, 158.8,
151.9, 150.5, 130.5, 129.0, 113.5, 81.8, 77.6, 72.3, 70.0, 59.9, 57.2, 55.0, 54.2,
46.8, 43.4, 29.5, 29.3, 29.2, 29.0, 28.4, 28.3, 27.9, 26.1, 25.9, 21.9 ppm; IR
(neat): n˜ =3369, 2975, 2929, 2855, 1729, 1682, 1574, 1514, 1473, 1389,
1
(c=0.88 in CHCl3); H NMR (500 MHz, CDCl3): d=11.50 (br, 1H), 8.34
(br, 1H), 7.27 (d, J=8.6 Hz, 2H), 6.87 (d, J=8.6 Hz, 2H), 5.21 (dd, J=
8.6, 4.3 Hz, 1H), 4.42 (s, 2H), 4.15 (m, 2H), 3.95 (ddd, J=11.5, 8.1,
7.7 Hz, 1H), 3.80 (s, 3H), 3.73 (ddd, J=12.4, 8.6, 3.3 Hz, 1H), 3.46 (dd,
J=12.4, 6.8 Hz, 2H), 3.42 (t, J=6.8 Hz, 2H), 3.22 (ddd, J=17.5, 8.6,
4.3 Hz, 1H), 2.15–1.93 (m, 2H), 1.78–1.64 (m, 4H), 1.62–1.53 (m, 2H),
1.51 (s, 9H), 1.50 (s, 9H), 1.49 (s, 9H), 1.48 (s, 9H), 1.41–1.19 ppm (m,
14H); 13C NMR (125 MHz, CDCl3): d=165.1, 163.6, 159.0, 158.8, 156.1,
153.3, 152.0, 150.8, 144.7, 130.8, 129.1, 113.7, 103.0, 83.1, 83.0, 79.6, 79.3,
72.5, 70.2, 63.6, 55.2, 53.0, 48.8, 40.4, 33.7, 31.2, 29.8, 29.6, 29.5, 29.46,
29.2, 28.3, 28.2, 28.1, 28.0, 26.3 26.2, 25.8, 24.8, 21.4 ppm; IR (neat): n˜ =
3332, 2979, 2931, 2856, 1739, 1731, 1723, 1715, 1704, 1695, 1643, 1633,
6886
www.chemeurj.org
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2005, 11, 6878 – 6888

Total Synthesis
FULL PAPER
1622, 1614, 1514, 1455, 1415, 1391, 1368, 1331 cmÀ1; HRMS (FAB): calcd
29.6, 29.5, 29.4, 29.3, 29.2, 29.1, 28.7, 28.5, 28.3, 28.2, 28.1, 28.0, 27.0, 26.3,
26.25, 25.8, 25.79, 24.8, 22.7, 21.4, 16.5, 14.1 ppm; IR (neat): n˜ =3331,
2978, 2929, 2855, 1738, 1732, 1695, 1641, 1614, 1576, 1456, 1416, 1390,
for C50H81N6O12 [M++H]: 957.5912; found: 957.5919.
Alcohol 59: DDQ (77 mg) was added to a solution of ester 58 (108.0 mg,
0.113 mmol) in CH2Cl2 (1.6 mL) and H2O (180 mL) at room temperature
and stirred for 1 h. The reaction mixture was poured into saturated
NaHCO3 aq. and extracted with ethyl acetate. The organic layer was
washed with brine, dried over MgSO4, filtered, and concentrated in
vacuo. The residue was purified on silica gel (hexane/EtOAc; 2:1) to give
alcohol 59 (62.2 mg, 66%) as a clear oil. [a]2D4 =23.2 (c=1.52 in CHCl3);
1H NMR (500 MHz, CDCl3): d=11.49 (br, 1H), 8.34 (br, 1H), 5.21 (dd,
J=8.5, 4.7 Hz, 1H), 4.16 (dt, J=12.4, 5.1 Hz, 2H), 3.95 (ddd, J=11.5,
8.1, 7.7 Hz, 1H), 3.73 (ddd, J=12.4, 8.6, 4.3 Hz, 1H), 3.62 (t, J=6.6 Hz,
2H), 3.46 (dd, J=12.4, 6.9 Hz, 2H), 3.22 (ddd, J=18.0, 8.6, 4.3 Hz, 1H),
2.92 (ddd, J=18.0, 9.0, 9.0 Hz, 1H), 2.12–1.96 (m, 2H), 1.78–1.41 (m,
6H), 1.51 (s, 9H), 1.49 (s, 9H), 1.48 (s, 9H), 1.48 (s, 9H), 1.41–1.18 ppm
(m, 14H); 13C NMR (125 MHz, CDCl3): d=165.2, 163.6, 158.9, 156.2,
153.3, 152.1, 150.8, 144.8, 103.0, 83.2, 83.1, 79.7, 79.4, 63.6, 63.0, 53.0, 48.8,
40.5, 33.6, 32.8, 31.2, 29.7, 29.4, 29.3, 29.26, 29.0, 28.3, 28.1, 28.0, 26.3,
25.9, 25.7, 24.7, 21.4 ppm; IR (neat): n˜ =3329, 2979, 2930, 2856, 1739,
1722, 1698, 1641, 1614, 1456, 1416, 1392, 1368, 1332 cmÀ1; HRMS (FAB):
calcd for C42H73N6O11 [M++H]: 837.5337; found: 837.5337.
1368, 1329 cmÀ1
;
HRMS (FAB): calcd for C78H120N9O17 [M++H]:
1454.8802; found: 1454.8811.
(+)-Batzelladine A (1): A catalytic amount of Pd/C was added to a solu-
tion of 61 (14.4 mg, 0.0099 mmol) in ethyl acetate (200 mL). The reaction
mixture was stirred at room temperature under hydrogen (balloon) for
3 h, and was filtered. The filtrates were concentrated in vacuo to give a
guanidine alcohol. DEAD (44 mL, 40% in toluene) was added to a solu-
tion of the guanidine alcohol (11.4 mg, 0.0096 mmol) and PPh3 (25.2 mg)
in toluene (300 mL). After stirring for 5 h, the reaction mixture was
quenched with H2O (10 mL) and concentrated in vacuo. The residue was
purified by silica gel column chromatography (CHCl3/MeOH; 1:1) to
give tricyclic guanidine 62. The tricyclic guanidine 62 (6.9 mg,
0.0059 mmol) was dissolved in 50% TFA in CH2Cl2 (500 mL) and stirred
for 30 min. The reaction mixture was concentrated in vacuo, and the resi-
due was purified by HPLC (50% MeCN aq. 0.1% TFA) to give (+)-bat-
zelladine A (1) (2.52 mg, 0.0023 mmol, 24% overall) as a viscous oil.
[a]2D5 =4.29 (c=0.25 in MeOH); 1H NMR (500 MHz, CD3OD): d=4.39
(t, J=6.1 Hz, 1H), 4.21 (t, J=6.4 Hz, 2H), 4.13 (t, J=6.7 Hz, 2H), 3.93
(m, 1H), 3.83 (m, 2H), 3.66 (m, 1H), 3.52 (m, 2H), 3.32 (m, 1H), 3.22 (t,
J=7.3 Hz, 2H), 3.12 (dd, J=4.6, 3.5 Hz, 1H), 2.98 (m, 1H), 2.35 (m,
1H), 2.28–2.17 (m, 3H), 2.10 (m, 1H), 1.76 (m, 2H), 1.72–1.52 (m, 9H),
1.48–1.23 (m, 29H), 1.27 (d, J=6.7 Hz, 3H), 0.89 ppm (t, J=6.7 Hz, 3H);
13C NMR (125 MHz, CD3OD): d=170.7, 166.2, 158.7, 153.1, 152.7, 151.5,
103.3, 66.0, 65.1, 57.7, 57.3, 53.2, 51.2, 49.9, 48.8, 45.6, 42.0, 37.5, 36.9,
34.2, 33.0, 31.9, 31.4, 29.7, 29.3, 27.0, 26.6, 26.2, 25.2, 23.7, 22.9, 18.4,
14.4 ppm; IR (neat): n˜ =2925, 2854, 1732, 1697, 1683, 1648, 1637, 1558,
1347, 1092 cmÀ1; HRMS (FAB): calcd for C42H74N9O4 [M++H]: 768.5864;
found: 768.5866.
Ester 60: EDCI (11.0 mg) and DMAP (1.0 mg) was added to a mixture
of crude carboxylic acid 35—obtained by Jones oxidation of correspond-
ing alcohol (12.8 mg, 0.017 mmol), alcohol 59 (13.2 mg, 0.016 mmol) in
CH2Cl2 (400 mL)—at 08C. After stirring at 08C for 3 h, the reaction mix-
ture was poured into H2O and extracted with Et2O. The extracts were
washed with saturated NaHCO3 aq. and brine, and dried over MgSO4.
The filtrates were concentrated in vacuo and the residue was purified by
column chromatography on silica gel (CH2Cl2/hexane/EtOAc; 16:8:3) to
give ester 60 (14.8 mg, 0.0094 mmol, 60%) as a clear oil. [a]2D4 =À52.4
1
(c=0.57 in CHCl3); H NMR (500 MHz, CDCl3): d=11.50 (br, 1H), 8.34
(br, 1H), 7.36–7.20 (m, 10H), 5.21 (dd, J=8.6, 4.7 Hz, 1H), 5.15 (d, J=
12.4, 1H), 4.97 (d, J=12.8, 1H), 4.90 (d, J=12.4, 1H), 4.87 (d, J=12.4,
1H), 4.48 (m, 1H), 4.25–4.10 (m, 3H), 4.10–4.02 (m, 1H), 4.05 (t, J=
6.8 Hz, 2H), 3.96 (ddd, J=11.5, 8.1, 7.7 Hz, 1H), 3.86 (m, 1H), 3.77–3.70
(m, 1H), 3.46 (dd, J=12.4, 6.4 Hz, 2H), 3.27–3.17 (m, 2H), 2.92 (ddd, J=
18.0, 9.0, 9.0 Hz, 1H), 2.26 (m, 2H), 2.18–1.92 (m, 2H), 1.90–1.45 (m,
14H), 1.51 (s, 9H), 1.50 (s, 9H), 1.49 (s, 9H), 1.48 (s, 9H), 1.45–1.20 (m,
29H), 0.95–0.80 (m, 12H), 0.04 (s, 3H), 0.03 ppm (s, 3H); 13C NMR
(125 MHz, CDCl3): d=169.9, 165.1, 163.6, 160.0, 158.9, 156.2, 153.3,
152.9, 152.0, 150.8, 150.2, 144.8, 137.2, 135.6, 128.3, 128.1, 128.06, 128.0,
127.4, 103.0, 83.1, 83.0, 79.6, 79.3, 71.1, 68.1, 66.8, 65.5, 63.6, 58.5, 56.3,
53.0, 52.4, 50.3, 48.8, 40.6, 40.4, 37.4, 33.7, 31.9, 31.3, 29.9, 29.7, 29.6, 29.5,
29.46, 29.3, 29.2, 28.8, 28.3, 28.27, 28.2, 28.1, 28.0, 27.4, 26.3, 25.9, 25.8,
24.8, 24.4, 22.7, 21.4, 16.4, 14.1, À4.3, À4.4 ppm; IR (neat): n˜ =3334, 2928,
2855, 1736, 1725, 1696, 1639, 1612, 1456, 1415, 1390, 1368, 1330, 1287,
1248 cmÀ1; HRMS (FAB): calcd for C84H134N9O17Si [M++H]: 1569.9697;
found: 1569.9678.
Acknowledgements
We thank Dr. Masami Suganuma for helpful discussion. We acknowledge
the fund from the Uehara Memorial Foundation. This work was also sup-
ported by Grant-in-Aid for Scientific Research on Priority Areas
17035025 from The Ministry of Education, Culture, Sports, Science, and
Technology (MEXT).
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Breen, R. P. Hertzberg, R. K. Johnson, J. W. Westley, B. C. M. Potts,
J. Org. Chem. 1995, 60, 1182–1188; b) A. D. Patil, A. J. Freyer, P. B.
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Alcohol 61: HF/pyridine (100 mL) was added to a solution of 60 (41.7 mg
0.027 mmol) in THF (300 mL) in a polypropylene tube at 08C. After stir-
ring for 4 h, saturated NaHCO3 aq. (500 mL) and solid NaHCO3 (100 mg)
were added. The mixture was dried over MgSO4, filtered through a pad
of Celite, and washed with ethyl acetate. The filtrates were concentrated
in vacuo and the residue was purified by column chromatography on
silica gel (hexane/EtOAc; 2:1) to give alcohol 61 (31.0 mg, 0.021 mmol,
1
80%). [a]2D4 =À66.3 (c=1.11 in CHCl3); H NMR (500 MHz, CDCl3): d=
11.50 (br, 1H), 8.54 (br, 1H), 7.36–7.16 (m, 10H), 5.20 (dd, J=8.5,
4.7 Hz, 1H), 5.14 (d, J=12.4 Hz, 1H), 5.00 (d, J=12.8 Hz, 1H), 4.82 (d,
J=12.4 Hz, 1H), 4,78 (d, J=12.4 Hz, 1H), 4.58 (m, 1H), 4.38 (m, 1H),
4.23–4.09 (m, 2H), 4.06 (dt, J=6.8, 3.4 Hz, 2H), 3.94 (m, 2H), 3.73 (m,
1H), 3.51 (br, 1H), 3.45 (dd, J=12.4, 6.8 Hz, 2H), 3.27–3.16 (m, 2H),
2.91 (ddd, J=18.0, 9.0, 9.0 Hz, 1H), 2.42–2.23 (m, 2H), 2.12–1.91 (m,
2H), 1.91–1.38 (m, 14H), 1.50 (s, 9H), 1.49 (s, 9H), 1.48 (s, 9H), 1.48 (s,
9H), 1.38–1.07 (m, 29H), 0.87 ppm (t, J=6.8 Hz, 3H); 13C NMR
(125 MHz, CDCl3): d=169.9, 165.1, 163.6, 159.3, 158.9, 156.2, 153.7,
153.3, 152.7, 152.0, 150.8, 144.8, 136.9, 135.1, 128.4, 128.1, 128.0, 127.9,
127.5, 127.47, 127.4, 103.0, 83.2, 83.1, 79.6, 79.3, 68.2, 66.4, 66.3, 65.8, 63.6,
56.9, 56.5, 53.2, 53.0, 51.0, 48.8, 44.4, 40.4, 37.0, 33.7, 31.9, 31.3, 30.0, 29.7,
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Received: July 20, 2005
Published online: September 14, 2005
6888
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Chem. Eur. J. 2005, 11, 6878 – 6888