Conformationally constrained analogues of diacylglycerol. 13. Protein kinase C ligands based on templates derived from 2,3-dideoxy-L- erythro(threo)-hexono-1,4-lactone and 2-deoxyapiolactone

Article abstract of DOI:10.1021/jm960525v

In the present investigation, the last two possible modes of generating conformationally semirigid diacylglycerol (DAG) analogues embedded into five- membered ring lactones as templates III and IV are investigated. The first two templates studied in previ

Full text of DOI:10.1021/jm960525v

4912
J . Med. Chem. 1996, 39, 4912-4919
Con for m a tion a lly Con str a in ed An a logu es of Dia cylglycer ol. 13.1 P r otein
Kin a se C Liga n d s Ba sed on Tem p la tes Der ived fr om
2,3-Did eoxy-L-er yth r o(th r eo)-h exon o-1,4-la cton e a n d 2-Deoxya p iola cton e
J eewoo Lee,†,‡ Nancy E. Lewin,§ Peter Acs,§ Peter M. Blumberg,§ and Victor E. Marquez*,†
Laboratories of Medicinal Chemistry and of Cellular Carcinogenesis and Tumor Promotion, Division of Basic Sciences,
National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
Received J uly 22, 1996X
In the present investigation, the last two possible modes of generating conformationally
semirigid diacylglycerol (DAG) analogues embedded into five-membered ring lactones as
templates III and IV are investigated. The first two templates studied in previous investiga-
tions corresponded to 2-deoxyribonolactone (template I) and 4,4-disubstituted γ-butyrolactone
(template II), with the latter producing potent protein kinase C (PK-C) ligands with low
nanomolar binding affinities. The templates reported in this work correspond to 2,3-dideoxy-
L-erythro- or -threo-hexono-1,4-lactone (template III) and 2-deoxyapiolactone (template IV).
Compounds constructed with the dideoxy-L-erythro- or -threo-hexono-1,4-lactone template were
synthesized stereospecifically from tri-O-acetyl-L-glucal and L-galactono-1,4-lactone, respectively.
Compounds constructed with the 2-deoxyapiolactone template were synthesized stereoselectively
from di-O-isopropylidene-R-D-apiose. Inhibition of the binding of [3H]phorbol-12,13-dibutyrate
to PK-CR showed that only the threo-isomer, 5-O-tetradecanoyl-2,3-dideoxy-L-threo-hexono-
1,4-lactone (2) was a good PK-C ligand (Ki ) 1 µM). The rest of the ligands had poorer affinities
with Ki values between 10 and 28 µM. With these results, the order of importance of five-
membered ring lactones as competent templates for the construction of semirigid DAG
surrogates with effective PK-C binding affinity can be established as II . I ∼ III > IV.
In tr od u ction
in the regulation of cellular processes of growth and
differentiation. However, despite being the paradigm
of PK-C activators with binding affinities that are
several orders of magnitude higher than any DAG, the
phorbol esters may act supraphysiologically and could
activate responses that are not normally elicited by
DAG.14 In an attempt to overcome this problem, we
have recently synthesized a series of “super DAG”
molecules that bind 2 orders of magnitude tighter to
PK-C than DAG, by virtue of the smaller entropic
penalty associated with their binding.1,15,16 With these
molecules, the affinity gap between phorbol esters and
DAG has been narrowed, while still maintaining a
desirable structural identity with the latter. The con-
formationally restricted DAG molecules have been
derived by constraining the glycerol backbone to five-
membered ring lactones, such as 2-deoxyribonolactone17
(template I) and 5,5-disubstituted tetrahydro-2-fura-
none (template II, also known as 4,4-disubstituted
γ-butyrolactone),15,16 with the latter giving rise to the
kind of super DAG molecules mentioned above. These
templates resulted from two lactonization stragegies
depicted in Scheme 1 as paths a and b, respectively. In
the present paper, we report the results with the two
remaining templates corresponding to lactonization
options c and d (Scheme 1). With the inclusion of these
templates, a comprehensive SAR analysis on the use of
five-membered ring lactones as DAG surrogates can be
completed. Such analysis is the subject of the present
investigation.
Protein kinase C (PK-C) represents a family of at least
11 isozymes that are integrally coordinated with other
important pathways in cell signal transduction.2-5 The
biological significance of this heterogeneity suggests
that, in addition to their different tissue distribution,
each isozyme might respond differently to various
combinations of activating lipids present in the mem-
brane.6 With the exception of the atypical isozymes, the
second messenger, diacylglycerol (DAG), appears to be
the “common denominator” lipid required for PK-C
activation.2-6 Two important classes of DAG, differing
in their fatty acid composition, can be identified as PK-C
activators: (a) DAG derived from the receptor-activated
hydrolysis of phosphatidylinositol 4,5-diphosphate (PIP2)
and (b) DAG derived from phosphatidyl choline (PC)
hydrolysis. Although both forms of DAG appear capable
of activating PK-C,7 their involvement in cellular PK-C
activation may differ.6,7 Thus, DAG resulting from PIP2
hydrolysis is rapidly inactivated to phosphatidic acid by
DAG kinase, whereas DAG derived from PC appears
to be involved in a more sustained activation of PK-C
owing its poorer substrate affinity for DAG kinase.8-10
All DAG-activated isozymes bind to DAG through a
cysteine-rich, zinc finger-like motif present in the
regulatory C1 domain of the protein.11 In a similar
manner, the phorbol esters can bind directly to the same
site, causing a PK-C activation that bypasses the normal
physiological, signal-mediated mechanism.12 For this
reason, the phorbol esters have become essential phar-
macological tools for studying the involvement of PK-C
Ch em istr y
† Laboratory of Medicinal Chemistry.
‡ Present address: Laboratory of Medicinal Chemistry, College of
Pharmacy, Seoul National University, Seoul, Korea.
§ Laboratory of Cellular Carcenogenesis and Tumor Promotion.
X Abstract published in Advance ACS Abstracts, November 15, 1996.
Con str u ction of Com p ou n d s w ith Tem p la te III.
Restriction of the glycerol backbone according to path c
affords a 2,3-dideoxyhexono-1,4-lactone template. When
S0022-2623(96)00525-0
This article not subject to U.S. Copyright. Published 1996 by the American Chemical Society

Conformationally Constrained Analogues of Diacylglycerol
J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 25 4913
Sch em e 1
Sch em e 3a
a
Reagents: (a) ref 18; (b) H2, Pd/C, EtOAc (99%); (c) 2 N HCl,
THF, ∆ (93%); (d) (i) n-Bu2SnO, CHCl3-MeOH, (ii) CsF, BnBr,
DMF (92%); (e) C13H27COCl, py, DMAP, CH2Cl2 (98%); (f) BCl3,
CH2Cl2, -78 °C (92%).
Sch em e 2
Sch em e 4a
this process is performed on the active, chiral (S)-DAG,
both erythro (1) and threo (2) isomers are possible, owing
to the creation of a new chiral center (Scheme 2). As
was the case with the other lactones,1,15-17 the lipophilic
side chain was initially maintained constant as the
tetradecanoate ester for a preliminary investigation on
the worthiness of the new template.
a
Reagents: (a) ref 19; (b) H2, Pd/C, Et3N, EtOAc (98%); (c) SmI2,
HMPA, ethylene glycol-THF (62%); (d) 1 N HCl, THF, ∆ (90%);
(e) (i) n-Bu2SnO, CHCl3-MeOH, (ii) CsF, BnBr, DMF (94%); (f)
C
13H27COCl, py, DMAP, CH2Cl2 (97%); (g) BCl3, CH2Cl2, -78 °C
(92%).
elimination-hydrogenolysis of the â-acetoxy group to
give the triacetate 15 in same manner as reported for
the D-form19 (Scheme 4). The R-acetoxy group was then
removed by a SmI2-mediated radical reduction to afford
the diacetate 16. Deacetylation of 16 under acidic
conditions gave the desired diol 17. As before, the IR
absorption at 1759 cm-1 and the 13C-NMR resonance
at 180.44 ppm confirmed the γ-lactone structure. From
the diol 17, an identical approach to the one used for
the synthesis of 1 produced the desired threo isomer 2.
Con str u ction of Com p ou n d s w ith Tem p la te IV.
The structure of template IV was very appealing due
to its similarity to template II, which led to the
construction of compounds with potencies in the nano-
molar range.15,16 As with the other templates, facile acyl
migration from one alcohol function to the other was a
potential problem. However, the situation was even
more favorable in this case for rapid acyl migration
between the tertiary and primary alcohol groups of
targets 3′ and 5′ (Scheme 5). Hence, the strategy of
reversing the ester function1 was employed and targets
3 and 5 were proposed instead. Additional changes
included a one-carbon extension of the primary alcohol
chain to generate targets 4 and 6, as suggested by the
molecular superposition of this template onto the phor-
Synthesis of the erythro isomer 1 started with com-
mercially available tri-O-acetyl-L-glucal (7), which was
oxidized with pyridinium chlorochromate (PCC) to the
R,â-unsaturated δ-lactone 8 as published18 (Scheme 3).
Catalytic hydrogenation of 8 gave the saturated lactone
9, which after deacetylation under acidic conditions
rearranged exclusively to the γ-lactone 10. The IR
absorption at 1762 cm-1 and the 13C-NMR resonance
at 180.25 ppm confirmed the γ-lactone structure. At
this stage, the benzyl group was introduced selectively
at the primary position via the dibutylstannylene
intermediate to give the monobenzyl ether 11, which
was then acylated with tetradecanoyl chloride to give
the penultimate intermediate 12. Due to the ease with
which acyl migration occurs with this type of com-
pounds, removal of the benzyl group in 12 by BCl3 at
-78 °C was followed by a careful extraction of the
product in a mixture of ether and a pH 7 buffer solution.
For the same reason, compound 1 was not chromato-
graphed on silica gel and was purified instead by
recrystallization from hexane.
For the threo isomer 2, commercially available L-ga-
lactono-1,4-lactone (13) was peracetylated to the tetra-
O-acetyl derivative 14 and subjected to a tandem

4914 J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 25
Lee et al.
Sch em e 5
Sch em e 7a
a
Reagents: (a) CH2dCHMgBr, CuBr‚SMe2, THF-ether, -40
°C (68%); (b) LiAlH4, THF; (c) NaH, BnBr, THF (79% from 30);
(d) AcOH-H2O, 80 °C; (e) AgCO3/Celite, benzene (76% from 32);
(f) SmI2, HMPA, ethylene glycol-THF (98%); (g) BCl3, CH2Cl2,
-10 °C; (h) CrO3, H2SO4, acetone; (i) C14H29OH, DCC, DMAP,
CH2Cl2 (56% from 34); (j) OsO4, 4-NMO, NaIO4, aqueous acetone,
room temperature, 14 h; (k) NaBH4, MeOH, -10 °C (72% from
35).
Sch em e 6a
in the presence of propionic acid to give intermediate
24 as the major product. The desired stereochemistry
of C-3 resulted from the rearrangement occurring from
the less hindered side of the molecule. However, this
mixture of C-3 epimers was not well resolved by column
chromatography until after reduction of the ester and
benzyl ether protection of the resulting alcohol to give
26 (79%), together with 8% of its C-3 epimer. Lacton-
ization was accomplished after removal of the 1,2-O-
isopropylidene group with acid hydrolysis to give com-
pound 27, followed selective oxidation of the resulting
hemiacetal. Subsequently, deoxygenation of the R-hy-
droxy lactone with SmI2 gave the 2-deoxy lactone 28.
At this stage, the benzyl group was removed with BCl3,
and the resulting alcohol was oxidized to the acid via
J one’s oxidation. The acid was then esterified with
tetradecanol, thus completing the top, â-side of the
target compound. Finally, oxidative cleavage of the
terminal olefin with OsO4/NaIO4 gave the corresponding
aldehyde, which was converted to the desired target 3
after sodium borohydride reduction.
a
Reagents: (a) ref 21; (b) Ph3PCHCO2Me, benzene, ∆ (96%);
Synthesis of the optical antipode of 3 (compound 5,
Scheme 7) started with compound 22a ,b (mixture of
isomers). Addition of vinylmagnesium bromide to the
R,â-unsaturated ester from the less hindered side of the
molecule gave exclusively compound 30 with the desired
stereochemistry at C-3. As before, the ester function
was reduced to the alcohol and protected as the benzyl
ether to give compound 32. From this point onward,
the synthetic steps leading to the enantiomeric target
5 were identical to those used in the previous scheme.
Compounds 4 and 6, corresponding to the one-carbon
homologues of 3 and 5, were easily accessed from
compounds 28 and 34, respectively (Scheme 8). Sepa-
rately, compounds 4 and 6 were obtained in four steps
comprising hydroboration of the terminal olefin to the
alcohol, oxidation, esterification of the acid with tet-
radecanol, and removal of the benzyl ether protection.
(c) DIBAL, CH2Cl2, -30 °C (96%); (d) Me(OEt)3, HCO2Et, 135 °C,
14 h (79%); (e) LiAlH4, THF; (f) NaH, BnBr, THF (79% from 24);
(g) AcOH-H2O, 80 °C; (h) AgCO3/Celite, benzene (76% from 26);
(i) SmI2, HMPA, ethylene glycol-THF (98%); (j) BCl3, CH2Cl2, -10
°C; (k) CrO3, H2SO4, acetone; (l) C14H29OH, DCC, DMAP, CH2Cl2
(56% from 28); (m) OsO4, 4-NMO, NaIO4, aqueous acetone, room
temperature, 14 h; (n) NaBH4, MeOH, -10 °C (72% from 29).
bol esters.20 The synthesis of all four target compounds
(3-6) started from 1,2:3,5-di-O-isopropylidene-R-D-threo-
apiofuranose (20). The synthesis of compound 3 is
illustrated in Scheme 6. It commenced with the selec-
tive deprotection of 20 followed by diol cleavage to the
3-ulose 21.21 Wadsworth-Emmons reaction of 21 with
methyl (triphenylphosphoranylidene)acetate produced
a 4:1 mixture of E/Z-isomers (22a ,b), which were
separated and individually characterized. Selective
reduction of the ester function with diisobutylaluminum
hydride (DIBAL) gave the corresponding allylic alcohols
(23a ,b), setting the stage for the Claisen rearrangement
of the intermediate enol ester. This was formed by
reacting 23a ,b (as a mixture) with triethyl orthoacetate
Biologica l Resu lts
The affinity of these ligands for PK-C was assessed
in terms of their ability to displace bound [3H-20]phorbol

Conformationally Constrained Analogues of Diacylglycerol
J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 25 4915
Sch em e 8a
those in which a single methyl substituent at the sn-1
position of DAG resulted in a decrease of PK-C agonist
activity that was independent of the stereochemistry.22
All the compounds built with template IV were disap-
pointingly weak ligands. Even factoring a 4-fold in-
crease in the Ki value (4-fold reduction in binding
affinity) that results from the transposition of the
oxygen in the ester function,1 the values for the “normal
esters” would not have even approached 1 µM. Inter-
estingly, in these “reversed esters” the stereochemistry
of the only asymmetric carbon in the molecule is of little
relevance, since R-isomer 3 and S-isomer 5 have nearly
the same affinity for the enzyme. Finally, a one-carbon
extension of the hydroxymethyl chain resulted in only
a slight affinity improvement for compound 6 with the
S-configuration.
a
Reagents: (a) (i) BH3‚SMe2, THF, 0 °C, (ii) NaBO3, H2O (35%);
(b) CrO3, H2SO4, acetone; (c) C14H29OH, DCC, DMAP, CH2Cl2 (76%
for two steps); (d) H2, Pd/C, EtOH, AcOH (98%).
Ta ble 1. Apparent Ki (µM) Values for Ligands as Inhibitors of
PDBU Binding to PK-CR
With these results, and those from our previous
investigations with templates I and II, the following
structure-activity summary can be assembled:
1. The creation of an additional asymmetric center
by the intramolecular folding of DAG at sn-1 (Scheme
1, paths a and c), which leads to templates I17 and III,
offers little or no entropic advantage over the open chain
DAG. The most potent compounds constructed with
this template have equal affinity for PK-C as DAG.
2. The maintenance of just one asymmetric center
by the intramolecular folding of DAG at sn-2, according
to path b (Scheme 1), results in a large entropic
advantage of 100-fold over the open chain DAG mol-
ecule.16 The most potent compounds constructed with
this template have affinities for PK-C in the 10-20 nM
range.16 The use of this template alters the stereo-
chemical preference from R to S, relative to DAG.16
3. The maintenance of just one asymmetric center
by the intramolecular folding of DAG at sn-2, according
to path d (Scheme 1), results in compounds with
indistinct stereochemical preference, no entropic ad-
vantage, and loss of binding affinity.
4. From the three previous observations, it is con-
cluded that the importance of five-membered ring
lactones for the construction of semirigid DAG sur-
rogates follows the sequence II . I ∼ III > IV.
12,13-dibutyrate (PDBU) from a recombinant single
isozyme PK-CR. The inhibition curves obtained for
these ligands were of the type expected for competitive
inhibition, and the ID50 values were determined by fit
of the data points to the theoretical noncooperative
competition curve.1,15-17 The Ki values for inhibition of
binding were calculated from the ID50 values. With this
preliminary assay one can compare the efficiency of the
various templates before pursuing further biological
evaluation of the most potent compounds. The results
from this type of assay will constitute the basis for the
structure-activity analysis of this work. A comparison
of the Ki values for 1, 2, and 3-6 (Table 1), derived from
templates III and IV, respectively, suggests that these
templates are not very good for the construction of
potent DAG surrogates, since even the best ligand
(compound 1) has an affinity for PK-C in the same range
as the structurally equivalent DAG analogue, glycerol
1-myristate 2-acetate.17 The difference between com-
pounds 1 and 2 shows that introduction of a new
asymmetric center at the sn-1 position of DAG is
important for the stereospecific interaction of the glyc-
erol backbone with PK-C. Although both compounds
have the same absolute stereochemistry as natural (S)-
DAG at the sn-2 position, only diastereoisomer 1 with
the S,R-configuration (Scheme 2) shows good binding
affinity for the enzyme. These results contrast with
Exp er im en ta l Section
Gen er a l Exp er im en ta l. All chemical reagents were com-
mercially available. Melting points were determined on a Mel-
Temp II apparatus, Laboratory Devices, USA, and are uncor-
rected. Silica gel column chromatography was performed on
silica gel 60, 230-400 mesh (E. Merck). Proton and 13C NMR
spectra were recorded on a Bruker AC-250 instrument at 250
and 62.9 MHz, respectively. Spectra were referenced to the
solvent in which they were run (7.24 ppm for CDCl3). Infrared
spectra were recorded on a Perkin-Elmer 1600 Series FTIR.
Elemental analyses were performed by Atlantic Microlab, Inc.,
Atlanta, GA.
An a lysis of In h ibition of [3H]P DBU Bin d in g by Non -
r a d ioa ctive Liga n d s. Enzyme-ligand interactions were
analyzed by competition with [3H]PDBU binding essentially
as described in our previous work,15 except that the PK-C
preparation used here was the single isozyme PK-CR. This
recombinant PK-CR was expressed in the baculovirus system
and was isolated as described in ref 23. The ID50 values were
determined from the competition curves, and the correspond-
ing Ki values for the ligands were calculated from the ID50
values as described before.1,15-17,23 Values represent the mean
( standard error (three determinations).
4,6-Di-O-a cetyl-2,3-d id eoxy-L-er yth r o-h ex-2-en on o-1,5-
la cton e (8). This compound was prepared from tri-O-acetyl-
L-glucal (7) according to the literature.18

4916 J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 25
Lee et al.
4,6-Di-O-a cet yl-2,3-d id eoxy-L-er yth r o-h exon o-1,5-la c-
ton e (9). A solution of 8 (1.60 g, 7 mmol) in EtOAc (100 mL)
was hydrogenated under a balloon of hydrogen for 2 h. The
reaction mixture was filtered through Celite, and the filtrate
was concentrated under reduced pressure. The residue was
purified by flash column chromatography on silica gel with
EtOAc:hexanes (3:1) as eluant to give 9 as a colorless oil (1.60
g, 99%): [R]D ) -22.15 (c 2.19, CHCl3); IR (neat) 1741 (CdO)
trichloride in CH2Cl2 (1 M, 3 mL, 3 mmol). After being stirred
for 2.5 h at -78 °C, the reaction mixture was quenched with
saturated NaHCO3 solution (3 mL) and immediately parti-
tioned between ether and a pH 7 buffer solution. The organic
layer was washed with the pH 7 buffer five times, dried
(MgSO4), and concentrated under reduced pressure to give 1
as a solid. The solid was dissolved in ether (3 mL), cooled over
an ice bath, and crystallized by adding cold hexanes. The
deposited solid was filtered to give pure 1 as a white solid:
mp 52.5 °C; [R]D ) -7.44 (c 0.86, CHCl3); IR (CHCl3) 3481
(OH), 1778 and 1738 (CdO) cm-1; 1H NMR (CDCl3) δ 5.04 (ddd
quartet, 1 H, J ) 4.6 Hz, H-5), 4.71 (ddd, quartet, 1 H, J )
7.0 Hz, H-4), 3.82 (AB d, 2 H, J ) 4.5 Hz, H-6), 2.50-2.60 (m,
2 H, H-2), 2.05-2.40 (m, 4 H, H-3 and OC(O)CH2C12H25), 1.60
(m, 2 H, OC(O)CH2CH2C11H23), 1.15-1.35 (m, 20 H, OC(O)CH2-
CH2(C10H20)CH3), 0.86 (distorted t, 3 H, CH3); 13C NMR
(CDCl3) δ 176.41, 173.40, 77.52, 74.36, 61.43, 34.23, 31.89,
29.64, 29.60, 29.56, 29.40, 29.32, 29.19, 29.05, 27.92, 24.86,
23.54, 22.65, 14.09; FAB MS m/z (relative intensity) 357 (MH+,
100). Anal. (C20H36O5) C, H.
1
cm-1; H NMR (CDCl3) δ 5.04 (q, 1 H, J ) 5.9 Hz, H-4), 4.53
(m, 1 H, H-5), 4.25 (AB d, 2 H, J ) 4.3 Hz, H-6), 2.51-2.78
(m, 2 H, H-2), 2.08 (s, 3 H, OAc), 2.07 (s, 3 H, OAc), 1.90-2.30
(m, 2 H, H-3); 13C NMR δ 170.26, 169.73, 169.16, 78.25, 65.41,
62.83, 26.31, 23.67, 20.80, 20.53. Anal. (C10H14O6) C, H.
2,3-Did eoxy-L-er yth r o-h exon o-1,4-la cton e (10). A solu-
tion of 9 (1.60 g, 6.95 mmol) in 1 N HCl (50 mL) and THF (50
mL) was refluxed for 4 h and then cooled over an ice bath.
The reaction mixture was neutralized with solid NaHCO3 and
concentrated under reduced pressure. The semisolid mixture
was dissolved in THF, filtered, and reconcentrated under
reduced pressure. The residue was purified by flash column
chromatography on silica gel with CHCl3:MeOH (9:1 to 7:1)
2,5,6-Tr i-O-acetyl-3-deoxy-L-xylo-h exon o-1,4-lacton e (15).
This compound was prepared from L-galactono-1,4-lactone in
two steps according to the published literature.19
as eluant to give 10 as a colorless oil (0.94 g, 93%): [R]D
)
-5.36 (c 5.19, MeOH); IR (neat) 3384 (OH), 1762 (CdO) cm-1
;
1H NMR (DMSO-d6) δ 5.10 (d, 1 H, J ) 5.3 Hz, OH), 4.68 (t,
1 H, J ) 5.6 Hz, OH), 4.53 (ddd sextet, 1 H, J ) 7.1, 7.1, 3.8
Hz, H-4), 3.65 (m, 1 H, H-5), 3.25-3.42 (m, 2 H, H-6), 2.37-
2.50 (m, 2 H, H-2), 2.00-2.20 (m, 2 H, H-3); 13C NMR (CD3-
OD) δ 180.25, 82.14, 73.54, 63.73, 29.30, 23.03. Anal. (C6H10O4)
C, H.
5,6-Di-O-a ce t yl-2,3-d id e oxy-L-t h r eo-h e xon o-1,4-la c-
ton e (16). Hexamethylphosphoramide (9.6 mL, 55.18 mmol)
and ethylene glycol (4.28 mL, 76.8 mmol) were added to a
solution of 15 (1.85 g, 6.4 mmol) in THF (64 mL) at room
temperature. A solution of samarium iodide in THF (0.1 M,
200 mL, 20 mmol) was added dropwise while the mixture was
stirred. After 1 h, the reaction was quenched with saturated
NaHCO3 solution, and then the mixture was reduced to
dryness under reduced pressure. The residue was partitioned
between EtOAc and water, and the organic layer was washed
with sodium thiosulfate solution and water, dried (MgSO4),
and concentrated under reduced pressure. The residue was
purified by flash column chromatography on silica gel with
EtOAc:hexanes (2:1) as eluant to give 16 as a colorless oil (0.9
g, 62%): [R]D ) -2.83 (c 2.30, CHCl3); IR (neat) 1781 and 1746
(CdO) cm-1; 1H NMR (CDCl3) δ 5.17 (dt, 1 H, J ) 6.6, 4.2 Hz,
H-5), 4.70 (ddd sextet, 1 H, J ) 6.8, 3.7 Hz, H-4), 4.35 (dd, 1
H, J ) 11.8, 4.5 Hz, H-6a), 4.15 (dd, 1 H, J ) 11.8, 6.8 Hz,
H-6b), 2.52 (irregular t, 2 H, H-2), 2.10 (s, 3 H, OAc), 2.04 (s,
3 H, OAc), 1.90-2.40 (m, 2 H, H-3); 13C NMR δ 176.09, 170.29,
169.96, 77.47, 71.57, 62.12, 27.78, 23.58, 20.63, 20.50. Anal.
(C10H14O6) C, H.
2,3-Did eoxy-L-th r eo-h exon o-1,4-la cton e (17). This com-
pound was obtained from 16 by acid hydrolysis similar to the
procedure used for the synthesis of 10. The compound was
obtained as a colorless oil in 90% yield: [R]D ) +58.18 (c 2.03,
MeOH); IR (neat) 3384 (OH), 1759 (CdO) cm-1; 1H NMR (CD3-
OD) δ 4.68 (distorted t, 1 H, H-4), 3.55-3.65 (m, 3 H, H-5 and
H-6), 2.43-2.64 (m, 2 H, H-2), 2.10-2.40 (m, 2 H, H-3); 13C
NMR (CD3OD) δ 180.44, 81.79, 74.53, 63.77, 29.34, 24.68. Anal.
(C6H10O4) C, H.
6-O-Ben zyl-2,3-d id eoxy-L-er yth r o-h exon o-1,4-la ct on e
(11). A solution of 10 (0.94 g, 6.43 mmol) in chloroform (90
mL) and MeOH (10 mL) was treated with dibutyltin oxide (1.6
g, 6.43 mmol) and refluxed for 3 h until a clear solution was
obtained. The solution was concentrated under reduced pres-
sure, and the residue was treated with cesium fluoride (1.95
g, 12.86 mmol) and dried overnight under high vaccum. The
mixture was dissolved in DMF (20 mL) and treated with benzyl
bromide (1.21 g, 7.07 mmol). The reaction mixture was stirred
for 48 h at room temperature, quenched with EtOAc (50 mL)
and water (1 mL), and stirred for 30 min. The mixture was
filtered through a short pad of silica gel and eluted with
EtOAc. The organic filtrate was washed with water, dried
(MgSO4), and concentrated under reduced pressure. The
residue was purified by flash column chromatography on silica
gel with EtOAc:hexanes (2:1) as eluant to give 11 as a colorless
oil (1.40 g, 92%): [R]D ) -11.96 (c 3.27, CHCl3); IR (neat) 3440
1
(OH), 1770 (CdO) cm-1; H NMR (CDCl3) δ 7.20-7.40 (m, 5
H, phenyl), 4.44-4.60 (m, 3 H, H-4 and PhCH2O), 3.91 (m, 1
H, H-5), 3.50-3.65 (m, 2 H, H-6), 2.40-2.64 (m, 2 H, H-2),
2.16-2.30 (m, 2 H, H-3); 13C NMR (CDCl3) δ 177.36, 137.42,
128.39, 127.83, 127.69, 79.81, 73.46, 70.84, 70.35, 28.12, 22.67.
Anal. (C13H16O4) C, H.
6-O-Ben zyl-5-O-t et r a d eca n oyl-2,3-d id eoxy-L-er yth r o-
h exon o-1,4-la cton e (12). A solution of 11 (0.47 g, 2.0 mmol)
in CH2Cl2 (40 mL) was treated with pyridine (0.65 mL, 8.0
mmol), a catalytic amount of DMAP, and tetradecanoyl
chloride (1.1 mL, 4.0 mmol). After 3 h of stirring at room
temperature, the reaction mixture was concentrated under
reduced pressure. The residue was dissolved in ether, filtered,
and reduced to dryness under vacuum. The residue was
purified by flash column chromatography on silica gel with
EtOAc:hexanes (1:2) as eluant to give 12 as a colorless oil (0.87
g, 98%): [R]D ) +3.93 (c 3.74, CHCl3); IR (neat) 1785 and 1742
6-O-Ben zyl-2,3-dideoxy-L-th r eo-h exon o-1,4-lacton e (18).
This compound was obtained from 17 by the same procedure
used for the synthesis of 11. The compound was obtained as
a white solid in 94% yield: mp 103 °C; [R]D ) +45.96 (c 1.88,
CHCl3); IR (CHCl3) 3440 (OH), 1769 (CdO) cm-1 1H NMR
;
(CDCl3) δ 7.20-7.40 (m, 5 H, phenyl), 4.50-4.60 (m, 3 H, H-4
and PhCH2O), 3.82 (m, 1 H, H-5), 3.58 (AB d, 2 H, J ) 5.9 Hz,
H-6), 2.40-2.62 (m, 2 H, H-2), 2.16-2.30 (m, 2 H, H-3); 13C
NMR (CDCl3) δ 177.49, 137.51, 128.40, 127.83, 127.74, 79.76,
73.49, 72.00, 70.73, 28.27, 23.72. Anal. (C13H16O4) C, H.
6-O-Ben zyl-5-O-tetr a d eca n oyl-2,3-d id eoxy-L-th r eo-h ex-
on o-1,4-la cton e (19). This compound was obtained from 18
by the same procedure used for the synthesis of 12. The
1
(CdO) cm-1; H NMR (CDCl3) δ 7.20-7.40 (m, 5 H, phenyl),
5.18 (ddd quartet, 1 H, J ) 5.0 Hz, H-5), 4.74 (ddd sextet, J )
7.0, 5.0, 5.0 Hz, 1 H, H-4), 4.51 (s, 2 H, PhCH2O), 3.64 (m, 2
H, H-6), 2.46-2.56 (m, 2 H, H-2), 2.12-2.35 (m, 4 H, H-3 and
OC(O)CH2C12H25), 1.60 (m, 2 H, OC(O)CH2CH2C11H23), 1.10-
1.65 (m, 20 H, OC(O)CH2CH2(C10H20)CH3), 0.86 (distorted t,
3 H, CH3); 13C NMR (CDCl3) δ 176.51, 172.79, 137.52, 128.43,
127.84, 127.61, 77.98, 73.44, 72.03, 67.88, 34.24, 31.89, 29.64,
29.62, 29.58, 29.41, 29.33, 29.21, 29.03, 27.96, 24.88, 23.21,
22.66, 14.10. Anal. (C27H42O5) C, H.
compound was obtained as a colorless oil in 97% yield: [R]D
)
+16.17 (c 3.76, CHCl3); IR (neat) 1783 and 1741 (CdO) cm-1
;
1H NMR (CDCl3) δ 7.20-7.40 (m, 5 H, phenyl), 5.11 (ddd
sextet, 1 H, J ) 5.8, 3.7 Hz, H-5), 4.82 (ddd, 1 H, J ) 7.6, 6.7,
3.7 Hz, 1 H, H-4), 4.55 (d, 1 H, J ) 11.8 Hz, PhCHHO), 4.48
(d, 1 H, J ) 11.8 Hz, PhCHHO), 3.65 (dd, 1 H, J ) 10.0, 6.1,
10.05 Hz, H-6a), 3.60 (dd, 1 H, J ) 10.0, 5.8 Hz, H-6b), 2.50
(irregular t, 2 H, H-2), 2.20-2.37 (m, 3 H, H-3a, OC(O)-
CH2C12H25), 1.98 (m, 1 H, H-3b), 1.60 (m, 2 H, OC(O)-
5-O-Tet r a d eca n oyl-2,3-d id eoxy-L-er yth r o-h exon o-1,4-
la cton e (1). A solution of 12 (0.45 g, 1.0 mmol) in CH2Cl2
(20 mL) was cooled to -78 °C and treated dropwise with boron

Conformationally Constrained Analogues of Diacylglycerol
J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 25 4917
CH2CH2C11H23), 1.15-1.40 (m, 20 H, OC(O)CH2CH2C10H20
-
23b: Z-isomer; [R]D ) +176.2 (c 2.00, CHCl3); IR (neat) 3440
(OH) and 1656 (CdC) cm-1; 1H NMR (CDCl3) δ 5.88 (d, 1 H, J
) 4.2 Hz, H-1), 5.77 (m, 1 H, HCd), 5.14 (d, 1 H, J ) 4.2 Hz,
H-2), 4.65 (dm, J ) 12.5 Hz, 1 H, H-4a), 4.27-4.38 (m, 3 H,
H-4b and CH2OH), 1.48 (s, 3 H, C(CH3)), 1.36 (s, 3 H, C(CH3));
13C NMR δ 139.10 (s), 125.17 (d), 112.21 (s), 106.02 (d), 77.14
(d), 70.05 (t), 60.00 (t), 27.20 (q), 27.04 (q). Anal. (C9H14O4)
C, H.
CH3), 0.86 (distorted t, 3 H, CH3); 13C NMR (CDCl3) δ 176.41,
172.82, 137.40, 128.25, 127.66, 127.47, 77.68, 73.24, 72.36,
67.81, 34.03, 31.73, 29.48, 29.46, 29.41, 29.26, 29.17, 29.06,
28.89, 27.93, 24.72, 23.48, 22.51, 13.95. Anal. (C27H42O5) C,
H.
5-O-Tetr a d eca on yl-2,3-d id eoxy-L-th r eo-h exon o-1,4-la c-
ton e (2). This compound was obtained from 19 by the same
procedure used for the synthesis of 1. It was obtained as a
white solid in 92% yield: mp 61 °C; [R]D ) +7.40 (c 1.0,
(3R)-3-C-[(Ben zyloxy)eth yl]-3-C-vin yl-1,2-O-isop r op y-
lid en e-r-D-er yth r o-fu r a n ose (26). A mixture of 23a and 23b
(2.0 g, 10.8 mmol), triethyl orthoacetate (14 mL, 75.6 mmol),
and propionic acid (0.27 mL, 3.6 mmol) was heated at 135 °C
for 16 h with removal of ethanol. After concentration under
reduced pressure, the residue was purified by flash column
chromatography over silica gel with EtOAc:hexanes (1:4 to 4:1)
as eluant to give an inseparable mixture of 24 and the
undesirable regioisomer as a colorless oil (10:1, 1.76 g, 64%),
along with starting material (0.413 g, 15%). The above crude
ester 24 (1.90 g, 7.41 mmol) was dissolved in THF (80 mL),
cooled to -10 °C, and treated dropwise with LiAlH4 in THF
(1 M, 10 mL, 10 mmol). After 30 min of stirring, the reaction
mixture was quenched with water and 15% NaOH solution
(total volume 2 mL), followed by the slow addition of water.
The reaction mixture was stirred overnight at room temper-
ature and filtered, and the filtrate was concentrated under
reduced pressure to give alcohol 25, which was further dried
under high vacuum. This crude alcohol was used for the next
step without further purification. Hence, 25 was dissolved in
THF (100 mL) and treated with NaH (60% dispersion, 0.568
g, 14.2 mmol) at 0 °C. After 20 min of stirring at room
temperature, the reaction mixture was treated with benzyl
bromide (1.26 mL, 10.64 mmol) and tetrabutylammonium
iodide (0.13 g, 0.355 mmol). The resulting solution was stirred
overnight at room temperature, quenched with acetic acid (1
mL), and diluted with ether. The suspension was filtered
through a short pad of silica gel by eluting with ether. The
combined filtrate was concentrated under reduced pressure,
and the residue was purified by flash column chromatography
over silica gel with EtOAc:hexanes (1:3) as eluant to give 26
(2.0 g, 79%, combined yield of 2 steps) and its C-3 epimer (0.2
g) as colorless oils.
CHCl3); IR (CHCl3) 3487 (OH), 1777 and 1737 (CdO) cm-1
;
1H NMR (CDCl3) δ 4.98 (ddd sextet, 1 H, J ) 5.4, 3.8 Hz, H-5),
4.80 (m, 2 H, H-4), 3.85 (dd, 1 H, J ) 11.8, 5.3 Hz, H-6a), 3.78
(dd, 1 H, J ) 11.8, 5.7 Hz, H-6b), 2.48-2.58 (m, 2 H, H-2),
2.25-2.42 (m, 3 H, H-3a, OC(O)CH2C12H25), 1.90-2.10 (m, 1
H, H-3b), 1.60 (m, 2 H, OC(O)CH2CH2C11H23), 1.15-1.35 (m,
20 H, OC(O)CH2CH2C10H20CH3), 0.86 (distorted t, 3 H, CH3);
13C NMR (CDCl3) δ 176.44, 173.54, 77.88, 74.70, 61.51, 34.21,
31.89, 29.60, 29.56, 29.42, 29.32, 29.20, 29.06, 28.05, 24.88,
23.80, 22.65, 14.09; FAB MS m/z (relative intensity) 357 (MH+,
100). Anal. (C20H36O5) C, H.
1,2-O-Isop r op ylid en e-r-D-glycer o-tetr ose-3-u lose (21).
This compound was prepared from 1,2:3,5-di-O-isopropylidene-
R-D-threo-apiofuranose (20) in two steps according to the
method of Carey et al.21
(E)-3-Deoxy-3-C-[(m eth oxyca r bon yl)m eth ylid en e]-1,2-
O-isop r op ylid en e-r-D-er yth r o-fu r a n ose (22a ) a n d (Z)-3-
Deoxy-3-C-[(m et h oxyca r b on yl)m et h ylid en e]-1,2-O-iso-
p r op ylid en e-r-D-er yth r o-fu r a n ose (22b). A solution of 20
(2.56 g, 16.2 mmol) in benzene (100 mL) was treated with
methyl (triphenylphosphoranylidene)acetate (8.12 g, 24.3 mmol)
and a catalytic amount of benzoic acid. After 1 h of reflux,
the reaction mixture was cooled and concentrated under
reduced pressure. The residue was purified by silica gel flash
column chromatography with EtOAc:hexanes (1:3) as eluant
to give both E- and Z-isomers as a colorless oils in 77% and
19% yield, respectively.
22a : E-isomer, Rf ) 0.52 (EtOAc:Hex ) 1:2); [R]D ) +149.05
(c 6.02, CHCl3); IR (neat) 1716 (CdO) and 1678 (CdC) cm-1
;
1H NMR (CDCl3) δ 6.09 (m, 1 H, HCd), 5.88 (d, 1 H, J 1,2 ) 3.9
Hz, H-1), 4.94-5.00 (m, 3 H, H-2 and H-4); 3.72 (s, 3 H,
COOCH3), 1.45 (s, 3 H, C(CH3)), 1.38 (s, 3 H, C(CH3)); 13C NMR
δ 165.85 (s), 157.61 (s), 116.28 (d), 112.72 (s), 104.57 (d), 81.04
(d), 69.90 (t), 51.55 (q), 27.43 (q), 27.32 (q). Anal. (C10H14O5)
C, H.
26: [R]D ) +53.30 (c 3.85, CHCl3); IR (neat) 1637 (CdO)
cm-1; 1H NMR (CDCl3) δ 7.20-7.40 (m, 5 H, phenyl), 5.92 (dd,
1 H, J ) 11.0, 17.8 Hz, CHdCH2), 5.84 (d, 1 H, J ) 3.52 Hz,
H-1), 5.21 (d, 1 H, J ) 11.0 Hz, CHdCHH), 4.98 (d, 1 H, J )
17.8 Hz, CHdCHH), 4.46 (s, 2 H, PhCH2O), 4.38 (d, 1 H, J )
3.5 Hz, H-2), 3.95 (d, 1 H, J ) 8.5 Hz, H-4a), 3.77 (d, 1 H, J )
8.5 Hz, H-4b), 3.55 (t, 2 H, J ) 6.65 Hz, BnOCH2), 1.78 (m, 2
H, BnOCH2CH2), 1.48 (s, 3 H, C(CH3)), 1.39 (s, 3 H, C(CH3));
13C NMR δ 138.09, 136.04, 128.26, 127.47, 127.43, 116.10,
111.59, 105.70, 85.38, 72.90, 72.33, 66.61, 51.62, 33.68, 26.55,
26.13. Anal. (C18H24O4) C, H.
22b: Z-isomer, Rf ) 0.44 (EtOAc:Hex ) 1:2); [R]D ) +220.68
(c 4.10, CHCl3); IR (neat) 1725 (CdO) and 1684 (CdC) cm-1
;
1H NMR (CDCl3) δ 5.88-5.94 (m, 2 H, HCd and H-1), 5.66
(m, 1 H, H-2), 4.76 (dq, 1 H, J ) 14.3, 2.1, 1.3 Hz, H-4a), 4.42
(dd, 1 H, J ) 14.3, 1.5 Hz, H-4b), 3.76 (s, 3 H, COOCH3), 1.49
(s, 3 H, C(CH3)), 1.41 (s, 3 H, C(CH3)); 13C NMR δ 165.28 (s),
155.17 (s), 115.28 (d), 112.71 (s), 106.13 (d), 77.05 (d), 70.00
(t), 51.70 (q), 27.17 (q), 26.94 (q). Anal. (C10H14O5) C, H.
(E)-3-Deoxy-3-C-(h yd r oxyeth ylid en e)-1,2-O-isop r op y-
lid en e-r-D-er yth r o-fu r a n ose (23a ) a n d (Z)-3-Deoxy-3-C-
(h yd r oxyet h ylid en e)-1,2-O-isop r op ylid en e-r-D-er yth r o-
fu r a n ose (23b). A cooled solution of each ester 22a or 22b
(1.07 g, 5.0 mmol) in CH2Cl2 (200 mL) at -40 °C was treated
with a solution of DIBAL in toluene (1.5 M, 12 mL, 18 mmol)
which was added slowly via syringe. After 2 h, the reaction
mixture was carefully quenched with a solution of potassium
sodium tartrate (0.5 M, 100 mL) and stirred at room temper-
ature until a clear solution was obtained. The organic layer
was separated, washed with water and brine, dried (MgSO4),
and concentrated under reduced pressure. The residue was
purified by flash column chromatography over silica gel with
EtOAc:hexanes (2:1) as eluant to give allylic alcohols 23a and
23b as a colorless oils (90%).
(3R )-3-C-[(Be n zyloxy)e t h yl]-3-C-vin yl-D-e r yt h r on ic
γ-La cton e (27). A solution of 26 (2.0 g, 6.57 mmol) in aqueous
acetic acid (60%, 100 mL) was heated at 80 °C for 6 h and
concentrated under reduced pressure. The residue was puri-
fied by flash column chromatography over silica gel with
EtOAc:hexanes (2:1) as eluant to give the corresponding
hemiacetal, which was immediately dissolved in benzene (80
mL) and treated with silver carbonate over Celite (50% w/w,
5.44 g, 9.86 mmol) at reflux for 1 h. The reaction mixture was
cooled, filtered, and concentrated under reduced pressure. The
residue was purified by flash column chromatography over
silica gel with EtOAc:hexanes (1:1) as eluant to give 27 as a
colorless oil (1.3 g, 76% combined yield of 2 steps): [R]D
)
-36.24 (c 2.93, CHCl3); IR (neat) 3422 (OH), 1785 (CdO), 1638
1
(CdC) cm-1; H NMR (CDCl3) δ 7.20-7.40 (m, 5 H, phenyl),
5.84 (dd, 1 H, J ) 17.8, 11.1 Hz, CHdCH2), 5.38 (d, 1 H, J )
11.1 Hz, CHdCHH), 5.30 (d, 1 H, J ) 17.8 Hz, CHdCHH),
4.47 (s, 2 H, PhCH2O), 4.42 (d, 1 H, J ) 9.8 Hz, H-4a), 4.28 (d,
1 H, J ) 4.2 Hz, H-2), 4.02 (d, 1 H, J ) 9.8 Hz, H-4b), 3.58 (m,
2 H, BnOCH2), 3.15 (d, 1 H, J ) 4.2 Hz, OH), 1.80-2.10 (m, 2
H, BnOCH2CH2); 13C NMR δ 175.73, 137.33, 133.74, 128.44,
127.84, 127.67, 117.83, 75.58, 73.34, 72.44, 66.36, 49.35, 36.02.
Anal. (C15H18O4) C, H.
23a : E-isomer; [R]D ) +129.87 (c 3.07, CHCl3); IR (neat)
3432 (CdO) and 1654 (CdC) cm-1 1H NMR (CDCl3) δ 5.90
;
(m, 1 H, HCd), 5.82 (d, 1 H, J ) 3.9 Hz, H-1), 4.85 (d, 1 H, J
) 3.9 Hz, H-2), 4.54 (m, 2 H, CH2OH), 4.15 (AB d, 2 H, H-4),
1.49 (s, 3 H, C(CH3)), 1.35 (s, 3 H, C(CH3)); 13C NMR δ 138.10
(s), 126.57 (d), 112.31 (s), 104.87 (d), 81.70 (d), 66.94 (t), 59.93
(t), 27.25 (q), 26.88 (q). Anal. Calcd for C9H14O4: C, 58.05;
H, 7.58. Found: C, 57.90; H, 7.56.

4918 J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 25
Lee et al.
(3R )-3-C-[(Be n zyloxy)e t h yl]-3-C-vin yl-γ-b u t yr ola c-
ton e (28). A solution of 27 (1.31 g, 5 mmol) in THF (50 mL)
was treated with hexamethylphosphoramide (7.5 mL, 43.1
mmol) and ethylene glycol (3.25 mL, 60 mmol). This solution
was treated dropwise with a solution of SmI2 in THF (0.1 M,
150 mL, 15 mmol) and stirred for 30 min at room temperature.
The reaction was quenched with saturated NaHCO3 solution
(20 mL), and the mixture was concentrated to a small volume.
The solution was diluted with EtOAc, and the organic layer
was washed with sodium thiosulfate solution, water, and brine.
The organic layer was dried (MgSO4) and concentrated under
reduced pressure. The residue was purified by flash column
chromatography over silica gel with EtOAc:hexanes (2:3) as
eluant to give 28 as a colorless oil (1.21 g, 98%): [R]D ) -41.55
aldehyde as an oil. The aldehyde was dissolved in MeOH (10
mL), cooled to -10 °C, and treated with sodium borohydride
portionwise until the starting material was consumed. The
reaction was quenched with acetone followed by acetic acid,
and the mixture was concentrated. The residue was parti-
tioned between ether and water, and the aqueous layer was
extracted with ether. The combined organic layer was washed
with water, dried (MgSO4), and concentrated under reduced
pressure. The residue was purified by flash column chroma-
tography on silica gel with EtOAc:hexanes (2:3) as eluant to
give 3 as a white solid (0.053 g, 72% for two steps): mp 41
°C; [R]D ) -3.75 (c 0.64, CHCl3); IR (CHCl3) 3482 (OH), 1764
and 1728 (CdO); 1H NMR (CDCl3) δ 4.31 (d, 1 H, J ) 9.6 Hz,
H-4a), 4.15 (d, 1 H, J ) 9.6 Hz, H-4b), 4.07 (t, 2 H, J ) 6.8 Hz,
COOCH2(CH2)12CH3), 3.67 (s, 2 H, CH2OH), 2.60 (s, 2 H, CH2-
COO), 2.58 (d, 1 H, J ) 17.7 Hz, H-2a), 2.50 (d, 1 H, J ) 17.7
Hz, H-2b), 1.60 (m, 2 H, COOCH2CH2(CH2)11CH3), 1.10-1.70
(m, 22 H, COOCH2CH2(CH2)11CH3), 0.86 (distorted t, 3 H,
CH3); 13C NMR (CDCl3) δ 175.90, 170.90, 74.03, 65.62, 65.31,
42.23, 38.85, 36.81, 31.89, 29.62, 29.53, 29.46, 29.32, 29.17,
28.48, 25.86, 22.65, 14.08; FAB MS m/e (relative intensity) 371
(MH+, 23), 175 (MH - C14H28, 100). Anal. (C21H38O5) C, H.
(3S)-3-C-[(Met h oxyca r b on yl)m et h yl]-3-C-vin yl-1,2-O-
isop r op ylid en e-r-D-er yth r o-fu r a n ose (30). A solution of
vinylmagnesium bromide (1 M in THF, 36 mL, 36 mmol) was
cooled to -40 °C, treated with copper(I) bromide-dimethyl
sulfide complex (0.74 g, 3.6 mmol), and stirred for 10 min. A
solution of 22a ,b (2.58 g, 12.0 mmol) in ether (36 mL) was
then slowly added during the course of 1 h and stirred for an
additional hour. The reaction mixture was quenched with a
saturated NH4Cl solution and allowed to warm up to room
temperature. The mixture was diluted with ether, and the
organic layer was washed with water and brine, dried (MgSO4),
and concentrated under reduced pressure. The residue was
purified by flash column chromatography on silica gel with
EtOAc:hexanes (1:3 to 1:2) as eluant to give 30 as a colorless
oil (1.97, 68%): [R]D ) +20.0 (c 3.40, CHCl3); IR (neat) 1740
(CdO), 1639 (CdC) cm-1; 1H NMR (CDCl3) δ 5.83 (dd, 1 H, J
) 17.6, 10.9 Hz, CHdCH2), 5.78 (d, 1 H, J ) 3.5 Hz, H-1),
5.23 (d, 1 H, J ) 17.6 Hz, CHdCHH), 5.21 (d, 1 H, J ) 10.9
Hz, CHdCHH), 4.46 (d, 1 H, J ) 3.5 Hz, H-2), 4.06 (d, 1 H, J
) 8.8 Hz, H-4a), 3.89 (d, 1 H, J ) 8.8 Hz, H-4b), 3.64 (s, 3 H,
COOCH3), 2.70 (AB q, J ) 16.0 Hz, CH2COOCH3), 1.50 (s, 3
H, C(CH3)), 1.31 (s, 3 H, C(CH3)); 13C NMR δ 171.65 (s), 138.52
(d), 116.36 (t), 111.94 (s), 105.47 (d), 84.95 (d), 73.78 (t), 51.55
(q), 50.39 (s), 36.40 (t), 26.82 (q), 26.40 (q). Anal. (C12H18O5)
C, H.
1
(c 2.84, CHCl3); IR (neat) 1781 (CdO), 1638 (CdC) cm-1; H
NMR (CDCl3) δ 7.20-7.40 (m, 5 H, phenyl), 5.78 (dd, 1 H, J )
17.5, 10.8 Hz, CHdCH2), 5.21 (d, 1 H, J ) 10.8 Hz, CHdCHH),
5.12 (d, 1 H, J ) 17.5 Hz, CHdCHH), 4.43 (s, 2 H, PhCH2O),
4.25 (d, 1 H, J ) 9.3 Hz, H-4a), 4.15 (d, 1 H, J ) 9.3 Hz, H-4b),
3.49 (t, 2 H, J ) 6.0 Hz, BnOCH2), 2.55 (AB t, 2 H, J ) 18.2
Hz, H-2), 1.88 (t, 2 H, J ) 6.0 Hz, BnOCH2CH2); 13C NMR δ
175.82, 139.30, 137.77, 128.10, 127.35, 127.28, 114.93, 76.02,
72.81, 66.29, 44.96, 39.43, 36.91. Anal. (C15H18O3) C, H.
(3R)-3-C-[(Tetr a d eca n oxyca r bon yl)m eth yl]-3-C-vin yl-
γ-bu tyr ola cton e (29). A solution of 28 (0.493 g, 2.0 mmol)
in CH2Cl2 (20 mL) was cooled to -78 °C and treated dropwise
with BCl3 in CH2Cl2 (1 M, 6 mL, 6 mmol). The reaction
mixture was warmed to -10 °C and stirred for 1 h. The
mixture was quenched with saturated NaHCO3 solution (6 mL)
and partitioned between CH2Cl2 and water. The organic layer
was washed with water, dried (MgSO4), and concentrated
under reduced pressure to give the intermediate crude alcohol,
which was used for the next step without further purification.
The alcohol was dissolved in acetone (20 mL), cooled to 0 °C,
and treated dropwise with J one’s reagent (8 N, 2.0 mL, 16
mmol). After the mixture was stirred for 30 min at 0 °C, a
small amount of 2-propanol was added to destroy the excess
oxidizing reagent. The reaction mixture was partitioned
between chloroform and water, and the aqueous layer was
extracted twice with chloroform. The combined organic extract
was washed with water, dried (MgSO4), and concentrated
under reduced pressure to the crude acid. The above acid was
dissolved in CH2Cl2 (15 mL), and the solution was treated with
tetradecanol (0.514 g, 2.0 mmol) and 4-(dimethylamino)-
pyridine (0.048 g, 0.4 mmol). A solution of dicyclohexylcar-
bodiimide in CH2Cl2 (1 M, 4 mL, 4 mmol) was added dropwise,
and after stirring for 1 h at room temperature, the reaction
mixture was quenched with acetic acid (0.35 mL, 6 mmol) and
further stirred for 1 h. The mixture was concentrated under
reduced pressure, dissolved in cold hexane, filtered, and
concentrated. The residue was purified by flash column
chromatography on silica gel with EtOAc:hexanes (1:5) as
eluant to give ester 29 as a white solid (0.41 g, 56% for 3
steps): mp 41 °C; [R]D ) -15.58 (c 1.9, CHCl3); IR (CHCl3)
1762 and 1730 (CdO) cm-1; 1H NMR (CDCl3) δ 5.92 (dd, 1 H,
J ) 17.5, 10.8 Hz, CHdCH2), 5.21 (d, 1 H, J ) 10.8 Hz,
CHdCHH), 5.17 (d, 1 H, J ) 17.5 Hz, CHdCHH), 4.30 (AB d,
2 H, J ) 9.5 Hz, H-4), 4.05 (t, 2 H, J ) 6.7 Hz, COOCH2(CH2)12-
CH3), 2.65 (s, 2 H, CH2COO), 2.60 (AB d, J ) 15.5 Hz, H-2),
1.60 (m, 2 H, COOCH2CH2(CH2)11CH3), 1.15-1.40 (m, 22 H,
COOCH2CH2(CH2)11CH3), 0.87 (distorted t, 3 H, CH3); 13C
NMR δ 175.29, 170.05, 138.74, 115.45, 75.71, 65.07, 44.10,
41.56, 39.47, 31.87, 29.60, 29.51, 29.45, 29.37, 29.30, 29.14,
28.47, 25.85, 22.64, 14.06. Anal. (C22H38O4) C, H.
(3S)-3-C-[(Ben zyloxy)eth yl]-3-C-vin yl-1,2-O-isop r op y-
lid en e-r-D-er yth r o-fu r a n ose (32). This compound was ob-
tained from 30 by following the same procedure used for the
synthesis of 26: [R]D ) +25.28 (c 2.35, CHCl3); IR (neat) 1637
1
(CdC) cm-1; H NMR (CDCl3) δ 7.20-7.40 (m, 5 H, phenyl),
5.72 (d, 1 H, J ) 3.4 Hz, H-1), 5.71 (dd, 1 H, J ) 17.6, 10.9
Hz, CHdCH2), 5.21 (d, 1 H, J ) 10.9 Hz, CHdCHH), 5.18 (d,
1 H, J ) 17.6 Hz, CHdCHH), 4.45 (s, 2 H, PhCH2O), 4.35 (d,
1 H, J ) 3.4 Hz, H-2), 3.93 (d, 1 H, J ) 8.7 Hz, H-4a), 3.85 (d,
1 H, J ) 8.7 Hz, H-4b), 3.50 (m, 2 H, BnOCH2), 1.95 (m, 2 H,
BnOCH2CH2), 1.51 (s, 3 H, C(CH3)), 1.30 (s, 3 H, C(CH3)); 13
C
NMR δ 139.31, 138.27, 128.19, 127.34, 127.31, 116.08, 111.66,
105.35, 85.17, 73.83, 72.77, 66.61, 51.31, 30.97, 26.83, 26.29.
Anal. (C18H24O4) C, H.
(3S )-3-C-[(Be n zyloxy)e t h yl]-3-C-vin yl-D-e r yt h r on ic
γ-La cton e (33). This compound was obtained from 32 by
following the same procedure for the synthesis of 27: [R]D
)
(3R)-3-C-[(Tet r a d eca n oxyca r b on yl)m et h yl]-3-C-(h y-
d r oxym eth yl)-γ-bu tyr ola cton e (3). A solution of 29 (0.073
g, 0.2 mmol) in aqueous acetone (50%, 10 mL) was treated with
4-methylmorpholine N-oxide (0.047 g, 0.4 mmol), sodium
metaperiodate (0.086 g, 0.4 mmol), and OsO4 (2.5% solution
in 2-methyl-2-propanol, 0.05 mL, 0.004 mmol). After 14 h of
stirring at room temperature, the reaction mixture was diluted
with EtOAc (100 mL). The organic layer was washed with a
solution of sodium thiosulfate solution, water, and brine, dried
(MgSO4), and concentrated under reduced pressure. The
residue was purified by flash column chromatography on silica
gel with EtOAc:hexanes (2:3) as eluant to give the intermediate
-4.77 (c 3.84, CHCl3); IR (neat) 3421 (OH), 1788 (CdO), 1640
1
(CdC) cm-1; H NMR (CDCl3) δ 7.20-7.40 (m, 5 H, phenyl),
5.88 (dd, 1 H, J ) 17.5, 10.9, CHdCH2), 5.23 (d, 1 H, J ) 10.9
Hz, CHdCHH), 5.19 (d, 1 H, J ) 17.5 Hz, CHdCHH), 4.57 (d,
1 H, J ) 11.6 Hz, PhCHHO), 4.31 (d, 1 H, J ) 11.6 Hz,
PhCHHO), 4.10-4.30 (m, 3 H, H-4 and H-2), 3.62 (m, 1 H,
BnOCHH), 3.50 (td, 1 H, J ) 12.3, 2.3 Hz, BnOCHH), 2.05
(m, 1 H, BnOCH2CHH), 1.75 (ddd, 1 H, J ) 15.3, 5.3, 2.3 Hz,
BnOCH2CHH); 13C NMR δ 176.02 (s), 139.20 (d), 136.79 (s),
128.55 (d), 128.28 (d), 128.09 (d), 116.00 (t), 73.85 (d), 73.25
(t), 72.65 (t), 65.91 (t), 49.67 (s), 32.26 (t). Anal. (C15H18O4)
C, H.

Conformationally Constrained Analogues of Diacylglycerol
J ournal of Medicinal Chemistry, 1996, Vol. 39, No. 25 4919
(3S )-3-C-[(Be n zyloxy)e t h yl]-3-C-vin yl-γ-b u t yr ola c-
ton e (34). This compound was obtained from 33 by following
the procedure for the synthesis of its optical antipode 28: [R]D
) +41.35 (c 4.0, CHCl3); the IR, 1H NMR, and 13C NMR spectra
were identical to those of 28. Anal. (C15H18O3) C, H.
(3S)-3-C-[(Tetr a d eca n oxyca r bon yl)m eth yl]-3-C-vin yl-
γ-bu tyr ola cton e (35). This compound was obtained from 34
by following the procedure for the synthesis of its optical
antipode 29: white solid; mp 41 °C; [R]D ) +15.08 (c 1.26,
CHCl3); the IR, 1H NMR, and 13C NMR spectra were identical
to those of 29. Anal. (C22H38O4) C, H.
Refer en ces
(1) Previous reference in the sequence: Lee, J .; Sharma, R.; Wang,
S.; Milne, G. W. A.; Lewin, N. E.; Szallazi, Z.; Blumberg, P. M.;
George, C.; Marquez, V. E. Conformationally Constrained Ana-
logues of Diacylglycerol. 12. Ultrapotent Protein Kinase C
Ligands Based on a Chiral 4,4-Disubstituted Heptono-1,4-lactone
Template. J . Med. Chem. 1996, 39, 36-45.
(2) Pears, C. Structure and Function of the Protein Kinase C Gene
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(3S)-3-C-[(Tet r a d eca n oxyca r b on yl)m et h yl]-3-C-(h y-
d r oxym eth yl)-γ-bu tyr ola cton e (5). This compound was
obtained from 35 by following the procedure for the synthesis
of its optical antipode 3: white solid: mp 42 °C; [R]D ) +4.12
(c 0.97, CHCl3); the IR, 1H NMR, 13C NMR, and FAB MS
spectra were identical to those of 1. Anal. (C21H38O5) C, H.
(3R)-3-C-[(Tet r a d eca n oxyca r b on yl)m et h yl]-3-C-(h y-
d r oxyeth yl)-γ-bu tyr ola cton e (4). A solution of 28 (0.12 g,
0.5 mmol) in THF (10 mL) was cooled to -78 °C and treated
dropwise with a borane-methyl sulfide complex in THF (2 M,
0.5 mL, 1.0 mmol). The reaction mixture was gradually
allowed to reach 0 °C and stirred for 14 h. The mixture was
quenched with a sodium perborate solution (2 equiv) which
was added slowly at 0 °C. The cooling bath was removed and
stirring continued for 3 h. The mixture was diluted with
EtOAc, and the organic layer was washed with water and
brine. The solution was dried (MgSO4) and concentrated under
reduced pressure. The residue was purified by flash column
chromatography on silica gel with EtOAc:hexanes (3:1) as
eluant to give the corresponding alcohol as a colorless oil (0.05
g, 35%). The alcohol (0.05 g, 0.19 mmol) was dissolved in
acetone (5 mL), cooled to 0 °C, and treated with J one’s reagent
(8 N, 0.1 mL). After being stirred for 30 min at 0 °C, the
reaction mixture was treated with 2-propanol to destroy the
excess oxidizing reagent and partitioned between chloroform
and water. The aqueous layer was extracted twice with
chloroform, and the combined organic layer was washed with
water, dried (MgSO4), and concentrated under reduced pres-
sure to the crude acid. The acid was dissolved in CH2Cl2, and
the solution was treated with tetradecanol (0.1 g, 0.5 mmol)
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and a catalytic amount of 4-(dimethylamino)pyridine.
A
solution of dicyclohexylcarbodiimide in CH2Cl2 (1 M, 1 mL, 1
mmol) was then added dropwise, and stirring was continued
for 2 h at room temperature. The reaction mixture was
quenched with acetic acid (0.05 mL) and stirred for 1 h. The
mixture was concentrated, dissolved in cold hexane, filtered,
and concentrated under reduced pressure. The residue was
purified by flash column chromatography over silica gel with
EtOAc:hexanes (1:4) as eluant to give the corresponding ester.
Finally, the ester (0.047, 0.1 mmol) was dissolved in ethanol
(10 mL) containing 2 drops of acetic acid and treated with 10%
palladium on carbon (0.05 g). The mixture was hydrogenated
under a balloon of hydrogen for 2 h and then filtered. The
filtrate was concentrated under reduced pressure, and the
residue was purified by flash column chromatography on silica
gel with EtOAc:hexanes (1:1) as eluant to give 4 as a white
solid: mp 53 °C; [R]D ) +6.06 (c 0.66, CHCl3); IR (CHCl3)
3496 (OH), 1762 and 1732 (CdO); 1H NMR (CDCl3) δ 4.27 (AB
d, 1 H, J ) 9.6 Hz, H-4a), 4.22 (AB d, 1 H, J ) 9.6 Hz, H-4b),
4.06 (t, 2 H, J ) 6.7 Hz, C13H27CH2OC(O)), 3.78 (t, 2 H, J ) 6
Hz, CH2CH2OH), 2.50-2.70 (m, 4 H, H-2 and CH2COOC14H29),
1.88 (t, 2 H, J ) 6.0 Hz, CH2CH2OH), 1.60 (m, 2 H, C12H25CH2-
CH2OC(O)), 1.1-1.7 (m, 22 H, CH3(C11H22)CH2CH2OC(O)),
0.86 (distorted t, 3 H, CH3); 13C NMR (CDCl3) δ 175.94, 170.62,
76.24, 64.88, 58.74, 40.66, 40.32, 40.28, 38.18, 31.64, 29.37,
29.29, 29.23, 29.08, 28.93, 28.25, 25.63, 22.41, 13.84; FAB MS
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m/e (relative intensity) 385 (MH+, 33), 171 (MH+ - HOC14H29
,
100). Anal. (C22H40O5) C, H.
(3S)-3-C-[(Tetr adecan oxycar bon yl)m eth yl]-3-C-(h ydr ox-
yeth yl)-γ-bu tyr ola cton e (6). This compound was obtained
from 34 by following the procedure for the synthesis of its
optical antipode 4: white solid; mp 53 °C; [R]D ) -6.67 (c
0.90, CHCl3); the IR, 1H NMR, 13C NMR and FAB MS spectra
were identical to those of 2. Anal. Calcd for C22H40O5: C,
68.71; H, 10.49. Found: C, 68.64; H, 10.43.
J M960525V