Conformationally constrained analogues of diacylglycerol (DAG). 27. Modulation of membrane translocation of protein kinase C (PKC) isozymes α and δ by diacylglycerol lactones (DAG-lactones) containing rigid-rod acyl groups

Article abstract of DOI:10.1021/jm061289j

Highly rigid and geometrically well-defined rods composed of ethynylene-substituted aromatic spacers [oligo-(p-phenyleneethynylene), OPE] were incorporated as acyl moieties on diacylglycerol lactones (DAG-lactones) and investigated for their ability to bind to protein kinase C (PKC) and translocate PKC α and δ isoforms to plasma and internal membranes. The kinetics of PKC translocation were correlated with biological responses, viz. ERK phosphorylation, induction of IL-6 secretion, inhibition of cell proliferation, and induction of cellular attachment, that display very different time courses. Because OPE rods assemble through noncovalent forces and form stable films, they may influence the microdomain environment around the DAG-lactone membrane-binding site. A comparison of two DAG-lactones (1 and 10), one with two PE units (1) and the other with an equivalent flexible acyl chain (10) of matching lipophilicity, clearly demonstrated the effect of the rigid OPE chain in substantially prolonging the translocated state of both PKC α and δ.

Full text of DOI:10.1021/jm061289j

962
J. Med. Chem. 2007, 50, 962-978
Conformationally Constrained Analogues of Diacylglycerol (DAG). 27. Modulation of
Membrane Translocation of Protein Kinase C (PKC) Isozymes r and δ by Diacylglycerol
Lactones (DAG-Lactones) Containing Rigid-Rod Acyl Groups
Krishnan Malolanarasimhan,†,| Noemi Kedei,‡ Dina M. Sigano,† James A. Kelley,† Christopher C. Lai,† Nancy E. Lewin,‡
Robert J. Surawski,‡ Vladimir A. Pavlyukovets,‡ Susan H. Garfield,§ Stephen Wincovitch,§ Peter M. Blumberg,‡ and
Victor E. Marquez*,†
Laboratory of Medicinal Chemistry, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick,
Maryland 21702, Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of
Health, Bethesda, Maryland 20892, and Laboratory of Cellular Carcinogenesis, Center for Cancer Research, National Cancer Institute,
National Institutes of Health, Bethesda, Maryland 20892
ReceiVed NoVember 3, 2006
Highly rigid and geometrically well-defined rods composed of ethynylene-substituted aromatic spacers [oligo-
(p-phenyleneethynylene), OPE] were incorporated as acyl moieties on diacylglycerol lactones (DAG-lactones)
and investigated for their ability to bind to protein kinase C (PKC) and translocate PKC R and δ isoforms
to plasma and internal membranes. The kinetics of PKC translocation were correlated with biological
responses, viz. ERK phosphorylation, induction of IL-6 secretion, inhibition of cell proliferation, and induction
of cellular attachment, that display very different time courses. Because OPE rods assemble through
noncovalent forces and form stable films, they may influence the microdomain environment around the
DAG-lactone membrane-binding site. A comparison of two DAG-lactones (1 and 10), one with two PE
units (1) and the other with an equivalent flexible acyl chain (10) of matching lipophilicity, clearly
demonstrated the effect of the rigid OPE chain in substantially prolonging the translocated state of both
PKC R and δ.
Introduction
which is constitutively present in membranes.3 Cholesterol’s
rigid ring system and its ability to fill interstitial spaces facilitate
a more tightly packed Id state for the acyl chains of the bilayer.4
Hence, cholesterol is an important determinant of membrane
organization. The cholesterol concentration in different cellular
organelles varies; for example, the plasma membrane and the
Golgi apparatus have a high concentration of cholesterol and
highly ordered membranes.3 The endoplasmic reticulum (ER),
however, has a low concentration of cholesterol and a more
disordered membrane organization.3 These different biophysical
properties in membranes can have an important effect on the
regulation of signal transduction by aiding or preventing the
formation of microdomains that bring together both lipids and
proteins involved in cell signaling5,6
Natural membranes possess a lamellar bilayer organization
as revealed by X-ray crystallography.1 The lipid composition
of the membrane controls whether such a lamellar bilayer exists
in a liquid disordered state (Id)a or in a liquid ordered state (Io).2
In general, lipids that contain unsaturated fatty acid chains with
kinks drive the bilayer toward an Id state, whereas saturated
acyl chains tend to stabilize an ordered Io state. The equilibrium
between the Id and Io states is dynamic and can be affected by
several factors, most notably by the concentration of cholesterol,
* Corresponding author. Phone: 301-846-5954. Fax: 301-846-6033.
E-mail: marquezv@mail.nih.gov.
† National Cancer Institute-Frederick, National Institutes of Health.
‡ Laboratory of Cancer Biology and Genetics, Center for Cancer
Research, National Cancer Institute, National Institutes of Health.
§ Laboratory of Cellular Carcinogenesis, Center for Cancer Research,
National Cancer Institute, National Institutes of Health.
During the course of our work with diacylglycerol lactones
(DAG-lactones), which function as potent surrogates of dia-
cylglycerol to strongly activate protein kinase C (PKC), the
nature of the alkyl groups at both the acyl (R1) and R-alkylidene
(R2) positions emerged as one of the principal determinants in
controlling biological activity (Figure 1).7 For example, switch-
ing from simple n-alkyl chains to branched alkyl chains8 or
incorporating aromatic moieties at R1 and/or R2 produced
compounds that in some cases displayed significant degrees of
specificity for PKC isozymes and other proteins containing
DAG-responsive C1 domains.9
| Current address: Astrazeneca India Pvt Ltd, Bellary Road, Hebbal, Ban-
galore 560024 India. E-mail: krishnan.malolanarasimhan@astrazeneca.com.
a Abbreviations: BOP-Cl, bis(2-oxo-3-oxazolidinyl)phosphinic acid
chloride; CAN, ceric ammonium nitrate; CHO, Chinese hamster ovary;
DAG, diacylglycerol; DMAP, dimetheylaminopyridine; DMEM, Dulbecco’s
modified Eagle’s medium; DMF, dimethylformamide; DMSO, dimethyl
sulfoxide; ELISA, enzyme-linked immunosorbent assay; ER, endoplasmic
reticulum; ERK, extracellular signal-regulated kinase; FRET-responsive,
fluorescence resonance energy transfer-responsive; GFP-tagged, green
fluorescent protein-tagged; Id, liquid disordered state; IL, interleukin; Io,
liquid ordered state; LDA, lithium diisopropylamide; LNCaP, androgen-
sensitive human prostate carcinoma cells; MRCK, myotonic dystrophy
kinase-related cdc42-binding kinase; MsCl, methanesulfonyl chloride; Munc-
13, unc-13 homolog; NBA, 3-nitrobenzyl alcohol; OPE, oligo(p-phenyle-
neethynylene); PDBu, [20-3H]phorbol 12,13-dibutyrate; PE, p-phenylene-
ethynylene; PEG, polyethyleneglycol; PKC, protein kinase C; PKD, protein
kinase D; PMA, phorbol 12-myristate 13-acetate; RasGRP, ras guanyl
releasing protein; RPMI-1640, medium culture developed at Roswell Park
Memorial Institute; SDS-PAGE, sodium dodecyl sulfate polyacrylamide
gel electrophoresis; SEM, standard error of the mean; TBAF, tetra-n-
butylammonium fluoride; TFA, trifluoroacetic acid; THF, tetrahydrofuran;
WEHI-231, immature B-cell line.
Because of its unique role, we initially considered modifying
the acyl chain of DAG-lactones with the rigid cholesterol ring
system. However, because the resulting DAG-lactones would
be extremely lipophilic, we decided instead to replace the acyl
chain with an ensemble of simpler, repetitive rigid elements
that could be fine-tuned to a desired length and lipophilicity
capable of mimicking the effects of cholesterol on the biophysi-
cal properties of the membrane. To that effect, we selected
10.1021/jm061289j This article not subject to U.S. Copyright. Published 2007 by the American Chemical Society
Published on Web 02/07/2007

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 963
Table 1. PKC Binding Affinities (Ki) for the R Isozyme and log P18
Values of Target Compounds
compound
log P
Ki (nM)
1
2
3
4
5
6
7
8
9
10
3.24
4.64
4.67
4.21
5.61
9.28
6.05
6.19
3.68
3.68
5.23 ( 0.5
11.6 ( 0.3
5.88 ( 0.91
15.8 ( 5.9
126.9 ( 7.3
52.7 ( 5.4
111.1 ( 6.9
18.3 ( 2.6
1391 ( 57
15.9 ( 1.1
Figure 1. General structure of a DAG-lactone with acyl (R1) and
R-alkylidene (R2) substitutions.
Scheme 1
Scheme 2a
a Conditions and reagents: (a) i. LDA Acetone, THF, -78 °C. ii. MsCl,
DMAP, CH2Cl2. (b) BCl3, CH2Cl2, -78 °C; (c) CAN, CH3CN/H2O.
to explore as acyl chains in a novel set of DAG-lactones that
we report herein.
Design of DAG-Lactones with OPE Acyl Chains. The
simplest OPE-containing DAG-lactones targeted for synthesis
were those with 2 and 3 phenyleneethynylene (PE) units (1 and
2, Scheme 1A, Table 1). Compounds with more than three PE
units proved to be poorly soluble and difficult to purify, possibly
as a result of the well-known propensity of OPEs to form
aggregates in solution.14 This limitation on solubility prevented
us from attempting to build DAG-lactones with OPE tethers
matching the ca. 30 Å hydrophobic portion of the membrane,
so as to span the entire width of the membrane with the rigid
rod. Nevertheless, it is possible that the required length of the
OPE tether to reach the outer surface of the membrane might
be significantly shorter on the basis of the fact that the activated
PKC C1 domain penetrates the membrane to a depth of at least
10 Å.15,16
1 and 2 were soluble and appeared to be optimal in terms of
the log P value (Table 1). Log P, which measures a compound’s
ability to distribute between aqueous and lipid milieus, was
between 4 and 5, well within the desirable range of other active
DAG-lactones (Table 1), while an extra PE unit would increase
the log P to 6.04. For the sake of simplicity and to avoid the
separation of geometrical E and Z isomers, the R-alkylidene
fragment was maintained constant as a 3-(methylethylidene)
group in all of the compounds.
We also investigated the effect of non-ionizable and ionizable
polar substituents located at various distances from the terminus
of the OPE (Scheme 1). One objective was to modulate
interactions with the inner core of the lipid bilayer; a second
objective was to explore the possibility of spanning the width
of the membrane to interact with the polar outer surface. For a
polar, non-ionizable group on the shorter rod, we chose the OMe
group (3, n ) 1, Scheme 1B). For a polar ionizable group, we
chose the CH2CO2Me group (4, n ) 1, Scheme 1B), which
might be expected to undergo hydrolysis by esterases in the
cellular medium. The CH2CO2Me was also placed at the end
of the longer OPE rod (5, n ) 2, Scheme 1B) and at the end of
a 14-carbon alkyl chain attached to the OPE that was long
enough to span the width of the membrane (6, n ) 1, Scheme
highly rigid and geometrically well-defined oligo(p-phenyle-
neethynylene) (OPE) acyl units of different lengths as membrane
phase-modulators designed to achieve various levels of mem-
brane organization and penetration. It is well known that DAGs
containing different acyl chain lengths and degrees of unsat-
uration differentially perturb membranes and PKC activation.10
Therefore, we expected that rigid OPE rods on DAG-lactones
would stabilize a flat lamellar phase11 and perhaps counter the
nonbilayer-prone effect of typical DAGs that tend to induce a
localized negative curvature on the membrane.10 These OPE
rigid rods with a conjugated π-electron system have gained
considerable attention as polymeric structures in material science
because they tend to form main-chain liquid crystals;12 thus,
we expected that their shape-persistent architecture would induce
a more ordered Io state microdomain around the DAG-lactone
membrane-binding environment. Because these highly conju-
gated systems tend to form molecular aggregates, it was also
important to explore several rigid-rod sizes to match the optimal
length with maximal biological activity. In addition to the
expected effect on membrane organization, the OPE backbone
could also complex with hydrophobic patches on the surface
of PKC as has been reported with other proteins.13 Taken
together, these observations made OPEs attractive candidates

964 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5
Malolanarasimhan et al.
Scheme 3a
a Conditions and reagents: (a) NaNO2, HCl, KI. (b) TMSCH2CH2OH, BOP-Cl, CH2Cl2. (c) 17, PdCl2(PPh3)2, piperidine, CuI, THF. (d) TFA, CH2Cl2.
Scheme 4a
a Conditions and reagents: (a) for 22: i. 19, TBAF, THF. ii. BOP-Cl, DMAP, 13, CH2Cl2. For 23: i. 19, TBAF, THF. ii. BOP-Cl, DMAP, 14, CH2Cl2.
For 24: i. 21, TBAF, THF. ii. BOP-Cl, DMAP, 13, CH2Cl2. For 25: decanoic anhydride, DMAP, 13, CH2Cl2. (b) CAN, CH3CN/H2O, CH2Cl2.
1B). As mentioned before, compounds with longer rods (n >
2) were not soluble and formed molecular aggregates. Inspired
by the work of Matile et al.,17 who used plain oligo(1,4-
phenylene) amphiphiles in cell membrane recognition studies,
we also chose to attach at the terminus of the OPE a similar
polyethylene glycol tether capped with an ion-chelating imi-
nodiacetate moiety or oxocarbonyliminodiacetate, both of which
were synthesized as bis-t-butyl esters 7 and 8 (n ) 1, Scheme
1C). The hydrolysis of 8 under special conditions afforded 9 (n
) 1) as a free dicarboxylic acid. Finally, to discriminate between
the effect of a rigid OPE chain on membrane organization versus
an effect on lipophilicity (log P), which controls the partition
of the molecule into a lipid environment, for direct comparison
we synthesized DAG-lactone 10 (log P ) 3.68) with a flexible
decanoic acid chain closely matching the lipophilicity of the
simplest OPE-containing DAG-lactone 1 (log P ) 3.24).
available sodium salt. Following the selective removal of the
terminal TMS group of 19 with trifluoroacetic acid (TFA),
further coupling with 17, also under Sonogashira conditions,
gave the elongated trimeric OPE acyl rod precursor 21.
Alternatively, the trimethylsilylethyl group and the terminal
TMS group in 19 were easily removed under neutral conditions
with tetra-n-butylammonium fluoride (TBAF), and the fully
deprotected acid underwent BOP-Cl mediated coupling with
lactones 13 and 14, respectively, to give 22 (78%) and 23 (62%)
after two steps (Scheme 4). The longer, trimeric OPE acid rod
was obtained from 21 in a similar manner with TBAF and
coupling with 13 gave 24 in 68% yield. To compare the role of
the rigid OPE acyl chain in 22 to that of an equivalent flexible
chain, acylation of 13 with decanoic anhydride in the presence
of DMAP was carried out to give 25. CAN-mediated depro-
tection of the PMP groups in 22, 24, and 25 provided the
corresponding targets 1 (75%), 2 (64%), and 10 (71%).
Chemistry
DAG-Lactones with Terminally Functionalized Ope Acyl
Rods. With the idea of exploring the effect of a polar cap at
the end of the rigid rod, some simple compounds ending with
phenylmethoxy (3) or methyl phenoxyacetate (4) moieties were
synthesized (Scheme 1B). For the phenylmethoxy compound,
coupling of 22 with p-iodoanisole was to be avoided because
of the susceptibility of the anisyl group to oxidation with CAN
during the final deprotection step. Therefore, extension of the
already assembled benzyl-protected DAG-lactone 23 with
p-iodoanisole was attempted under Sonogashira’s conditions in
the presence of Cs2CO3. The desired DAG-lactone 26 was
obtained in 50% yield accompanied by a small amount of the
dimer 27 (12%) (Scheme 5). However, when the coupling was
performed without Cs2CO3, formation of the dimer predomi-
nated. Deprotection of 26 with BCl3 afforded 3 in 60% yield.
Deprotection of 27 gave dimer 28, which was not purified.
To synthesize the compound capped with the methyl phe-
noxyacetate moiety, commercially available 4-iodophenoxy-
Starting from racemic lactone 11,19,20 aldol condensation with
acetone followed by mesylation and elimination of the aldol
product gave 12 in 84% yield (Scheme 2). Parallel deprotection
of 12 with BCl3 or ceric ammonium nitrate (CAN) afforded
either 13 or 14 in 94 and 90% yields, respectively.
DAG-Lactones with Plain OPE Acyl Rods. For the
synthesis of DAG-lactones with OPE acyl rods that are two to
three PE units long (Scheme 1A), the corresponding OPE acids
were prepared first. The shorter ester precursor 19 was obtained
in 65% yield by coupling [2-(trimethylsilyl)ethyl]-4-ethynyl-
benzoate (18) with 4-[(trimethylsilyl)ethynyl]iodobenzene 17,21
under Sonogashira conditions22 (Scheme 3). 17 was prepared
from commercially available 2-[(trimethylsilyl)ethynyl]aniline
(15) according to the literature,21 and 18 was obtained after
BOP-Cl [bis(2-oxo-3-oxazolidinyl)phosphinic acid chloride]
mediated coupling of 4-ethynylbenzoic acid (16) and 2-(trim-
ethylsilyl)ethanol. Acid 16 was obtained from the commercially

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 965
Scheme 5a
a Conditions and reagents: (a) 4-iodoanisole, PdCl2(PPh3)2, Et3N, CuI, THF or 4-iodoanisole, PdCl2(PPh3)2, CsCO3, CuI, THF. (b) BCl3, -78 °C, CH2Cl2.
Scheme 6a
a Conditions and reagents: (a) MeI, NaHCO3, DMF. (b) 4-ethynylaniline (31), PdCl2(PPh3)2, piperidine, CuI, THF. (c) NaNO2, 2 N HCl, KI. (d) i. MeI,
NaHCO3, DMF, 40 °C. ii. TsCl, DMAP, CH2Cl2. (e) 4-iodophenol, CsCO3, DMF.
Scheme 7a
acetic acid (29) was converted to its methyl ester 30, which
was then coupled under Sonogashira conditions with 4-ethy-
nylaniline (31) to give compound 32 in 74% yield (Scheme 6).
Diazotization of the amine in the presence of KI afforded the
corresponding iodide 33. For reasons discussed earlier in this
article, we wanted to move the polar ester moiety away from
the end of the rigid rod, and for that purpose, commercially
available 16-hydroxyhexadecanoic acid (34) was esterified, and
the terminal hydroxyl group was converted to the tosyl ester to
give 35. The tosyl group in 35 was then displaced with
p-iodophenol to give 36, which, relative to 30, separated the
polar ester moiety 14-carbon atoms away from the end of the
OPE rod (Scheme 6).
In addition to being a final DAG-lactone target, 1 also served
as a useful partner for palladium-catalyzed couplings with the
various substituted aryl iodides 30, 33, and 36 (Scheme 6),
a Conditions and reagents: (a) Pd(PPh3)4, CsCO3, Ag2O, THF, 60 °C.
bypassing the final deprotection step. As explained later, the
(b) Monmorillonite KSF, CH3CN, microwave.
reaction conditions developed by Mori and co-workers23 using
Pd(PPh3)4 and Ag2O as an activator and the inclusion of Cs2-
CO3 to reduce the formation of dimeric products instead of the
standard Sonogashira conditions. Coupling of 1 with 30, 33,
and 36 under these conditions gave 4, 5, and 6 in yields ranging
from 58 to 63% (Scheme 7).
Another manner of capping the rigid acyl rod that was ex-
plored employed a more complex multifunctional unit consisting
of a short polyethyleneglycol (PEG) spacer connected to an imi-
nodiacetate moiety (Scheme 1C) in a fashion similar to that
done by Matile et al. with some amphiphilic poly(phenylene)
rods.17 The functionalization of the PEG spacer was accom-
plished by reacting commercially available 37 and 4-iodophenol
at 50 °C to give 38 (Scheme 8). The reaction of this intermediate
with di-t-butyliminodiacetate gave the ester-protected tertiary
amino derivative 39, whereas a similar reaction in the presence
of equimolar amounts of CsCO3 acting as a carboxylating
reagent24 gave the neutral carbamate 40 (Scheme 8).
proceed well under the standard Sonogashira conditions possibly
as a result of the apparent chelation of Pd2+ with the PEG
component of 39 and 40. The reaction was then conducted under
the conditions developed by Mori et al.23 as mentioned previ-
ously. Coupling of 1 with 39 or 40 under these conditions gave
7 and 8 in 45 and 56% yields, respectively. Of the two PEG-
tethered products, the synthesis and purification of 7 was
difficult, whereas that of 8 was more reproducible, and hence
this compound was hydrolyzed under microwave conditions
using a clay mineral, montmorillonite (Na0.2Ca0.1Al2Si4O10-
(OH)2(H2O)10) KSF25,26 in acetonitrile to give 9 in 27% yield
(Scheme 7).
PKC Binding Studies. Enzyme-ligand interactions were
assessed in vitro in terms of the ability of the ligand to displace
bound [20-3H]phorbol 12,13-dibutyrate (PDBu) from a recom-
binant single isozyme (PKC R) in the presence of phosphati-
dylserine.27 The partition coefficients (log P) were calculated
according to the atom-based program MOE Slog P18 (Table 1).
DAG-Lactones with Plain OPE Acyl Rods (Scheme 1A).
1 and 2 are the simplest OPE-containing DAG-lactones with
The syntheses of elongated DAG-lactones containing the
terminal PEG spacer connected to the iminodiacetate or oxy-
carbonyliminodiacetate “caps” (7 and 8, Scheme 1C) did not

966 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5
Malolanarasimhan et al.
Scheme 8a
a Conditions and reagents: (a) 4-iodophenol, CsCO3, DMF, 50 °C. (b) Di-t-butyliminodiacetate, DMF, 50 °C. (c) Di-t-butyliminodiacetate, CsCO3, DMF,
50 °C.
Figure 2. (A) Translocation of PKC R in CHO cells by 10 (top) and 1 (bottom) as a function of time. Cells were treated at 10 µM. Results are
representative of three independent experiments. (B) Translocation of PKC δ in CHO cells by 10 (top) and 1 (bottom) as a function of time. Cells
were treated at 10 µM. Results are representative of three independent experiments.
two and three PE units, respectively (Scheme 1A). 1 showed
excellent affinity for PKC in the low nanomolar range (Table
1). Surprisingly, increasing the length of the acyl rod by one
additional PE unit (2) reduced binding affinity by more than
1/2 despite an increase in log P of 1.4. As with previous DAG-
lactones synthesized in our laboratory, we have sought to
develop potent ligands with the lowest possible log P value in
order to minimize nonselective lipid binding.28,29 Therefore, the
same principle of achieving the lowest possible log P value
compatible with a high binding affinity was also pursued in
this investigation. A comparison of the binding affinities of the
flexible DAG-lactone 10 and of the OPE-containing DAG-
lactone 1, both of which have comparable log P values,
illustrates this approach. 1, with the rigid acyl rod, was 3-fold
more potent than 10 even though it was 0.45 log P units more
hydrophilic than DAG-lactone 10. Therefore, 1 looked like an
excellent template for further exploration in our quest to
construct target-specific PKC agonists (vide infra).
DAG-Lactones with Terminally Functionalized OPE Acyl
Rods (Scheme 1, B and C). Lengthening the two-unit PE acyl
rod in 1 by replacing the terminal hydrogen with a phenyl-
methoxy moiety (3, Scheme 1B) restored most of the binding

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 967
Figure 3. Translocation of PKC R (top) and PKC δ (bottom) in CHO
cells by 2 (20 µM). Results are representative of three independent
experiments.
Figure 4. Translocation of PKC R (top) and PKC δ (bottom) in CHO
cells by 6 (20 µM). Results are representative of three independent
experiments.
the cytosol to the plasma membrane with kinetics dependent
on their potencies and on their applied concentrations relative
to their potencies. Higher relative concentrations of ligands
usually result in faster kinetics.30 PKC δ is unusual among PKC
isoforms in that it translocates not only to the plasma mem-
brane but also to other internal membrane compartments
(nuclear membrane, mitochondria, other cellular organel-
les).31 The pattern of PKC δ localization depends on the
structure and lipophilicity of the activating drug.30 The localiza-
tion the of activated PKC isoform is very important in
determining the downstream biological response, because PKC
will only phosphorylate those substrates to which it has access
through co-localization.
Addressing the biological activity of these DAG-lactones, we
first tested the pattern and kinetics of the translocation of PKC
R and δ in CHO cells. Both DAG-lactone 1 with a rigid OPE
acyl rod and the hydrophobically equivalent DAG-lactone 10
with a flexible acyl chain translocated PKC R (Figure 2A) and
PKC δ (Figure 2B) very quickly, within minutes. PKC δ
translocated simultaneously to the plasma membrane and internal
membranes (Figure 2B). Interestingly, the translocation of PKC
R and PKC δ caused by 10 was transient, unlike that of 1. This
transient translocation was not due to desensitization of the
PKCs because both PKC isoforms translocated again after the
addition of new compound (data not shown), suggesting that
the instability of 10 in the presence of the cells is the probable
explanation.
An increase in the OPE acyl rod length by just one PE
segment (2) had a dramatic effect (Figure 3, top). PKC-induced
translocation by 2 even at high concentrations (20 µM) was
much slower than that induced by 1 and 10; PKC R translocation
started in 20 min and reached completion after 120 min.
Translocation of PKC δ was even slower; it began to become
evident after 30-40 min and had not reached completion within
120 min (Figure 3, bottom).
Behavior similar to that of 2, but with even slower kinetics
of translocation, was observed for 3 at 20 µM where translo-
cation of PKC R started after ca. 120 min. Translocation of
PKC δ was even slower and was incomplete after 120 min (data
not shown). Remarkably, there was no observable translocation
over this time span with 4 and 5 even at 20 µM, possibly because
the polar carboxylate moiety resulting from hydrolysis by
esterases in the medium prevented the insertion of the acyl rod
into the membrane.
lost in 2 with little change in log P (Table 1). However, a similar
enlargement of 1 with a methyl phenoxyacetate moiety (4) was
not as effective as the binding affinity decreased by ca. 3-fold,
whereas the log P decreased only slightly. Surprisingly, the same
methyl phenoxyacetate moiety positioned at the terminus of the
longer OPE DAG-lactone 2 caused a 24-fold decrease in binding
affinity (5), suggesting that increasing the OPE rigid rod beyond
three PE units might be unproductive. The loss of binding in 5
appears to be associated more with the number of PE units rather
than with the absolute length of the acyl chain because spacing
the polar methyl acetate moiety in 4 by 15 carbons from the
OPE terminus gave 6, which registered a lower 10-fold decrease
in binding affinity relative to that of 1 and only a ca. 3-fold
decrease in binding relative to that of 4. From the binding data
(Table 1), the 2-PE acyl rod unit in 1 appears to be optimal in
combining binding affinity and log P value.
When the terminus of the rigid acyl rod of 1 was capped
with the short polyethyleneglycol (PEG) spacer used by Matile
et al.17 bearing the esterified iminodiacetate moiety (7) or the
esterified oxocarbonyliminodiacetate moiety (8), the results
showed that 8 with the oxocarbonyliminodiacetate terminus was
6-fold more potent than 7 and only 3.5-fold less potent than 1
(Table 1). This striking difference between 7 and 8, which have
comparable log P values, could be related to a change of polarity
in going from a basic amine to a neutral carbamate. Unfortu-
nately, the binding affinity of 8 decreased 76-fold when it was
hydrolyzed to 9, which displays a free oxocarbonyliminodiacetic
acid moiety. It is likely that the neutral di-t-butyl esters in 8
can be better accommodated inside the lipid bilayer as opposed
to the ionized oxocarbonyliminodiacetic acid moiety in 9. We
believe that the acyl moieties in 7-9 are perhaps too short to
span the lipid bilayer; consequently, the polar termini of these
molecules have difficulty settling inside the hydrophobic core.
These observations were confirmed in cellular translocation
studies in which 6 appears to be the only compound with
measurable biological activity that is capable of spanning the
30 Å width of the cellular membrane (vide infra).
Cellular Translocation Studies of PKC R and PKC δ in
CHO Cells. Translocation of PKCs from cytosol to membrane
compartments provides one measure of their activation. This
process can be detected in real time by overexpressing different
green fluorescent protein-tagged (GFP-tagged) PKC isoforms
in Chinese hamster ovary (CHO) cells and following their
localization before and after ligand treatment using confocal
microscopy. DAGs and phorbol esters translocate PKCs from
6 was of particular interest in terms of translocation. It
translocated PKC R and PKC δ slowly, beginning after ca. 30

968 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5
Malolanarasimhan et al.
Figure 5. (A) ERK phosphorylation induced by the short rigid-rod DAG-lactones (10, 1, 3, and 6) and PMA after 30 min in LNCaP cells. Western
blots were probed with anti-ERK and anti-phospho-ERK antibodies. (B) Relative intensities of phospho-ERK from Western blots (PMA at 100 nM
) 100%) for the compounds in A plus DAG-lactones 2 and 8). Results are representative of three independent experiments except for 2, which
represents a single experiment. (B) Phosphorylation of ERK after 30 min of treatment of LNCaP cells with rigid-rod compounds.
min (Figure 4). PKC δ translocated to the plasma membrane
first, followed later by translocation to the internal membranes
and the nuclear membrane. The delay in PKC δ translocation
to the plasma membrane and the internal membranes was longer
than that caused by phorbol 12-myristate 13-acetate (PMA) (data
not shown). This longer interval between these two destinations
for PKC δ translocation could potentially result in different
biology.
Not surprisingly, PKC-induced translocation with the more
complex DAG-lactone 8 was even slower (starting after ca. 90-
120 min) than that induced by 6 (data not shown). 8 had sol-
ubility problems reflected by the appearance in the medium of
drug aggregates. No PKC translocation was achieved with 9.
In summary, we conclude that none of the rigid-rod com-
pounds were able to change the pattern of PKC δ translocation
significantly, in particular by translocating PKC δ to the plasma
membrane but not to internal membranes. There was a large
difference in the kinetics of translocation caused by the different
DAG-lactones because the one with the shortest OPE rod (two
PE units) induced a quick translocation, and the ones with three
or more PE units caused progressively slower translocation. The
kinetics of translocation varied markedly, and 6 was noteworthy
because of the long delay between PKC δ translocation to the
plasma membrane and to the internal membranes. The potential
consequences of these kinetic variations in translocation were
investigated using a series of biological end points that differed
in their time courses for response.
Other Biological Assays. In response to PMA treatment,
stimulation of ERK phosphorylation in LNCaP cells occurs in
minutes, secretion of IL-6 from WEHI-231 cells occurs over
hours, and inhibition of WEHI-231 cell proliferation or dif-
ferentiation of U937 cells occurs over several days. We
evaluated these responses upon treatment with the rigid-rod
DAG-lactones and compared them with the responses of PMA.
ERK Phosphorylation in LNCaP Cells. DAGs and phorbol
ester induce ERK phosphorylation in many cellular systems.9
Phosphorylation of ERK occurs shortly (10-30 min) after
agonist treatment, as revealed by the appearance of the bands
detected with anti-phosphoERK antibodies. The quickly acting
1 and 10 activated ERK phosphorylation very effectively with
approximate EC50 values (as assessed from the graph) of 0.4
and 3 µM, respectively (Figure 5). Slowly acting 2 was less
efficient and less potent in this short term assay, unlike its
methoxy derivative 3. The rigid-rod-containing DAG-lactone
6 with the 15-carbon chain linked to the rigid rod was also able
to induce a strong response of ERK phosphorylation at 10 µM.
These results agree with the previously shown results for
translocation and indicate that 6 can translocate and probably
span the width of the membrane. There is some variability in
this assay caused by the short-term treatment (variations in the

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 969
Figure 6. Induction of IL-6 secretion in WEHI-231 cells after 6 and 24 h. The level of secretion was normalized to that induced by 10 nM PMA
after 6 h. Values represent the mean ( SEM of three independent experiments, except for 6, which represents the results of a single experiment.
PMA (0.1, 1, 10, 100, and 300 nM), 10 (1, 10, and30 µM), 1 (0.1, 1, 3, 10, and30 µM), 2 (0.1, 1, 3, 10, and 30 µM), 3 (0.1, 1, 3, 10, and 30 µM),
and 6 (0.1, 1, 10, and 30 µM).
Figure 7. Inhibition of WEHI-231 cell proliferation. PMA (0.1, 1, 10, and 100 nM), 10 (1 and 10 µM), 1 (0.1, 1, and 10 µM), 2 (0.1, 1, and 10
µM), 3 (0.1, 1, 10, and 30 µM), 6 (0.1, 1, and 10 µM), and 8 (0.1, 1, and 10 µM). Values represent the mean ( SEM of three independent
experiments, except for treatment with 1 µM of 10, which was performed once.
drug absorption at 10 and 30 min) and the semiquantitative
nature of western blotting.
dose of ingenol 3-angelate; at 24 h the response to both
compounds is similar.32 We measured secreted IL-6 after 6 and
24 h of treatment with the rigid-rod compounds and compared
the responses with those of PMA.
All of the the compounds that were active in ERK phospho-
rylation could induce IL-6 secretion. The quickly acting 1 was
special in the IL-6 secretion assay as it caused a biphasic dose-
response curve after 6 h of treatment, unlike PMA but similar
Secretion of IL-6 from WEHI-231 Cells. We showed
previously that PMA and other phorbol esters induce secretion
of IL-6 from WEHI-231 pre-B cells starting about 3 to 4 h after
treatment.32 Ingenol 3-angelate induces a biphasic IL-6 response
at early time points (6 h), whereas the response to PMA is
monophasic and fails to reach the level induced by the optimal

970 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5
Malolanarasimhan et al.
Figure 8. Attachment of U937 cells to the bottom of the dish after 48 h treatment. PMA (0.1, 1, 10, and 100 nM), 10 (1, 10, and 30 µM), 1 (0.1,
1, and 10 µM), 2 (0.1, 1, 10, and 30 µM), 3 (0.1, 1, 10, and 30 µM), 6 (0.1, 1, 10, and 30 µM), and 8 (0.1, 1, and 10 µM). Values are the mean
( SEM of three independent experiments, except for treatment with 30 µM of 10 and 30 µM of 6 that were performed once.
to the behavior we described earlier for ingenol 3-angelate. The
other rigid-rod compounds tested did not show a biphasic curve,
but interpretation is clouded by relatively low potencies, which
might mean that sufficient doses were not achieved to reveal
the biphasic response. At higher concentrations (3 µM and
above), there is a solubility problem with many of the
compounds (2, 3, and 8); drug aggregates in the aqueous phase
were visible by light microscopy. 6 did not show unique
behavior in this assay. Interestingly, 10, which caused only
transient translocation of PKCs, was much less effective in these
assays at 6 and 24 h: 10 (30 µM) induced about 80% of the
level of IL-6 secreted upon 10 nM PMA treatment for 6 h and
only 25% of the level induced by PMA at 24 h. This result
highlights the role of the rigid rod, in that 10 contains a flexible
side chain lipophilically equivalent to that of 1.
Inhibition of WEHI-231 Cell Proliferation. Phorbol esters
inhibit the proliferation of many cell types. We checked the
effect of the rigid-rod compounds on the proliferation of WEHI-
231 pre-B cells after 48 h of treatment with different concentra-
tions of compound. PMA inhibited proliferation of WEHI-231
cells with an EC50 of about 0.85 nM. In this assay, 2 and 3
were the most potent of the rigid-rod compounds with EC50
values of 0.4 ( 0.14 and 0.43 ( 0.03 µM, respectively, followed
by 1 and 6 with an EC50 about 3 µM (Figure 7). The detailed
dose-response curves of 2 and 3 showed no difference between
the two compounds (data not shown). 8, which caused very slow
PKC translocation and had little activity in short term assays,
showed 35% inhibition of cell proliferation at 10 µM. 10, which
caused transient translocation of PKCs, had hardly any effect
on WEHI-231 cell proliferation.
the differentiation and attachment induced by PMA.33 We tested
the rigid-rod compounds for differentiation of U937 monocytes
after 48 h of treatment to check the long-term potency of the
compounds and to see if any of them show bryostatin-1-like
unique effects. In this assay, the most potent DAG-lactones were
those with longer rigid rods, which were the same ones that
showed slow kinetics of translocation. PMA induced differentia-
tion and attachment of U937 monocytes with an EC50 of 0.45
( 0.08 nM, and 2 and 3 had EC50 values of 0.25 ( 0.046 and
0.26 ( 0.065 µM, respectively. 2 (30 µM) reproducibly reduced
U937 cell attachment by reducing the number of total cells. 6
was potent in this assay with an EC50 of 1 ( 0.43 µM. 1 and
8 were less potent, although 8 was more potent in this assay
than in the short-term assays, possibly reflecting the slow
kinetics of the compound. 10 did not have any effect in this
assay, similar to its lack of inhibition of WEHI-231 cell
proliferation.
Conclusions
The lipophilic second messenger sn-1,2-diacylglycerol is a
central element in cellular signaling, controlling many down-
stream biological responses including cell proliferation, dif-
ferentiation, apoptosis, and secretion.34 Functioning as the DAG
recognition motif, DAG-responsive C1 domains are present in
multiple families of signal-transducing proteins, including PKC,
PKD, RasGRP, the chimaerins, MRCK, and Munc-13, as well
as in DAG kinases.35 Additional complexity to the signaling is
contributed by the different specificities of the individual
members within a signaling family, with individual members
even being antagonistic in their functions. For example, PKC
δ is often pro-apoptotic, in contrast to PKC ꢀ, which is anti-
apoptotic.36 Moreover, there can be cross talk between these
families of DAG-responsive signaling proteins. PKC phospho-
rylation of PKD and RasGRP3 contributes to their activation;
DAG kinase metabolizes DAG, terminating response from PKC
Attachment of U937 Cells. Treatment of the U937 mono-
cytic cell line with PMA and other phorbol esters results in
their differentiation and attachment to the bottom of the cell
culture dish. Bryostatin 1 is special in this aspect as it does not
cause differentiation and attachment by itself, and it inhibits

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 971
and the other families of DAG-responsive signaling proteins.37,38
A central question in biology is how the cell controls the flow
of information through these signaling pathways in a selective
fashion.
From the perspective of therapeutics, the corresponding
question is how one can exploit such mechanisms of selectivity
to obtain novel and selective drug action for this class of drug
targets. The compounds described here represent one potential
strategy, drawing together several conceptual themes that have
emerged from studies on PKC regulation and pharmacology.
Our initial structural exploration of these rigid-rod-substituted
DAG-lactones has helped to delineate the chemical and phar-
macological feasibility of this approach.
Although the described structures represent only the first
generation of such compounds, we have defined structures that
show a much longer persistence of action compared to the
corresponding aliphatic chain substituted analog. We have
likewise shown that we can achieve marked control over the
rate of induction of translocation, presumably reflecting variable
rates of penetration of the ligands, as shown directly elsewhere
with fluorescent phorbol esters.45 Using a battery of assays of
biological responses chosen to reflect responses possessing
different intrinsic time courses for responses, we have demon-
strated that the patterns of biological response correlate with
the persistence and time course of translocation for the different
ligands. In addition, we have identified at least one ligand that
displays substantial separation of the time courses for plasma
membrane and internal translocation of PKC δ, providing a tool
with which to identify potential consequences of this temporal
separation of PKC δ activation at these different sites. Finally,
we have demonstrated that at least one of these ligands displays
the profile of induction of the cytokine IL-6 characteristic of
the PKC activator ingenol 3-angelate (PEP005) rather than that
characteristic of PMA, in which ingenol 3-angelate is under
evaluation as a cancer chemotherapeutic agent and PMA is a
tumor promoter.32
An early observation has been that much of the diversity of
the effect of natural products acting through C1 domains is
driven by their patterns of lipophilic substitution on a conserved
binding motif. A powerful example is the inhibition of tumor
promotion exerted by the short-chain substituted 12-deoxyphor-
bol esters such as prostratin in contrast to the tumor promoting
activity of its more lipophilic congener 12-deoxyphorbol 13-
tetradecanoate.39 Likewise, phorbol diesters with unsaturated
side chains have long been characterized as being inflammatory
but only weakly tumor promoting, unlike their corresponding
analogs with saturated aliphatic chains.40
PKC has relatively broad substrate requirements. An impor-
tant contributor to selectivity is therefore its selective proximity
to appropriate substrates. We have described how PKC ligands
with different patterns of biological response induce different
patterns of localization of PKC δ, visualized using GFP-tagged
PKC δ. The tumor promoting derivatives PMA and 12-
deoxyphorbol 13-tetradecanoate first cause the accumulation of
GFP-tagged PKC δ at the plasma membrane, followed by a
shift to the internal membranes and the nuclear membrane. In
contrast, bryostatin 1 and ingenol 3-angelate cause little plasma
membrane translocation of PKC δ.30,32 In elegant complemen-
tary studies, Newton and co-workers have employed a FRET-
responsive PKC substrate, positioned in different cellular
compartments, to show that different PKC isoforms have
different kinetics of activation and different patterns of substrate
phosphorylation.41
The relationship of the ligand relative to the surface of the
membrane represents a third potential opportunity for selectivity.
Cho and co-workers42 have shown that different C1 domains
penetrate the lipid surface to different extents. Such penetration
will be controlled both by residues on the outer surface of the
C1 domain, less conserved than the binding cleft itself, or indeed
by other portions of the protein. The influence of structural
elements other than the C1 domains on the behavior of PKC is
reflected in the large differences observed between the behavior
of isolated C1 domains and that of the intact protein. A
mechanism driving such differences is the need to disrupt
intramolecular contacts to render the C1 domains accessible.42
This mechanism is strongly supported by the effects of peptides
mimicking such postulated sites of interaction43 and, in the case
of â2-chimaerin, is shown directly from the X-ray structure, in
which the C1 domain is shielded in the inactive conformation
of the protein by interdomain linkers.44
We believe that the approach described here with the rigid-
rod-substituted DAG-lactones has the potential to probe these
different opportunities for selectivity. Aggregation of ligand
within the surface of the membrane may lead to a distinct pattern
of distribution of PKC. Selectivity of interaction with lipids may
yield preferential localization in membrane compartments.
Different kinetics of penetration will yield different kinetics of
response. Rigid rods capped with appropriately hydrophilic
substituents may insert into the membrane but penetrate no
further, sequestering the PKC at the inner face of the membrane.
Experimental Section
Analysis of Inhibition of [3H]PDBu Binding by NonRadio-
active Ligands. Enzyme-ligand interactions were analyzed by
competition with [3H]PDBu binding to the single isozyme PKC R
essentially as described previously.27 The ID50 values were deter-
mined by least-squares fitting of the theoretical sigmoidal competi-
tion curve to the binding data. The Ki values were calculated from
the ID50 values according to the relationship Ki ) ID50/(1 + L/Kd),
where L is the concentration of free [3H]PDBu at the ID50 and Kd
is the dissociation constant for [3H]PDBu under the assay condi-
tions.27 Values represent the mean ( standard error (three deter-
minations). The octanol/water partition coefficients (log P) were
calculated according to the atom-based program MOE Slog P.18
Biological Experiments. Translocation of GFP-Tagged PKC
Isoforms in CHO Cells. CHO cells were purchased from the
American Type Culture Collection (Manassas, VA) and cultured
in F12-K medium supplemented with 10% fetal bovine serum and
antibiotics (penicillin 50 units/mL and streptomycin 0.05 mg/mL).
CHO cells plated onto T delta dishes (Bioptechs Inc, Butler, PA)
were transfected with GFP-tagged PKC R or PKC δ using
Lipofectamine reagent (Invitrogen, Carlsbad, CA).32 For confocal
images, cells were examined with a Zeiss LSM 510 confocal
microscope (Carl Zeiss Inc, Thornwood, NY) with an Axiovert
100M inverted microscope operating with a 25 mW argon laser
tuned to 488 nm. Cells were imaged with a 63 × 1.4 NA Zeiss
Plan-Apochromat oil immersion objective and with varying zooms
(1.4 to 2). Time-lapse images were collected every 30 s using the
Zeiss AIM software, in which the green emission was collected in
a PMT with a LP 505 filter.
ERK Phosphorylation in LNCaP Cells. Androgen-sensitive
LNCaP prostate cancer cells were purchased from the American
Type Culture Collection (Manassas, VA) and cultured in RPMI-
1640 medium supplemented with 10% fetal bovine serum and
antibiotics (penicillin 50 units/mL and streptomycin 0.05 mg/mL).
Cells were plated in 6 cm dishes at about 60% confluency and 24
h later were treated with different concentrations of the test
compound for 15 or 30 min. After treatment, the cells were washed
with phosphate buffered saline, total cell lysates were prepared,
and the lysates were analyzed by 10% SDS-PAGE followed by
electrotransfer and immunostaining. The primary antibodies used
for immunostaining against phospho-ERK (9101) and total ERK

972 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5
Malolanarasimhan et al.
(9102) were from Cell Signaling (Danvers, MA). The immun-
ostaining was visualized by ECL (Amersham Biosciences). Films
were scanned, densitometry was performed using Image J (devel-
oped at National Institute of Mental Health, NIH), and the results
were expressed relative to the intensity of the phosphorylated ERK
band induced by 100 nM PMA. Values for the mean ( SEM of
three independent experiments (except for 2, which was a single
experiment) were graphed using Prism2 (GraphPad Software Inc,
San Diego, CA).
Induction of IL-6 Secretion in WEHI-231 Cells. WEHI-231
cells were purchased from the American Type Culture Collection
(Manassas, VA) and cultured in DMEM supplemented with 10%
fetal bovine serum, antibiotics (penicillin 50 units/mL and strep-
tomycin 0.05 mg/mL), and 50 µM â-mercaptoethanol. The con-
centration of IL-6 secreted from WEHI-231 cells was determined
as described previously32 using an IL-6 ELISA kit (Biosource
International Inc, Camarillo, CA). One × 105 viable cells/mL were
plated in six-well plates (2 mL) treated after 24 h with the specified
concentrations of the compounds (final DMSO concentration 0.1%)
for 6 and 24 h, after which aliquots of supernatant were removed
for IL-6 determination. Cells were pelleted from supernatants by
centrifugation at 1000g for 10 min. The IL-6 concentration in the
supernatants was measured following the manufacturer’s protocol.
Secreted IL-6 was determined in a single measurement per
experiment and expressed as a percentage of IL-6 induced by 10
nM PMA at 6 h. The values for the mean ( SEM from three
experiments (except for 6, a single measurement) were graphed
using Prism2 (GraphPad Software Inc, San Diego, CA).
Inhibition of WEHI-231 Cell Proliferation. One × 105 viable
cells/mL were plated in six-well plates (2 mL) and treated after 24
h with the specified concentrations of the compounds (final DMSO
concentration 0.1%) for 48 h. After trituration to form a single cell
suspension, cells were counted using a Coulter particle counter.
The numbers of cells were presented as a percentage of that of the
DMSO treated control. The values of the mean ( SEM from three
independent experiments were graphed using Prism2 (GraphPad
Software Inc, San Diego, CA).
Attachment of U937 Cells. U937 cells, purchased from the
American Type Culture Collection (Manassas, VA), were cultured
in RPMI-1640 medium supplemented with 10% fetal bovine serum
and antibiotics (penicillin 50 units/mL and streptomycin 0.05 mg/
mL). Attachment of U937 cells to the bottom of the culture dishes
was measured as described previously with some modifications.33
Cells plated at 1 × 105 cells/mL in 2 cm dishes were treated with
different concentrations of compounds (final DMSO concentration
0.1%) for 48 h. Non-attached and attached cells (the latter measured
after trypsinization) were counted using a Coulter particle counter.
The numbers of attached cells were expressed as a percentage of
total cells. The values of the mean ( SEM from three independent
experiments were graphed using Prism2 (GraphPad Software Inc,
San Diego, CA).
a resolution of 1200, whereas accurate mass analysis (HRFABMS)
was carried out at a resolution of 3500-4500. For the latter, a
limited-range V/E scan was employed under control of a MASPEC-
II32 data system for Windows (MasCom GmbH, Bremen, Germany).
Matrix-derived ions, including K+ adducts, were utilized as the
internal mass references for accurate mass determinations. Both
1H and 13C NMR data were used to set constraints for the calculation
of all of the possible elemental compositions within 10 ppm of the
measured accurate mass. In each case where an accurate mass was
reported, a unique molecular formula could be determined by
consideration of the molecular ion species and appropriate fragment
ions. Elemental analyses were performed by Atlantic Microlab, Inc.,
Atlanta, GA.
5-[(4-Methoxyphenoxy)methyl]-3-(methylethylidene)-5-[(phe-
nylmethoxy)methyl]-4,5-dihydrofuran-2-one (12). A stirred solu-
tion of lactone 1119,20
(1.16 g, 3.39 mmol) in THF (8 mL) was
treated with LDA (2.0 M, 3.4 mL, 6.8 mmol) at -78 °C. After 50
min, acetone (1.25 mL, 17.0 mmol) was added and stirred for 1.5
h at the same temperature. The reaction was quenched with saturated
aqueous NH4Cl and concentrated under reduced pressure. The
residue was dissolved in CH2Cl2 (50 mL), washed with saturated
aqueous NH4Cl solution (2 × 25 mL), dried (MgSO4), and
concentrated under reduced pressure. The crude product was then
dissolved in CH2Cl2 (20 mL) and treated with MsCl (0.52 mL, 6.8
mmol) and DMAP (1.66 g, 13.6 mmol) at room temperature
overnight. The reaction mixture was then diluted with CH2Cl2 (50
mL), washed with saturated aqueous NH4Cl (2 × 25 mL), and dried
(MgSO4). Purification by column chromatography on silica gel
(EtOAc/hexanes, 1/3) afforded 12 (1.2 g, 88%); mp 78-79 °C;
FTIR (neat) 2360 (CH), 2840 (CH), 1729 (CdO), 1666 (CdC)
1
cm-1; H NMR (400 MHz, CDCl3): δ 7.23-7.32 (m, 5H, C6H5-
CH2OCH2C), 6.79 (s, 4H, CH3OC6H4OCH2C), 4.56 (AB q, J )
12.2 Hz, 2H C6H5CH2OCH2C), 3.99 (AB q, J ) 9.7 Hz, 2 H, CH3-
OC6H4OCH2C), 3.73 (s, 3H, CH3OC6H4OCH2C), 3.63 (AB q, J )
10.2 Hz, 2H, C6H5CH2OCH2C), 2.76-2.88 (m, 2H, H-4a,b), 2.25
(t, J ) 2.1 Hz, 3H, CdC(CH3)2), 1.83 (s, 3H, CdC(CH3)2); 13C
NMR (100 MHz, CDCl3): δ 169.11, 154.16, 152.55, 150.61,
137.65, 128.31, 127.64, 137.50, 119.19, 115.65, 114.53, 80.92,
73.56, 71.99, 70.57, 55.60, 32.63, 24.45, 19.80. FAB MS (m/z,
relative intensity) 382 (M•+, 100); Anal. (C23H26O5) C, H.
5-(Hydroxymethyl)-5-[(4-methoxyphenoxy)methyl]-3-(meth-
ylethylidene)-4,5-dihydrofuran-2-one (13). A solution of BCl3 in
CH2Cl2 (1.0 M, 31.4 mL) was added to a solution of 12 (175 mg,
0.46 mmol) in CH2Cl2 (15 mL) and stirred at -78 °C for 2 h. The
reaction was quenched with saturated NaHCO3 solution (30 mL),
warmed to room temperature, and extracted with CH2Cl2 (2 × 50
mL). The organic layer was dried (MgSO4) and concentrated.
Purification by column chromatography on silica gel (EtOAc/
hexanes, 1/1) afforded 13 (118 mg, 88%) as a white solid, mp 78-
79 °C; FTIR (neat) 3442 (OH), 2934 (CH), 1744 (CdO), 1665
1
(CdC) cm-1; H NMR (400 MHz, CDCl3): δ 6.81 (s, 4H, CH3-
OC6H4OCH2C), 3.99 (AB q, J ) 9.5 Hz, 2H, CH3C6H4CH2-
OCH2C), 3.79 (AB q, J ) 12.1 Hz, 2H, HOCH2C), 3.75 (s, 3H,
CH3C6H4CH2OCH2C), 2.77-2.93 (m, 2H, H-4a,b), 2.53 (br s, 1H,
HOCH2C), 2.26(t, J ) 2.2 Hz, 3H, CdC(CH3)2), 1.88 (s, 3H, Cd
C(CH3)2); 13C NMR (100 MHz, CDCl3): δ 169.30, 154.26, 152.48,
151.58, 119.14, 115.61, 114.62, 81.74, 70.29, 65.39, 55.67, 32.08,
24.56, 19.93; FAB MS (m/z, relative intensity) 292 (M•+,100); Anal.
(C16H20O5) C, H.
5-(Hydroxymethyl)-3-(methylethylidene)-5-[(phenylmethoxy)-
methyl]-4,5-dihydrofuran-2-onephenylmethoxy)methyl]-4,5-di-
hydrofuran-2-one (14). Cerium(IV) ammonium nitrate (300 mg,
0.55 mmol) was added to a solution of 12 (69 mg, 0.18 mmol) in
CH3CN (2 mL) and H2O (0.5 mL) and stirred for 10 min. The
reaction was then quenched with sodium thiosulfate (60 mg) and
concentrated to a solid under reduced pressure. The residue was
dissolved in EtOAc (25 mL), washed with H2O (25 mL), and dried
(MgSO4). Purification by column chromatography on silica gel
(EtOAc/hexanes, 1/3) afforded 14 (45 mg, 91%) as an oil; FTIR
(neat) 3464 (OH), 2872 (CH), 2836 (CH), 1744 (CdO),1663 (Cd
C) cm-1; 1H NMR (400 MHz, CDCl3): δ 7.27-7.37 (m, 5H, C6H5),
General Chemical Procedures. All of the chemical reagents
were commercially available. Column chromatography was per-
1
formed on silica gel 60, 230-400 mesh (E. Merck). H and 13C
NMR spectra were recorded on a Varian Unity Inova instrument
at 400 and 100 MHz, respectively. Spectra are referenced to the
solvent in which they were run (7.26 ppm for CDCl3). Infrared
spectra were recorded on a Jasco model 615 FTIR instrument. Fast-
atom bombardment (FAB) mass spectra were run on a VG 7070E-
HF double-focusing mass spectrometer and were obtained in
positive ion mode except where noted. A sample matrix of
3-nitrobenzyl alcohol (NBA) was employed in all cases, and
ionization was effected by a beam of xenon atoms generated in a
saddle-field ion gun at 8.0 ( 0.5 kV. The FAB mass spectra of all
of the compounds indicated a molecular species (MH+, M+•, M +
Na+, or M - H) and fragment ions that are highly indicative of
structure. In some cases, molecular identity was additionally
confirmed in the positive ion mode by alkali metal cationization to
form a M + K+ species by adding 1.0 µL 1.0 N KCl in 90%
methanol/H2O to the sample before mixing with matrix and
subsequent FABMS analysis. Nominal mass MS were obtained at

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 973
4.57 (AB q, J ) 12.1 Hz, 2H C6H5CH2OCH2C), 3.70 (AB q, J )
11.9 Hz, 2H, HOCH2C), 3.56 (AB q, J ) 9.9 Hz, 2H, C6H5CH2-
OCH2C), 2.70-2.81 (m, 2H, H-4a,b), 2.25 (t, J ) 2.2 Hz, 3H, Cd
C(CH3)2), 2.11 (br s, 1H, CH2OH), 1.86 (br s, 3H, CdC(CH3)2);
13C NMR (100 MHz, CDCl3): δ 169.51, 150.92, 137.58, 128.34,
127.71, 127.52, 119.45, 82.24, 73.57, 72.04, 65.45, 32.08, 24.46,
19.82. FAB MS (m/z, relative intensity) 277 (MH+, 93). Anal.
(C16H20O4 0.25 H2O) C, H.
3,3-Dimethyl-3-silabutyl 4-ethynylbenzoate (18). A solution
of 4-ethynylbenzoic acid (869 mg, 5.95 mmol), trimethylsilyl
ethanol (808 mg, 6.85 mmol), and DMAP (2.5 g, 20.5 mmol) in
CH2Cl2 was treated with BOP-Cl (3.46 g, 13.6 mmol). After 30
min of stirring, the reaction mixture was diluted with CH2Cl2 (50
mL) and washed with 2 N HCl (2 × 25 mL). The organic layer
was dried (MgSO4) and concentrated under reduced pressure.
Purification by column chromatography on silica gel (EtOAc/
hexanes, 1/19) afforded ester 18 (1.35 g) as a yellow oil in 92%
yield; FTIR (neat) 3297, 1717 cm-1; 1H NMR (CDCl3, 400 MHz):
δ 7.90 (d, J ) 8.6 Hz, 2H), 7.45 (d, J ) 8.5 Hz, 2H), 4.36-4.31
(m, 2 H), 3.16 (s, 1H), 1.07-1.03 (m, 2H), 0.0 (s, 9H); 13C NMR
(CDCl3) δ 165.9, 131.9. 130.6, 129.3, 126.5, 82.8, 79.9, 63.4, 17.3,
-1.5; FAB MS (m/z, relative intensity) 219 (MH+-C2H4). Anal.
(C14H18O2Si), C, H.
3,3-Dimethyl-3-silabutyl 4-{2-[4-(3,3-dimethyl-3-silabut-1-
ynyl)phenyl]ethynyl} benzoate (19). A solution of 18 (849 mg,
3.44 mmol), 17 (1.04 g, 3.44 mmol), PdCl2(PPh3)2 (48 mg, 68.8
µmol, 2 mol %), and piperidine (10 mL) in THF (50 mL) was
degassed and treated with CuI (26 mg, 136.8 µmol, 4 mol %). After
stirring for 3 h, the reaction was concentrated under reduced
pressure. The residue was dissolved in CH2Cl2 (50 mL), washed
with saturated aqueous NH4Cl (2 × 25 mL), dried (MgSO4), and
concentrated under reduced pressure. Purification by column
chromatography on silica gel (hexanes/CH2Cl2, 3/1) afforded 19
(930 mg, 65%) as a white solid, mp 97-98 °C; FTIR (neat) 2953
(CH), 1705(CdO) cm-1; 1H NMR (400 MHz, CDCl3): δ 7.57 and
8.02 (doublets, J ≈ 9 Hz, 4H, (CH3)3SiCtCC6H4CtCC6H4CO2-
CH2CH2Si(CH3)3), 7.45 (m, 4H, (CH3)3SiCtCC6H4CtCC6H4CO2-
CH2CH2Si(CH3)3), 4.43 (m, 2H, (CH3)3SiCtCC6H4CtCC6H4-
CO2CH2CH2Si(CH3)3), 1.14 (m, 2H, (CH3)3SiCtCC6H4Ct
CC6H4CO2CH2CH2Si(CH3)3), 0.26 (s, 9H, (CH3)3SiCtCC6H4Ct
CC6H4CO2CH2CH2Si(CH3)3), 0.09 (s, 9H, (CH3)3SiCtCC6H4Ct
CC6H4CO2CH2CH2Si(CH3)3); 13C NMR (100 MHz, CDCl3): δ
166.13, 131.93, 131.49, 131.45, 130.19, 129.44, 127.47, 123.41,
122.73, 104.47, 96.61, 91.77, 90.50, 63.45, 17.43, -0.11, -1.45.
FAB MS (m/z, relative intensity) 419 (MH+, 16), 418 (M•+, 26).
Anal. (C25H30O2Si2) C, H.
3,3-Dimethyl-3-silabutyl 4-[2-(4-ethynylphenyl)ethynyl]ben-
zoate (20). Trifluroacetic acid (0.5 mL) was added to a solution of
19 (220 mg, 0.53 mmol) in CH2Cl2 (2 mL). After stirring for 1.5
h, the reaction was quenched with NaHCO3 and extracted with CH2-
Cl2 (2 × 25 mL). The combined organics were dried (MgSO4) and
concentrated under reduced pressure. Purification by column
chromatography on silica gel (hexanes/CH2Cl2, 3/1) afforded 20
(150 mg, 82%) as a white solid, mp 91-92 °C; FTIR (neat) 2954
(CH), 1706(CdO) cm-1; 1H NMR (400 MHz, CDCl3): δ 8.02 and
7.58 (doublets, J ) 8.6 Hz, 4H, HCtCC6H4CtCC6H4CO2CH2-
CH2Si(CH3)3), 7.49 (s, 4H, HCtCC6H4CtCC6H4CO2CH2CH2Si-
(CH3)3), 4.41-4.45 (m, 2H, HCtCC6H4CtCC6H4CO2CH2CH2-
Si(CH3)3), 3.19 (s, 1H, HCtCC6H4CtCC6H4CO2CH2CH2Si(CH3)3),
1.14 (m, 2H, HCtCC6H4CtCC6H4CO2CH2CH2Si(CH3)3), 0.09 (s,
9H, HCtCC6H4CtCC6H4CO2CH2CH2Si(CH3)3); 13C NMR (100
MHz, CDCl3): δ 166.15, 132.12, 131.58, 131.49, 130.27, 129.46,
127.39, 123.19, 122.38, 91.54, 90.57, 83.14, 79.16, 63.48, 17.44,
-1.44. FAB MS (m/z, relative intensity) 347 (MH+, 17). Anal.
(C22H22O2Si‚0.5 H2O) C, H.
The residue was dissolved in CH2Cl2 (25 mL), washed with
saturated aqueous NH4Cl (2 × 15 mL), and dried (MgSO4).
Purification by column chromatography on silica gel (CH2Cl2/
hexanes, 1/1) afforded 21 (120 mg, 68%) as a white solid, mp 176-
178 °C; FTIR (neat) 2157 (CH), 1709 (CdO) cm-1; H NMR (400
MHz, CDCl3): δ 7.58 and 8.02 (doublets, J ) 8.2 Hz, 4H, (CH3)3-
SiCtCC6H4CtCC6H4CtCC6H4CO2CH2CH2Si(CH3)3), 7.52 (s,
4H, (CH3)3SiCtCC6H4CtCC6H4CtCC6H4CO2CH2CH2Si(CH3)3),
7.45 (s, 4H, (CH3)3SiCtCC6H4CtCC6H4CtCC6H4CO2CH2CH2-
Si(CH3)3),4.41-4.45(m,2H,(CH3)3SiCtCC6H4CtCC6H4CtCC6H4-
CO2CH2CH2Si(CH3)3), 1.12-1.17 (m, 2H, (CH3)3SiCtCC6H4Ct
CC6H4CtCC6H4CO2CH2CH2Si(CH3)3), 0.26 (s, 9H, (CH3)3SiCt
CC6H4CtCC6H4CtCC6H4CO2CH2CH2Si(CH3)3), 0.09 (s, 9H,
(CH3)3SiCtCC6H4CtCC6H4CtCC6H4CO2CH2CH2Si(CH3)3); 13
C
NMR (100 MHz, CDCl3): δ 166.17, 131.93, 131.68, 131.59,
131.49, 131.41, 130.22, 129.46, 127.48, 123.32 123.21, 122.97,
122.73, 104.54, 96.51, 91.80, 91.15, 90.85, 90.62, 63.48, 17.44,
-0.10, -1.44. FAB MS (m/z, relative intensity) 519 (MH+, 30),
518 (M•+, 47); HRMS (FAB): (MH+) calcd for C33H35O2Si2,
519.2176; found, 519.2182. HRMS (FAB): (M•+) calcd for
C33H35O2Si2, 518.2097; found, 518.2111.
{2-[(4-Methoxyphenoxy)methyl]-4-(methylethylidene)-5-oxo-
2-2,3-dihydrofuryl}methyl 4-[2-(4-ethynylphenyl)ethynyl]ben-
zoate (22). Tetrabutylammonium fluoride (TBAF, 5 mL, 5 mmol,
1M in THF) was added to 19 (450 mg, 1.08 mmol). After stirring
for 15 min, the reaction was quenched with dilute HCl, and the
product was extracted with EtOAc (2 × 20 mL). The combined
organic layers were dried (MgSO4) and concentrated under reduced
pressure. The residue was azeotroped with toluene, then combined
with 13 (314 mg, 1.08 mmol) and DMAP (788 mg, 6.46 mmol) in
CH2Cl2 (10 mL), and treated with BOP-Cl (1.09 g, 4.3 mmol).
After stirring for 1 h, the reaction mixture was concentrated under
reduced pressure. Purification by column chromatography on silica
gel (hexanes/EtOAc, 6/1) afforded 22 (440 mg, 78%), mp 144-
146 °C; FTIR (neat) 2926 (CH), 2854 (CH), 1752 (CdO), 1724
1
(CdO), 1666 (CdC) cm-1; H NMR (400 MHz, CDCl3): δ 7.57
and 7.96 (doublets, 4H, J ) 8.1 Hz, HCtCC6H4CtCC6H4CO2-
CH2C), 7.49 (br s, 4H, HCtCC6H4CtCC6H4CO2CH2C), 6.81-
6.86 (m, 4H, CH3OC6H4CH2OCH2C), 4.58 (AB q, J ) 11.8 Hz,
2H HCtCC6H4CtCC6H4CO2CH2C), 4.09 (AB q, J ) 9.5 Hz, 2H
CH3OC6H4CH2OCH2C), 3.76 (s, 3H, CH3OC6H4CH2OCH2C), 3.20
(s, 1H, HCtCC6H4CtCC6H4CO2CH2C), 2.95 (br AB q, J ) 16.5
Hz, 2H, H-4a,b), 2.27 (s, 3 H, CdC(CH3)2), 1.87 (s, 3 H,
CdC(CH3)2); 13C NMR (100 MHz, CDCl3): δ 168.73, 165.37,
154.48, 152.29, 151.53, 132.11, 131.59, 129.65, 128.86, 128.08,
123.01, 122.49, 118.70, 115.69, 114.71, 92.03, 90.34, 83.09, 79.58,
79.25, 70.57, 66.78, 55.70, 33.16, 24.58, 19.94. FAB MS (m/z,
relative intensity) 521 (MH+, 28). Anal. (C33H28O6) C, H.
{4-(Methylethylidene)-5-oxo-2-[(phenylmethoxy)methyl]-2-
2,3-dihydrofuryl}methyl 4-[2-(4-ethynylphenyl)ethynyl]benzoate
(23). TBAF (162 µL, 1 M in THF) was added to 19 (34 mg, 81
µmol) and stirred for 10 min. The reaction was then quenched with
diluted HCl and extracted with EtOAc (2 × 10 mL). The combined
organic phases were dried (MgSO4) and concentrated under reduced
pressure. The residue was azeotroped with toluene, then combined
with 14 (22 mg, 79.7 µmol) and DMAP (59 mg, 0.49 mmol) in
CH2Cl2 (2 mL), and treated with BOP-Cl (82 mg, 0.32 mmol).
After stirring for 1 h, the reaction mixture was concentrated under
reduced pressure. Purification by column chromatography on silica
gel (hexanes/EtOAc, 6/1) afforded 23 (25 mg, 62%), mp 98-100
°C; FTIR (neat) 2867 (CH), 1749 (CdO), 1724 (CdO), 1666 (Cd
C) cm-1; 1H NMR (400 MHz, CDCl3): δ 7.56 and 7.93 (doublets,
J ) 8.1 Hz, 4H, HCtCC6H4CtCC6H4CO2), 7.50 (br s, 4H, HCt
CC6H4CtCC6H4CO2CH2C), 7.30-7.33 (m, 5H, C6H5CH2OCH2C),
4.60 (s, 2H, C6H5CH2OCH2C), 4.48 (AB q, J ) 11.7 Hz, 2H HCt
CC6H4CtCC6H4CO2CH2C), 3.64 (AB q, J ) 9.9 Hz, 2H, C6H5-
CH2OCH2C), 3.20 (s, 1H, HCtCC6H4CtCC6H4CO2CH2C), 2.75
(br AB q, J ) 16.5 Hz, 2 H, H-4a,b), 2.24 (t, J ) 2.0 Hz, 3H,
CdC(CH3)2), 1.83 (s, 3H, CdC(CH3)2); 13C NMR (100 MHz,
CDCl3): δ 168.91, 165.32, 150.87, 137.34, 132.09, 131.56, 131.51,
129.61, 128.93, 128.42, 127.94, 127.86, 127.68, 122.99, 122.46,
3,3-Dimethyl-3-silabutyl 4-[2-(4-{2-[4-(3,3-dimethyl-3-silabut-
1-ynyl)phenyl]ethynyl} phenyl)ethynyl]benzoate (21). A solution
of 20 (125 mg, 0.30 mmol), 17 (108 mg, 0.36 mmol), PdCl2(PPh3)2
(14 mg, 19.9 µmol, 6.7 mol %), and piperidine (1 mL) in THF (8
mL) was degassed and treated with CuI (4.5 mg, 23.6 µmol, 8 mol
%). After 3 h, the solution was concentrated under reduced pressure.

974 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5
Malolanarasimhan et al.
119.01, 91.95, 90.35, 83.06, 80.32, 79.26, 73.67, 71.71, 66.81,
33.11, 24.47, 19.83. FAB MS (m/z, relative intensity) 505 (MH+,
65). Anal. (C33H28O5‚0.5 H2O) C, H.
CdC(CH3)2); 13C NMR (100 MHz, CDCl3): δ 168.96, 165372,
151.80, 132.14, 131.62, 129.71, 128.71, 128.25, 122.99, 122.54,
118.91, 92.15, 90.30, 83.10, 81.33, 79.27, 66.35 64.85, 32.32, 24.59,
19.96; FAB MS (m/z, relative intensity) 415 (MH+, 58). Anal.
(C26H22O5‚0.25H2O) C, H.
{2-[(4-Methoxyphenoxy)methyl]-4-(methylethylidene)-5-oxo-
2-2,3-dihydrofuryl}methyl 4-(2-{4-[2-(4-Ethynylphenyl)ethynyl]-
phenyl}ethynyl)benzoate (24). TBAF (0.3 mL, 0.3 mmol) was
added to 21 (66 mg, 0.13 mmol, 1M in THF). After stirring for 15
min, the reaction was quenched with diluted HCl, and the product
was extracted with EtOAc (2 × 20 mL). The combined organic
layers were dried (MgSO4) and concentrated under reduced pressure.
The residue was azeotroped with toluene, then combined with 13
(37 mg, 0.13 mmol) and DMAP (140 mg, 1.14 mmol) in CH2Cl2
(2 mL), and treated with BOP-Cl (193 mg, 0.75 mmol). After
stirring for 1 h, the reaction mixture was then directly chromato-
graphed on silica gel (hexanes/EtOAc, 6/1) to afford 24 (53 mg,
68%), mp 173-175 °C; FTIR (neat) 2925 (CH), 1724 (CdO), 1666
[2-(Hydroxymethyl)-4-(methylethylidene)-5-oxo-2-2,3-dihy-
drofuryl]methyl 4-(2-{4-[2-(4-Ethynylphenyl)ethynyl]phenyl}-
ethynyl)benzoate (2). CAN (80 mg, 0.14 mmol) was added to a
suspension solution of 24 (30 mg, 0.048 mmol) in CH3CN (1 mL),
CH2Cl2 (0.5 mL), and H2O (0.25 mL). After stirring 10 min, the
reaction was quenched with solid sodium thiosulfate, and the
mixture was concentrated under reduced pressure. The residue was
taken up in EtOAc (20 mL), washed with water (10 mL), and dried
(MgSO4). Purification by column chromatography on silica gel
(hexanes/EtOAc 11/9) afforded 2 (16 mg, 64%) as a white solid,
mp 205-207 °C; FTIR (neat) 2968 (CH), 1707 (CdO), 1666 (Cd
1
C) cm-1; H NMR (400 MHz, CD3OD/CDCl3): δ 7.56 and 7.95
(CdO) cm-1 1H NMR (400 MHz, CDCl3): δ 7.57 and 7.96
;
(doublets, J ) 8.2 Hz, 4H, HCtCC6H4CtCC6H4CtCC6H4CO2-
CH2C), 7.50 (s, 4H, HCtCC6H4CtCC6H4CtCC6H4CO2CH2C),
7.45 (s, 4H, HCtCC6H4CtCC6H4CtCC6H4CO2CH2C), 4.45 (AB
q, J ) 11.6 Hz, 2H, HCtCC6H4CtCC6H4CtCC6H4CO2CH2C),
3.73 (AB q, J ) 12 Hz, 2H, HOCH2C), 3.15 (s, 1H, HCtCC6H4Ct
CC6H4CtCC6H4CO2CH2C), 2.80 (br AB q, J ) 16.4 Hz, 2H,
H-4a,b), 2.23 (br s, 3H, CdC(CH3)2), 1.83 (s, 3H, CdC(CH3)2);
13C NMR (100 MHz, CDCl3): δ 168.91, 165.74, 151.81,132.11,
131.72, 131.63, 131.62, 131.50, 129.73, 128.67, 128.32, 123.41,
123.38, 122.61, 122.19, 118.89, 92.40, 91.02, 90.88, 90.37, 83.18,
81.30, 79.00, 66.33, 64.87, 32.33, 24.60, 19.97; FAB MS (m/z, rela-
tive intensity) 515 (MH+, 22). Anal. (C34H26O5‚1.25H2O) C, H.
[2-(Hydroxymethyl)-4-(methylethylidene)-5-oxo-2-2,3-dihy-
drofuryl]methyl Decanoate (10). CAN (89 mg, 0.162 mmol) was
added to a solution of 25 (24 mg, 0.059 mmol) in CH3CN (1 mL)
and H2O (0.25 mL), and stirred for 10 min. The reaction was then
quenched with sodium thiosulfate (60 mg) and concentrated under
reduced pressure. The solid residue was rinsed with EtOAc (25
mL); the filtrate was dried (MgSO4) and concentrated under reduced
pressure. Purification by column chromatography on silica gel
(EtOAc/hexanes 1/3) afforded 10 (13 mg, 71%) as an oil; FTIR
(neat) 3459 (OH), 2927 (CH), 2856 (CH), 1738 (CdO), 1667 (Cd
(doublets, J ) 8.3 Hz, 4H, HCtCC6H4CtCC6H4CtCC6H4CO2-
CH2C), 7.52 (s, 4H, HCtCC6H4CtCC6H4CtCC6H4CO2CH2C),
7.48 (s, 4H, HCtCC6H4CtCC6H4CtCC6H4CO2CH2C), 6.81-
6.87 (m, 4H, CH3OC6H4OCH2C), 4.58 (AB q, J ) 11.8 Hz, 2H,
HCtCC6H4CtCC6H4CtCC6H4CO2CH2C), 4.09 (AB q, J ) 9.6
Hz, CH3OC6H4OCH2C), 3.76 (s, 3H, CH3OC6H4OCH2C), 3.19 (s,
1H, HCtCC6H4CtCC6H4CtCC6H4CO2CH2C), 3.03 (br AB q, J
) 16 Hz, 2H, H-4ab),2.28 (br s, 3H, CdC(CH3)2), 1.87 (s, 3H,
CdC(CH3)2); 13C NMR (100 MHz, CDCl3): δ 168.72, 165.36,
154.46, 152.28, 151.49, 132.07, 131.69, 131.60, 131.56, 131.46,
129.64, 128.82, 128.12, 123.33, 122.61, 122.16, 118.70, 115.67,
114.69, 92.26, 90398, 90.88, 90.41, 83.16, 79.75, 79.10, 70.56,
66.77, 55.68, 33.14, 24.57, 19.92. FAB MS (m/z, relative intensity)
621 (MH+, 23). Anal. (C41H32O6‚0.5H2O) C, H.
{2-[(4-Methoxyphenoxy)methyl]-4-(methylethylidene)-5-oxo-
2-2,3-dihydrofuryl} Methyl Decanoate (25). Decanoic anhydride
(44 µL, 119.5 µmol) was added to a stirring solution of 13 (23 mg,
78.7 µmol) and DMAP (29 mg, 237.7 µmol) in CH2Cl2 (1 mL).
After 30 min, the reaction mixture was diluted with CH2Cl2 (20
mL) and washed with water (2 × 10 mL). The combined organic
layers were dried (MgSO4) and concentrated under reduced pressure.
Purification by column chromatography on silica gel (EtOAc/
hexanes 15/85) afforded 25 (34 mg, 97%) as an oil; FTIR (neat)
2926 (CH), 2855 (CH), 1746 (CdO), 1668 (CdC) cm-1; 1H NMR
(400 MHz, CDCl3): δ 6.82 (s, 4H, CH3OC6H4OCH2C), 4.31 (AB
q, J ) 11.6 Hz, 2H, CH3C6H12CH2CH2C(O)OCH2C), 3.98 (AB q,
J ) 9.2 Hz, 2H CH3C6H4CH2OCH2C), 3.76 (s, 3H, CH3C6H4CH2-
OCH2C), 2.96 (dm, J ) 16.8 Hz, 1H, H-4a), 2.75 (dm, J ) 16.8
Hz, 1H, H-4b), 2.23-2.33 (m, 5H, CH3C6H12CH2CH2C(O)OCH2C
and CdC(CH3)2), 1.88 (s, 3H, CdC(CH3)2), 1.58 (m, 1H,
CH3C6H12CH2CH2C(O)OCH2C), 1.24 (br s, 12H, CH3C6H12CH2-
CH2C(O)OCH2C), 0.88 (irregular t, 3H, CH3C6H12CH2CH2C(O)-
OCH2C); 13C NMR (100 MHz, CDCl3): δ 173.27, 168.69, 154.41,
152.34, 151.54, 118.59, 115.64, 114.66, 79.52, 70.32, 65.67, 55.68,
34.07, 32.87, 31.82, 29.36, 29.23, 29.17, 29.08, 24.80, 24.59, 22.64,
19.95, 14.07; FAB MS (m/z, relative intensity) 446 (M•+,100). Anal.
(C26H38O6) C, H.
[2-(Hydroxymethyl)-4-(methylethylidene)-5-oxo-2-2,3-dihy-
drofuryl]methyl 4-[2-(4-Ethynylphenyl)ethynyl]benzoate (1).
CAN (2.4 g, 4.4 mmol) was added to a stirred solution of 22 (800
mg, 1.54 mmol) in CH3CN (8 mL) and H2O (2 mL). After 10 min,
the reaction was quenched with 5% sodium thiosulfate and
concentrated under reduced pressure. The residue was dissolved
in CH2Cl2 (25 mL), washed with water (15 mL), and dried
(MgSO4). Purification by column chromatography on silica gel
(hexanes/EtOAc 2.5/1) afforded 1 (476 mg, 75%), mp 138-140
°C; FTIR (neat) 3413 (OH), 3288 (OH), 2925 (CH), 1717 (CdO),
1667 (CdC) cm-1; 1H NMR (400 MHz, CDCl3): δ 7.56 and 7.90
(doublets, J ) 8.0 Hz, 4H, HCtCC6H4CtCC6H4CO2CH2C), 7.43
(s, 4H, HCtCC6H4CtCC6H4CO2CH2C), 4.41 (AB q, J ) 12.0
Hz, 2H, HCtCC6H4CtCC6H4CO2CH2C), 3.70 (AB q, J ) 12 Hz,
2H, HOCH2C), 3.19 (s, 1H, HCtCC6H4CtCC6H4CO2CH2C), 2.76
(AB q, J ) 16.4 Hz, 2H, H-4ab), 2.25 (t, J ) 2.1 Hz, 3H, Cd
C(CH3)2), 1.86 (s, 3H, CdC(CH3)2); 13C NMR (CDCl3, 100 MHz)
1
C) cm-1; H NMR (400 MHz, CDCl3): δ 4.21 (AB q, J ) 11.8
Hz, 2H, CH3C6H12CH2CH2C(O)OCH2C), 3.65 (AB q, J ) 12.1
Hz, 2H HOCH2C), 2.76 (dm, J ) 16.5 Hz, 1H, H-4a), 2.58 (dm, J
) 16.5 Hz, 1H, H-4b), 2.33 (t, J ) 7.6 Hz, 2H, CH3C6H12CH2CH2C-
(O)OCH2C), 2.26 (irregular t, 2H, CdC(CH3)2), 1.88 (s, 3H, Cd
C(CH3)2), 1.60 (irregular pentet, 1H, CH3C6H12CH2CH2C(O)-
OCH2C), 1.26 (br s, 12H, CH3C6H12CH2CH2C(O)OCH2C), 0.88
(irregular t, 3H, CH3C6H12CH2CH2C(O)OCH2C); 13C NMR (100
MHz, CDCl3): δ 173.72, 168.91, 151.80, 118.79, 81.05, 65.27,
64.82, 34.08, 32.14, 31.83, 29.38, 29.32, 29.23, 29.10, 24.82, 24.60,
22.65, 19.98, 14.09; FAB MS (m/z, relative intensity) 341 (MH+,-
100). Anal. (C19H32O5) C, H.
{4-(Methylethylidene)-5-oxo-2-[(phenylmethoxy)methyl]-2-
2,3-dihydrofuryl}methyl 4-(2-{4-[2-(4-Methoxyphenyl)ethynyl]-
phenyl}ethynyl)benzoate (26). A solution of 23 (264 mg, 0.53
mmol), 4-methoxyiodobenzene (135 mg, 0.58 mmol), PdCl2(PPh3)2
(15 mg, 0.02 mmol, 2 mol %), and Cs2CO3 (205 mg, 0.64mmol)
in THF (5 mL) was degassed and treated with CuI (2.5 mg, 0.01
mmol, 2.5 mol %). After stirring for 5 h, the reaction mixture was
concentrated under reduced pressure. The residue was dissolved
in CH2Cl2 (25 mL), washed with water (2 × 15 mL), and dried
(MgSO4). Purification by column chromatography on silica gel
(EtOAc/hexanes 1/6) afforded 26 (162 mg, 50%) and dimeric
byproduct 27 (40 mg, 12%).
26: mp 104-106 °C; FTIR (neat) 2913 (CH), 1750 (CdO), 1722
1
(CdO), 1666 (CdC) cm-1; H NMR (400 MHz, CDCl3): δ 7.56
and 7.92 (doublets, J ) 8.7 Hz, 4H, CH3OC6H4CtCC6H4Ct
CC6H4CO2CH2C), 7.51 (s, 4H, CH3OC6H4CtCC6H4CtCC6H4CO2-
CH2C), 7.48 (d, J ) 8.9 Hz, 2H, CH3OC6H4CtCC6H4CtCC6H4-
CO2CH2C), 7.28-7.33 (m, 5H, C6H5CH2OCH2C), 6.89 (d, J ) 8.9
Hz, 2H, CH3OC6H4CtCC6H4CtCC6H4CO2CH2C), 4.60 (s, 2H,
C6H5CH2OCH2C), 4.48 (AB q, J ) 11.7 Hz, 2H, CH3OC6H4Ct

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 975
CC6H4CtCC6H4CO2CH2C), 3.83 (s, 3H, CH3OC6H4CtCC6H4Ct
CC6H4CO2CH2C), 3.64 (AB q, J ) 9.9 Hz, 2H, C6H5CH2OCH2C),
2.86 (br AB q, J ) 16.3 Hz, 2H, H-4ab), 2.25 (br s, 3H,
CdC(CH3)2), 1.83 (s, 3H, CdC(CH3)2); 13C NMR (100 MHz,
CDCl3): δ 168.93, 165.37, 159.81, 150.89, 137.36, 133.09, 131.62,
131.48, 131.37, 129.61, 128.80, 128.43, 128.14, 127.87, 127.69,
124.10, 121.90, 119.02, 114.95, 114.03, 92.41, 91.74, 90.11, 87.73,
80.33, 73.68, 71.73, 66.80, 55.28, 33.12, 24.48, 19.84. FAB MS
(m/z, relative intensity) 611 (MH+, 40). Anal. (C40H34O6‚1.3H2O)
C, H.
Cl2 (25 mL), washed with saturated aqueous NH4Cl (2 × 25 mL),
and dried (MgSO4). Purification by column chromatography on
silica gel (hexanes/EtOAc 3/1) afforded 32 (193 mg, 74%), mp
144-146 °C; FTIR (neat) 3461 (NH2), 3357 (NH2), 2359 (CH),
1
2341 (CH), 1741 (CdO) cm-1; H NMR (400 MHz, CDCl3): δ
7.32 and 7.45 (app doublets, J ≈ 8.3 Hz, 4H, CH3O2CCH2-
OC6H4CtCC6H4NH2), 6.62 and 6.88 (app doublets, J ≈ 9.2 Hz,
4H, CH3O2CH2OC6H4CtCC6H4NH2), 4.64 (s, 2H, CH3O2CCH2-
OC6H4CtCC6H4NH2), 3.81 (s, 3H, CH3O2CH2OC6H4CtCC6H4-
NH2); 13C NMR (100 MHz, CDCl3): δ 169.11, 157.25, 146.43,
132.81, 132.79, 117.33, 114.74, 114.59, 112.79, 89.03, 86.78, 65.26,
52.29; FAB MS (m/z, relative intensity) 282 (MH+, 55), 281 (M•+,
100). Anal. (C17H15NO3‚0.25H2O) C, H.
Methyl 2-{4-[2-(4-Iodophenyl)ethynyl]phenoxy}acetate (33).
Aqueous NaNO2 (278 mL) was added to 32 (1.06 g) in 2 N HCl
(25 mL) at 0 °C and stirred for 15 min. Solid KI (913 mg) was
added, and the reaction mixture was stirred for an additional 20
min. The reaction was then quenched with sodium thiosulfate, and
the product was extracted with CH2Cl2 (2 × 25 mL). The combined
organic layers were dried (MgSO4) and concentrated under reduced
pressure. Purification by column chromatography on silica gel
(hexanes/EtOAc, 9/1) afforded 33 (371 mg, 44%), mp 174-175
°C; FTIR (neat) 2960 (CH), 2360 (CH), 2341 (CH), 1726 (CdO)
cm-1; 1H NMR (400 MHz, CDCl3): δ 7.45 and 7.68 (app doublets,
J ≈ 8.0 Hz, 4H, CH3O2CCH2OC6H4CtCC6H4I), 6.88 and 7.22
(app doublets, J ≈ 8.4 Hz, 4H, CH3O2CCH2OC6H4CtCC6H4I),
4.66 (s, 2H, CH3O2CCH2OC6H4CtCC6H4I), 3.81 (s, 3H, CH3O
CCH2OC6H4CtCC6H4I); 13C NMR (100 MHz, CDCl3): δ 168.97,
157.87, 137.46 ,133.14, 132.95, 122.95, 116.26, 114.70, 93.77,
90.43, 87.56, 65.21, 52.33; FAB MS (m/z, relative intensity) 393
(MH+, 43), 392 (M•+, 100); HRMS (FAB): (M+) calcd for
C17H13O3I, 391.991; found, 391.990.
27: FTIR (neat) 2920 (CH), 2867 (CH), 1748 (CdO), 1725 (Cd
1
O), 1666 (CdC) cm-1; H NMR (400 MHz, CDCl3): δ 7.56 and
7.93 (doublets, J ) 8.4 Hz, 8H, CCH2O2CC6H4CtCC6H4CtC-
CtCC6H4CtCC6H4CO2CH2C), 7.53 (s, 8H, CCH2O2CC6H4Ct
CC6H4CtC-CtCC6H4CtCC6H4CO2CH2C), 7.30-7.33 (m, 10H,
2 × C6H5CH2OCH2C), 4.60 (s, 4H, 2 × C6H5CH2OCH2C), 4.48
(AB q, J ) 11.7 Hz, 4H, CCH2O2CC6H4CtCC6H4CtC-Ct
CC6H4CtCC6H4CO2CH2C), 3.64 (AB q, J ) 9.9 Hz, 4H, 2 ×
C6H5CH2OCH2C), 2.83 (br AB q, J ) 16.5 Hz, 4H, 2 × H-4ab),
2.25 (br s, 6H, CdC(CH3)2), 1.84 (s, 6H, CdC(CH3)2); 13C NMR
(100 MHz, CDCl3): δ 168.95, 165.36, 150.95, 137.37, 132.49,
131.73, 131.57, 129.66, 129.04, 128.46 127.90, 127.72, 123.56,-
121.94 119.02, 114.05, 91.96, 91.15, 82.09, 80.34, 75.85, 73.72,
71.74, 66.86, 33.16, 24.52, 19.87. FAB MS (m/z, relative intensity)
1007 (MH+, 2).
[2-(Hydroxymethyl)-4-(methylethylidene)-5-oxo-2-2,3-dihy-
drofuryl]methyl 4-(2-{4-[2-(4-Methoxyphenyl)ethynyl]phenyl}-
ethynyl)benzoate (3). A solution of BCl3 in CH2Cl2 (380 µL, 0.38
mmol) was added to a solution of 26 (48 g, 0.95 mmol) in CH2Cl2
(15 mL) and stirred at -78 °C for 1.5 h. The reaction was quenched
with a saturated NaHCO3 solution (20 mL), warmed to room
temperature, and extracted with CH2Cl2 (2 × 30 mL). The combined
organic phases were dried (MgSO4) and concentrated under reduced
pressure. Purification by column chromatography on silica gel (CH2-
Cl2/MeOH, 50/1) afforded 3 (24 mg, 60%) as a white solid, mp
187-189 °C. FTIR (neat) 2923 (CH), 17470 (CdO), 1716 (Cd
Methyl 16-[(4-Methylphenyl)sulfonyloxy]hexadecanoate (35).
A suspension of commercially available juniperic acid (34, 1 g,
3.68 mmol), MeI (2.28 mL, 36.6 mmol), and NaHCO3 (615 mg,
7.32 mmol) in DMF (10 mL) was stirred at 40 °C for 2 days. The
reaction mixture was then diluted with EtOAc (25 mL) and washed
with water (2 × 20 mL). The organic layer was dried (MgSO4),
concentrated under reduced pressure, and then added to toluene,
forming an azeotrope. The residue was stirred with TsCl (1.05 g,
5.52 mmol) and DMAP (1.35 g, 11.03 mmol) in CH2Cl2 (20 mL)
for 1 h. Purification by column chromatography on silica gel
(hexanes/EtOAc 10/1) afforded 35 (900 mg, 55%) as a white solid,
mp 54-55 °C; FTIR (neat) 2915 (CH), 2849 (CH), 1733 (CdO)
1
O), 1668 (CdC) cm-1; H NMR (400 MHz, CDCl3): δ 7.58 and
7.97 (doublets, J ) 8.4 Hz, 4H, CH3OC6H4CtCC6H4CtCC6H4-
CO2CH2C), 7.51 (s, 4H, CH3OC6H4CtCC6H4CtCC6H4CO2CH2C),
6.89 and 7.47 (doublets, J ) 8.8 Hz, 4H, CH3OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 4.48 (AB q, J ) 11.8 Hz, 2H, CH3-
OC6H4CtCC6H4CtCC6H4CO2CH2C), 3.83 (s, 3H, CH3OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 3.73 (dd, J ) 12.0, 6.0 Hz, 1H,
HOCHHC), 3.80 (dd, J ) 12.0, 6.0 Hz, 1H, HOCHHC), 2.83 (br
AB q, J ) 16.4 Hz, 2H, H-4ab), 2.29 (app t, 1H, HOCH2C), 2.25
(s, 3H, CdC(CH3)2), 1.86 (s, 3H, CdC(CH3)2); 13C NMR (100
MHz, CDCl3): δ 168.97, 165.75, 159.85, 151.79, 133.12, 131.65,
131.58, 131.41, 129.70, 128.56, 128.43, 124.16, 121.88, 118.92,
114.99, 114.06, 92.61, 91.77, 90.05, 87.75, 81.35, 66.33, 64.85,
55.31, 32.31, 24.59, 19.95. FAB MS (m/z, relative intensity) 521
(MH+, 63), 520 (M•+, 71). Anal. (C33H28O6‚2H2O) C, H.
1
cm-1; H NMR (400 MHz, CDCl3): δ 7.30 and 7.75 (doublets, J
) 8.4 Hz, 4H, CH3O2CCH2CH2(CH2)11CH2CH2OSO2C6H4CH3),
4.01 (t, J ) 6.6 Hz, 2H, CH3O2CCH2CH2(CH2)11CH2CH2OSO2C6H4-
CH3), 3.66 (s, 3H, CH3O2CCH2CH2(CH2)11CH2CH2OSO2C6H4-
CH3), 2.44 (s, 3H, CH3O2CCH2CH2(CH2)11CH2CH2OSO2C6H4CH3),
2.30 (t, J ) 7.6 Hz, 2H, CH3O2CCH2CH2(CH2)11CH2CH2OSO2C6H4-
CH3), 1.57-1.66 (m, 4H, CH3O2CCH2CH2(CH2)11CH2CH2-
OSO2C6H4CH3), 1.21-1.31 (m, 22H, CH3O2CCH2CH2(CH2)11CH2-
CH2OSO2C6H4CH3); 13C NMR (100 MHz, CDCl3): δ 174.30,
144.56, 133.26, 129.75, 127.85, 70.68, 51.40, 34.10, 29.59, 29.56,
29.46, 29.42, 29.36, 29.23, 29.13, 28.90, 28.79, 25.30, 24.94, 21.61;
FAB MS (m/z, relative intensity) 441 (MH+, 91); HRMS (FAB):
(MH+) calcd for C24H41O5S, 441.267; found, 441.270.
Methyl 2-(4-iodophenyl)acetate (30). Methyl iodide (4.67 mL,
74.9 mmol) was added to a suspension of 29 (4.17 g, 15 mmol)
and NaHCO3 (1.37 g, 16.5 mmol) in DMF. After stirring for 2
days, the reaction mixture was diluted with EtOAc (100 mL) and
washed with water (3 × 25 mL). The combined organic layers were
dried (MgSO4) and concentrated under reduced pressure. Purifica-
tion by column chromatography on silica gel (hexanes/ EtOAc 9/1)
afforded 30 (3.9 g, 89%), mp 104-106 °C. FTIR (neat) 2970 (CH),
1768 (CdO) cm-1; 1H NMR (400 MHz, CDCl3): δ 6.54 and 7.57
(doublets, J ≈ 8 Hz, 4H, CH3O2CCH2OC6H4I), 4.61 (s, 2H, CH3O2-
CCH2OC6H4I), 3.80 (s, 3H, CH3O2CCH2OC6H4I); 13C NMR (100
MHz, CDCl3): δ 168.90, 157.54, 138.27, 116.90, 84.07, 65.13,
52.25; FAB MS (m/z, relative intensity) 293 (MH+, 22), 292 (M•+,
71). Anal. (C9H9IO3) C, H, I.
Methyl 2-{4-[2-(4-Aminophenyl)ethynyl]phenoxy}acetate (32).
A solution of 4-ethynylaniline (31, 110 mg, 0.94 mmol), 30 (270
mg, 0.92 mmol), PdCl2(PPh3)2 (13 mg, 18.5 µmol, 2 mol %), and
piperidine (2 mL) in THF (10 mL) was degassed and treated with
CuI (7 mg, 36.8 µmol, 4 mol %). After stirring for 3 h, the reaction
mixture was concentrated under reduced pressure, dissolved in CH2-
Methyl 16-(4-Iodophenoxy)hexadecanoate (36). A suspension
of 35 (470 mg, 1.07 mmol), 4-iodophenol (235 mg, 1.07 mmol),
Cs2CO3 (348 mg, 1.07 mmol) in DMF (5 mL) was stirred at 50 °C
overnight. The reaction mixture was then diluted with EtOAc (20
mL) and washed with water (2 × 15 mL). The organic layer was
dried (MgSO4) and concentrated under reduced pressure. Purifica-
tion by column chromatography on silica gel (hexanes/EtOAc 10/
1) afforded 36 (500 mg, 96%) as a white solid, mp 154-155 °C;
1
FTIR (neat) 2918 (CH), 2849 (CH), 1736 (CdO) cm-1; H NMR
(400 MHz, CDCl3): δ 6.67 and 7.52 (doublets, J ) 8.0 Hz, 4H,
CH3O2CCH2CH2(CH2)11CH2CH2OC6H4I), 3.90 (t, J ) 6.6 Hz, 2H,
CH3O2CCH2CH2(CH2)11CH2CH2OC6H4I), 3.66 (s, 3H, CH3O2-
CCH2CH2(CH2)11CH2CH2OC6H4I), 2.29 (t, J ) 7.6 Hz, 2H CH3O2-
CCH2CH2(CH2)11CH2CH2OC6H4I), 1.72-1.79 (m, 2H, CH3O2-

976 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5
Malolanarasimhan et al.
CCH2CH2(CH2)11CH2CH2OC6H4I),1.58-1.65(m,2H,CH3O2CCH2CH2
(CH2)11CH2CH2OC6H4I), 1.25 (br s, 22H, CH3O2CCH2CH2(CH2)11-
CH2CH2OC6H4I); 13C NMR (100 MHz, CDCl3): δ 174.30, 158.98,
138.10, 116.91, 82.34, 68.10, 51.41, 34.10, 29.61, 29.57, 29.43,
29.34, 29.24, 29.12, 25.96, 24.94; FAB MS (m/z, relative intensity)
489 (MH+, 65), 488 (M•+, 100); HRMS (FAB): (MH+) calcd for
C23H37O3I, 489.187; found: 489.185; HRMS (FAB): Calcd for
C23H37O3I (M•+); 488.179; found, 488.176.
reduced pressure and directly purified by column chromatography
on silica gel (hexanes/EtOAc 2/1) to give 6 (9.1 mg, 61%) as a
white solid, mp 174-176 °C; FTIR (neat) 3406 (OH), 2918 (CH),
2915 (CH), 1716 (CdO), 1668 (CdC) cm-1; 1H NMR (400 MHz,
CDCl3): δ 7.59 and 7.98 (doublets, J ) 8.3 Hz, 4H, CH3O2C(CH2)15-
OC6H4CtCC6H4CtCC6H4CO2CH2C), 7.51-7.54 (m, 4H, CH3O2C-
(CH2)15OC6H4CtCC6H4CtCC6H4CO2CH2C), 6.88 and 7.46 (dou-
blets, J ) 8.8 Hz, 4H, CH3O2C (CH2)15OC6H4CtCC6H4CtCC6H4-
CO2CH2C), 4.49 (AB q, J ) 11.8 Hz, 2H, CH3O2C(CH2)15OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 3.98 (t, J ) 6.6 Hz, 2H, CH3O2C-
(CH2)14CH2OC6H4CtCC6H4CtCC6H4CO2CH2C), 3.82 (br AB q,
J ) 12.1 Hz, 2H, HOCH2C), 3.67 (s, 3H, CH3O2C(CH2)15OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 2.84 (br AB q, J ) 16.0 Hz, 2H,
H-4a,b), 2.30 (t, J ) 7.6 Hz, 2H, CH3O2CCH2(CH2)14OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 2.26 (t, J ) 2.0 Hz, 3H, CdC(CH3)2),
1.87 (s, 3 H, CdC(CH3)2), 1.75-1.83, 1.60-1.64 and 1.26-1.54
(multiplets, 26H, CH3O2CCH2(CH2)13CH2OC6H4CtCC6H4Ct
CC6H4CO2CH2C); 13C NMR (100 MHz, CDCl3): δ 168.90, 165.77,
159.48, 151.83, 133.10, 131.69, 131.65, 131.60, 131.41, 129.72,
128.56, 128.47, 124.25, 121.84, 118.88, 114.70, 114.60, 92.65,
91.93, 90.04, 87.66, 81.29, 68.12, 66.31, 64.88, 51.43, 34.12, 32.34,
29.64, 29.59, 29.45, 29.38, 29.26, 29.16, 26.02, 24.97, 24.60, 24.58,
24.57, 19.97; FAB MS (m/z, relative intensity) 775 (MH+, 32),
774 (M•+, 43); HRMS (FAB): (MH+) calcd for C49H59O8, 775.424;
found, 775.422; (M•+) 774.418; found, 774.413.
Methyl 2-{4-[2-(4-{2-[4-({[2-(hydroxymethyl)-4-(methyleth-
ylidene)-5-oxo-2-2,3-dihydrofuryl]methyl}oxycarbonyl)phenyl]-
ethynyl}phenyl)ethynyl]phenoxy}acetate (4). A suspension of 1
(2.9 mg, 7 µmol), 30 (2.3 mg, 8.2 mmol), Pd(PPh3)4 (1.6 mg, 1.4
µmol) Cs2CO3 (1.2 mg, 3.5 µmol), and Ag2O (0.9 mg, 3.9 µmol)
in THF (3 mL) was degassed and heated to 60 °C. After stirring at
60 °C for 90 min, the reaction mixture was cooled to room
temperature and concentrated under reduced pressure. Purification
by column chromatography on silica gel (hexanes/EtOAc 2/1)
afforded 4 (2.5 mg, 63%) as a white solid, mp 188-190 °C; FTIR
(neat) 2958 (CH), 2926 (CH), 1721 (CdO), 1669 (CdC) cm-1
;
1H NMR (400 MHz, CDCl3): δ 7.58 and 7.97 (doublets, J ) 8.1
Hz, 4H, CH3O2CCH2OC6H4CtCC6H4CtCC6H4CO2CH2C), 7.49
(s, 4H, CH3O2CCH2OC6H4CtCC6H4CtCC6H4CO2CH2C), 6.89
and 7.48 (doublets, J ) 8.5 Hz, 4H, CH3O2CCH2OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 4.67 (s, 3H, CH3O2CCH2OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 4.48 (AB q, J ) 11.6 Hz, 2H,
CH3O2CCH2OC6H4CtCC6H4CtCC6H4CO2CH2C), 3.82, (s, 2H,
CH3O2CCH2OC6H4CtCC6H4CtCC6H4CO2CH2C), 3.77 (AB q, J
) 12.0 Hz, 2H, HOCH2C), 2.84 (br AB q, J ) 16.5 Hz, 2 H, H-4a,b),
2.25 (s, 3H, CdC(CH3)2), 1.88 (s, 3 H, CdC(CH3)2); 13C NMR
(100 MHz, CDCl3): δ 168.99, 168.95, 165.74, 157.92, 151.79,
133.21, 131.66, 131.59, 131.46,129.71, 128.59, 128.40, 123.98,
122.04, 118.91, 116.29, 114.73, 92.55, 91.34, 90.11, 88.11, 81.33,
66.33, 65.22, 64.86, 52.35, 32.32, 24.60, 19.96; FAB MS (m/z,
relative intensity) 579 (MH+, 36), 578 (M•+, 44). HRMS (FAB):
(MH+) calcd for C35H30O8, 579.202; found, 579.201; (M•+) calcd
for C35H30O8, 578.194; found 578.195.
2-{2-[2-(4-Iodophenoxy)ethoxy]ethoxy}ethyl 4-methylbenze-
nesulfonate (38). Commerically available tri(ethylene glycol) di-
p-tosylate (37, 458 mg, 1 mmol) was added to a mixture of
4-iodophenol (220 mg, 1 mmol) and Cs2CO3 (326 mg, 2 mmol) in
DMF (5 mL) and stirred at 50 °C for 24 h. The reaction mixture
was cooled to room temperature, diluted with EtOAc (40 mL), and
washed with saturated NH4Cl (2 × 20 mL). The organic layer was
dried (MgSO4) and concentrated under reduced pressure. Purifica-
tion by column chromatography on silica gel (hexanes/EtOAc 9/1)
afforded 38 (216 mg, 42%) and the double displacement product
(133 mg, 21%), which was not fully characterized. FTIR (neat)
1
2873 (CH) cm-1; H NMR (400 MHz, CDCl3): δ 7.20 and 7.70
Methyl 2-[4-(2-{4-[2-(4-{2-[4-({[2-(Hydroxymethyl)-4-(meth-
ylethylidene)-5-oxo-2-2,3-dihydrofuryl]methyl}oxycarbonyl)-
phenyl]ethynyl}phenyl)ethynyl]phenyl} ethynyl)phenoxy]acetate
(5). A suspension of 1 (9 mg, 21.7 µmol), 33 (9 mg, 22.9 µmol),
Pd(PPh3)4 (5.3 mg, 4.6 µmol), Cs2CO3 (39 mg, 0.12 mmol) and
Ag2O (3.0 mg, 12.9 µmol) in THF (5 mL) was degassed and stirred
at 60 °C for 50 min. The reaction mixture was concentrated under
reduced pressure and directly purified by preparative TLC (SiO2,
MeOH/CH2Cl2 1/49) to afford 5 (8.5 mg, 58%) as a white solid,
mp 180-184 °C; FTIR (neat) 2956 (CH), 2925 (CH), 1721 (Cd
(doublets, J ) 8.0 Hz, 4H, CH3C6H4SO3CH2CH2OCH2CH2OCH2-
CH2OC6H4I), 6.60 and 7.45 (app doublets, J ≈ 8.8 Hz, 4H,
CH3C6H4SO3CH2CH2OCH2CH2OCH2CH2OC6H4I), 3.48-4.10 (mul-
tiplets, 12H, CH3C6H4SO3CH2CH2OCH2CH2OCH2CH2OC6H4I),
2.33 (s, 3H, CH3C6H4SO3CH2CH2OCH2CH2OCH2CH2OC6H4I); 13
C
NMR (100 MHz, CDCl3): δ 158.33, 144.51, 137.78, 132.57,
129.54, 116.76, 82.60, 70.34, 69.24, 69.02, 68.31, 37.18, 21.33.
FAB MS (m/z, relative intensity) 507 (MH+, 100). Anal. (C19H23-
IO6S) C, H, I, S.
1
O), 1666 (CdC) cm-1; H NMR (400 MHz, CH3OD/CDCl3): δ
tert-Butyl 2-[{[(tert-Butyl)oxycarbonyl]methyl}(2-{2-[2-(4-io-
dophenoxy)ethoxy] ethoxy}ethyl)amino]acetate (39). A solution
of 38 (718 mg, 1.35 mmol), and di-tert-butyliminodiacetate (661
mg, 2.7mmol) in DMF (5 mL) was stirred at 50 °C for 3 days. The
reaction mixture was cooled to room temperature and concentrated
under reduced pressure. The residue was then dissolved in EtOAc
(40 mL) and washed with water (2 × 20 mL). The organic layer
was dried (MgSO4) and concentrated under reduced pressure.
Purification by column chromatography on silica gel (hexanes/
EtOAc 9/1) afforded 39 (550 mg, 70%); FTIR (neat) 2975 (CH),
7.88 (d, J ) 8.6 Hz, 2H, CH3O2CCH2OC6H4CtCC6H4CtCC6H4Ct
CC6H4CO2CH2C), 7.40-7.53 (m, 12H, CH3O2CCH2OC6H4Ct
CC6H4CtCC6H4CtCC6H4CO2CH2C), 6.83 (d, J ) 9.0 Hz, 2H,
CH3O2CCH2OC6H4CtCC6H4CtCC6H4CtCC6H4CO2CH2C), 4.60
(s, 2H, CH3O2CCH2OC6H4CtCC6H4CtCC6H4CtCC6H4CO2-
CH2C), 4.39 (AB q, J ) 11.8 Hz, 2H, CH3O2CCH2OC6H4Ct
CC6H4CtCC6H4CtCC6H4CO2CH2C), 3.75, (s, 3H, CH3O2CCH2-
OC6H4CtCC6H4CtCC6H4CtCC6H4CO2CH2C), 3.66 (AB q, J )
12.2 Hz, 2H, HOCH2C), 2.78 (br AB q, J ) 16.7 Hz, 2H, H-4a,b),
2.17 (s, 3H, CdC(CH3)2), 1.79 (s, 3 H, CdC(CH3)2); 13C NMR
(100 MHz, CH3OD/CDCl3): δ 169.89, 165.61, 157.73 ,151.61,
133.05, 131.57, 131.46, 131.40, 131.27, 129.47, 128.60, 123.46,
123.39, 122.35, 122.31, 119.20, 116.21, 116.07, 114.58, 92.26,
91.19, 90.97, 90.51, 90.14, 88.61, 88.01, 81.92, 66.49, 65.03, 64.35,
32.09, 19.72; FAB MS (m/z, relative intensity) 679 (MH+, 5), 678
(M•+, 5); HRMS was not possible because of the formation of
aggregates.
1
2929 (CH), 1738 (CdO) cm-1; H NMR (400 MHz, CDCl3): δ
6.70 and 7.54 (app doublets, J ) 7.2 Hz, 4H, NCH2CH2OCH2-
CH2OCH2CH2OC6H4I), 4.07 (m, 2H, NCH2CH2OCH2CH2OCH2CH2-
OC6H4I), 3.84 (m, 2H, NCH2CH2OCH2CH2OCH2CH2OC6H4I), 3.70
(m, 2H, NCH2CH2OCH2CH2OCH2CH2OC6H4I), 3.63 (m, 4H,
NCH2CH2OCH2CH2OCH2CH2OC6H4I), 3.50 (s, 4H, ((CH3)3CO2-
CCH2)2N), 2.95 (m, 2H, NCH2CH2OCH2CH2OCH2CH2OC6H4I),
1.44 (s, 18H, ((CH3)3CO2CCH2)2N); 13C NMR (100 MHz,
CDCl3): δ 170.75, 158.66, 138.12, 117.03, 82.87, 80.83, 70.79,
70.47, 70.33, 69.56, 67.51, 56.65, 53.35, 28.15; FAB MS (m/z,
relative intensity) 580 (MH+, 59). HRMS (FAB): (MH+) calcd
for C24H39O7N, 580.177; found, 580.175.
Methyl 16-{4-[2-(4-{2-[4-({[2-(Hydroxymethyl)-4-(methyleth-
ylidene)-5-oxo-2-2,3-dihydrofuryl]methyl}oxycarbonyl)phenyl]-
ethynyl}phenyl)ethynyl]phenoxy}hexadecanoate (6). A suspen-
sion of 1 (8 mg, 19.3 µmol), 36 (9.4 mg, 19.3 µmol), Pd(PPh3)4
(4.5 mg, 3.9 µmol), Cs2CO3 (3.2 mg, 9.5 µmol), and Ag2O (2.3
mg, 1.95 µmol) in THF (6 mL) was degassed and stirred at 60 °C
for 90 min. The reaction mixture was then concentrated under
tert-Butyl 2-[N-{[(tert-Butyl)oxycarbonyl]methyl}(2-{2-[2-(4-
iodophenoxy)ethoxy] ethoxy}ethoxy)carbonylamino]acetate (40).
A suspension of 38 (2.1 g, 4.15 mmol), di-tert-butyliminodiacetate

Analogues of Diacylglycerol (DAG)
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 5 977
(1.0 g, 4.15 mmol), and Cs2CO3 (1.4 g, 4.15 mmol) in DMF (20
mL) was stirred at 70 °C for 30 h. The reaction mixture was then
cooled to room temperature, diluted with EtOAc (50 mL), washed
with saturated aqueous NH4Cl solution (2 × 25 mL), dried
(MgSO4), and concentrated. Purification by column chromatography
on silica gel (hexanes/EtOAc/AcOH 13/5/2) afforded small amounts
of 39 (1.32 mg) and 40 (600 mg, 51%).
CH2O), 3.64-3.81 (m, 8H, NCO2CH2CH2OCH2CH2OCH2CH2O
and HOCH2C), 2.90 (dm, J ) 16.8 Hz, 1H, H-4a), 2.75 (dm, J )
16.8 Hz, 1H, H-4b), 2.40 (br s, 1H, HOCH2C), 2.25 (t, J ) 2.0 Hz,
3H, CdC(CH3)2), 1.85 (s, 3H, CdC(CH3)2), 1.45 and 1.46 (s, 6H,
(CH3)3CO2CCH2N); 13C NMR (100 MHz, CDCl3): δ 168.94,
168.68, 168.55, 165.75, 159.09, 156.07, 151.78, 133.09, 131.65,
131.58, 131.41, 129.71, 128.57, 128.44, 124.18, 121.88, 118.91,
115.14, 114.72, 92.62, 91.78, 90.05, 87.77, 81.91, 81.88, 81.32,
70.83, 70.64, 69.67, 69.41, 67.49, 66.32, 65.18, 64.86, 49.97, 49.82,
32.32, 28.08, 28.06, 24.59, 19.96. FAB MS (m/z, relative intensity)
909 (M•+, 9). Anal. (C51H59NO14‚H2O) C, H, N.
2-(N-(Carboxymethyl){2-[2-(2-{4-[2-(4-{2-[4-({[2-(hydroxym-
ethyl)-4-(methyl ethylidene)-5-oxo(2-2,3-dihydrofuryl)]methyl}-
oxycarbonyl)phenyl]ethynyl}phenyl)ethynyl]phenoxy}ethoxy)-
ethoxy]ethoxy}carbonylamino)acetic acid (9). A suspension of
8 (6.1 mg, 6.6 µmol) and montmorillonite KSF (17 mg) in MeCN
(1 mL) was microwaved for 7 min (ramp 2 min, reaction time 5
min) at 145 °C. The reaction mixture was filtered, and the filtrate
was directly purified by semipreparative reverse-phase HPLC using
a 250 mm × 20 mm YMC ODS-H80 column eluted with a gradient
of H2O/MeCN (9/1) to 100% MeCN over 40 min. At 25 min, the
collected fraction afforded 9 (1.5 mg, 27%) as a solid, mp 194-
195 °C; FTIR (neat) 2954 (CH), 2899 (CH), 1709 (CdO), 1606
(CdO) cm-1; 1H NMR (400 MHz, CD3OD δ): 7.60 and 7.95 (app
doublets, J ≈ 8.4 Hz, 4H, OC6H4CtCC6H4CtCC6H4CO2), 7.50
(app doublet, J ≈ 4.8 Hz, 4H, OC6H4CtCC6H4CtCC6H4CO2),
6.94 and 7.44 (app doublets, J ≈ 8.8 Hz, 4H, OC6H4Ct
CC6H4CtCC6H4CO2), 4.48 (AB q, J ) 11.8 Hz, 2H, OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 4.23 (m, 2H, NOCOCH2CH2OCH2-
CH2OCH2CH2O), 4.16 (NOCOCH2CH2OCH2CH2OCH2CH2O),
4.07 and 4.08 (singlets, 4H, ((CH3)3CO2CCH2)2N), 3.87 (m,
2H, NOCOCH2CH2OCH2CH2OCH2CH2O), 3.66-3.74 (m, 8H,
NOCOCH2CH2OCH2CH2OCH2CH2O and HOCH2C), 2.88 (br AB
q, J ) 18 Hz, 2H, H-4a,b), 2.21 (t, J ) 1.9 Hz, 3H, CdC(CH3)2),
1.88 (s, 3H, CdC(CH3)2); FAB MS (m/z, relative intensity) 796
(M-H, 50); HRMS was not possible because of the formation of
aggregates.
40: FTIR (neat) 2979 (CH), 2881 (CH), 1742 (CdO), 1712 (Cd
O) cm-1 1H NMR (400 MHz, CDCl3): δ 6.68 and 7.52 (app
;
doublets, J ≈ 9.2 Hz, 4H, OCH2CH2OCH2CH2OCH2CH2OC6H4I),
4.24 (m, 2H, OCH2CH2OCH2CH2OCH2CH2OC6H4I), 4.07 (m, 2H,
OCH2CH2OCH2CH2OCH2CH2OC6H4I), 4.00 (s, 2H, (CH3)3CO2-
CCH2N), 3.95 (s, 2H, (CH3)3CO2CCH2N), 3.82 (m, 2H, OCH2-
CH2OCH2CH2OCH2CH2OC6H4I), 3.60-3.69 (m, 6H, OCH2CH2-
OCH2CH2OCH2CH2OC6H4I), 1.44 (s, 3H, ((CH3)3CO2CCH2)2N),
1.45 (s, 3H, ((CH3)3CO2CCH2)2N); 13C NMR (100 MHz, CDCl3):
δ 168.60, 168.47, 158.62, 155.98, 138.09, 117.00, 82.83, 81.83,
81.80, 70.75, 70.58, 69.58, 69.34, 67.47, 65.11, 56.62, 49.90, 49.75,
28.13, 28.03. FAB MS (m/z, relative intensity) 624 (MH+, 13),
623 (M•+, 16); HRMS (FAB): (M+) calcd for C25H38O9NI, 623.159;
found, 623.158. Anal. (C25H38INO9) C, H, I, N.
tert-Butyl 2-({[(tert-Butyl)oxycarbonyl]methyl}{2-[2-(2-{4-[2-
(4-{2-[4-({[2-(hydroxymethyl)-4-(methylethylidene)-5-oxo(2-2,3-
dihydrofuryl)]methyl}oxycarbonyl) phenyl]ethynyl}phenyl)-
ethynyl]phenoxy}ethoxy)ethoxy]ethyl}amino)acetate (7). A
suspension of 1 (2 mg, 4.6 µmol), 39 (3 mg, 5.18 µmol), Pd(PPh3)4
(0.4 mg, 0.3 µmol, 8 mol %), Cs2CO3 (2 mg, 12.3 µmol), and Ag2O
(1 mg, 4.3 µmol) in THF (10 mL) was degassed and stirred at 60
°C for 50 min. After cooling to room temperature, the reaction
mixture was concentrated under reduced pressure and purified by
preparative TLC (SiO2, CH2Cl2/MeOH 100/1) to give 7 (2 mg,
45%) as a semisolid product; 1H NMR (400 MHz, CDCl3): δ 7.52
and 7.98 (app doublets, J ≈ 8.4 Hz, 4H, OC6H4CtCC6H4Ct
CC6H4CO2CH2C), 7.50 (s, 4H, OC6H4CtCC6H4CtCC6H4CO2-
CH2C), 6.80 and 7.45 (app doublets, J ≈ 8.8 Hz, OC6H4Ct
CC6H4CtCC6H4CO2CH2C), 4.48 (AB q, J ) 11.8 Hz, 2H,
OC6H4CtCC6H4CtCC6H4CO2CH2C), 4.15 (irregular t, 2H, ((CH3)3-
CO2CCH2)2NCH2CH2O(CH2)2OCH2CH2O), 3.87 (irregular t, 2H,
((CH3)3CO2CCH2)2NCH2CH2O(CH2)2OCH2CH2O), 3.59-3.75 (m,
6H, ((CH3)3CO2CCH2)2NCH2CH2O(CH2)2OCH2CH2O), 3.49 (s,
4H, ((CH3)3CO2CCH2)2NCH2CH2O(CH2)2OCH2CH2O), 2.95 (t, 2H,
J ) 6.0 Hz, ((CH3)3CO2CCH2)2NCH2CH2O(CH2)2OCH2CH2O),
2.84 (br AB q, J ) 16.0 Hz, 2H, H-4a,b), 2.26 (t, J ) 2.0 Hz, 3H,
CdC(CH3)2), 1.86 (s, 3H, CdC(CH3)2), 1.45 (s, 18H, ((CH3)3CO2-
CCH2)2NCH2CH2O(CH2)2OCH2CH2O). FAB MS (m/z, relative
intensity) 904 (M + K+, 34), 888 (M + Na+, 5), 866 (MH+, 21).
HRMS (FAB): (M + K+) calcd for C50H59NO2K, 904.37; found,
904.34; (M + Na+) 866.38; found, 866.39. Isotopic distributions
are the same as those calculated for expected elemental analysis.
{2-[2-(2-{4-[2-(4-{2-[4-({[2-(Hydroxymethyl)-4-(methyleth-
ylidene)-5-oxo(2-2,3-dihydrofuryl)]methyl}oxycarbonyl)phenyl]-
ethynyl}phenyl)ethynyl]phenoxy}ethoxy)ethoxy]ethoxy}-
carbonylamino)acetate (8). A suspension of 1 (40 mg, 0.096
mmol), 40 (44 mg, 0.070 mmol), Pd(PPh3)4 (20 mg, 17.3 µmol),
Cs2CO3 (40 mg, 3.5 µmol), and Ag2O (24 mg, 0.1 mmol) in THF
(15 mL) was degassed and stirred at 60 °C for 30 min. After cooling
to room temperature, the reaction mixture was concentrated under
reduced pressure. The residue was then taken up in water (20 mL)
and extracted with CH2Cl2 (2 × 20 mL). The combined organic
phases were then dried (MgSO4) and concentrated. Purification by
column chromatography on silica gel (ether/EtOAc 9/1) afforded
8 (36 mg, 56%), mp 82-83 °C; FTIR (neat) 2981 (CH), 2881 (CH),
1743 (CdO), 1699 (CdO) cm-1; 1H NMR (400 MHz, CDCl3): δ
7.57 and 7.96 (app doublets, J ≈ 8.8 Hz, 4H, OC6H4CtCC6H4Ct
CC6H4CO2CH2C), 7.50 (d, J ) 0.8 Hz, 4H, OC6H4CtCC6H4Ct
CC6H4CO2CH2C), 6.90 and 7.95 (app doublets, J ≈ 8.8 Hz, 4H,
OC6H4CtCC6H4CtCC6H4CO2CH2C), 4.47 (AB q, J ) 11.8 Hz,
2H, OC6H4CtCC6H4CtCC6H4CO2CH2C), 4.26 (m, 2H, NOCOCH2-
CH2OCH2CH2OCH2CH2O), 4.15 (m, 2H, NOCOCH2CH2OCH2-
CH2OCH2CH2O), 4.01 (s, 2H, (CH3)3CO2CCH2N), 3.96 (s, 2H,
(CH3)3CO2CCH2N), 3.86 (m, 2H, NOCOCH2CH2OCH2CH2OCH2-
Acknowledgment. This research was supported by the
Intramural Research Program of the NIH, National Cancer
Institute, Center for Cancer Research. The content of this
publication does not necessarily reflect the views or policies of
the Department of Health and Human Services, nor does the
mention of trade names, commercial products, or organizations
imply endorsement by the U.S. Government.
Supporting Information Available: 1H NMR spectra, 13C
NMR spectra, and combustion analysis results. This material is
available free of charge via the Internet at http://pubs.acs.org.
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