Synthesis of photoactivatable analogues of lysophosphatidic acid and covalent labeling of plasma proteins

Article abstract of DOI:10.1021/jo052030w

Lysophosphatidic acids hearing a benzophenone group in either the sn-1 or sn-2 chain of an oleoyl-type ester or oleyl-type ether chain and ³²P in the phosphate group were synthesized. The benzophenone moiety was introduced by selective hydrobor

Full text of DOI:10.1021/jo052030w

Synthesis of Photoactivatable Analogues of Lysophosphatidic Acid
and Covalent Labeling of Plasma Proteins
Zaiguo Li,† Daniel L. Baker,‡,§ Gabor Tigyi,§,| and Robert Bittman*,†
Department of Chemistry and Biochemistry, Queens College of the City UniVersity of New York, Flushing,
New York 11367-1597, Department of Medicine and the Vascular Biology and Genomics & Bioinformatics
Centers of Excellence, The UniVersity of Tennessee Health Science Center, Memphis, Tennessee 38163,
The UniVersity of Tennessee Cancer Institute, Memphis, Tennessee 38163, and Department of Physiology,
The UniVersity of Tennessee Health Science Center, Memphis, Tennessee 38163
robert.bittman@qc.cuny.edu
ReceiVed September 27, 2005
Lysophosphatidic acids bearing a benzophenone group in either the sn-1 or sn-2 chain of an oleoyl-type
ester or oleyl-type ether chain and 32P in the phosphate group were synthesized. The benzophenone moiety
was introduced by selective hydroboration of the double bond of enyne 11 at low temperature, followed
by a Suzuki reaction with 4-bromobenzophenone. The key intermediates for the preparation of ester-
linked lysophosphatidic acid (LPA) 1 and 3 were obtained in one pot by a modified DIBAL-H reduction
of orthoformate intermediate 22. These probes were shown to covalently modify a single protein target
in rat plasma containing albumin and several protein targets in rat plasma containing a low level of
albumin.
Introduction
of unsaturation of a hydrocarbon chain linked to a glycerol
backbone via ester,6 ether,7 or vinyl ether8 bonds at either the
sn-1 or sn-2 position. Different LPA family members have
distinct biological activities.9 LPA plays a key role in a myriad
of physiological processes, including Ca2+ flux, vascular and
neuronal function, cell growth/death, and cell migration.2,10 It
is now appreciated that LPA has numerous intracellular,
extracellular, and cell-surface targets. LPA exerts its activities
mainly through several cell-surface G protein-coupled receptors
(GPCR), including the widely reported LPA1, LPA2, and LPA3
Lysophosphatidic acid (LPA) has the simplest structure of
natural phospholipids, yet it has attracted significant attention
because of the diversity and importance of its biological
effects.1-5 LPA is not a single compound; rather, it comprises
a family of related mediators that differ in the length and degree
* To whom correspondence should be addressed. Phone: (718) 997-3279.
Fax: (718) 997-3349.
† Queens College of the City University of New York.
‡ Department of Medicine and the Vascular Biology and Genomics &
Bioinformatics Centers of Excellence, The University of Tennessee Health
Science Center.
(6) Baker, D. L.; Desiderio, D. M.; Miller, D. D.; Tolley, B.; Tigyi, G.
J. Anal. Biochem. 2001, 292, 287-295.
§ The University of Tennessee Cancer Institute.
| Department of Physiology, The University of Tennessee Health Science
Center.
(7) Tokumura, A.; Sinomiya, J.; Kishimoto, S.; Tanaka, T.; Kogure, K.;
Sugiura, T.; Satouchi, K.; Waku, K.; Fukuzawa, K. Biochem. J. 2002, 365,
617-628.
(1) Bittman, R. Chem. Phys. Lipids 2004, 129, 111-131.
(2) Tigyi, G.; Parrill, A. L. Prog. Lipid Res. 2003, 42, 498-526.
(3) Mills, G. B.; Moolenaar, W. H. Nat. ReV. Cancer 2003, 3, 582-
591.
(4) Luquain, C.; Sciorra, V. A.; Morris, A. J. Trends Biochem. Sci. 2003,
28, 377-383.
(5) Ye, X.; Ishii, I.; Kingsbury, M. A.; Chun, J. Biochim. Biophys. Acta
2002, 1585, 108-113.
(8) Liliom, K.; Fischer, D. J.; Virag, T.; Sun, G.; Miller, D. D.; Tseng,
J. L.; Desiderio, D. M.; Seidel, M. C.; Erickson, J. R.; Tigyi, G. J. Biol.
Chem. 1998, 273, 13461-13468.
(9) Bandoh, K.; Aoki, J.; Taira, A.; Tsujimoto, M.; Arai, H.; Inoue, K.
FEBS Lett. 2000, 478, 159-165.
(10) Ishii, I.; Fukushima, N.; Ye, X.; Chun, J. Annu. ReV. Biochem. 2004,
73, 321-354.
10.1021/jo052030w CCC: $33.50 © 2006 American Chemical Society
Published on Web 12/03/2005
J. Org. Chem. 2006, 71, 629-635
629

Li et al.
SCHEME 1. Retrosynthetic Strategy
receptor subtypes. Recently, the LPA4/GPR23/P2Y9 receptor11
and the nuclear transcription factor PPARγ12 were identified
as LPA receptors. LPA also interacts with numerous binding
proteins, including albumin13 and gelsolin.14 It has been
speculated that interactions with binding proteins may modulate
the biological activity of LPA.
of [32P]-LPA, as well as the O-methoxymethyl (MOM)-protected
photoreactive analogues of [32P]-LPA (denoted as 20P and 27P).
In the current analogues, benzophenone was employed as the
photoprobe for labeling of proteins because it is readily activated
with long-wavelength UV light, is stable in most of the chemical
reactions used during the synthesis of the probe, and generally
yields covalent products modified at a single site.21 In the four
probes reported herein, the benzophenone moiety is linked to
the end of a ∆9 cis hydrocarbon chain. These analogues were
characterized via the covalent modification of rat plasma
proteins.
Despite recent progress elucidating many of the biological
properties of LPA, a detailed understanding of the key roles of
LPA in many disease processes has not yet been achieved. To
gain insights into the protein targets of LPA, we have prepared
photoreactive analogues of LPA. Photoactivatable lipid ana-
logues have been widely employed to study hydrophobic binding
sites of lipid targets.15 Recently, we reported the first synthesis
and characterization of two photoactivatable analogues of
sphingosine 1-phosphate (S1P).16 Likewise, photoactivatable
analogues of bioactive glycerophospholipids17 and lysosphin-
gophospholipids18 have been reported recently. One previous
study reported the synthesis and characterization of a photo-
reactive LPA analogue containing a trifluoromethylphenyldiaz-
irine group for labeling of fetal bovine serum and LPA
responsive cells.19 In this paper, we report the syntheses of
additional photoactivatable analogues of acyl- and O-alkyl-
linked LPAs in which the long chain resembles an oleoyl (ester)
or oleyl (ether) chain, respectively. The rationale for this
approach is that the oleoyl chain has been shown to represent
the maximally effective fatty acyl chain of natural LPAs in
previous structure-activity studies.20 We have prepared both
the 2-lyso (1 and 2) and 1-lyso (3 and 4) regioisomeric analogues
Results and Discussion
Retrosynthetic Analysis. Our retrosynthetic strategy for the
synthesis of 1 and 2 is outlined in Scheme 1. Analogues 1 and
2 were envisioned as being produced via enzymatic phosphor-
ylation and deprotection of 2-MOM-protected 3-hydroxyglyceryl
ester 5 (X ) O) or ether (X ) H2), respectively. Compound 5
can be generated by the selective removal of the sn-3 protecting
group (PG) from 6, whereas intermediate 6 is accessible from
carboxylic acid 7 (X ) O) or from the corresponding alcohol
(X ) H2). The introduction of the benzophenone probe into 7
may be achieved by the regioselective addition of 9-BBN to
the double bond in 8, provided that no reaction occurs at the
internal triple bond, followed by Suzuki coupling with 4-bro-
mobenzophenone. Compounds 3 and 4 can be prepared from
the regioisomers of 5-8 using similar schemes.
Conversion of 2-Decyn-1-ol to Alcohol 14. Scheme 2
outlines the synthesis of ∆9 alcohol 14. The acetylene zipper
reaction of commercially available 2-decyn-1-ol22 gave terminal
acetylide 9. After the hydroxy group was protected as a THP
ether to give 10 in nearly quantitative yield, addition of allyl
bromide to the lithium anion of 9 provided enyne 11 in 79%
yield. The benzophenone moiety was introduced by selective
hydroboration of the double bond of 11 at low temperature,
without reaction of the organoborane with the triple bond,
followed by the Suzuki reaction of the terminal boronate with
4-bromobenzophenone. After the THP group of 12 was re-
(11) Noguchi, K.; Ishii, S.; Shimizu, T. J. Biol. Chem. 2003, 278, 25600-
25606.
(12) McIntyre, T. M.; Pontsler, A. V.; Silva, A. R.; Hilaire, A. St.; Xu,
Y.; Hinshaw, J. C.; Zimmerman, G. A.; Hama, K.; Aoki, J.; Arai, H.;
Prestwich, G. D. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 131-136.
(13) (a) Tigyi, G.; Henschen, A.; Miledi, R. J. Biol. Chem. 1991, 266,
20602-20609. (b) Tigyi, G.; Miledi, R. J. Biol. Chem. 1992, 267, 21360-
21367.
(14) (a) Meerschaert, K.; De Corte, V.; De Ville, Y.; Vandekerckhove,
J.; Gettemans, J. EMBO J. 1998, 17, 5923-5930. (b) Goetzl, E. J.; Lee,
H.; Azuma, T.; Stossel, T. P.; Turck, C. W.; Karliner, J. S. J. Biol. Chem.
2000, 275, 14573-14578.
(15) For a recent review, see: Lala, A. K. Chem. Phys. Lipids 2002,
116, 177-188.
(16) Lu, X.; Cseh, S.; Byun, H.-S.; Tigyi, G.; Bittman, R. J. Org. Chem.
2003, 68, 7046-7050.
(17) (a) Li, G.; Samadder, P.; Arthur, G.; Bittman, R. Tetrahedron 2001,
57, 8925-8932. (b) Wang, P.; Blank, D. H.; Spencer, T. A. J. Org. Chem.
2004, 69, 2693-2702.
(18) Lu, X.; Bittman, R. J. Org. Chem. 2005, 70, 4746-4750.
(19) van der Bend, R. L.; Brunner, J.; Jalink, K.; van Corven, E. J.;
Moolenaar, W. H.; van Blitterswijk, W. J. EMBO J. 1992, 11, 2495-2501.
(20) Fujiwara, Y.; Sardar, V.; Tokumura, A.; Baker, D. L.; Murakami-
Murofushi, K.; Parrill, A. L.; Tigyi, G. J. Biol. Chem. 2005, 280, 35038-
35050.
(21) For a review, see: Dorma´n, G.; Prestwich, G. D. Trends Biotechnol.
2000, 18, 64-77.
(22) Abrams, S. R.; Shaw, A. C. Org. Synth. Coll. 8, 146-148.
630 J. Org. Chem., Vol. 71, No. 2, 2006

Photoprobes of Ester- and Ether-Linked LPAs
SCHEME 2. Synthesis of Long-Chain Alcohol 14a
SCHEME 4. Synthesis of 1 and 3a
a (a) LiNH(CH2)3NH2, t-BuOK/H2N(CH2)3NH2; (b) DHP, PPTS, CH2Cl2;
(c) (i) n-BuLi, THF, -78 °C to room temperature and (ii) allyl bromide,
CuI, THF, -78 °C; (d) (i) 9-BBN, THF, -15 °C to room temperature and
(ii) 4-bromobenzophenone, Pd(PPh3)4, K3PO4, THF/DMF, reflux, 2 h; (e)
PPTS (cat.), MeOH; (f) H2, Lindlar, MeOH.
a (a) (i) HC(OMe)3, CSA (cat.), CH2Cl2, room temperature and (ii)
DIBAL-H, 0 °C; (b) 15, PPh3, DIAD, THF, 0 °C to room temperature; (c)
CAN, CH3CN/H2O (6:1); (d) (i) DGK, [32P]ATP, pH 6.6, 37 °C, 2 h and
(ii) TMSBr, CH2Cl2, 0 °C.
SCHEME 3. Synthesis of Glyceride 20 via FMOC-Ester 18a
reported with a similar diol.23 Treatment of 18 with MOM-Cl
provided glyceride 19, and removal of the FMOC group (10%
piperidine in CH2Cl2) afforded 20. Although this multistep
synthesis is straightforward, the overall yield of ester 20 is low
and the method does not allow for the preparation of the
regioisomer of 20. To overcome these deficiencies, an alternative
synthetic strategy was designed (see Scheme 4).
Syntheses of 1 and 3 via 3-O-PMP-sn-glycerol (21). Our
revised synthetic scheme begins with the conversion of 3-O-
PMP-sn-glycerol (21)24 to glyceride 20 and its regioisomer 27
(Scheme 4). The MOM protecting group was introduced into
diol 21 prior to ester formation by transesterification with
trimethyl orthoformate using a modification of a previously
reported procedure.25 The key step in this scheme is the
protection of one of the hydroxy groups of diol 21 as a MOM
ether via orthoformate intermediate 22, followed by reduction
with DIBAL-H in toluene. When the reduction was conducted
at -78 °C, regioisomers 23 and 24 were obtained in a ratio of
23:1 and an overall yield of 96% after chromatography. Thus,
this methodology is a highly efficient route to the precursor of
1-lyso-LPA product 3 but not to the 2-lyso-LPA product 1. We
altered the reduction conditions to obtain an adequate amount
of primary alcohol 24 for conversion to 1-acyl-LPA product 1,
which is needed in the photolabeling experiments. When the
DIBAL-H reduction was carried out at 0 °C, compound 24 was
obtained in 14% yield, which sufficed for the preparation of 1.
Esterification of 23 and 24 with acid 15 using Mitsunobu
reaction conditions, followed by removal of the PMP group in
25 and 26 with CAN, provided 27 and 20. Compounds 1 and
3 were obtained by phosphorylation of 27 and 20 with
a (a) PDC/DMF, room temperature, 2 days; (b) (R)-(-)-2,2-dimethyl-
1,3-dioxolane-4-methanol, DCC, DMAP, CH2Cl2, room temperature; (c)
0.4 N HCl/90% dioxane, room temperature; (d) FMOC-chloroformate,
DMAP, CH2Cl2, -10 °C; (e) MOMCl, i-Pr2NEt, CH2Cl2; (f) piperidine,
CH2Cl2.
moved, Lindlar-catalyzed hydrogenation of the triple bond in
13 afforded Z alcohol 14 in very high yield.
Synthesis of Ester-Linked LPA Probes 1 and 3. Conver-
sion of Alcohol 14 to Glyceride 20. Oxidation of alcohol 14
with PDC gave acid 15, which was converted to ester 16 by
reaction with (R)-isopropylideneglycerol (Scheme 3). After
removal of the acetonide protecting group in 16 afforded diol
17, monoacylation of the resultant primary hydroxy group was
accomplished according to a reported procedure23 with 1 equiv
of FMOC-chloroformate, providing secondary alcohol 18 in
28% yield based on diol 17. This yield is comparable to that
(24) (a) Wang, Z. M.; Zhang, X. L.; Sharpless, K. B. Tetrahedron Lett.
1993, 34, 2267-2270. (b) Vilche`ze, C.; Bittman, R. J. Lipid Res. 1994,
35, 734-738. (c) Byun, H.-S.; Kumar, E. R.; Bittman, R. J. Org. Chem.
1994, 59, 2630-2633. (d) Marino-Albernas, J.; Bittman, R.; Peters, A.;
Mayhew, E. J. Med. Chem. 1996, 39, 3241-3247.
(25) He, L.; Byun, H.-S.; Bittman, R. J. Org. Chem. 2000, 65, 7618-
7626.
(23) Bibak, N.; Hajdu, J. Tetrahedron Lett. 2003, 44, 5875-5877.
J. Org. Chem, Vol. 71, No. 2, 2006 631

Li et al.
SCHEME 5. Synthesis of Ether-Linked Probes 2 and 4a
the ability to photolabel plasma proteins. Probes 1 and 2 allow
for a comparison of the sn-1 acyl vs O-alkyl analogues, whereas
2 and 4 allow for a comparison of the sn-1 vs sn-2 regioisomers.
Comparisons between compounds 1 and 3 were not made
because of facile acyl migration inherent in probe 3.28 However,
the sn-3 phosphorylation products (20P and 27P) of synthetic
intermediates 20 and 27 afford an additional comparison
between the acyl regioisomers of LPA without the risk of acyl
migration. Plasma from the Sprague-Dawley rat (“normal rat
plasma” (NRP)) contains 19.4 mg of albumin per milliliter29
and was used as a surrogate for normal human plasma.
Conversely, plasma from the Nagase analbuminemic rat (“anal-
buminemic rat plasma” (ARP)) contains only 0.4 mg of albumin
per milliliter.29 This material was used as a tool to examine
binding to plasma proteins other than albumin.
Benzophenone-containing LPA probes were characterized by
UV-dependent labeling of plasma proteins (Figure 1). Probes
1, 2, 4, 20P, and 27P all showed time- (Figure 1A) and
concentration-dependent (data not shown) labeling of predomin-
antly one protein band in NRP. On the basis of the fact that
LPA was initially purified from serum as biological activity
associated with albumin13 and the size of the labeled band in
this study (∼70 kDa), we conclude that this protein is likely
albumin. In contrast, four or five targets were identified on
photolabeling of plasma with a low content of albumin (ARP)
with the same probes (Figure 1B). Once again, labeling for all
probes was time (Figure 1B) and dose (data not shown)
dependent. The intensity of the individual labeled bands varied
among the probes, but all of the probes modify similar targets
in both NRP and ARP. This was expected because these targets
are presumed to be transport proteins in which the interactions
are based more on hydrophobicity than on stereochemistry or
regiochemistry. Further identification and characterization of
plasma protein targets of LPA-containing benzophenones, as
well as examination of the pharmacology of these reagents at
individual LPA GPCR and cellular targets, is currently underway
in our laboratories.
a (a) (i) CH3SO2Cl, Et3N, 0 °C to room temperature and (ii) LiBr, THF,
reflux; (b) (i) (n-Bu)2SnO, CHCl3/MeOH (10:1), reflux and (ii) 28, CsF,
18-crown-6, DMF, room temperature, 1 day; (c) MOMCl, i-Pr2NEt, CH2Cl2;
(d) CAN, CH3CN/H2O (6:1); (e) (i) DGK, [32P]ATP and (ii) TMSBr,
CH2Cl2, 0 °C.
diacylglycerol kinase (DGK) and [32P]ATP.26 The final step,
deprotection of the MOM group of 20P and 27P, was ac-
complished in quantitative yield with trimethylsilyl bromide in
dry CH2Cl2 at 0 °C.
Experimental Section
Synthesis of Ether-Linked LPA Probes 2 and 4. Scheme
5 depicts the strategy we used to introduce an O-alkyl chain
bearing a benzophenone probe into the sn-1 or sn-2 position of
glycerol. Reaction of diol 21 with dibutyltin oxide afforded
cyclic tin intermediate 29,27 which was used without purification.
Ethers 30 and 31 were obtained in 80 and 10% yields,
respectively, by nucleophilic substitution of bromide 28 with
intermediate 29. After the hydroxy group in 30 or 31 was
protected as a MOM ether, the PMP group was removed with
CAN to give precursor 34 or 35 in high yield. Ether-linked
probes 2 and 4 were obtained from 34 and 35 using the same
phosphorylation and deprotection methodology as that described
for the preparation of 1 and 3.
Tetrahydro-2-(tridec-12-en-9-ynyloxy)-2H-pyran (11). To a
solution of alkyne 10 (2.00 g, 8.40 mmol) in 20 mL of dry THF
was added n-BuLi (3.5 mL, 10.1 mmol, a 2.89 M solution in
hexane) at -78 °C under N2. After being stirred for 1 h at -78
°C, the reaction mixture was warmed to room temperature and
stirred for an additional 1.5 h. The mixture was then slowly added
to a solution of allyl bromide (1.22 g, 10.1 mmol) and CuI (100
mg, 0.50 mmol) in 20 mL of THF at -78 °C. After the reaction
mixture was stirred overnight at room temperature, the mixture was
filtered through a short silica gel column. The solvent was removed,
and the residue was purified by chromatography (hexane/EtOAc
20:1) to afford 11 (1.85 g, 79%) as a colorless oil: 1H NMR δ
1.24-1.90 (m, 18H), 2.14-2.22 (m, 2H), 2.90-2.97 (m, 2H),
3.34-3.41 (m, 1H), 3.48-3.52 (m, 1H), 3.69-3.76 (m, 1H), 3.84-
3.89 (m, 1H), 4.55-4.59 (m, 1H), 5.06-5.11 (m, 1H), 5.27-5.36
(m, 1H), 5.77-5.84 (m, 1H); 13C NMR δ 18.7, 19.6, 23.1, 25.4,
26.1, 28.8, 29.0, 29.0, 29.3, 29.7, 30.7, 62.2, 67.6, 76.4, 82.8, 98.8,
115.5, 133.3; HR-MS [MNa+] m/z calcd for C18H30O2Na 301.2138,
found 301.2107.
Plasma Protein Photolabeling. The goal of this research was
to generate tools that can be used to distinguish targets of
individual LPA family members, i.e., acyl vs O-alkyl and sn-1
vs sn-2 linked aliphatic benzophenones. To that end, we tested
five of the synthesized target compounds and intermediates for
(28) For the occurrence of intramolecular acyl migration in a related
lysophospholipid, see: (a) Plu¨ckthun, A.; Dennis, E. A. Biochemistry 1982,
21, 1743-1750. (b) Croset, M.; Brossard, N.; Polette, A.; Lagarde, M.
Biochem. J. 2000, 345, 61-67.
(29) Hama, K.; Bandoh, K.; Kakehi, Y.; Aoki, J.; Arai, H. FEBS Lett.
2002, 523, 187-192.
(26) Waggoner, D. W.; Go´mez-Mun˜oz, A.; Dewald, J.; Brindley, D. N.
J. Biol. Chem. 1996, 271, 16506-16509. See Supporting Information for
experimental details.
(27) Yokoyama, K.; Baker, D. L.; Virag, T.; Liliom, K.; Byun, H.-S.;
Tigyi, G.; Bittman, R. Biochim. Biophys. Acta 2002, 1582, 295-308.
632 J. Org. Chem., Vol. 71, No. 2, 2006

Photoprobes of Ester- and Ether-Linked LPAs
FIGURE 1. Covalent modification of plasma proteins by benzophenone-containing LPA analogues. Plasma (5% in PBS) from Sprague-Dawley
(19.4 mg albumin/mL) (A) or Nagase rats (0.4 mg albumin/mL) (B) was incubated with compounds 1, 2, 4, 20P, and 27P (50 nM, DMSO 10%
final concentration) in the dark for 30 min prior to UV irradiation for up to 10 min on ice. Samples were diluted with 2 × sample loading buffer
and separated by SDS-PAGE. Gels were subsequently dried, and radioactive bands were visualized by autoradiography.
4-(13-(Tetrahydro-2H-pyran-2-yloxy)tridec-4-ynyl)benzophen-
one (12). A flask charged with 11 (1.11 g, 4.00 mmol) and 15 mL
of THF was cooled to -15 °C in a salt-ice bath, and 9-BBN (12
mL, 6.0 mmol, a 0.5 M solution in THF) was added dropwise under
N2. After the addition, the reaction mixture was warmed to room
temperature and stirred for 5 h. 4-Bromobenzophenone (1.04 g,
4.00 mmol), Pd(PPh3)4 (230 mg, 0.20 mmol), DMF (15 mL), and
anhydrous K3PO4 (1.57 g, 8.00 mmol) were added, and the resulting
mixture was heated at reflux for 2 h. The reaction mixture was
poured into 100 mL of water and extracted with CH2Cl2 (4 × 40
mL). The combined organic layers were washed with 100 mL of
water and dried (Na2SO4). The solvent was removed under vacuum,
and the residue was purified by chromatography (hexane/EtOAc
8:1) to provide 12 (1.21 g, 66%) as a colorless oil: 1H NMR δ
1.28-1.90 (m, 20H), 2.12-2.22 (m, 4H), 2.80 (t, 2H, J ) 7.6 Hz),
3.32-3.40 (m, 1H), 3.43-3.50 (m, 1H), 3.68-3.74 (m, 1H), 3.82-
3.87 (m, 1H), 4.53-4.58 (m, 1H), 7.28-7.80 (m, 9H). 13C NMR
δ 18.0, 18.5, 19.5, 25.3, 26.0, 28.6, 28.9, 29.2, 29.5, 30.2, 30.6,
34.6, 62.1, 67.4, 77.2, 79.1, 80.9, 98.6, 128.0, 128.3, 129.7, 130.1,
132.0, 135.1, 137.7, 146.9, 196.1; HR-MS [MNa+] m/z calcd for
C31H40O3Na 483.2870, found 483.2880.
4-(13-Hydroxytridec-4-ynyl)benzophenone (13). A solution of
12 (370 mg, 0.80 mmol) and a catalytic amount of PPTS in MeOH
was heated at reflux for 3 h. Concentration, followed by purification
of the residue by chromatography (hexane/EtOAc 4:1), provided
13 (282 mg, 93%): 1H NMR δ 1.25-1.60 (m, 12H), 1.80-1.85
(m, 2H), 2.14-2.21 (m, 4H), 2.75 (s, 1H), 2.80 (t, 2H, J ) 7.6
Hz), 3.58 (t, 2H, J ) 6.8 Hz), 7.27-7.79 (m, 9H); 13C NMR δ
17.9, 18.5, 25.5, 28.5, 28.8, 28.9, 29.1, 30.0, 32.4, 34.5, 62.3, 79.1,
80.9, 127.9, 128.2, 129.6, 130.1, 132.0, 134.9, 137.5, 146.9, 196.2;
HR-MS [MNa+] m/z calcd for C26H32O2Na 399.2294, found
399.2285.
0.72 mmol) in 10 mL of MeOH. The mixture was stirred under a
hydrogen balloon until the starting alkyne was consumed (monitored
by thin-layer chromatography (TLC), hexane/EtOAc 2:1). The
solvent was removed under vacuum, and the residue was purified
by chromatography (hexane/EtOAc 4:1) to give 14 (262 mg, 97%)
as an oil: 1H NMR δ 1.25-1.48 (m, 10H), 1.50-1.56 (m, 2H),
1.68-1.74 (m, 2H), 1.96-2.13 (m, 4H), 2.45 (s, 1H), 2.69 (t, 2H,
J ) 7.6 Hz), 3.59 (t, 2H, J ) 6.8 Hz), 5.33-5.40 (m, 2H), 7.25-
7.77 (m, 9H); 13C NMR δ 25.6, 26.5, 27.1, 29.0, 29.2, 29.3, 29.5,
30.9, 32.5, 35.2, 62.5, 128.0, 128.2, 128.7, 129.7, 130.1, 130.5,
132.0, 134.9, 137.6, 147.7, 196.4; HR-MS [MNa+] m/z calcd for
C26H34O2Na 401.2451, found 401.2454.
(Z)-13-(4-Benzoylphenyl)-9-tridecenoic Acid (15). A solution
of 14 (730 mg, 1.93 mmol) and PDC (7.3 g, 19.3 mmol) in DMF
(20 mL) was stirred at room temperature for 2 days. Water (100
mL) was added, and the mixture was extracted with CH2Cl2 (3 ×
50 mL). The combined organic layers were washed with water (100
mL) and dried (Na2SO4). The solvent was removed under vacuum,
and the residue was purified by chromatography (hexane/EtOAc
2:1) to give 15 (657 mg, 87%) as a viscous oil: 1H NMR δ 1.24-
1.40 (m, 8H), 1.58-1.75 (m, 4H), 1.96-2.12 (m, 4H), 2.33 (t, 2H,
J ) 7.2 Hz), 2.70 (t, 2H, J ) 7.6 Hz), 5.33-5.44 (m, 2H), 7.26-
7.79 (m, 9H); 13C NMR δ 24.6, 26.7, 27.2, 28.9, 29.0, 29.1, 29.5,
31.0, 34.0, 35.4, 128.1, 128.3, 128.9, 129.9, 130.3, 130.6, 132.1,
135.0, 137.8, 147.8, 179.9, 196.5; HR-MS [MNa+] m/z calcd for
C26H32O3Na 415.2244, found 415.2255.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenoyl)-3-O-FMOC-sn-
glycerol (18). DCC (6.3 mg, 0.031 mmol) and DMAP (1.0 mg,
8.1 µmol) were added to a solution of 15 (10.0 mg, 0.025 mmol)
and (R)-(-)-2,2-dimethyl-1,3-dioxolane-4-methanol (4.0 mg, 0.031
mmol) in 1 mL of CH2Cl2. After the mixture was stirred at room
temperature for 40 h, the solvent was removed under vacuum, and
the residue was purified by chromatography (hexane/EtOAc 4:1)
to provide (Z)-13-benzoylphenyl-9-tridecenoic acid (S)-(2,2-di-
4-((Z)-13-Hydroxytridec-4-enyl)benzophenone (14). Lindlar
catalyst (15 mg, 5.5 wt %) was added to a solution of 13 (270 mg,
J. Org. Chem, Vol. 71, No. 2, 2006 633

Li et al.
methyl-1,3-dioxolan-4-yl)methyl ester (16) (11.9 mg, 92%): 1H
NMR δ 1.23-1.37 (m, 8H), 1.37 (s, 3H), 1.43 (s, 3H), 1.60-1.75
(m, 4H), 1.96-2.12 (m, 4H), 2.34 (t, 2H, J ) 7.6 Hz), 2.70 (t, 2H,
J ) 7.6 Hz), 3.71-3.75 (m, 1H), 4.05-4.18 (m, 3H), 4.28-4.33
(m, 1H), 5.33-5.42 (m, 2H), 7.26-7.80 (m, 9H); 13C NMR δ 24.8,
25.3, 26.6, 26.7, 27.1, 29.0, 19.0, 29.0, 29.5, 31.0, 34.0, 35.4, 64.4,
66.2, 73.5, 109.7, 128.1, 128.4, 128.9, 129.8, 130.2, 130.5, 132.1,
135.0, 137.8, 147.7, 173.5, 196.3.
One drop of concentrated HCl was added to a solution of 16
(90 mg, 0.18 mmol) in 90% dioxane (3 mL). After the mixture
was stirred at room temperature for 4 h, the solvent was removed
under vacuum and the residue was purified by chromatography
(hexane/EtOAc 1:1) to give 1-((Z)-13-(4-benzoylphenyl)-9-tridec-
enoyl))-sn-glycerol (17) (60 mg, 73%): 1H NMR δ 1.23-1.38 (m,
8H), 1.55-1.68 (m, 4H), 1.95-2.12 (m, 4H), 2.33 (t, 2H, J ) 7.6
Hz), 2.70 (t, 2H, J ) 7.6 Hz), 2.75 (br s, 2H), 3.55-3.68 (m, 2H),
3.88-3.94 (m, 1H), 4.15 (t, 2H, J ) 4.8 Hz), 5.34-5.43 (m, 2H),
7.25-7.79 (m, 9H); 13C NMR δ 24.8, 26.6, 27.1, 29.0, 29.0, 29.0,
29.5, 31.0, 34.0, 35.4, 63.3, 65.0, 70.1, 128.2, 128.3, 128.9, 129.9,
130.3, 130.6, 132.2, 135.0, 137.8, 147.9, 174.2, 196.7.
A solution of 17 (58 mg, 0.12 mmol) and DMAP (15 mg, 0.12
mmol) in 1 mL of dry CH2Cl2 was cooled to -10 °C in a salt-ice
bath. A solution of FMOC-chloroformate (32 mg, 0.12 mmol) in
2 mL of dry CH2Cl2 was added dropwise. After the reaction mixture
was stirred for 30 min, the solution was washed with water (5 mL)
and dried (Na2SO4). A small amount (12 mg) of starting material
17 was recovered after chromatography, and 18 (19 mg, 28%) was
also obtained after chromatography (hexane/EtOAc 1:3): 1H NMR
δ 1.22-1.76 (m, 12H), 1.95-2.21 (m, 5H), 2.35 (t, 2H, J ) 7.6
Hz), 2.70 (t, 2H, J ) 7.6 Hz), 4.10-4.28 (m, 5H), 4.41 (d, 2H, J
) 7.2 Hz), 5.33-5.42 (m, 2H), 7.24-7.80 (m, 17H); 13C NMR δ
24.8, 26.7, 27.2, 29.1, 29.1, 29.6, 30.9, 31.1, 34.1, 35.5, 46.7, 64.8,
68.1, 68.5, 70.1, 120.1, 125.1, 127.2, 127.9, 128.2, 129.0, 129.9,
130.3, 130.6, 132.2, 135.1, 137.9, 141.3, 143.2, 147.8, 155.2, 173.8,
196.6, 207.0; HR-MS [MNa+] m/z calcd for C44H48O7Na 711.3292,
found 711.3302.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenoyl)-2-O-methoxy-
methyl-3-O-FMOC-sn-glycerol (19). Chloromethyl methyl ether
(7 mg, 87 µmol) was added to a stirred solution of 18 (6 mg, 8.7
µmol) and i-Pr2NEt (11 mg, 87 µmol) in dry CH2Cl2 (1 mL) under
N2 at 0 °C. After the mixture was stirred at 0 °C for 2 h and at
room temperature for 2 days, water (5 mL) and CH2Cl2 (5 mL)
were added. The organic layer was washed with brine (5 mL) and
water (5 mL) and then dried (Na2SO4). Product 19 (4.2 mg, 66%
yield) was obtained after removal of the solvent and purification
by chromatography (hexane/EtOAc 4:1): 1H NMR δ 1.21-1.39
(m, 12H), 1.57-1.75 (m, 4H), 1.95-2.12 (m, 4H), 2.34 (t, 2H, J
) 7.6 Hz), 2.70 (t, 2H, J ) 7.6 Hz), 3.40 (s, 3H), 4.03-4.33 (m,
5H), 4.41 (d, 2H, J ) 7.1 Hz), 4.73 (s, 2H), 5.33-5.44 (m, 2H),
7.24-7.83 (m, 17H); 13C NMR δ 24.9, 26.8, 27.3, 29.1, 29.6, 31.1,
34.1, 35.5, 46.7, 55.7, 63.0, 67.0, 70.0, 72.4, 96.0, 100.0, 120.1,
125.1, 127.2, 127.9, 128.2, 128.4, 129.0, 130.0, 130.3, 130.7, 132.2,
135.1, 137.9, 141.3, 143.3, 147.8, 155.0, 173.4, 196.5; HR-MS
[MNa+] m/z calcd for C46H52O8Na 755.3560, found 755.3598.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenoyl)-2-O-methoxy-
methyl-sn-glycerol (20) from 19. Piperidine (0.2 mL) was added
to a solution of 19 (1.3 mg, 1.7 µmol) in dry CH2Cl2 (2 mL) under
nitrogen. The mixture was stirred at room temperature until the
starting material was consumed (TLC, hexane/EtOAc 4:1). Con-
centration and purification by chromatography (hexane/EtOAc 2:1)
afforded 20 (0.6 mg, 66%). The Rf value and the 1H NMR spectrum
were identical with data obtained for the same compound prepared
from 26 (see below).
was stirred at room temperature until diol 21 was fully consumed
(TLC, hexane/EtOAc 1:1). The mixture was cooled to 0 °C, and
12 mL of DIBAL-H (18 mmol, a 1.5 M solution in toluene) was
added slowly. Stirring was continued at 0 °C until the ortho ester
intermediate disappeared (TLC, hexane/EtOAc 4:1). A solution of
potassium sodium tartrate (10.2 g, 36.0 mmol) in water (40 mL)
was added cautiously to quench the reaction, and the resulting
mixture was stirred at room temperature overnight. The organic
layer was separated, and the aqueous layer was extracted with CH2-
Cl2 (3 × 30 mL). The combined organic extracts were washed with
water (50 mL) and dried (Na2SO4 and a small amount of K2CO3).
The solvent was removed under vacuum, and the residue was
purified by chromatography (a gradient of hexane/EtOAc from 10:1
to 1:1) to provide 603 mg (83%) of 23 and 99 mg (14%) of 24.
Data for compound 23: 1H NMR δ 3.31 (s, 1H), 3.35 (s, 3H),
3.65-3.77 (m, 5H), 3.96 (d, 2H, J ) 5.8 Hz), 4.08-4.15 (m, 1H),
4.65 (s, 2H), 6.77-6.86 (m, 4H); 13C NMR δ 55.0, 55.3, 68.9,
69.2, 69.4, 96.6, 114.4, 115.3, 152.5, 153.8; HR-MS [MNa+] m/z
calcd for C12H18O5Na 265.1046, found 265.1049. Data for com-
pound 24: 1H NMR δ 2.69 (s, 1H), 3.43 (s, 3H), 3.71-3.86 (m,
5H), 3.93-4.04 (m, 3H), 4.79 (s, 2H), 6.78-6.87 (m, 4H); 13C
NMR δ 55.6, 62.9, 68.3, 78.0, 96.7, 114.6, 115.4, 152.6, 154.0;
HR-MS [MNa+] m/z calcd for C26H34O2Na 265.1046, found
265.1037.
1-O-Methoxymethyl-2-O-(13-(4-benzoylphenyl)-9-(Z)-tridec-
enoyl)-3-O-(4-methoxyphenyl)-sn-glycerol (25). DIAD (10 mg,
49.5 µmol) was added to a solution of acid 15 (16 mg, 41.3 µmol),
alcohol 23 (10 mg, 41.3 µmol), and PPh3 (13 mg, 49.5 µmol) in
dry THF (2 mL) at 0 °C. After the mixture was warmed to room
temperature and stirred for 24 h, water (5 mL) and CH2Cl2 (5 mL)
were added. The aqueous layer was extracted with CH2Cl2 (3 × 5
mL), and the combined organic layers were washed twice with water
(5 mL) and dried (Na2SO4). After the solvents were removed under
vacuum, the residue was purified by chromatography (hexane/
EtOAc 4:1) to give 25 (19 mg, 76%): 1H NMR δ 1.24-1.36 (m,
8H), 1.58-1.76 (m, 4H), 1.95-2.12 (m, 4H), 2.35 (t, 2H, J ) 7.6
Hz), 2.70 (t, 2H, J ) 7.6 Hz), 3.34 (s, 3H), 3.76 (s, 3H), 3.79 (d,
2H), 4.06-4.13 (m, 2H), 4.64 (s, 2H), 5.29-5.35 (m, 1H), 5.36-
5.44 (m, 2H), 6.80-6.87 (m, 4H), 7.27-7.82 (m, 9H); 13C NMR
δ 24.9, 26.8, 27.3, 29.0, 29.1, 29.2, 29.6, 31.1, 34.3, 35.5, 55.3,
55.7, 65.8, 67.0, 70.8, 96.5, 114.6, 115.6, 128.2, 128.4, 129.0, 130.0,
130.4, 130.7, 132.2, 135.1, 137.9, 147.8, 152.7, 154.1, 173.3, 196.5;
HR-MS [MNa+] m/z calcd for C38H48O7Na 639.3292, found
639.3298.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenoyl)-2-O-methoxy-
methyl-3-O-(4-methoxyphenyl)-sn-glycerol (26). Compound 26
was prepared in 78% yield according to the procedure used to
prepare compound 25: 1H NMR δ 1.24-1.35 (m, 8H), 1.58-1.78
(m, 4H), 1.95-2.13 (m, 4H), 2.30-2.35 (m, 2H), 2.68-2.73 (m,
2H), 3.41 (s, 3H), 3.76 (s, 3H), 4.02 (d, 2H, J ) 5.3 Hz), 4.11-
4.17 (m, 1H), 4.22-4.28 (m, 1H), 4.33-4.38 (m, 1H), 4.77 (s,
2H), 5.36-5.42 (m, 2H), 6.80-6.86 (m, 4H), 7.26-7.82 (m, 9H);
13C NMR δ 24.9, 26.8, 27.2, 29.1, 29.1, 29.2, 29.6, 31.1, 34.1,
35.5, 55.6, 55.7, 63.6, 68.2, 73.3, 96.1, 114.6, 115.5, 128.2, 128.3,
129.0, 129.9, 130.3, 130.6, 132.1, 135.1, 137.9, 147.8, 152.7, 154.1,
173.5, 196.5; HR-MS [MNa+] m/z calcd for C38H48O7Na 639.3292,
found 639.3297.
1-O-Methoxymethyl-2-O-(13-(4-benzoylphenyl)-9-(Z)-tridec-
enoyl)-sn-glycerol (27). CAN (181 mg, 0.33 mmol) was added to
a solution of 25 (85 mg, 0.14 mmol) in 7 mL of CH3CN/water
(6:1) at room temperature. The mixture was stirred until compound
25 was consumed (∼1 h, TLC, hexane/EtOAc 1:1) and was then
diluted with water (10 mL) and CH2Cl2 (10 mL). The aqueous layer
was extracted with CH2Cl2 (3 × 6 mL), and the combined organic
extracts were washed with brine (10 mL), dried (Na2SO4), filtered,
and concentrated. The residue was purified by chromatography
(hexane/EtOAc 2:1) to furnish 27 (49 mg, 69%): 1H NMR δ 1.23-
1.38 (m, 8H), 1.57-1.77 (m, 4H), 1.96-2.13 (m, 4H), 2.35 (t, 2H,
J ) 7.6 Hz), 2.70 (t, 2H, J ) 7.6 Hz), 3.36 (s, 3H), 3.70-3.83 (m,
1-(4-Methoxyphenoxy)-3-(methoxymethoxy)propan-(2R)-2-
ol (23) and 3-(4-Methoxyphenoxy)-(2R)-2-(methoxymethoxy)-
propan-1-ol (24). Trimethyl orthoformate (0.66 mL, 6.0 mmol)
was added to a stirred suspension of diol 21 (594 mg, 3.0 mmol)
and D-10-camphorsulfonic acid (12 mg, 50 µmol) in 36 mL of dry
CH2Cl2 at room temperature under nitrogen. The reaction mixture
634 J. Org. Chem., Vol. 71, No. 2, 2006

Photoprobes of Ester- and Ether-Linked LPAs
4H), 4.63 (s, 2H), 5.01-5.07 (m, 1H), 5.34-5.45 (m, 2H), 7.27-
7.81 (m, 9H); 13C NMR δ 24.9, 26.7, 27.2, 29.1, 29.1, 29.2, 29.6,
31.1, 34.3, 35.5, 55.4, 62.3, 66.3, 73.1, 96.6, 128.2, 128.4, 129.0,
130.0, 130.4, 130.6, 132.2, 135.1, 137.9, 147.9, 173.6, 196.6; HR-
MS [MNa+] m/z calcd for C31H42O6Na 533.2874, found 533.2865.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenoyl)-2-O-methoxy-
methyl-sn-glycerol (20) from Compound 26. Compound 20 was
prepared in 73% yield by the same procedure used to prepare
compound 27: 1H NMR δ 1.24-1.38 (m, 8H), 1.56-1.76 (m, 4H),
1.95-2.17 (m, 4H), 2.33 (t, 2H, J ) 7.6 Hz), 2.71 (t, 2H, J ) 7.6
Hz), 3.42 (s, 3H), 3.58-3.71 (m, 2H), 3.80-3.85 (m, 1H), 4.14-
4.24 (m, 2H), 4.74 (s, 2H), 5.35-5.44 (m, 2H), 7.24-7.82 (m,
9H); 13C NMR δ 24.9, 26.7, 27.2, 29.1, 29.1, 29.6, 31.1, 34.1, 35.5,
55.7, 62.6, 63.2, 77.7, 96.6, 128.2, 128.3, 129.0, 129.9, 130.3, 130.6,
132.2, 135.1, 137.9, 147.8, 173.7, 196.5; HR-MS [MNa+] m/z calcd
for C31H42O6Na 533.2874, found 533.2863.
4-((Z)-Bromotridec-4-enyl)benzophenone (28). To 3 mL of
CH2Cl2 under N2 were added alcohol 14 (108 mg, 0.29 mmol) and
Et3N (43 mg, 0.43 mmol) at 0 °C. After the mixture was stirred
for 5 min, methanesulfonyl chloride (49 mg, 0.43 mmol) was added,
and the resulting reaction mixture was stirred at room temperature
overnight, quenched with 5 mL of water, and extracted with CH2-
Cl2 (3 × 5 mL). The combined organic phases were washed with
brine, dried (Na2SO4), filtered, and concentrated. The crude mesylate
was dissolved in dry THF (5 mL), and lithium bromide (50 mg,
0.57 mmol) was added. The reaction mixture was heated at reflux
overnight and then cooled to room temperature and poured into
water (5 mL) and CH2Cl2 (5 mL). The aqueous phase was extracted
with CH2Cl2 (3 × 5 mL). The combined organic phases were
washed with water (10 mL), dried (Na2SO4), and concentrated. The
resulting yellow oil was purified by chromatography (hexane/EtOAc
10:1) to provide 28 (113 mg, 90%) as a colorless oil: 1H NMR δ
1.22-1.45 (m, 10H), 1.68-1.86 (m, 4H), 1.96-2.12 (m, 4H), 2.70
(t, 2H, J ) 7.8 Hz), 3.37 (t, 2H, J ) 6.8 Hz), 5.35-5.44 (m, 2H),
7.25-7.82 (m, 9H); 13C NMR δ 26.6, 27.1, 28.0, 28.6, 29.1, 29.2,
29.5, 31.0, 32.7, 33.9, 35.4, 128.1, 128.2, 128.9, 129.8, 130.2, 130.5,
132.0, 135.0, 137.8, 147.7, 196.2; HR-MS [MNa+] m/z calcd for
C26H33BrONa 463.1607, found 463.1600.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenyl)-3-O-(4-meth-
oxyphenyl)-sn-glycerol (30) and 2-O-(13-(4-Benzoylphenyl)-9-
(Z)-tridecenyl)-3-O-(4-methoxyphenyl)-sn-glycerol (31). Di-n-
butyltin oxide (64 mg, 0.26 mmol) was added to a solution of diol
21 (51 mg, 0.26 mmol) in 3 mL of CHCl3/MeOH (10:1). After the
resulting suspension was heated at reflux for 3 h to give a clear
solution, the solvents were evaporated to give cyclic stannoxane
intermediate 29 as a white solid. Cesium fluoride (78 mg, 0.51
mmol) and 18-crown-6 (8 mg, 26 µmol) were added, and the solid
mixture was dried overnight under high vacuum. After DMF (3
mL) and bromide 28 (71 mg, 0.16 mmol) were added, the reaction
mixture was stirred at room temperature for 1 day. Water (0.5 mL)
and EtOAc (10 mL) were added, and the mixture was stirred for
an additional 1 h and was subsequently filtered through a pad of
silica gel to remove an insoluble byproduct. The filtrate was washed
with water (5 mL), dried (Na2SO4), and concentrated. The residue
was purified by chromatography (hexane/EtOAc 2:1) to provide
30 (72 mg, 80%) and 31 (8.7 mg, 10%). Data for compound 30:
1H NMR δ 1.21-1.38 (m, 8H), 1.52-1.76 (m, 4H), 1.94-2.12
(m, 4H), 2.54 (br s, 1H), 2.70 (t, 2H, J ) 7.6 Hz), 3.43-3.64 (m,
4H), 3.75 (s, 3H), 3.93-4.01 (m, 2H), 4.09-4.16 (m, 1H), 5.33-
5.45 (m, 2H), 6.79-6.88 (m, 4H), 7.25-7.82 (m, 9H); 13C NMR
δ 26.0, 26.7, 27.2, 29.2, 29.4, 29.4, 29.5, 29.6, 31.0, 35.4, 55.6,
69.1, 69.7, 71.5, 71.7, 114.6, 115.5, 128.1, 128.3, 128.9, 129.9,
130.3, 130.7, 132.1, 135.1, 137.9, 147.8, 152.7, 154.0, 196.4; HR-
MS [MNa+] m/z calcd for C36H46O5Na 581.3237, found 581.3249.
Data for compound 31: 1H NMR δ 1.22-1.38 (m, 8H), 1.52-
1.77 (m, 4H), 1.95-2.14 (m, 4H), 2.68 (t, 2H, J ) 7.8 Hz), 3.52-
3.86 (m, 5H), 3.76 (s, 3H), 3.94-4.04 (m, 2H), 5.34-5.45 (m,
2H), 6.79-6.91 (m, 4H), 7.25-7.81 (m, 9H); 13C NMR δ 26.1,
26.8, 27.3, 29.3, 29.5, 29.5, 29.7, 30.1, 31.1, 35.5, 55.7, 62.5, 68.1,
70.7, 78.2, 114.7, 115.5, 128.2, 128.4, 129.0, 130.0, 130.4, 130.8,
132.2, 135.1, 138.0, 147.9, 152.8, 154.0, 196.6; HR-MS [MNa+]
m/z calcd for C36H46O5Na 581.3237, found 581.3252.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenyl)-2-O-methoxy-
methyl-3-O-(4-methoxyphenyl)-sn-glycerol (32). Chloromethyl
methyl ether (40 mg, 497 µmol) was added under N2 to a stirred
solution of 30 (56 mg, 99 µmol) and i-Pr2NEt (64 mg, 497 µmol)
in dry CH2Cl2 (3 mL) at 0 °C. The reaction mixture was stirred at
room temperature for 2 days. The solvent was removed, and the
residue was purified by chromatography (hexane/EtOAc 4:1) to
afford unreacted 30 (10 mg) and 32 (45 mg, 91%): 1H NMR δ
1.22-1.38 (m, 8H), 1.52-1.76 (m, 4H), 1.96-2.15 (m, 4H), 2.70
(t, 2H, J ) 7.8 Hz), 3.41 (s, 3H), 3.41-3.50 (m, 2H), 3.56-3.65
(m, 2H), 3.75 (s, 3H), 3.99-4.11 (m, 3H), 4.79 (s, 3H), 5.34-
5.45 (m, 2H), 6.79-6.87 (m, 4H), 7.28 (d, 2H, J ) 8.3 Hz), 7.47
(t, 2H, J ) 7.8 Hz), 7.57 (t, 1H, J ) 7.3 Hz), 7.72-7.81 (m, 4H);
13C NMR δ 26.0, 26.7, 27.2, 29.2, 29.4, 29.4, 29.6, 29.6, 31.1,
35.4, 55.4, 55.6, 68.7, 70.4, 71.7, 84.5, 96.2, 114.5, 115.4, 128.1,
128.3, 128.9, 129.9, 130.3, 130.7, 132.1, 135.1, 137.9, 147.8, 152.9,
153.8, 196.4; HR-MS [MNa+] m/z calcd for C38H50O6Na 625.3500,
found 625.3519.
1-O-Methoxymethyl-2-O-(13-(4-benzoylphenyl)-9-(Z)-tridec-
enyl)-3-O-(4-methoxyphenyl)-sn-glycerol (33). Compound 33 was
prepared in 89% yield from 31 by the same procedure used to
prepare 32: 1H NMR δ 1.22-1.39 (m, 8H), 1.55-1.62 (m, 2H),
1.68-1.76 (m, 2H), 1.97-2.04 (m, 2H), 2.07-2.13 (m, 2H), 2.70
(t, 2H, J ) 7.8 Hz), 3.34 (s, 3H), 3.58-3.80 (m, 5H), 3.76 (s, 3H),
3.97-4.08 (m, 2H), 4.65 (s, 2H), 5.34-5.44 (m, 2H), 6.80-6.88
(m, 2H), 7.26-7.81 (m, 9H); 13C NMR δ 26.0, 26.7, 27.3, 29.3,
29.4, 29.5, 29.7, 30.0, 31.1, 35.5, 55.2, 55.7, 66.9, 68.2, 70.7, 77.1,
96.7, 114.6, 115.5, 128.2, 128.3, 128.9, 129.9, 130.3, 130.8, 132.1,
135.1, 137.9, 147.8, 153.0, 153.9, 196.5; HR-MS [MNa+] m/z calcd
for C38H50O6Na 625.3500, found 625.3497.
1-O-(13-(4-Benzoylphenyl)-9-(Z)-tridecenyl)-2-O-methoxy-
methyl-sn-glycerol (34). Compound 34 was prepared in 86% yield
using the procedure described to prepare compound 27: 1H NMR
δ 1.24-1.39 (m, 8H), 1.52-1.60 (m, 2H), 1.68-1.77 (m, 2H),
1.97-2.04 (m, 2H), 2.06-2.13 (m, 2H), 2.70 (t, 2H, J ) 7.6 Hz),
3.42 (s, 3H), 3.40-3.80 (m, 7H), 4.75 (s, 2H), 5.34-5.45 (m, 2H),
7.27-7.82 (m, 9H); 13C NMR δ 26.0, 26.7, 27.3, 29.2, 29.4, 29.4,
29.6, 29.7, 31.1, 35.5, 55.6, 63.7, 71.1, 71.8, 78.5, 96.6, 128.2,
128.3, 128.9, 129.9, 130.3, 130.7, 132.1, 135.1, 137.9, 147.8, 196.5;
HR-MS [MNa+] m/z calcd for C31H44O5Na 519.3081, found
519.3079.
1-O-Methoxymethyl-2-O-(13-(4-benzoylphenyl)-9-(Z)-tridec-
enyl)-sn-glycerol (35). The same method used to prepare 34 was
used to prepare 35 in 88% yield: 1H NMR δ 1.22-1.40 (m, 8H),
1.52-1.77 (m, 4H), 1.95-2.13 (m, 4H), 2.70 (t, 2H, J ) 7.6 Hz),
3.37 (s, 3H), 3.46-3.77 (m, 7H), 4.63 (s, 2H), 5.34-5.45 (m, 2H),
7.27-7.82 (m, 9H); 13C NMR δ 26.1, 26.7, 27.3, 29.2, 29.4, 29.5,
29.7, 30.0, 31.1, 35.5, 55.3, 62.6, 67.0, 70.3, 78.5, 96.7, 128.2,
128.3, 128.9, 129.9, 130.3, 130.7, 132.2, 135.1, 137.9, 147.8, 196.5;
HR-MS [MNa+] m/z calcd for C31H44O5Na 519.3081, found
519.3095.
Acknowledgment. We thank Dr. George Kaysen, University
of California at Davis, for providing analbuminemic rat plasma.
Financial support from National Institutes of Health Grant
CA92160 is gratefully acknowledged.
Supporting Information Available: Procedures for enzymatic
incorporation of [32P]-phosphate into the benzophenone-containing
analogues, for covalent modification of plasma proteins, and for
1
the preparation of compounds 9 and 10 and H and 13C NMR
spectra for all new compounds and intermediates. This material is
available free of charge via the Internet at http://pubs.acs.org.
JO052030W
J. Org. Chem, Vol. 71, No. 2, 2006 635