Total Syntheses of (±)-Anchinopeptolide D and (±)-Cycloanchinopeptolide D

Article abstract of DOI:10.1021/jo991454l

The first synthesis of (±)-anchinopeptolide D (4) has been accomplished in seven steps in 10% overall yield from octopamine hydrochloride (17), N-(Boc)glycine (16), and 5-amino-2-hydroxypentanoic acid (22). The key step is the aldol dimerization and hemiaminal formation of α-keto amide 26, which gives primarily protected anchinopeptolide D 27 under kinetically controlled conditions. Cycloanchinopeptolide D (31) has been prepared by the unprecedented head-to-head photodimerization of the two hydroxystyrylamides of 4 using the hydrophobic effect in water to force the two side chains into close proximity so that [2 + 2] cycloaddition is faster than trans to cis double bond isomerization. Coupling of amine 21 with pyroglutamic acid affords the naturally occurring tripeptide 35, which had been assigned glutamic acid structure 34.

Full text of DOI:10.1021/jo991454l

J . Org. Chem. 2000, 65, 793-800
793
Tota l Syn th eses of (()-An ch in op ep tolid e D a n d
(()-Cycloa n ch in op ep tolid e D
Barry B. Snider,* Fengbin Song, and Bruce M. Foxman
Department of Chemistry, Brandeis University, Waltham, Massachusetts 02454-9110
Received September 14, 1999
The first synthesis of (()-anchinopeptolide D (4) has been accomplished in seven steps in 10%
overall yield from octopamine hydrochloride (17), N-(Boc)glycine (16), and 5-amino-2-hydroxypen-
tanoic acid (22). The key step is the aldol dimerization and hemiaminal formation of R-keto amide
26, which gives primarily protected anchinopeptolide D 27 under kinetically controlled conditions.
Cycloanchinopeptolide D (31) has been prepared by the unprecedented head-to-head photodimer-
ization of the two hydroxystyrylamides of 4 using the hydrophobic effect in water to force the two
side chains into close proximity so that [2 + 2] cycloaddition is faster than trans to cis double bond
isomerization. Coupling of amine 21 with pyroglutamic acid affords the naturally occurring
tripeptide 35, which had been assigned glutamic acid structure 34.
In tr od u ction
head [2 + 2] cycloaddition between the two hydroxystyry-
lamido groups resulted in the formation of a cyclobutane
fused to a 12-membered ring.2 At first glance, it appears
that this cycloaddition should occur photochemically.
However, enamides such as 8 undergo only trans to cis
isomerization to give 7 on irradiation in solution.4 We
have recently shown that head-to-tail photodimerization
occurs on irradiation of crystalline enamides in which the
molecules stack in the proper orientation.5 For instance,
irradiation of crystalline 8 provides 89% of 9.5 In crystal-
line 8, cyclobutane formation is faster than rotation about
the double bond because the two molecules are held
properly aligned in close proximity.
The dimeric peptide alkaloids anchinopeptolides A-D
(1-4) were isolated by Minale and co-workers from the
sponge Anchinoe tenacior collected off the coast of
Tunisia.1,2 Anchinopeptolides B-D displace specific ligands
from the somatostatin receptor (62-73%), the human B2
bradykinin receptor (52-71%), and the neuropeptide Y
receptor (57-80%) at 5 µg/mL.2 These alkaloids are
dimers of the modified tripeptide 5, containing an R-keto
acid derived from arginine, glycine or alanine, and
hydroxystyrylamide, probably formed from tyrosine.3 An
aldol reaction will form the carbon-carbon bond. Addi-
tion of the amide to the remaining ketone will form the
5-hydroxypyrrolidinone.
We chose to undertake a biomimetic synthesis of
anchinopeptolide D (4) by the aldol dimerization of 26, a
protected modified tripeptide 5 (R1 ) R2 ) H), to make
these compounds more readily available for biological
evaluation, to explore the stereochemistry of the aldol
(1) Casapullo, A.; Finamore, E.; Minale, L.; Zollo, F. Tetrahedron
Lett. 1993, 34, 6297.
(2) Casapullo, A.; Minale, L.; Zollo, F.; Lavayre, J . J . Nat. Prod.
1994, 57, 1227.
(3) Schmidt, U.; Lieberknecht, A. Angew. Chem., Int. Ed. Engl. 1983,
22, 550.
(4) Hoffmann, R. W.; Eicken, K. R. Tetrahedron Lett. 1968, 1759;
Chem. Ber. 1969, 102, 2987.
(5) Song, F.; Snook, J . H.; Foxman, B. M.; Snider, B. B. Tetrahedron
1998, 54, 13035.
They also isolated an additional alkaloid, cycloanchi-
nopeptolide C (6), in which an intramolecular head-to-
10.1021/jo991454l CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/14/2000

794 J . Org. Chem., Vol. 65, No. 3, 2000
Snider et al.
reaction and 5-hydroxypyrrolidinone formation, and to
provide a substrate to explore the intramolecular [2 +
2] cycloaddition leading to cycloanchinopeptolide D. Aldol
reactions of pyruvamides, which can give only a single
aldol product, have been extensively explored.6-9 The
aldol adduct cyclizes to give a mixture of 5-hydroxypyr-
rolidinones. For instance, treatment of 10 with NaOMe
in MeOH or Et3N affords an equilibrium 30:70 mixture
of 11a and 11b.9 The individual isomers reequilibrate in
MeOH at reflux for 1 h. Aldol dimerizations of longer
chain R-keto amides, which will give mixtures of diaster-
eomers, have not been examined. We therefore prepared
N-benzyl-2-oxobutanamide (12c) to examine the stereo-
chemistry of the aldol reaction in a simple system.
Treatment of 13a with NaOH in MeOH at reflux for 1
h results in isomerization of the 5-hydroxypyrrolidinone
to give 88% of a 10:1 mixture of 13b and 13a . NOEs
observed between H4 at δ 1.69 and 1.51, and H4′ at δ 2.35,
between C5-OH at δ 5.52 and H3′ at δ 0.83, and between
H4′ at δ 2.35 and C5′-OH at δ 7.04 established the
stereochemistry of 13b. An X-ray crystallographic struc-
ture determination confirmed the stereochemistry of 13b.
Treatment of a solution of 13b with NaH in THF at
25 °C for 2 h affords 75% of 13a , 5% of 13b, and 10% of
ketoamide 12c. This establishes that the selective forma-
tion of 13a in THF and 13b in MeOH is a result of a
remarkable solvent effect on the stability of the hydroxy-
pyrrolidinones rather than the kinetically favored forma-
tion of 13a in THF. Presumably, 13a is more stable in
THF because of intramolecular hydrogen bonding be-
tween the two hydroxy groups. In the protic solvent,
MeOH, intramolecular hydrogen bonding is less impor-
tant and 13b is more stable.
Having established that a biomimetic aldol dimeriza-
tion should lead selectively to 5-hydroxypyrrolidinones
with the anchinopeptolide stereochemistry, we turned our
attention to the construction of the suitably protected
modified tripeptide 26 to investigate the dimerization in
a fully functionalized system. DCC coupling of N-(Boc)-
glycine (16) with octopamine hydrochloride (17) and
acetylation of the crude product affords 51% of diacetate
amide 18. Heating 18 with K2CO3 in DMSO at 90 °C11
induces elimination of the acetate to introduce the
styrene and partially hydrolyzes the aryl acetate giving
a mixture of 19 and 20. Reacetylation of the mixture
affords 67% of styrylamide 20. Removal of the Boc group
in 1:1 TFA/CH2Cl2 at 25 °C for 10 min provides 94% of
amine 21.
Resu lts a n d Discu ssion
Reaction of 2-oxobutanoic acid (12a ) with R,R-dichlo-
romethyl methyl ether10 gives 2-oxobutanoyl chloride
(12b), which reacts with BnNH2 and Et3N in THF to
afford 59% of N-benzyl-2-oxobutanamide (12c). We were
delighted to find that treatment of 12c with NaH in THF
for 6 h at 25 °C provides 89% of a 15:1 mixture of 13a
and 13b. The structure of 13a , which has the same
stereochemistry as the anchinopeptolides, was estab-
lished by NOE studies in DMSO-d6, in which the hydroxy
and amide protons can be easily observed and assigned
by HSQC and HMBC experiments. NOEs were observed
between H4 at δ 1.61 and H4′ at δ 2.64, between C5-OH
at δ 5.15 and H3′ at δ 0.87, between C5-OH at δ 5.15 and
C5′-OH at δ 5.88, and between C5′-OH at δ 5.88 and H3′
at δ 0.87. The numbering system is based on that
previously used for the anchinopeptolides.1,2
This establishes that the aldol reaction in THF occurs
with the desired stereochemistry. The formation of aldol
product 15 can be rationalized by consideration of a
chelated transition state for the aldol reaction. Enoliza-
tion should give the Z-enolate to avoid steric interactions
between the amide and methyl groups. Transition state
14, which leads to aldol product 15, should be favored
for the aldol reaction since the sodium can bind to all
four oxygens.
Reaction of 5-amino-2-hydroxypentanoic acid (22)12,13
with N,N ′-bis-Boc-1-guanidylpyrazole (23)14 gives 77%
of the protected arginic acid derivative 24. We were not
(6) Scudi, J . V. J . Am. Chem. Soc. 1937, 59, 1403.
(7) Pojer, P. M.; Rae, I. D. Aust. J . Chem. 1972, 25, 1737.
(8) Haeusler, J .; Schmidt, U. Monatsch. Chem. 1978, 109, 147.
(9) Stewart, K. D.; Bailey, C.; Hall, W. R.; Crouch, R. J . Heterocycl.
Chem. 1993, 30, 1153.
(10) Ottenheijm, H. C. J .; Tijhuis, M. W. Org. Synth. 1983, 61, 1.
(11) Dali, H.; Sugumaran, M. Org. Prep. Proced. Int. 1988, 20, 191.
(12) Kristiansen, U.; Hedegaard, A.; Herdeis, C.; Lund, T. M.;
Nielsen, B.; Hansen, J . J .; Falch, E.; Hjeds, H.; Krogsgaard-Larsen,
P. J . Neurochem. 1992, 58, 1150.
(13) For another synthesis of 22, see: Sefler, A. M.; Kozlowski, M.
C.; Guo, T.; Bartlett, P. A. J . Org. Chem. 1997, 62, 93.
(14) Wu, Y.; Matsueda, G. R.; Bernatowicz, M. Synth. Commun.
1993, 23, 3055.

Total Synthesis of (()-Anchinopeptolide D
J . Org. Chem., Vol. 65, No. 3, 2000 795
able to selectively protect the guanidine of arginic acid
directly. Coupling of acid 24 with amine 21 using DCC
and HOBT in MeCN gives 85% of hydroxy amide 25.
Oxidation of 25 with Dess-Martin periodinane in CH2-
Cl2 provides 49% of the requisite R-keto amide 26 and
27% of recovered 25.
and C5′-OH at δ 6.63 established that the two OH groups
and the guanidinoethyl chain are cis. The structure of
the hydroxypyrrolidinone isomer 28 was established by
an NOE between C5′-OH at δ 7.45 and H4′ at δ 2.42 and
the absence of NOEs between C5-OH at δ 5.34 and H4′
at δ 2.42 and between the two hydroxy groups. The
structure of the minor isomer 30 was established by
NOEs between C5-OH at δ 5.58 and H4′ at δ 2.54 and
between C5′-OH at δ 6.86 and H3′ at δ 1.74.
Equilibration studies confirmed these stereochemical
assignments. Heating a solution of either pure 27 or 28
in CD3OD at reflux for 1 h affords an equilibrium 2:1
mixture of 28 and 27. This confirms the stereochemical
assignments made by NOE studies, since equilibration
of the hydroxypyrrolidinone isomers 27 and 28 will occur
readily as observed in the equilibration of the stereoiso-
mers of 11 and 13. Equilibration of the aldol stereoiso-
mers must occur more slowly than equilibration at the
hemiaminal center, since opening to the acyclic keto
amide, followed by enolization or a retro-aldol/aldol
sequence are required to equilibrate the aldol stereoiso-
mers. Similarly, treatment of either pure 27 or 28 with
KOH in 1:1 THF/MeOH at 25 °C for 17 h provides a 6:3:1
mixture of 28, 27, and 30.
The synthesis of anchinopeptolide D (4) was completed
by cleavage of the Boc protecting groups of 27 in 1:1 TFA/
CH2Cl2 for 1 h at 25 °C, which gives 91% of 4 as the bis
1
trifluoroacetate salt. The H and 13C NMR in both CD3-
OD and DMSO-d6 are identical to those previously
reported.18 The stereochemistry of 4 was confirmed by
NOE studies as reported for the natural product.2 NOEs
between C5-OH at δ 5.59, C5′-OH at δ 6.97, and H3′ at δ
1.62 and 1.77 indicate that the two hydroxy groups and
the guanidinoethyl chain are cis. Similarly, deprotection
of 28 affords 94% of epi-anchinopeptolide D (29). NOEs
between C5′-OH at δ 7.44 and H4′ at δ 2.34, but not with
C5-OH at δ 5.48 established the stereochemistry.
Syn th esis of Cycloa n ch in op ep tolid e D. Our initial
attempts at intramolecular photochemical [2 + 2] cy-
cloaddition of anchinopeptolide D (4) were predictably
disappointing. Irradiation of either 27 or the bis trifluo-
roacetate salt of 4 in CD3OD at 350 nm for 4 h results in
trans to cis isomerization of the double bonds as expected
based on solution studies of other enamides.4,5 We
hypothesized that the choice of solvent should have a
profound effect on the photochemistry. The bis trifluo-
roacetate salt of 4 should be soluble in water because it
is a dication. In water, the hydrophobic effect should
cause the two hydroxystyrylamido groups to pack closely
together to minimize repulsive interactions between
water and the two nonpolar side chains. If the orientation
of the side chains is appropriate, [2 + 2] cycloaddition
could be faster than trans to cis isomerization of the
double bond. The hydrophobic effect has been shown to
lead to different products from irradiation of stilbenes
and alkyl cinnamates in water and nonpolar solvents.19-22
Treatment of R-keto amide 26 with KOH in 1:1 THF/
MeOH at 0 °C for 20 min affords 58% of the desired
5-hydroxypyrrolidinone 27, 19% of 5-hydroxypyrrolidi-
none 28, with the same aldol stereochemistry, but the
opposite stereochemistry at the hemiaminal center, and
<5% of a third adduct 30, derived from the other aldol
adduct. Other reaction conditions, including NaH in THF,
gave lower yields or less selectivity for 27. The stereo-
chemistry of the products was established by NOE
experiments in DMSO-d6. The protons were assigned by
COSY, HSQC and HMBC experiments. In the major
adduct 27, NOEs between C5-OH at δ 5.41, H3′ at δ 1.78,
(15) Hagihara, M.; Schreiber, S. L. J . Am. Chem. Soc. 1992, 114,
6570.
(16) Bastiaans, H. M. M.; van der Baan, J . L.; Ottenheijm, H. C. J .
Tetrahedron Lett. 1995, 36, 5963.
(17) Bernatowicz, M.; Wu, Y.; Matsueda, G. R. Tetrahedron Lett.
1993, 34, 3389.
(18) Our 13C NMR data for 4, which were referenced to the central
peak of CD3OD at δ 49.15, are 0.3 ppm downfield from the literature
data, which are referenced to δ 48.85. The coupling constants for H4′
are 4.8 and 10 Hz. C5′ absorbs at δ 91.0 not 90.1 as reported. Dr.
Agostino Casapullo, private communication, J anuary 1999.

796 J . Org. Chem., Vol. 65, No. 3, 2000
Snider et al.
We were delighted to find that irradiation of a 0.005
M solution of the bis trifluoroacetate salt of 4 in D2O at
350 nm at 28 °C for 5 h provides 48% of cycloanchinopep-
tolide D (31). In CD3OD, the cyclobutane protons, H9 at
δ 4.56, H9′ at δ 4.83, H10 at δ 4.11, and H10′ at δ 4.00,
were assigned by COSY, HSQC, and HMBC experiments.
NOEs between H9′ at δ 4.83 and H12′ at δ 6.79, between
H9 at δ 4.56 and H12 at δ 6.72, and between H9′ at δ 4.83
and H9 at δ 4.56, establish that the cyclobutane was
formed by head-to-head dimerization of trans hydroxy-
styrylamides. The stereochemistry of the pyrrolidinone
of 31 was assumed to be the same as that of 4. The
relative stereochemistry between the pyrrolidinone and
the cyclobutane was not determined, as was the case in
the structure determination of cycloanchinopeptolide C
(6).2
tolides.25 The structure was established by NMR spec-
troscopic analysis. Hydrolysis with 6 N HCl, reaction with
Marfey’s reagent, and HPLC analysis established the
L-glutamic acid configuration. We chose to prepare this
tripeptide since acetoxystyrylglycine (21) was available
from our anchinopeptolide D synthesis. DCC coupling of
protected glutamic acid 32 with 21 followed by hydrolysis
of the acetate with sodium carbonate affords 71% of 33.
Cleavage of the Boc groups with 1:1 TFA/CH2Cl2 provides
the trifluoroacetate salt of 34.
1
The H and 13C NMR spectra of 34 are very different
than those reported for the natural product. The NMR
spectra of amino acids are very sensitive to pH. We
therefore examined the spectra of 34 in basic, neutral
and acidic CD3OD. The spectral data of the natural
product do not match well with those of the synthetic
material obtained at any pH. The carboxylic acid carbon
at δ 170.4 does not match that reported at δ 181.5. The
C2 methylene group triplet at δ 2.56 does not match the
reported multiplets at δ 2.35 and 2.55 for this methylene
group.
The very different chemical shifts of the C2 methylene
protons of the natural product suggested that this carbon
is in a ring. Tripeptide 35 with a pyroglutamate should
have proton and carbon shifts similar to those reported
and will give L-glutamic acid on hydrolysis. The failure
to observe a parent ion at m/z 321 with either EI or FAB
ionization is also consistent with 35 which could give a
parent ion at m/z 303 that could be misinterpreted as
loss of water from 34 in the mass spectrometer.
The spectral data for cycloanchinopeptolide D (31) are
very similar to those reported for cycloanchinopeptolide
C (6). The geminal coupling constant for the C7 methylene
protons of 31, 17.0 Hz, is very close to that observed for
glycine in proteins and in 6. The geminal coupling
constant for the C7’ methylene protons, 13.4 Hz, is much
smaller than typical for glycine and initially caused some
concern. In 6, this coupling constant is not observed since
an alanine rather than glycine is present in this chain.
Barfield suggested that the geminal coupling constants
in the glycine residues of a peptide backbone depend on
both dihedral angles φ and θ in the backbone. The
variation of the coupling constants was calculated to be
as much as 8 Hz.23,24 Molecular mechanics calculations
indicate that 31 exists in one highly preferred conforma-
tion with φ and θ values that should result in a small
coupling constant.
We therefore prepared 35 in 74% yield by treatment
of 21 with L-pyroglutamic acid and DCC in acetonitrile
1
and hydrolysis of the acetate with Na2CO3. The H and
13C NMR spectral data for 35 are identical to those
reported for the natural product18 indicating that the
structure of the natural tripeptide should be revised from
34 to 35. The optical rotation of synthetic 35, [R]25D +2.9,
is very different from the reported value for the tripep-
Syn th esis of Tr ip ep tid es 34 a n d 35. Minale and co-
workers also reported the isolation of 5.6 mg of tripeptide
34 from the same sponge that produced the anchinopep-
(19) Devanathan, S.; Ramamurthy, V. J . Photochem. Photobiol. A
1987, 40, 67.
(20) Syamala, M. S.; Ramamurthy, V. J . Org. Chem. 1986, 51, 3712.
(21) Ito, Y.; Kajita, T.; Kunimoto, K.; Matsuura, T. J . Org. Chem.
tide, [R]25 -4.6. We are unable to comment on the
D
significance of this discrepancy, except to note that only
5.6 mg of natural tripeptide was isolated and the sign of
optical rotation is very sensitive to trace impurities
because the magnitude is so small.
1989, 54, 587.
(22) Li, Y.; Deng, X. H.; Wang, X. H.; Tung, C. H. Chin. Chem. Lett.
1994, 5, 287.
(23) Barfield, M.; Hruby, V. J .; Meraldi, J . P. J . Am. Chem. Soc.
1976, 98, 1308.
(24) Bystrov, V. F. Prog. Nucl. Magn. Reson. Spectrosc. 1976, 10,
(25) Casapullo, A.; Minale, L.; Zollo, F. Tetrahedron Lett. 1994, 35,
41.
2421.

Total Synthesis of (()-Anchinopeptolide D
J . Org. Chem., Vol. 65, No. 3, 2000 797
P h otoch em istr y of Am in e 36 a n d Am m on iu m Sa lt
36a . We briefly examined the photochemistry of hydroxy-
styrylglycine 36. Cleavage of the Boc group of 19 with
TFA/CH2Cl2 affords 85% of 36. Irradiation of 36 at 350
nm in CD3OD results only in trans to cis isomerization.
No reaction occurs on irradiation of crystalline 36. Rapid
evaporation of a solution of 36 in MeOH affords a thin
film that gives 40% of head-to-tail dimer 37 on irradiation
for 16 h at 350 nm. The spectral data of 37 are similar
to those of analogous cyclobutanes such as 9 that we have
previously prepared by solid-state photodimerization.5
Presumably, rapid evaporation of the MeOH solution of
36 affords a phase with closely packed and properly
oriented hydroxystyrylamido residues that undergoes [2
+ 2] cycloaddition on irradiation. The different phase
formed on slow evaporation does not have properly
oriented hydroxystyrylamido residues and cannot un-
dergo either cycloaddition or trans to cis double bond
isomerization on irradiation.
dimerization of the two hydroxystyrylamides of 4 using
the hydrophobic effect in water to force the two side
chains into close proximity so that [2 + 2] cycloaddition
is faster than trans to cis double bond isomerization.
Coupling of amine 21 with pyroglutamic acid affords the
naturally occurring tripeptide 35, which had been incor-
rectly assigned glutamic acid structure 34.
Exp er im en ta l Section
Gen er a l Meth od s. NMR spectra were recorded at 400 MHz
in CDCl3, CD3OD, or DMSO-d6 as indicated. Negative NOEs
were observed for 4 and 27-31 in DMSO-d6. Positive NOEs
were observed for all compounds in CD3OD and for 13 in
DMSO-d6. Chemical shifts are reported in δ and coupling
constants in Hz. IR spectra are reported in cm-1. Reversed-
phase chromatography was carried out on J . T. Baker Bak-
erbond Octadecyl (C18) 40 µm prep LC packing.
2-Oxo-N-(p h en ylm eth yl)bu ta n a m id e (12c). A mixture of
2-oxobutanoic acid (1.021 g, 10 mmol) and R,R-dichloromethyl
methyl ether (0.91 mL, 10 mmol) was heated at 50 °C for 30
min in a flask that was connected to an open CaCl2 drying
tube. The residue was dissolved in 5 mL of THF, and the acid
chloride solution was added to a solution of benzylamine (1.09
mL, 10 mmol) and Et3N (1.40 mL, 10 mmol) in 15 mL of THF
at 0 °C over 30 min with rapid stirring. The solid was filtered
off, and water was added to the filtrate. The solution was
extracted with three portions of EtOAc. The combined extracts
were dried over Na2SO4. The solvent was removed and the
residue was purified on silica gel (3:1 CH2Cl2/hexane) to give
1
1.128 g (59%) of 12c: mp 79-80 °C; H NMR (CDCl3) 7.25-
7.37 (m, 5), 7.28 (br, 1, NH), 4.47 (d, 2, J ) 6.1), 2.98 (q, 2, J
) 7.2), 1.11 (t, 3, J ) 7.2); 13C NMR (CDCl3) 199.5, 159.9, 137.0,
128.8 (2 C), 127.84 (2 C), 127.80, 43.3, 30.3, 7.0; IR (KBr) 3253,
1723, 1671.
(2R,3R,4R)-4-E t h yl-2,4-d ih yd r oxy-3-m et h yl-5-oxo-N,1-
bis(p h en ylm eth yl)-2-p yr r olid in eca r boxa m id e (13a ). To a
solution of 12c (191 mg, 1 mmol) in 5 mL of THF at 25 °C,
was added a suspension of NaH (60% w/w in mineral oil) (80
mg, 2 mmol) in 5 mL of THF over 2 h with rapid stirring. After
addition, the mixture was stirred for 4 h and neutralized with
0.1 N HCl. The mixture was concentrated under reduced
pressure, and the residue was extracted with four portions of
CHCl3. The combined extracts were dried over MgSO4 and
concentrated to give a 15:1 mixture of 13a and 13b. The
mixture was purified on silica gel (3:1 CH2Cl2/EtOAc) to give
Since we have shown that use of water as the solvent
has a profound effect on the photochemistry of the
dication anchinopeptolide D (4), we examined the pho-
tochemistry of 36a , the trifluoroacetate salt of 36, in both
water and MeOH. Irradiation in CD3OD for 16 h provides
a mixture of the 36a , the cis isomer, and decomposition
products. Irradiation for 30 h affords only decomposition
products. On the other hand, irradiation of 36a in D2O
for 50 h affords 40% of the dimeric dication 37a , which
provides diamine 37 on neutralization. This suggests that
ammonium salt 36a aggregates in water due to the
hydrophobic effect to place the enamide double bonds of
two molecules in close proximity in a head-to-tail orienta-
tion so that cycloaddition is faster than trans to cis
isomerization.
In conclusion, we have completed the first synthesis
of (()-anchinopeptolide D (4), which proceeds in seven
steps in 10% overall yield from octopamine hydrochloride
(17), N-(Boc)glycine (16), and 5-amino-2-hydroxypen-
tanoic acid (22). We have shown that the aldol dimer-
ization and hemiaminal formation of R-keto amide 12c
gives primarily diastereomer 13a with NaH in THF. In
basic MeOH, equilibration of the hemiaminal center
affords mainly 13b, which can be reconverted to 13a with
NaH in THF. Cycloanchinopeptolide D (31) has been
prepared by the unprecedented head-to-head photo-
1
159 mg (83%) of 13a : mp 164-165 °C; H NMR (DMSO-d6)
8.69 (t, 1, J ) 6.1, NH), 7.16-7.29 (m, 10), 5.88 (s, 1, OH),
5.15 (s, 1, OH), 4.33 (d, 1, J ) 15.9), 4.22 (dd, 1, J ) 6.1, 14.7),
4.17 (dd, 1, J ) 6.1, 14.7), 4.12 (d, 1, J ) 15.9), 2.64 (q, 1, J )
7.3), 1.61 (q, 2, J ) 7.3), 0.87 (d, 3, J ) 7.3), 0.82 (t, 3, J )
7.3); 13C NMR (DMSO-d6) 175.7, 169.4, 139.3, 137.6, 128.2 (2
C), 127.8 (2 C), 127.6 (2 C), 127.1 (2 C), 126.7, 126.5, 90.5,
75.2, 43.7, 42.6, 41.3, 28.7, 8.2, 7.5; IR (KBr) 3370, 1685.
(2R,3â,4â)-4-E t h yl-2,4-d ih yd r oxy-3-m et h yl-5-oxo-N,1-
bis(p h en ylm eth yl)-2-p yr r olid in eca r boxa m id e (13b). A
solution of 13a (18.3 mg, 0.048 mmol) in 1 mL of CH3OH was
treated with NaOH (2 mg, 0.05 mmol). The mixture was
heated at 60 °C for 1 h. The solvent was removed, and H2O
was added. The mixture was extracted with 4 portions of
CHCl3. The combined extracts were dried over MgSO4 and
concentrated to give a 1:10 mixture of 13a and 13b. The
residue was purified on silica gel (3:1 CH2Cl2/EtOAc) to give
1
14.7 mg (80%) of 13b: mp 159-161 °C; H NMR (DMSO-d6)
9.03 (t, 1, J ) 6.1, NH), 7.14-7.31 (m, 10), 7.04 (s, 1, OH),
5.52 (s, 1, OH), 4.30 (d, 1, J ) 15.2), 4.17 (dd, 1, J ) 6.1, 15.2),
4.16 (d, 1, J ) 15.2), 4.11 (dd, 1, J ) 6.1, 15.2), 2.35 (q, 1, J )
7.3), 1.69 (dq, 1, J ) 7.3, 14.6), 1.51 (dq, 1, J ) 7.3, 14.6) 0.83
(d, 3, J ) 7.3), 0.82 (t, 3, J ) 7.3); 13C NMR (DMSO-d6) 174.1,
171.1, 138.6, 137.5, 128.2 (2 C), 127.9 (2 C), 127.7 (2 C), 127.2
(2 C), 126.9, 126.7, 91.0, 76.6, 44.7, 42.6, 42.4, 26.2, 8.5, 6.3;
1H NMR (CD3OD) 7.16-7.32 (m, 10), 4.46 (d, 1, J ) 15.2), 4.34
(d, 1, J ) 15.2), 4.17 (d, 1, J ) 14.8), 4.02 (d, 1, J ) 14.8), 2.34
(q, 1, J ) 7.2), 1.88 (qd, 1, J ) 7.3, 15.2), 1.65 (qd, 1, J ) 7.3,

798 J . Org. Chem., Vol. 65, No. 3, 2000
Snider et al.
15.2), 0.93 (d, 3, J ) 7.2), 0.90 (t, 3, J ) 7.3); 13C NMR (CD3-
OD) 176.9, 172.7, 139.5, 138.2, 129.8 (2 C), 129.7 (2 C), 129.4
(2 C), 128.8 (2 C), 128.5, 128.5, 92.7, 79.0, 46.8, 44.4, 44.0, 27.4,
9.0, 6.7; IR (KBr) 3309, 1685.
(2:1 CHCl3/MeOH) to give 540 mg (94%) of 21: mp 136-137.5
°C; 1H NMR (CD3OD) 7.45 (d, 1, J ) 14.8), 7.35 (d, 2, J ) 8.8),
7.01 (d, 2, J ) 8.8), 6.24 (d, 1, J ) 14.8), 3.36 (s, 2), 2.26 (s, 3);
13C NMR (CD3OD) 172.8, 171.4, 151.0, 135.8, 127.4 (2 C),
123.9, 123.1 (2 C), 113.8, 45.1, 21.1; IR (KBr) 3390, 3274, 1750,
1645. Anal. Calcd for C12H14N2O3: C, 61.53; H, 6.02; N, 11.96.
Found: C, 61.38; H, 5.95; N, 11.85.
5-[[Bis[[(1,1-d im et h oxy)ca r b on yl]a m in o]m et h ylen e]-
a m in o]-2-h yd r oxyp en ta n oic Acid (24). To a mixture of
5-amino-2-hydroxypentanoic acid (22)12,13 (148 mg, 1.11 mmol)
and diisopropylethylamine (446 µL, 2.56 mmol) in 3 mL of
formamide was added N,N ′-bis-Boc-1-guanidylpyrazole (23)14
(480 mg, 1.53 mmol) in 1.5 mL of 1,4-dioxane dropwise. The
reaction mixture was stirred at 25 °C for 18 h, 9 mL of 1 M
HCl was added, and the mixture was extracted with six
portions of EtOAc. The combined EtOAc extracts were washed
with brine and dried over Na2SO4. The solvent was removed
under reduced pressure, and the residue was purified on silica
gel (15:1 CH2Cl2/MeOH containing 0.1% formic acid) to give
0.321 g (77%) of 24: mp 84-85 °C; 1H NMR (CD3OD) 4.16 (dd,
1, J ) 3.6, 7.2), 3.41 (t, 2, J ) 6.8), 1.85 (m, 1), 1.72 (m, 3),
1.53 (s, 9), 1.48 (s, 9); 13C NMR (CD3OD) 177.9, 164.5, 157.7,
154.3, 84.6, 80.7, 71.3, 41.6, 32.6, 28.7 (3 C), 28.4 (3 C), 26.3;
IR (KBr) 3333, 1723, 1641, 1618.
(E)-5-[[Bis[[(1,1-dim eth oxy)car bon yl]am in o]m eth ylen e]-
a m in o]-2-h yd r oxyp en ta n oyl-N-[2-(4-a cetoxyp h en yl)eth -
en yl]glycin a m id e (25). A mixture of 24 (180 mg, 0.48 mmol),
21 (113 mg, 0.48 mmol), DCC (109 mg, 0.53 mmol), and HOBt
(65 mg, 0.48 mmol) in 5 mL of CH3CN was stirred at 25 °C for
12 h. The mixture was filtered, and the filtrate was evaporated
to dryness. The residue was purified on silica gel (3:1 EtOAc/
CH2Cl2) to give 241 mg (85%) of 25: 1H NMR (CDCl3) 11.47
(s, 1, NH), 8.91 (d, 1, J ) 10.8, NH), 8.60 (t, 1, J ) 6.0, NH),
7.82 (t, 1, J ) 6.0, NH), 7.40 (dd, 1, J ) 10.8, 14.8), 7.27 (d, 2,
J ) 8.8), 6.98 (d, 2, J ) 8.8), 6.08 (d, 1, J ) 14.8), 6.07 (s, 1,
OH), 4.28 (br, 1), 4.09 (dd, 1, J ) 6.0, 16.1), 4.01 (dd, 1, J )
6.0, 16.1), 3.62 (m, 1), 3.38 (m, 1), 2.29 (s, 3), 2.00 (m, 1), 1.76
(m, 3), 1.49 (s, 18); 13C NMR (CDCl3) 176.2, 169.5, 166.6, 162.7,
156.9, 153.1, 149.2, 133.8, 126.4 (2 C), 122.4, 121.7 (2 C), 112.7,
83.6, 79.9, 72.6, 43.4, 39.9, 29.2, 28.2 (3 C), 28.0 (3 C), 26.5,
21.1; IR (KBr) 3330, 1718, 1654, 1612. Anal. Calcd for
Reequ ilibr a tion of 13b in THF w ith Na H. A solution of
13b (16 mg, 0.047 mmol) in 2 mL of THF was treated with
NaH (60% w/w in mineral oil) (7 mg, 0.175 mmol). The solution
was stirred at 25 °C for 2 h and neutralized with 0.1 N HCl.
The solution was extracted with three portions of EtOAc. The
combined extracts were dried over MgSO4 and concentrated
to give 15 mg of crude product. Analysis of the NMR spectrum
indicated that the mixture contained 75% of 13a , 5% of 13b,
10% of ketoamide 12c, and 10% of uncharacterized material.
N -[2-(4-Ac e t o x y p h e n y l)a c e t o x y e t h y l](B o c )g ly c in -
a m id e (18). To a mixture of N-(Boc)glycine (16) (1.752 g, 10
mmol) and DCC (2.269 g, 11 mmol) in 16 mL of CH2Cl2 were
added octopamine hydrochloride (17) (1.896 g, 10 mmol) and
N,N-diisopropylethylamine (1.75 mL, 10 mmol) in 8 mL of
DMF. The reaction mixture was stirred at 25 °C for 17 h,
filtered, and concentrated under reduced pressure to afford a
gummy oil. Acetic anhydride (10 mL) and pyridine (3 mL) were
added, and the mixture was heated at 100 °C under N2 for 1
h. The mixture was cooled and poured onto ice, and the
resulting solution was extracted with three portions of EtOAc.
The combined organic extracts were washed with water and
brine and dried over MgSO4. The solvent was removed under
reduced pressure and the residue was purified on silica gel
(2:1 EtOAc/CH2Cl2) to give 2.032 g (51%) of 18: mp 114-116
1
°C; H NMR (CDCl3) 7.36 (d, 2, J ) 8.8), 7.09 (d, 2, J ) 8.8),
6.38 (br, 1, NH), 5.85 (dd, 1, J ) 4.4, 8.0), 5.09 (br, 1, NH),
3.75 (d, 2, J ) 6.0), 3.71 (ddd, 1, J ) 4.4, 6.0, 14.0), 3.58 (ddd,
1, J ) 5.4, 8.0, 14.0), 2.30 (s, 3), 2.10 (s, 3), 1.46 (s, 9); 13C
NMR (CDCl3) 170.2, 169.6, 169.3, 156.0, 150.7, 135.1, 127.6
(2 C), 121.8 (2 C), 80.4, 73.7, 44.5, 44.1, 28.3 (3 C), 21.1, 21.1;
IR (KBr) 3392 (br), 1750, 1719, 1685.
(E )-N -[2-(4-Ac e t o x y p h e n y l)e t h e n y l](B o c )g ly c i n -
a m id e (20). A mixture of 18 (2.00 g, 5.07 mmol) and K2CO3
(1.68 g, 1.22 mmol) in 13 mL of DMSO was heated at 95 °C
under N2 for 2 h. The mixture was cooled to 25 °C and poured
onto ice. The resulting solution was extracted with six portions
of EtOAc. The combined organic extracts were washed with
brine and dried over MgSO4. The solvent was removed under
reduced pressure and the residue was purified on silica (3:1
CH2Cl2/EtOAc) to give 0.618 g (36%) of 20, followed by 0.070
g of a mixture of 20 and 19, and 0.508 g of 19.
C
28H41N5O9: C, 56.84; H, 6.98; N, 11.84. Found: C, 56.07; H,
6.44; N, 12.42.
(E)-5-[[Bis[[(1,1-dim eth oxy)car bon yl]am in o]m eth ylen e]-
a m in o]-2-oxp en t a n oyl-N-[2-(4-a cet oxyp h en yl)et h en yl]-
glycin a m id e (26). To a solution of 25 (110 mg, 0.186 mmol)
in 5 mL of CH2Cl2 at 0 °C was added Dess-Martin periodane
(87 mg, 0.21 mmol). The mixture was stirred at 0 °C for 30
min. A 1:1 (v/v) mixture of saturated NaHCO3 and 10%
Na2S2O3 solution was added. The resulting mixture was
extracted with three portions of EtOAc. The combined extracts
were dried over Na2SO4. The solvent was removed under
reduced pressure, and the residue was purified on silica gel
(2:1 CH2Cl2/EtOAc) to give 30 mg (27%) of recovered 25
preceded by 54 mg (49%) of 26: mp 160 °C dec; 1H NMR
(CDCl3) 11.47 (s, 1, NH), 8.52 (d, 1, J ) 10, NH), 8.41 (t, 1, J
) 5.4, NH), 7.70 (t, 1, J ) 5.9, NH), 7.40 (dd, 1, J ) 10.8, 14.8),
7.29 (d, 2, J ) 8.8), 7.00 (d, 2, J ) 8.8), 6.12 (d, 1, J ) 14.8),
4.08 (d, 2, J ) 6.0), 3.43 (dt, 2, J ) 5.9, 7.1), 2.99 (t, 2, J )
7.1), 2.30 (s, 3), 1.92 (tt, 2, J ) 7.1, 7.1), 1.50 (s, 9), 1.49 (s, 9);
13C NMR (CDCl3) 197.2, 169.6, 165.4, 163.3, 160.6, 156.4,
153.2, 149.4, 133.6, 126.6 (2 C), 122.1, 121.8 (2 C), 113.2, 83.3,
79.6, 42.9, 39.8, 34.2, 28.3 (3 C), 28.0 (3 C), 22.7, 21.1; IR (KBr)
3326, 1751, 1725, 1639. Anal. Calcd for C28H39N5O9: C, 57.03;
H, 6.67; N, 11.88. Found: C, 56.98; H, 6.37; N, 12.03.
(2r,3r,4r)-, (2r,3â,4â)-, a n d (2r,3r,4â)-3-[2-[[Bis[[(1,1-
d im et h oxy)ca r b on yl]a m in o]m et h ylen e]a m in o]et h yl-4-
[3-[[Bis[[(1,1-dimethoxy)carbonyl]amino]methylene]amino]-
p r op yl]-2,4-d ih yd r oxy-1[2-[[(1E)-2-(4-h yd r oxyp h en yl)-
ethenyl]amino]-2-oxoethyl]-5-oxoprolyl-N-[(1E)-2-(4-hydroxy-
p h en yl)eth en yl]glycin a m id e (27), (28), a n d (30). KOH (6
mg, 0.107 mmol) was added to a solution of 26 (28 mg, 0.048
mmol) in 2.5 mL of THF and 2.5 mL of MeOH at 0 °C. The
solution was stirred at 0 °C for 20 min, and then 200 µL of 1
M HCl and 5 mL of water were added. The mixture was
Data for 19: mp 187 °C dec; 1H NMR (CD3OD) 7.26 (d, 1, J
) 14.8), 7.15 (d, 2, J ) 8.8), 6.71 (d, 2, J ) 8.8), 6.19 (d, 1, J
) 14.8), 3.79 (s, 2), 1.46 (s, 9); 13C NMR 170.0, 158.6, 157.7,
129.2, 127.9 (2 C), 121.3, 116.6 (2 C), 115.4, 80.9, 44.6, 28.8 (3
C); IR (KBr) 3298, 1681, 1654.
Data for 20: mp 138-140 °C; 1H NMR (CDCl3) 8.18 (br, 1,
NH), 7.42 (dd, 1, J ) 11.2, 14.8), 7.31 (d, 2, J ) 8.8), 7.01 (d,
2, J ) 8.8), 6.13 (d, 1, J ) 14.8), 5.21 (br, 1, NH), 3.90 (d, 2, J
) 6), 2.29 (s, 3), 1.49 (s, 9); 13C NMR (CDCl3) 169.8, 167.4,
156.6, 149.5, 134.0, 126.6 (2 C), 122.5, 121.9 (2C), 113.0, 80.7,
44.6, 28.5 (3 C), 21.3; IR (KBr) 3334, 1698, 1677, 1655.
The mixture of 20 and 19 and pure 19 were dissolved in 5
mL of acetic anhydride and 0.20 mL of pyridine. The solution
was heated at 90 °C for 1 h. The reaction solution was cooled
to 25 °C and poured onto ice. The mixture was extracted with
six portions of EtOAc. The combined extracts were washed
with water and brine, and dried over MgSO4. The solvent was
removed under reduced pressure and the residue was purified
on silica gel (3:1 CH2Cl2/EtOAc) to give an additional 0.516 g
(31%) of 20.
(E)-N-[2-(4-Acet oxyp h en yl)et h en yl]glycin a m id e (21).
Enamide 20 (820 mg, 2.46 mmol) was dissolved in 5 mL of
CH2Cl2 and 5 mL of trifluoroacetic acid and the solution was
stirred at 25 °C for 10 min. The solvent was removed under
reduced pressure. EtOAc (30 mL) was added to the residue
and saturated Na2CO3 aqueous solution was added until the
pH was 8. The solution was filtered and the filtrate was
extracted with four portions of EtOAc. The combined extracts
were dried over Na2SO4. The solvent was removed under
reduced pressure, and the residue was purified on silica gel

Total Synthesis of (()-Anchinopeptolide D
J . Org. Chem., Vol. 65, No. 3, 2000 799
extracted with four portions of EtOAc. The combined extracts
were dried over Na2SO4. The solvent was removed under
reduced pressure, and the residue was purified on silica gel
(20:1 CH2Cl2/MeOH) to give 5 mg (19%) of 28, followed by 15
( 2 r, 3 r, 4 r) -3 -[ 2 -[ ( Am i n o i m i n o m e t h y l ) a m i n o ] -
e t h y l - 4 - [ 3 - [ ( a m i n o i m i n o m e t h y l ) a m i n o ] -
p r op yl]-2,4-d ih yd r oxy-1[2-[[(1E)-2-(4-h yd r oxyp h en yl)-
e t h e n yl]a m in o]-2-oxoe t h yl]-5-oxop r olyl-N -[(1E )-2-(4-
h yd r oxyp h en yl)eth en yl]glycin a m id e (An ch in op ep to-
lid e D, 4). A solution of 27 (11 mg, 9.34 µmol) in 2 mL of CH2-
Cl2 and 2 mL of trifluoroacetic acid was stirred at 25 °C for 1
h. The mixture was evaporated to dryness to give 11.5 mg
(91%) of the TFA salt of 4: 1H NMR (CD3OD) 7.25 (d, 1, J )
14.8), 7.22 (d, 1, J ) 14.8), 7.15 (d, 4, J ) 8.8), 6.71 (d, 4, J )
8.8), 6.18 (d, 1, J ) 14.8), 6.17 (d, 1, J ) 14.8), 4.22 (d, 1, J )
16.4), 4.13 (d, 1, J ) 16.4), 3.92 (d, 1, J ) 16.4), 3.90 (d, 1, J
) 16.4), 3.46 (m, 1), 3.25 (m, 1), 3.20 (t, 2, J ) 6.8), 2.70 (dd,
1, J ) 4.2, 9.8), 1.98-2.13 (m, 1), 1.74-1.93 (m, 4), 1.45-1.61
(m, 1); 13C NMR (CD3OD) 178.0, 173.7, 168.4, 168.1, 158.8,
158.8, 158.0, 157.9, 129.0, 128.9, 128.03 (2 C), 127.96 (2 C),
121.1, 120.9, 116.7 (4 C), 116.2, 115.7, 91.3, 76.8, 46.8, 45.2,
43.5, 42.6, 40.9, 34.7, 24.7, 24.1; 1H NMR (DMSO-d6) 10.33
(d, 1, J ) 10, NH), 10.20 (d, 1, J ) 10, NH), 9.47 (s, 1, OH),
9.45 (s, 1, OH), 8.76 (t, 1, J ) 6.0, NH), 7.85 (br, 1, NH), 7.70
(br, 1, NH), 6.70-7.50 (br, 8, guanidine NH), 7.17 (dd, 1, J )
10.0, 14.8), 7.15 (d, 4, J ) 8.8), 7.14 (dd, 1, J ) 10.0, 14.8),
6.97 (s, 1, OH), 6.69 (d, 2, J ) 8.8), 6.68 (d, 2, J ) 8.8), 6.17 (d,
1, J ) 14.8), 6.09 (d, 1, J ) 14.8), 5.59 (s, 1, OH), 4.05 (d, 1, J
) 16.4), 3.88 (br, 2), 3.75 (d, 1, J ) 16.4), 3.23 (m, 1), 3.10 (m,
3), 2.58 (dd, 1, J ) 5.2, 10), 1.82 (m, 1), 1.29-1.78 (m, 5); 13C
NMR (DMSO-d6) 175.3, 171.0, 166.5, 166.1, 156.9, 156.8, 156.4,
156.2, 127.0, 126.8, 126.6 (2 C), 126.5 (2 C), 120.4, 120.1, 115.57
(2 C), 115.56 (2 C), 113.3, 112.5, 89.2, 74.4, 44.7, 43.9, 42.3,
38-42 (2 carbons, obscured by DMSO-d6), 34.0, 23.4, 23.1; IR
(KBr) 3375, 1677, 1650. The spectral data are identical to those
reported for the natural product.2,18
(2r,3â,4â)-3-[2-[(Am in o im in o m e t h y l)a m in o ]e t h y l-
4 -[ 3 -[ ( a m i n o i m i n o m e t h y l ) a m i n o ] p r o p y l ] -2 , 4 -
d ih y d r o x y -1[2-[[(1E )-2-(4-h y d r o x y p h e n y l)e t h e n y l]-
amino]-2-oxoethyl]-5-oxoprolyl-N-[(1E)-2-(4-hydroxyphenyl)-
eth en yl]glycin a m id e (epi-An ch in op ep tolid e D, 29). A
solution of 28 (12 mg, 10.2 µmol) in 3 mL of CH2Cl2 and 3 mL
of trifluoroacetic acid was stirred at 25 °C for 1 h. The mixture
was evaporated to dryness to give 9.5 mg (94%) of the TFA
salt of 29: 1H NMR (CD3OD) 7.27 (d, 1, J ) 14.8), 7.23 (d, 1,
J ) 14.8), 7.16 (d, 2, J ) 8.8), 7.14 (d, 2, J ) 8.8), 6.71 (d, 2,
J ) 8.8), 6.70 (d, 2, J ) 8.8), 6.193 (d, 1, J ) 14.8), 6.187 (d, 1,
J ) 14.8), 4.08 (d, 1, J ) 16.4), 4.08 (d, 1, J ) 16.4), 3.96 (d, 1,
J ) 16.4), 3.85 (d, 1, J ) 16.4), 3.50 (m, 1), 3.38 (m, 1), 3.23 (t,
2, J ) 6.4), 2.40 (dd, 1, J ) 4.8, 9.2), 1.60-1.94 (m, 6); 13C
NMR (CD3OD) 176.5, 173.1, 168.0, 167.7, 158.8, 158.8, 157.9,
157.9, 129.1, 128.9, 128.0 (4 C), 121.2, 121.1, 116.7 (4 C), 116.0,
115.6, 92.6, 78.1, 51.1, 43.4, 43.3, 42.6, 41.2, 32.2, 24.9, 24.8;
1H NMR (DMSO-d6) 10.22 (d, 1, J ) 10, NH), 10.17 (d, 1, J )
10, NH), 9.44 (s, 1, OH), 9.43 (s, 1, OH), 8.96 (t, 1, J ) 6.0,
NH), 7.61 (br, 1, NH), 7.49 (br, 1, NH), 7.44 (s, 1, NH), 6.90-
7.40 (br, 8 H, guanidine NH), 7.19 (dd, 1, J ) 10.4, 14.8), 7.15
(d, 4, J ) 8.4), 7.13 (dd, 1, J ) 10.0, 14.8), 6.69 (d, 4, J ) 8.4),
6.12 (d, 1, J ) 14.8), 6.10 (d, 1, J ) 14.8), 5.48 (s, 1, OH), 4.01
(d, 1, J ) 16.0), 3.90 (t, 2, J ) 6.0), 3.64 (d, 1, J ) 16.0), 3.27
(m, 1), 3.12 (m, 3), 2.34 (dd, 1, J ) 4.4, 8.8), 1.30-1.75 (m, 6);
13C NMR (DMSO-d6) 173.6, 171.3, 165.7, 165.4, 156.8, 156.7,
156.3, 156.2, 126.9, 126.9, 126.5 (4 C), 120.5, 120.3, 115.6 (4
C), 112.8, 112.5, 90.8, 76.0, 48.2, 42.3, 42.0, 40.8, 31.2, 27.6,
23.6, 23.3.
1
mg (58%) of 27. A trace (∼5%) of 30 was seen in the crude H
NMR spectrum of the crude reaction product. Fractions
containing 30 collected from several runs were purified on
silica gel (20:1 CH2Cl2/MeOH) to give pure 30.
Data for 27: 1H NMR (CD3OD) 7.27 (d, 1, J ) 14.8), 7.21
(d, 1, J ) 14.8), 7.13 (d, 2, J ) 8.8), 7.13 (d, 2, J ) 8.8), 6.69
(d, 2, J ) 8.8), 6.68 (d, 2, J ) 8.8), 6.16 (d, 1, J ) 14.8), 6.13
(d, 1, J ) 14.8), 4.24 (d, 1, J ) 16.8), 4.09 (d, 1, J ) 16.8), 3.95
(d, 1, J ) 16.8), 3.92 (d, 1, J ) 16.8), 3.30-3.53 (m, 4), 2.72
(dd, 1, J ) 5.6, 8.4), J ) 1.97 (m, 2), 1.72-1.90 (m, 3), 1.51 (m,
1), 1.50 (s, 9), 1.49 (s, 9), 1.47 (s, 9), 1.45 (s, 9); 13C NMR (CD3-
OD) 178.1, 173.8, 168.4, 168.2, 164.7, 164.6, 157.9, 157.8 (3
C) 154.3 (2 C), 129.2, 129.0, 128.1 (2 C), 127.9 (2 C), 121.5,
121.1, 116.7 (2 C), 116.6 (2 C), 116.1, 115.2, 91.7, 84.6, 84.5,
80.6, 80.5, 77.1, 46.5, 45.4, 43.9, 42.0, 40.0, 34.7, 28.78 (3 C),
28.76 (3 C), 28.44 (3 C), 28.40 (3 C), 25.0, 24.3; 1H NMR
(DMSO-d6) 11.49 (s, 1, OH), 11.47 (s, 1, OH), 10.19 (d, 1, J )
10.0, NH), 10.10 (d, 1, J ) 10.0, NH), 9.39 (s, br, 1, NH), 9.35
(s, br, 1, NH), 8.65 (t, 1, J ) 6.3, NH), 8.27 (br, 1, NH), 8.26
(br, 1, NH), 7.15 (dd, 1, J ) 10.0, 15.1), 7.14 (d, 2, J ) 8.3),
7.13 (d, 2, J ) 8.3), 7.12 (dd, 1, J ) 10.0, 15.1), 6.68 (d, 2, J )
8.3), 6.66 (d, 1, J ) 8.3), 6.63 (s, 1, OH), 6.10 (d, 1, J ) 15.1),
6.06 (d, 1, J ) 15.1), 5.41 (s, 1, OH), 4.09 (d, 1, J ) 17.1), 3.93
(dd, 1, J ) 6.3, 16.6), 3.82 (d, 1, J ) 17.1), 3.77 (dd, 1, J ) 6.3,
16.6), 3.28 (m, 4), 2.53 (1, obscured by DMSO-d6), 1.78 (m, 3),
1.62 (m, 3), 1.45 (s, 18), 1.39 (s, 9), 1.38 (s, 9), 1.38(m, 1); IR
(KBr) 3334, 1719, 1654, 1618.
Data for 28: 1H NMR (CD3OD) 7.29 (d, 1, J ) 14.8), 7.24
(d, 1, J ) 14.8), 7.14 (d, 2, J ) 8.8), 7.13 (d, 2, J ) 8.8), 6.70
(d, 2, J ) 8.8), 6.68 (d, 2, J ) 8.8), 6.18 (d, 1, J ) 14.8), 6.15
(d, 1, J ) 14.8), 4.13 (d, 1, J ) 16.0), 4.05 (s, 2), 3.84 (d, 1, J
) 16.0), 3.68 (m, 1), 3.56 (m, 1), 3.41 (t, 2, J ) 7.2), 2.49 (dd,
1, J ) 4.0, 10.0), 1.84-1.95 (m, 2), 1.67-1.82 (m, 3), 1.59-
1.67 (m, 1), 1.52 (s, 9), 1.51 (s, 9), 1.47 (s, 9), 1.46 (s, 9); 13C
NMR (CD3OD) 176.5, 173.8, 167.8, 167.5, 164.7, 164.6, 158.0,
157.81, 157.75, 157.7, 154.3, 154.2, 129.2, 129.1, 128.0 (4 C),
121.4, 121.3, 116.7 (4 C), 115.6, 115.3, 92.9, 84.6, 84.5, 80.7,
80.5, 78.4, 48-50 (obscured by CD3OD), 43.6, 43.3, 42.0, 40.5,
32.3, 28.77 (3 C), 28.76 (3 C), 28.44 (3 C), 28.42 (3 C), 25.3,
1
25.1; H NMR (DMSO-d6) 11.53 (s, 1, OH), 11.51 (s, 1, OH),
10.12 (d, 1, J ) 9.8, NH), 10.04 (d, 1, J ) 9.8), 9.36 (s, 1, NH),
9.35 (s, 1, NH), 8.93 (t, 1, J ) 5.6, NH), 8.47 (t, 1, J ) 5.6,
NH), 8.27 (t, 1, J ) 5.6), 7.45 (s, 1, OH), 7.21 (dd, 2, J ) 9.8,
14.6), 7.14 (d, 2, J ) 8.4), 7.13 (d, 2, J ) 8.4), 6.67 (d, 4, J )
8.4), 6.094 (d, 1, J ) 14.6), 6.087 (d, 1, J ) 14.8), 5.34 (s, 1,
OH), 4.01 (d, 1, J ) 16.6), 3.96 (dd, 1, J ) 5.6, 16.4), 3.83 (dd,
1, J ) 5.6, 16.4), 3.56 (d, 1, J ) 16.6), 3.44 (m, 2), 3.30 (m, 2),
2.42 (dd, 1, J ) 3.2, 9.6), 1.48-1.72 (m, 6), 1.47 (s, 18), 1.39 (s,
18); IR (KBr) 3428, 1654.
Data for 30: 1H NMR (CD3OD) 7.26 (d, 1, J ) 14.8), 7.23
(d, 1, J ) 14.8), 7.17 (d, 1, J ) 8.8), 7.13 (d, 1, J ) 8.8), 6.71
(d, 2, J ) 8.8), 6.68 (d, 2, J ) 8.8), 6.20 (d, 1, J ) 14.8), 6.13
(d, 1, J ) 14.8), 4.45 (d, 1, J ) 17.2), 4.09 (d, 1, J ) 16.8), 3.94
(d, 1, J ) 16.8), 3.92 (d, 1, J ) 17.2), 3.47 (t, 2, J ) 6.8), 3.40
(m, 2), 2.69 (dd, 1, J ) 7.2, 7.6), 1.72-2.03 (m, 6), 1.51 (s, 9),
1.51 (s, 9), 1.47 (s, 9), 1.44 (s, 9); 13C NMR (CD3OD) 178.8,
173.5, 169.0, 168.2, 164.7, 164.7, 158.0, 157.8, 157.8, 157.8,
154.3, 153.7, 129.2, 128.9, 128.2 (2 C), 127.9 (2 C), 121.4, 121.1,
116.7 (4 C), 116.4, 115.2, 90.1, 84.5, 84.5, 80.6, 80.4, 77.5, 51.9,
48-50 (obscured by CD3OD), 45.4, 43.8, 42.1, 39.9, 33.1, 28.8
[3-[(1R,2S,2a S,5S,7a S,8R,9S,14a R)-8-[2-[(Am in oim in o-
m e t h yl)a m in o]e t h yl]h e xa d e ca h yd r o-7a .9-d ih yd r oxy-
1,2-b is(4-h yd r oxyp h en yl)4,7,10,13-t et r a oxocyclob u t [h ]-
pyrrolo[1,2-a ][1,4,7,10]tetraazacyclododeciny-9-yl]-propyl]-
gu a n id in e (Cycloa n ch in op ep tolid e D, 31). A solution of
the TFA salt of anchinopeptolide D (4) (10.5 mg, 11.4 µmol) in
2 mL of D2O in an NMR tube was degassed and purged with
N2 several times and then irradiated at 28 °C with fifteen 350
nm light bulbs for 4.75 h. The solution was evaporated to
dryness under reduced pressure, and the residue was purified
by flash chromatography on C18-coated silica gel (92.5:7.5 H2O/
MeOH) to give 5 mg (48%) of 31 which decomposed slowly in
CD3OD at 25 °C, probably by equilibration at the hemiaminal
center: 1H NMR (CD3OD) 6.79 (d, 2, J ) 8.8), 6.72 (d, 2, J )
1
(6 C), 28.4 (6 C), 24.5; H NMR (DMSO-d6) 11.50 (s, 1, OH),
11.49 (s, 1, OH), 10.54 (d, 1, J ) 9.6, NH), 10.15 (d, 1, J ) 9.6,
NH), 9.46 (s, 1, NH), 9.39 (s, 1, NH), 8.70 (t, 1, J ) 5.6), 8.32
(br, 2, NH), 7.17 (d, 2, J ) 8.6), 7.16 (dd, 1, J ) 9.6, 14.8), 7.14
(dd, 1, J ) 9.6, 14.8), 7.12 (d, 2, J ) 8.6), 6.86 (s, 1, OH), 6.69
(d, 2, J ) 8.6), 6.67 (d, 2, J ) 8.6), 6.15 (d, 1, J ) 14.8), 6.08
(d, 1, J ) 14.8), 5.58 (s, 1, OH), 4.31 (d, 1, J ) 17.1), 3.93 (dd,
1, J ) 5.6, 16.6), 3.82 (d, 1, J ) 17.1), 3.79 (dd, 1, J ) 5.6,
16.6), 3.31 (m, 4), 2.54 (1, obscured by DMSO-d6), 1.52-1.90
(m, 6), 1.46 (s, 9), 1.45 (s, 9), 1.39 (s, 9), 1.37 (s, 9).

800 J . Org. Chem., Vol. 65, No. 3, 2000
Snider et al.
8.8), 6.55 (d, 2, J ) 8.8), 6.52 (d, 2, J ) 8.8), 4.83 (dd, 1, J )
6.7, 7.3), 4.56 (dd, 1, J ) 7.3, 7.9), 4.38 (d, 1, J ) 13.4), 4.24
(d, 1, J ) 17.1), 4.11 (dd, 1, J ) 7.9, 10.3), 4.00 (dd, 1, J ) 6.7,
10.3), 3.95 (d, 1, J ) 17.0), 3.42 (d, 1, J ) 13.4), 3.21 (t, 2, J )
7.2), 3.10 (dd, 1, J ) 5.2, 9.2), 3.16 (m, 2), 1.78-1.96 (m, 5),
1.62 (m, 1); 13C NMR (CD3OD) (from HSQC and HMBC
experiments) 178.3, 173.8, 172.0, 170.4, 158.8, 158.8, 157.0,
157.0, 130.7, 130.4, 130.0 (4 C), 116.0 (2 C), 115.9 (2 C), 90.6,
76.5, 53.7, 52.4, 47.9, 47.9, 45.7, 43.9, 42.3 (2 C), 40.7, 34.6,
24.5, 24.4.
was concentrated under reduced pressure, and the residue was
extracted with six portions of EtOAc. The combined extracts
were dried over Na2SO4. The solvent was evaporated, and the
residue was purified on silica gel (4:1 CHCl3/MeOH) to give
19 mg (73%) of 35: 1H NMR (CD3OD) 7.26 (d, 1, J ) 14.6),
7.16 (d, 2, J ) 8.6), 6.71 (d, 2, J ) 8.6), 6.18 (d, 1, J ) 14.6),
4.25 (dd, 1, J ) 4.9, 8.6), 3.96 (s, 2), 2.52 (m, 1), 2.49 (m, 1),
2.32 (m, 1), 2.15 (m, 1); 13C NMR (CD3OD) 181.7, 175.8, 168.7,
157.8, 129.2, 127.9 (2 C), 121.2, 116.7 (2 C), 115.5, 58.4, 43.3,
30.6, 26.8; IR (KBr) 3282, 1654; [R]25 +2.9 (c 0.58, MeOH)
D
(E)-L-[N-Boc-R-glu ta m yl]-N-[2-(4-h yd r oxyp h en yl)eth e-
n yl]glycin a m id e ter t-Bu tyl Ester (33). A mixture of BOC-
Glu(OtBu)OH (32) (25.3 mg, 83 µmol), DCC (19.0 mg, 92 µmol),
and 21 (19.5 mg, 83 µmol) in 1.5 mL of CH2Cl2 was stirred at
25 °C for 1 h. The solution was filtered to remove dicyclohexy-
lurea, and the filtrate was evaporated to dryness. MeOH (2
mL), EtOAc (2 mL), and saturated Na2CO3 aqueous solution
(0.5 mL) were added to the residue, and the mixture was
stirred at room temperature for 40 min. 1 N HCl was added
until the pH was ∼2. The mixture was concentrated under
reduced pressure. The residue was extracted with four portions
of EtOAc. The combined extracts were dried over Na2SO4. The
solvent was evaporated and the residue was purified on silica
gel (1:1 EtOAc/CH2Cl2) to give 29 mg (71%) of 33: 1H NMR
(CD3OD) 7.26 (d, 1, J ) 14.8), 7.15 (d, 2, J ) 8.8), 6.71 (d, 2,
J ) 8.8), 6.35 (d, 1, J ) 14.8), 4.01 (dd, 1, J ) 5.6, 8.4), 3.98
(d, 1, J ) 17.2), 3.89 (d, 1, J ) 17.2), 2.37 (t, 2, J ) 7.2), 2.04
(m, 1), 1.90 (m, 1), 1.48 (s, 9), 1.46 (s, 9); 13C NMR (CD3OD)
175.5, 174.1, 169.0, 158.5, 157.8, 129.1, 127.9 (2 C), 121.0,
116.7 (2 C), 116.1, 82.0, 81.2, 56.3, 43.5, 32.7, 28.8 (3 C), 28.5
[lit.3 [R]25 -4.6 (c 1.0, MeOH)]. The NMR spectral data for
D
34 are identical to those reported for the natural product
assigned structure 34.18,25
(E)-N-[2-(4-Hyd r oxyp h en yl)eth en yl]glycin a m id e (36).
A solution of 19 (189 mg, 0.65 mmol) in 2.5 mL of CH2Cl2 and
2.5 mL of trifluoroacetic acid was stirred at 25 °C for 10 min.
The solution was evaporated to dryness. The residue was
dissolved in EtOAc and saturated Na2CO3 aqueous solution
was added until the pH was 10. The mixture was extracted
with 6 portions of EtOAc. The combined extracts were dried
over Na2SO4 and concentrated to give 106 mg (85%) of 36: mp
180-182 °C dec; 1H NMR (CD3OD) 7.28 (d, 1, J ) 14.8), 7.16
(d, 2, J ) 8.4), 6.72 (d, 1, J ) 8.4), 6.19 (d, 1, J ) 14.8), 3.46
(s, 2); 13C NMR (CD3OD) 170.8, 157.8, 129.1, 127.9 (2 C), 121.1,
116.7 (2 C), 115.5, 44.3; IR (KBr) 3273, 1672, 1649, 1610.
N,N ′-[(1R,2R,3â,4â)-2,4-(4-Hyd r oxyp h en yl)-1,3-cyclobu -
ta n ed iyl)bis[glycin a m id e] (37). A solution of 36 (10 mg, 52.6
µmol) in methanol (2 mL) was poured onto a Pyrex Petri dish
and the methanol was evaporated quickly by blowing N2 onto
the solution. A film of solid formed on the dish surface. The
film was irradiated with fifteen 350 nm light bulbs for 15 h.
The residue on the dish was purified on silica gel (3:1 CHCl3/
MeOH, then MeOH) to give 4.0 mg (40%) of 37: 1H NMR (CD3-
OD) 7.12 (d, 4, J ) 8.4), 6.77 (d, 4, J ) 8.4), 4.98 (dd, 2, J )
6.8, 8.4), 3.78 (dd, 2, J ) 6.8, 8.4) 3.08 (d, 2, J ) 16.4), 2.95 (d,
2, J ) 16.4); 13C NMR (CD3OD) 174.9, 157.6, 130.5 (2 C), 129.2,
116.3 (2 C), 50.7, 50.2, 44.9; IR (KBr) 3345, 1663.
(3 C), 27.9; IR (KBr) 3308, 1691, 1655, 1604; [R]25 +34.4 (c
D
0.625, MeOH).
(E)-L-R-Glu ta m yl-N-[2-(4-h yd r oxyp h en yl)eth en yl]gly-
cin a m id e (34). Protected tripeptide 33 (11 mg, 24 µmol) was
dissolved in 0.5 mL of CH2Cl2 and 0.5 mL of TFA. The solution
was stirred at room temperature for 1 h. The solution was
evaporated to dryness under reduced pressure to give 10 mg
(100%) of 34: 1H NMR (CD3OD) 7.25 (d, 1, J ) 14.8), 7.15 (d,
2, J ) 8.6), 6.71 (d, 2, J ) 8.6), 6.18 (d, 1, J ) 14.8), 4.006 (1,
obscured by CH2 singlet at 4.005), 4.005 (s, 2), 2.56 (t, 2, J )
8.0), 2.16 (m, 2); 13C NMR (CD3OD) 175.9, 170.5, 168.3, 157.8,
129.1, 127.9 (2 C), 121.2, 116.6 (2 C), 115.5, 53.9, 43.3, 30.2,
Ack n ow led gm en t. We thank the Institute of Gen-
eral Medicine, National Institutes of Health, for finan-
cial support. We thank Ms. Christine Hofstetter for
assistance in obtaining NOESY, HSQC, and HMBC
data and Dr. Agostino Casapullo, Dipartimento di
Scienze Farmaceutiche, Universita´ di Salerno, Italy, for
copies of the spectra of anchinopeptolide D, cycloanchi-
nopeptolide C, and the tripeptide.
27.8; IR (KBr) 3327 (br), 3088 (shoulder), 1672 (br); [R]25
+40.6 (c 0.26, MeOH).
D
(E)-L-P yr oglu t a m yl-N-[2-(4-h yd r oxyp h en yl)et h en yl]-
glycin a m id e (35). A mixture of L-pyroglutamic acid (11 mg,
85 µmol), DCC (19.4 mg, 94 µmol), and 21 (20 mg, 85 µmol) in
1 mL of CH3CN was stirred at room temperature for 40 min.
The solution was filtered to remove dicyclohexylurea, and the
filtrate was evaporated to dryness. MeOH (2 mL), EtOAc (2
mL), and saturated Na2CO3 aqueous solution (0.5 mL) were
added, and the mixture was stirred at room temperature for
40 min. 1 N HCl was added until the pH was ∼2. The mixture
Su p p or tin g In for m a tion Ava ila ble: X-ray structural
1
data for 13b including CIF file; H and 13C NMR spectra for
compounds 4, 13a , 13b, 27-31, and 33-37. This material is
available free of charge via the Internet at http://pubs.acs.org.
J O991454L