An efficient synthesis of γ-hydroxy-α,β-unsaturated aldehydic esters of 2-lysophosphatidylcholine

Article abstract of DOI:10.1016/j.bmc.2010.10.058

The diverse biological activities of γ-hydroxyalkenal phospholipids and their involvement in disease are the subject of intense study. Phospholipid aldehydes, such as the 4-hydroxy-7-oxohept-5-enoic acid ester of 2-lyso-phosphatidylcholine (HOHA-PC), the 5-hydroxy-8-oxo-6-octenoic acid ester of 2-lyso-PC (HOOA-PC), and the 9-hydroxy-12-oxododec-10-enoic acid ester of 2-lyso-PC (HODA-PC), are generated by oxidative cleavage of polyunsaturated fatty acyl phospholipids. To facilitate investigations of their chemistry and biology, we now report efficient total synthesis of HOOA, HODA, and HOHA phospholipids. Because the target γ-hydroxyalkenals readily decompose through oxidation of the aldehyde group to a carboxylic acid or through cyclization to furans, these synthesis generate the sensitive functional array of the target phospholipids under mild conditions from acetal derivatives that are suitable for long-term storage.

Full text of DOI:10.1016/j.bmc.2010.10.058

Bioorganic & Medicinal Chemistry 19 (2011) 580–587
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
An efficient synthesis of
c
-hydroxy-
a,b-unsaturated aldehydic esters
of 2-lysophosphatidylcholine
⇑
Jaewoo Choi, James M. Laird, Robert G. Salomon
Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106-7078, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
The diverse biological activities of c-hydroxyalkenal phospholipids and their involvement in disease are
the subject of intense study. Phospholipid aldehydes, such as the 4-hydroxy-7-oxohept-5-enoic acid ester
of 2-lyso-phosphatidylcholine (HOHA-PC), the 5-hydroxy-8-oxo-6-octenoic acid ester of 2-lyso-PC
Received 8 September 2010
Revised 26 October 2010
Accepted 28 October 2010
Available online 31 October 2010
(HOOA-PC), and the 9-hydroxy-12-oxododec-10-enoic acid ester of 2-lyso-PC (HODA-PC), are generated
by oxidative cleavage of polyunsaturated fatty acyl phospholipids. To facilitate investigations of their
chemistry and biology, we now report efficient total syntheses of HOOA, HODA, and HOHA phospholipids.
Because the target c-hydroxyalkenals readily decompose through oxidation of the aldehyde group to a
carboxylic acid or through cyclization to furans, these syntheses generate the sensitive functional array
of the target phospholipids under mild conditions from acetal derivatives that are suitable for long-term
Keywords:
c
-Hydroxy-a,b-unsaturated aldehyde
Oxidized phospholipid
HOHA-PC
HOOA-PC
storage.
HODA-PC
Ó 2010 Elsevier Ltd. All rights reserved.
Organic synthesis
Cardiovascular disease
Atherosclerosis
1
. Introduction
ligand, high-density lipoprotein, to SR-BI and consequently inter-
feres with SR-BI-mediated selective uptake of cholesteryl esters in
9
Free radical-induced oxidative cleavage of phospholipids con-
taining docosahexaenoate (C22), arachidonate (C20), or linoleate
hepatocytes. Thus, oxidative stress resulting in the accumulation
of specific oxidized phospholipids in plasma may have an inhibitory
effect on reverse cholesterol transport. HOOA-PC induces monocyte
(
C18) generates truncated, biologically active aldehydes including
1
0–12
c-hydroxyalkenal phospholipids, that is, the 4-hydroxy-7-oxoh-
binding to endothelial cells
and this may promote infiltration of
ept-5-enoic acid ester of 2-lyso-phosphatidylcholine (HOHA-PC),
the 5-hydroxy-8-oxo-6-octenoic acid ester of 2-lyso-PC (HOOA-
PC), and the 9-hydroxy-12-oxododec-10-enoic acid ester of 2-lyso-
monocyte macrophages into the subendothelial space where they
become foam cells through unregulated endocytosis of oxidized
low-density lipoprotein. Also, HOOA-PC inhibits lipopolysaccha-
ride-induced expression of E-selectin a major endothelial cell
PC (HODA-PC), respectively (Scheme 1). These
react with protein lysyl -amino residues to generate biologically
active carboxyalkylpyrrole derivatives (Scheme 1).
HOOA-PC and HODA-PC, and the derived protein adducts 2-(
boxyethyl)pyrroles (CEPs), 2-( -carboxypropyl)pyrroles (CPPs),
and 2-( -carboxyheptyl)pyrroles (CHPs), are present in human ath-
erosclerotic lesions.
c-hydroxyalkenals
1
0
e
adhesion molecule involved in neutrophil binding. Specifically,
HOOA-PC induces expression of chemokines that promote interac-
1,2
HOHA-PC,
-car-
1
3
x
tion with monocytes. Thus, HOOA-PC is important as a putative
proinflammatory molecule regulating leukocyte endothelial inter-
x
1
1,14
x
actions.
Furthermore, covalent modification of proteins by
3
–5
The
c-hydroxyalkenal phospholipids con-
HOOA-PC and HODA-PC results, inter alia, in impaired proteolytic
degradation of internalized macromolecules by mouse peritoneal
macrophages and inhibition of cathepsin B, a lysosomal protease.
HOHA-PC also inhibits posttranslational processing of the nascent
25 kDa membrane fusion protein Rab5a to produce the active
tribute to the generation of atherosclerotic plaques. Thus, they
promote the conversion of monocyte macrophages into foam cells
by serving as ligands for the scavenger receptor CD36 that mediates
endocytosis of oxidized low-density lipoprotein particles by macro-
6
,7
15
phage cells. Binding of these phospholipids, and their more oxi-
dized derivatives, to platelet CD36 receptors induces aggregation
23 kDa ‘mature’ Rab5a in phagosomal membranes. Most recently,
proteins containing CEPs, that are generated in vivo from HOHA-PC,
were shown to initiate destruction of the retina in age-related mac-
8
leading to thrombosis. Their binding to the macrophage scavenger
1
6
receptor class B, type I (SR-BI) prevents binding of its physiological
ular degeneration. We previously reported total syntheses of
1
,3
HOHA-, HOOA-, and HODA-PC. However, those syntheses were
lengthy and involved reactions that are difficult to perform. Herein,
we reportsuperior syntheses of HOOA, HODA, and HOHA derivatives
that will facilitate investigation of their biological involvements.
⇑
Corresponding author. Tel.: +1 216 368 2592; fax: +1 216 368 3006.
E-mail address: rgs@case.edu (R.G. Salomon).
0
968-0896/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2010.10.058

J. Choi et al. / Bioorg. Med. Chem. 19 (2011) 580–587
581
γ-Hydroxy- α,β-unsaturated
Pyrroles
PUFA Phospholipids
Aldehydes
protein
N
C H
5
11
(CH ) COO-PC
2 7
OH
O2
protein
NH2
linoleyl (LA -PC)
O
(CH ) COOH
2 7
(
CH ) COO-PC
2
7
HODA-PC
C H
CHP
2
5
(CH ) COO-PC
2 7
O2
linolenyl-PC
protein
N
OH
protein
NH2
O
C H
5
11
C H
5
11
4
-hydroxynonenal
C H
O2
5
11
(CH ) COO-PC
2 3
pentylpyrrole
γ- linolenyl-PC
OH
protein
N
O2
protein
NH2
C H
O
5
11
(CH ) COO-PC
2 3
2
(
CH ) COO-PC
2
3
arachidonyl (AA-PC)
(CH ) COOH
2 3
HOOA-PC
protein
N
OH
C H
2
CPP
5
(CH ) COO-PC
protein
3
2 3
NH
2
O
C H
2
5
C H
5
11
eicosapentaenoyl-PC
O2
O2
4
-hydroxynonenal
ethylpyrrole
protein
protein
N
OH
NH2
C H
2
O
5
(CH ) COO-PC
2 2
4
(
CH ) COO-PC
2 2
O
(CH ) COOH
2 2
docosahexaenoyl (DHA-PC)
HOHA-PC
R
O
P
O
O
CEP
PC =
O
N(CH )
3 3
Scheme 1. Oxidation of polyunsaturated fatty acids generates
c
-hydroxy-
a
,b-unsaturated aldehydes, that react with proteins and form 2-[x-carboxylalkyl)pyrroles.
2
2
. Results and discussion
.1. Synthetic design
2.2. HOHA ethyl ester
To test the feasibility of generating the requisite c-hydroxyalk-
enal functional array in two byselective reduction of a ketone from
an ester of 3 (n = 2, R = Me), we synthesized (E)-ethyl-4-hydroxy-7-
oxohept-5-enoate (11) (Scheme 3). The furyl ester 7a was
oxidatively ring opened with N-bromosuccinimide (NBS).17 The
resulting keto aldehyde 8 was selectively protected using trimethyl
c
-Hydroxyalkenals readily decompose through oxidation of the
aldehyde group to a carboxylic acid or cyclization to furans.
Therefore, a synthetic strategy was designed that generates the
sensitive functional array of the target phospholipids 1 under mild
conditions from stable acetal precursors 2 that are suitable for
long-term storage, and that might be readily converted to the
1
8
orthoformate and Montmorillonite K10 to give 9. Reduction of
the ketone carbonyl in 9 was readily accomplished in excellent
target
c
-hydroxyalkenal phospholipids under mild conditions
yield to provide the masked
c-hydroxyalkenal 11 could be generated by hydrolysis of the
c-hydroxyalkenal 10. The target
(Scheme 2). Masking of the aldehyde carbonyl as an acetal also
allows selective reduction of the ketone carbonyl in the ketoalke-
nal derivatives 3. The precursors 3 might be assembled through
cross-coupling of the known vinyl tin 4 and acid chlorides 5.
Alternatively, keto alkenal precursors 6 are readily available via
oxidation of furans 7.
dimethyl acetal in 10 promoted by the weak acid, pyridinium
O
O
O
a
b
O
OEt
OEt 60%
75%
2
O
8
7a
OH
O
OH
O
OMe
O
O
c
OMe
O
O
RO
n OPC
n OPC
MeO
OEt 95% MeO
OEt
1
OR
2
O
10
OH
9
O
3
O
O
6
O
d
e
RO
O
67%
n O
n OH
9
0%
OR
H
H
O
OEt
O
O
O
OH
11
O
O
n
O
RO
SnBu3
12
O
OR'
Cl
OR'
n
OR
H
Scheme 3. Synthesis of HOHA ethyl ester. Reagents and conditions: (a) NBS, THF/
4
5
7
acetone/H O (5:4:1), pyridine; (b) K 10/CH(OCH ) ; (c) NaBH , MeOH; (d) PPTS,
2
3
3
4
2 2 2
acetone/H O (2:1); (e) Amberlyst-15, acetone/H O (2:1), 67% or TFA/H O (95:5), rt,
61%.
Scheme 2. Retrosyntheses of c-hydroxyalkenal phospholipids.

5
82
J. Choi et al. / Bioorg. Med. Chem. 19 (2011) 580–587
p-toluenesufonic acid (PPTs). However, concomitant transesterifi-
cation delivered the lactone 12 in excellent yield when the hydro-
lysis was performed in the presence of stronger acid catalysts, such
as Amberlyst-15 or TFA.
OMe
O
OMe
O
a
b
MeO
OEt
O
MeO
c
OH
50%
78%
9
O
O
3a
OMe
OMe
O
2
.3. HOOA methyl ester
MeO
O-PC
8
5% MeO
O-PC
1
8a O
2
a
OH
In an alternative approach (Scheme 4), the requisite carbon
skeleton was assembled by regio- and stereoselective tributylstan-
O
O
O
nylcupration of 3,3-diethoxyprop-1-yne (13) with the Lipshutz re-
15 31
C H
d
O
O
1
9
3 2 2 3 2
agent, Bu SnCu(Bu)CNLi , followed by PdCl (CH CN) catalyzed
O
20
97%
O
acylation of the resulting vinyltin 4 with glutaric acid mono-
P O
methyl ester chloride (5b).21 Reduction of the resulting ketone
OH
O
NMe3
HOHA-PC (1a)
1
4b with sodium borohydride gave the stable masked
c-hydrox-
yalkenal 15b in excellent yield. The target -hydroxyalkenal 16
c
Scheme 5. Synthesis of HOHA-PC. Reagents and conditions: (a) porcine pancreatic
lipase, phosphate buffer; (b) -lysophosphatidylcholine (HO-PC), 2,6-dic-
hlorobenzoyl chloride, 1-methylimidazole, CH Cl ; (c) NaBH , MeOH, (d) PPTS,
could be generated by hydrolysis of 15b promoted by a weak acid.
However, as for the 10?11 conversion above, concomitant transe-
sterification delivered the lactone 17 when the hydrolysis was per-
formed in the presence of stronger acid catalysts.
L-a
2
2
4
2
THF/acetone/H O (5:4:1).
H
O
O
O
O
n
b
2
.4. HOHA-PC
EtO
SnBu
3
EtO
Cl
OMe
OMe
n
OEt H
OEt
Enzymatic hydrolysis of ethyl ester 9 with porcine pancreatic li-
5
b, n = 3
1
4b, n = 3 (65%)
pase (PPL) in phosphate buffer saline (PBS) buffer afforded key
intermediate 2 (Scheme 5), that is precursor for many oxidized
phospholipids. When lithium hydroxide was applied to hydro-
lyze methyl ester group, the diethyl acetal moiety was also depro-
tected. Therefore, selective enzymatic hydrolysis of the ester at pH
4
5c, n = 7
14c, n = 7 (60%)
2
2
O
O
O
O
d
e
c
EtO
EtO
OH
O-PC
n
n
OEt
b, n = 3 (58%)
3c, n = 7 (67%)
OEt
7
was considered. Synthesis of PC-ester 18 was efficiently accom-
3
18b, n = 3 (74%)
plished using the coupling reagents 2,6-dichlorobenzoyl chloride
and 1-methylimidazole,
and improved yield of the ester coupling product, as compared to
using general coupling reagents such as dicyclohexylcarboimide
and 4-N,N-dimethylaminopyridine, which adhere to silica gel
resulting in laborious separation via chromatography. Selective
reduction of ketone 18a using NaBH in methanol and subsequent
4
mild deprotection of the dimethylacetal 2a gave HOHA-PC 1a in
excellent yield.
1
8c, n = 7 (71%)
2
3,24
resulting in 50% shorter reaction time
O
15 31
C H
OH
O
OH
O
O
O
O
EtO
f
O
O
O
n
n
P
O
O
EtO
N
2
2
b, n = 3 (98%)
c, n = 7 (87%)
HOOA-PC (1b), n = 3 (85%)
HODA-PC 1c ,
(
) n = 7 (90%)
Scheme 6. Syntheses of HOOA and HODA-PCs. Reagents and conditions: (a) oxalyl
chloride, benzene; (b) PdCl (MeCN) (1 mol %), DMF, 0 °C; (c) porcine pancreatic
lipase, PBS; (d) -lysophosphatidylcholine (HO-PC), 2,6-dichlorobenzoyl chloride,
-methylimidazole, CH
2
2
2
.5. HOOA and HODA-PCs
L-a
1
2
Cl
2
; (e) NaBH
4 2
, MeOH; (f) PPTS, THF/acetone/H O (5:4:1).
HOOA-PC (1b) and HODA-PC (1c) were assembled by
2
0
2 3 2
PdCl (CH CN) -catalyzed acylation of vinylstannane 4 with glu-
O
O
taric acid monomethyl ester chloride (5b) or azelaeic acid mono-
OH
O
n
methyl ester chloride (5c)2
respectively (Scheme 6). Acylation of
HO-PC) with the carboxylic acids produced by hydrolysis of the
5–27
to generate ketones 14b or 14c,
-lysophosphatidylcholine
O
H
HOR
L
-
a
OR
O
(CH2)n
(
1
1, n = 2, R = Et
1
2, n = 2
7, n = 3
1
6, n = 3, R = Me
1
H
EtO
EtO
b
a
65%
O
EtO
SnBu3
Scheme 7. Lactone formation is promoted by strong acid.
C CH
O
81%
13
EtO 4 H
Cl
( )
3
O
O
methyl esters 3 followed by selective reduction of the ketone car-
O
O
5
b
EtO
bonyl delivered stable precursors 2 of the
pholipids 1.
c-hydroxyalkenal phos-
(
)3
O
OH
(
O
OEt
c
14b
O
O
)3
d
3. Conclusion
9
4%
1
6
OH
O
88%
New total syntheses readily deliver the c-hydroxy-a,b-unsatu-
EtO
O
e
rated aldehydic esters HOHA-PC (1a), HOOA-PC (1b), and HODA-
PC (1c) of 2-lysophosphatidylcholine from the corresponding
acetals 2. These relatively stable precursors are protected against
oxidative degradation of the aldehyde and cyclization to furans.
However, our model studies with 11 and 16 revealed a potential
pitfall, acid-catalyzed lactonization to 12 or 17, respectively
O
OEt
15b
8
7%
1
7
O
Scheme 4. Synthesis of HOOA methyl ester. Reagents and conditions: (a)
Bu SnCu(Bu)CNLi O; (b) PdCl (MeCN) (1 mol %), DMF, 0 °C;
c) NaBH , EtOH, 0 °C; (d) PPTS, acetone/H O (2:1), rt; (e) Amberlyst-15, TFA/H
95:5), rt.
3
2
, THF, À78 °C, then H
2
2
2
(
(
4
2
2
O
(Scheme 7). Since
L-a-lysophosphatidylcholine (HO-PC)—that

J. Choi et al. / Bioorg. Med. Chem. 19 (2011) 580–587
583
would be released by such lactonization of HOHA-PC (1a) or
HOOA-PC (1b)—is biologically active, it is important to avoid
strongly acidic conditions during the generation of these oxida-
tively truncated phospholipids from the stable acetal precursors.
5.9 mg, 0.022 mmol) was added and the mixture was stirred at
room temperature for 2 h. Solvents were then evaporated under
reduced pressure and the residue purified by flash chromatography
on a silica gel column (20% ethyl acetate/hexanes) to give 11
1
(
(
3.6 mg, 90%). TLC (45% ethyl acetate/hexanes, R
400 MHz, CDCl
f
= 0.20): H NMR
3
) d 9.60 (d, J = 7.8 Hz, 1H), 6.80 (dd, J = 15.7,
4
4
. Experimental section
4.4 Hz, 1H), 6.35 (ddd, J = 15.7, 7.8, 1.7 Hz, 1H), 4.54 (m,1H), 4.15
q, J = 7.1 Hz, 3H), 2.59 (d, J = 4.8 Hz, 1H), 2.50 (ddd, J = 1 7.1,
10.4, 7.6 Hz, 3H), 2.14–1.98 (m, 1H), 1.89 (dt, J = 14.4, 6.6 Hz, 2H),
.27 (t, J = 7.1 Hz, 6H). HRMS (FAB): m/z calcd for C
(
.1. Ethyl (E)-4,7-dioxohept-5-enoate (8)
N-Bromosuccinimide (NBS, 1.59 g, 8.9 mmol) was dissolved in
1
9 13 3
H O
+
(MH ÀH O), 169.0865; found, 169.0867.
2
tetrahydrofuran/acetone/H
a solution of ethyl-(3-(2-furyl)propanoate (7a, 1 g, 5.9 mmol) and
2
pyridine (962 L, 11.9 mmol) in tetrahydrofuran/acetone/H O
2
O (5:4:1, 12 mL) and slowly added to
4.5. (E)-3-(5-Oxotetrahydrofuran-2-yl)acrylaldehyde (12)
l
(
5:4:1, 8 mL) at À20 °C. The solution was stirred for 1 h at À20 °C
Method (A): Amberlyst-15 (15 mg) was added in small portions
to a stirred solution of acetal 10 (15 mg, 0.06 mmol) in acetone/
water = 3:1 (1.5 mL) and the mixture was stirred at room temper-
ature for 2 h. Solvents were then evaporated under reduced pres-
sure and the residue purified by flash chromatography on a silica
gel column (40% ethyl acetate/hexanes) to give lactone 12 (6 mg,
and 3 h at room temperature. The solvents were then evaporated
under reduced pressure and the residue purified by flash chroma-
tography on a silica gel column (30% ethyl acetate/hexanes, TLC:
R
9
7
= 0.3) to give 8 (653 mg, 60%). 1H NMR (400 MHz, CDCl
) d
f
3
.76 (d, J = 7.1 Hz, 1H), 6.89 (d, J = 16.2 Hz, 1H), 6.79 (dd, J = 16.9,
.0 Hz, 1H), 4.11 (q, J = 7.2 Hz, 2H), 2.99 (t, J = 6.2 Hz, 2H), 2.65 (t,
67%). TLC (50% ethyl acetate/hexanes, R = 0.15).
f
13
J = 6.1 Hz, 2H), 1.22 (t, J = 6.2 Hz, 3H). C NMR (100 MHz, CDCl
3
)
Method (B): Acetal 10 was dissolved in TFA/H O = 95:5 (1 mL)
2
1
98.2, 193.4, 172.3, 144.5, 137.7, 60.9, 35.8, 27.9, 14.2. HRMS
and stirred for 1.5 h. Solvents were then evaporated under reduced
pressure and the residue purified by flash chromatography on a sil-
+
(
FAB): m/z calcd for C
H
9 13
O
4
(MH ), 185.0814; found, 185.0818.
ica gel column (40% ethyl acetate/hexanes) to give lactone 12
1
4
.2. Ethyl (E)-7,7-dimethoxy-4-oxohept-5-enoate (9)
(5.5 mg, 61%). H NMR (400 MHz, CDCl ) d 9.60 (d, J = 7.6 Hz, 1H),
3
6
.80 (dd, J = 15.8, 4.7 Hz, 1H), 6.32 (ddd, J = 15.8, 7.6, 1.6 Hz, 1H),
Aldehyde 8 (299 mg, 1.6 mmol) was stirred with suspension of
5.31–5.10 (m, 1H), 2.69–2.43 (3H), 2.20–1.97 (m, 1H). HRMS
+
the Montmorillonite K-10 (500 mg) and trimethyl orthoformate
500 L) in dry dichloromethane (3 mL) at room temperature for
h. The mixture was then filtered through a pad of Celite 521, fol-
(FAB): m/z calcd for C H O (MH ), 141.0551; found, 141.0473.
7
9 3
1
(
1
l
The H NMR spectral data for 12 is in agreement with that reported
2
8,29
previously.
lowed by washing the residue with dichloromethane (10 mL). The
solvents were evaporated under reduced pressure and the residue
purified by flash chromatography on a silica gel column (10% ethyl
4.6. (E)-7,7-Dimethoxy-4-oxohept-5-enoic acid (3a)
acetate/hexanes) to give 9 (280 mg, 75%). TLC (30% ethyl acetate/
To increase solubility at room temperature ester 9 (205 mg,
0.89 mmol) was dissolved in PBS (pH 7.4, 50 mM, 7 mL) and meth-
anol (1 mL). To this rapidly stirred solution, was then added por-
cine pancreatic lipase (type II, crude, 50 mg), sodium chloride
(5 mg), and calcium chloride (10 mg). The pH of the reaction mix-
ture was maintained at 7.0–7.2 by addition of sodium hydroxide
solution (0.1 N). Upon completion, the solution was evaporated un-
der reduced pressure, the residue extracted with chloroform/meth-
anol (2:1, v/v), filtered, and dried with anhydrous magnesium
sulfate. Solvents were then evaporated from the combined organic
extracts under reduced pressure and the residue purified by flash
chromatography on a silica gel column (chloroform/metha-
nol = 20:1) to give 3a (90 mg, 50%). TLC (chloroform/methanol/
1
hexanes, R
f
= 0.32): H NMR (400 MHz, CDCl
3
) d 6.62 (dd, J = 19.5,
3
.9 Hz, 1H), 6.37 (dd, J = 16.2, 1.1 Hz, 1H), 4.93 (m, 1H), 4.11 (q,
J = 7.2 Hz, 2H), 3.32 (s, 6H), 2.89 (t, J = 6.6 Hz, 2H), 2.60 (t,
J = 6.6 Hz, 2H), 1.23 (t, J = 7.2 Hz, 3H). 13C NMR (100 MHz, CDCl
98.1, 172.8, 140.8, 131.9, 101.1, 60.8, 53.1, 35.3, 28.1, 14.4. HRMS
3
)
1
+
(
19 5
FAB): m/z calcd for C11H O (MH ), 231.1232; found, 231.1235.
4
.3. Ethyl (E)-4-hydroxy-7,7-dimethoxyhept-5-enoate (10)
Sodium borohydride (9.4 mg, 0.25 mmol) was added in small
portions over 5 min at 0 °C to a stirred solution of ester 9
47.7 mg, 0.2 mmol) in ethanol (1.5 mL). The reaction mixture
(
1
was stirred for 4 h and then quenched by addition of methanol
to destroy excess sodium borohydride. The mixture was neutral-
ized to pH 7 by addition of saturated sodium bicarbonate solution,
followed by addition of brine. The aqueous layer was extracted
with ethyl acetate. Solvents were evaporated from the combined
organic extracts under reduced pressure, and the residue purified
by flash chromatography on a silica gel column (20% ethyl ace-
H O = 80:19:1, R = 0.44): H NMR (400 MHz, CDCl ) d 6.63 (dd,
2
f
3
J = 16.4, 4 Hz, 1H), 6.38 (dd, J = 16.4, 1.2 Hz, 1H), 4.95 (dd, J = 4.0,
1.6 Hz, 1H), 3.33 (s, 6H), 2.90 (t, J = 6.4 Hz, 2H), 2.61 (t, J = 6.4 Hz,
1
3
2H). C NMR (100 MHz, CDCl ) 198.2, 178.4, 140.1, 131.8, 101.1,
3
+
9
53.2, 35.3, 28.1. HRMS (FAB): m/z calcd for C H14NaO5 (MNa ),
225.0740; found, 225.0746.
tate/hexanes) to give 10 (45.7 mg, 95%). TLC (45% ethyl acetate/
4.7. (E)-(7,7-Dimethoxy-4-oxohept-5-enoyl)-1-palmitoyl-sn-
glycero-3-phosphatidylcholine (18a)
1
hexanes, R
f
= 0.21): H NMR (400 MHz, CDCl
3
) d 5.88 (ddd,
J = 15.8, 5.7, 1.0 Hz, 1H), 5.69 (ddd, J = 15.8, 4.7, 1.3 Hz, 1H), 4.79
d, J = 4.8 Hz, 1H), 4.22 (m, 1H), 4.12 (q, J = 7.2 Hz, 2H), 3.31 (s,
H), 2.45 (t, J = 6.6 Hz, 2H), 2.06 (s, –OH), 2.00–1.74 (m, 2H), 1.23
(
6
1-Methylimidazole (18.7
zoyl chloride (37 L, 0.26 mmol) were added to a solution of acid
3a (31.7 mg, 0.16 mmol) and -lysophosphatidylcholine
(38.8 mg, 78 mol) in dry methylene chloride (4 mL). The resulting
lL, 0.23 mmol) and 2,6-dichloroben-
l
+
(
t, J = 7.2 Hz, 3H). HRMS (FAB): m/z calcd for C11
H20NaO
5
(MNa ),
L-a
2
55.1209; found, 255.1206.
l
mixture was stirred for 20 h at room temperature and monitored
by TLC for disappearance of starting material. Solvents were then
evaporated under reduced pressure and the residue purified by
4
.4. Ethyl (E)-4-hydroxy-7-oxohept-5-enoate (11)
Acetal 10 (5 mg, 0.02 mmol) was dissolved in acetone/
water = 2:1 (0.5 mL) and pyridinium p-toluenesulfonate (PPTS,
flash chromatography on a silica gel column (chloroform/metha-
1
nol/H O = 16:9:1, TLC: R = 0.23) to give 18a (41.5 mg, 78%).
2
f
H

5
84
J. Choi et al. / Bioorg. Med. Chem. 19 (2011) 580–587
NMR (400 MHz, CD
3
OD/CDCl
3
= 1:2) d 6.61 (dd, J = 16.2, 3.9 Hz,
4.11. Methyl (E)-8,8-diethoxy-5-oxooct-6-enoate (14b)
1
1
3
2
H), 6.36 (d, J = 16.2 Hz, 1H), 5.19 (m, 1H), 4.93 (m, 1H), 4.37 (m,
H), 4.34 (m, 1H), 4.14 (dd, J = 11.9, 6.4 Hz, 2H), 3.98 (m, 2H),
.83 (m, 2H), 3.37 (br s, 9H), 3.34 (s, 6H), 2.89 (m, 2H), 2.62 (m,
H), 2.27 (t, J = 7.6 Hz, 2H), 1.56 (m, 2H), 1.24 (24H), 0.87 (t,
The procedure was modified from that reported.21 Glutaric acid
monomethyl ester chloride (371
wise via syringe to a solution of stannane 4 (1.12 g, 2.68 mmol)
and PdCl (MeCN) (6.9 mg, 26.8 mol) in DMF (3 mL). The reaction
lL, 2.68 mmol) was added drop-
1
3
J = 7.0 Hz, 3H).
C NMR (100 MHz, CD
3
OD/CDCl
3
= 1:2) 198.1,
2
2
l
1
5
2
73.8, 172.3, 141.0, 131.8, 101.1, 76.9, 71.7, 71.6, 66.7, 63.7, 62.9,
9.5, 54.7, 53.3, 35.1, 34.3, 32.2, 29.9, 29.8, 29.7, 29.6, 29.5, 29.4,
8.1, 25.1, 22.3, 14.4. HRMS (FAB): m/z calcd for C33
mixture was then cooled in an ice bath and stirred for 1 h, and then
for 4 h at room temperature. Saturated aqueous sodium fluoride
and acetone were added to the brown-red reaction mixture to re-
move tributyltin chloride. The mixture was extracted with ethyl
acetate (3 Â 20 mL), followed by drying of the combined extracts
over anhydrous sodium sulfate. Solvent was evaporated under re-
duced pressure and the residue purified by flash chromatography
on a silica gel column (ethyl acetate/hexanes = 7:93) to give 14b
H
63NO11P
+
(
M ), 680.4139; found, 680.4131.
4
.8. (E)-2-(4-Hydroxy-7,7-dimethoxyhept-5-enoyl)-1-palmitoyl-
sn-glycero-3-phosphatidylcholine (2a)
Sodium borohydride (1.7 mg, 45.8
lmol) was slowly added at
(450 mg, 65%). TLC: (30% ethyl acetate/hexanes; R
NMR (400 MHz, CDCl ) d 6.62 (dd, J = 16, 4.4 Hz, 1H), 6.32 (dd,
= 0.38). 1
H
f
4
°C to a stirred solution of ester 18a (26 mg, 38
lmol) in dry meth-
3
ylene chloride (0.5 mL) and methanol (1 mL). Once complete, the
reaction mixture was neutralized with acetic acid, solvents were
evaporated under reduced pressure, and the residue purified by
J = 16.4, 1.2 Hz, 1H), 5.02 (m, 1H), 3.64 (s, 3H), 3.59–3.64 (m, 2H),
3.48–3.54 (m, 2H), 2.64 (t, J = 6.6 Hz, 2H), 2.34 (t, J = 7.2 Hz, 2H),
1.92 (tt, J = 7.2, 7.2 Hz, 2H), 1.20 (t, J = 7.2 Hz, 6H). 13C NMR
flash chromatography on a silica gel column (chloroform/metha-
3
(100 MHz, CDCl ) 199.6, 173.8, 141.5, 131.6, 99.7, 61.7, 51.8,
39.4, 33.2, 19.1, 15.4. HRMS (FAB): m/z calcd for C13H O (MH ),
23 5
1
+
nol/H
2
O = 11:9:1, TLC: R
f
= 0.27) to give 2a (22.1 mg, 85%).
H
NMR (400 MHz, CD
3
OD/CDCl
3
= 1:2) d 5.99 (dd, J = 16, 6 Hz, 1H),
259.1545; found, 259.1504.
5
1
.76 (dd, J = 16.4, 4.8 Hz, 1H), 5.34 (m, 1H), 4.89 (d, 1H), 4.51 (m,
H), 4.42 (m, 2H), 4.27 (dd, J = 12, 6.8 Hz, 2H), 4.12 (m, 2H), 3.82
4.12. Methyl (E)-8,8-diethoxy-5-hydroxyoct-6-enoate (15b)
(
2
(
1
5
2
m, 2H), 3.48 (s, 1H), 3.44 (br s, 9H), 3.37 (s, 6H), 2.56 (m, 2H),
.43 (m, 2H), 1.93 (m, 2H), 1.70 (m, 2H), 1.41 (24H), 0.98
Sodium borohydride (1.5 mg, 0.03 mmol) was added in small
portions over 2 min at 0 °C to a stirred solution of ester 14b
(10 mg, 0.03 mmol) in ethanol (1 mL). The reaction mixture was
stirred for 4 h and then quenched by addition of methanol to de-
stroy excess sodium borohydride. The mixture was neutralized to
pH 7 by addition of saturated sodium bicarbonate solution, fol-
lowed by addition of brine. The aqueous layer was extracted with
ethyl acetate, solvents were evaporated from the combined organic
extracts under reduced pressure, and the residue purified by flash
chromatography on a silica gel column (20% ethyl acetate/hexanes)
1
3
t, J = 6.8 Hz, 3H). C NMR (100 MHz, CD
3
OD/CDCl
73.0, 137.8, 128.6, 101.0, 76.9, 71.8, 71.6, 70.2, 66.4, 63.6, 62.9,
9.4, 54.7, 53.4, 35.1, 34.3, 32.1, 29.9, 29.8, 29.7, 29.6, 29.5, 29.4,
8.3, 25.2, 22.3, 14.4. HRMS (FAB): m/z calcd for C33
3
= 1:2) 173.8,
H63NNaO11P
+
(
(MÀH)Na ), 704.4115; found, 704.4119.
4
.9. (E)-2-(4-Hydroxy-7-oxohept-5-enoyl)-1-palmitoyl-sn-
glycero-3-phosphatidylcholine (HOHA-PC, 1a)
PPTS (1.3 mg, 5.1
(3.2 mg, 4.6 mol) in tetrahydrofuran/acetone/H
1 mL). The resulting mixture was stirred for 2 h at room tempera-
l
mol) was added to a stirred solution of ester
to give 15b (9.4 mg, 94%). TLC (45% ethyl acetate/hexanes,
1
2
(
a
l
2
O = 5:4:1
R
f
3
= 0.24): H NMR (400 MHz, CDCl ) d 5.86 (dd, J = 15.7, 6.0 Hz,
1H), 5.70 (ddd, J = 15.7, 5.0, 1.2 Hz, 1H), 4.89 (d, J = 5.0 Hz, 1H),
ture and monitored by TLC for disappearance of starting material.
Upon completion, the solvents were evaporated under reduced
pressure and the residue purified by flash chromatography on a sil-
4.12 (m, 1H), 3.68–3.58 (5H), 3.55–3.41 (m, 2H), 2.34 (m, 2H),
1.77–1.62 (3H), 1.62–1.50 (2H), 1.29–1.13 (6H). HRMS (FAB): m/z
+
calcd for C13
H24NaO
5
(MNa ), 283.1522; found, 283.1523.
ica gel column (chloroform/methanol/H
2
O = 11:9:1, TLC: R
OD/CDCl
f
= 0.2)
= 1:2)
to give 1a (2.9 mg, 97%). 1H NMR (400 MHz, CD
4.13. Methyl (E)-5-hydroxy-8-oxooct-6-enoate (16)
3
3
d 9.54 (d, J = 8 Hz, 1H), 6.92 (dd, J = 15.6, 4.4 Hz, 1H), 6.29 (dd,
J = 16, 8 Hz, 1H), 5.21 (m, 1H), 4.35 (m, 1H), 4.28 (m, 2H), 4.13
Acetal 15b (9.4 mg, 0.03 mmol) was dissolved in acetone/
water = 2:1 (1 mL), PPTS (10 mg, 0.033 mmol) was added, and the
mixture stirred at room temperature for 2 h. After completion, sol-
vents were evaporated under reduced pressure and the residue
purified by flash chromatography on a silica gel column (20% ethyl
(
2
(
m, 2H), 3.98 (m, 2H), 3.65 (m, 2H), 3.30 (s, 9H), 2.43–2.62 (m,
H), 2.27–2.34 (m, 2H), 1.80–1.97 (m, 2H), 1.57 (m, 2H), 1.23
24H), 0.85 (t, J = 6.8 Hz, 3H). HRMS (FAB): m/z calcd for
+
31
C H59NNaO10P (M+H ), 636.3876; found, 636.3850.
acetate/hexanes) to give 16 (5.9 mg, 88%). TLC (45% ethyl acetate/
1
4
.10. 1-Tributylstannyl-3,3-diethoxy-prop-1-ene (4)
hexanes,
R
f
= 0.20):
3
H NMR (400 MHz, CDCl ) d 9.58 (d,
J = 7.8 Hz, 1H), 6.81 (dd, J = 15.7, 4.5 Hz, 1H), 6.32 (ddd, J = 15.7,
7.8, 1.6 Hz, 1H), 4.45 (br s, –OH), 4.13 (q, J = 7.1 Hz, 1H), 3.67 (s,
According to the published procedure,21 3,3-diethoxy-1-propy-
ne (0.97 mL, 6.8 mmol) was added dropwise via syringe to a THF
solution of Bu SnCu(Bu)CNLi , and the reaction mixture was stir-
red for 2 h under À78 °C before quenching with water. The dark
solution was extracted with ether (3 Â 20 mL), followed by drying
of the combined extracts over anhydrous sodium sulfate. The sol-
vents were evaporated under reduced pressure and the residue
3H), 2.47–2.26 (2H), 1.86–1.51 (2H), 1.35–1.08 (2H). HRMS
+
3
2
(FAB): m/z calcd for C
167.0722.
H
9 13
O
3
2
(MH ÀH O), 167.0709; found,
4.14. (E)-3-(6-Oxotetrahydro-2H-pyran-2-yl)acrylaldehyde (17)
purified by flash chromatography on a silica gel column (ethyl ace-
Amberlyst-15 (10 mg) was added in small portions to a stirred
solution of acetal 15b (16 mg, 0.06 mmol) in TFA/water = 95:5
(1.5 mL) and the mixture was stirred at room temperature for
1.5 h. Solvents were then evaporated under reduced pressure and
the residue purified by flash chromatography on a silica gel column
1
tate/hexanes = 3:97, TLC: R
400 MHz, CDCl
f
= 0.28) to give 4 (2.56 g, 81%). H NMR
(
3
) d 6.40–6.26 (m, 1H), 6.03–5.88 (m, 1H), 4.89–
.72 (m, 1H), 3.63 (dq, J = 9.5, 7.1 Hz, 3H), 3.49 (dq, J = 9.5, 7.1 Hz,
H), 1.57–1.40 (9H), 1.36–1.25 (9H), 1.24–1.14 (6H), 0.93–0.80
4
3
1
(
9H). The H NMR spectral data for stannane 4 is in agreement with
(45% ethyl acetate/hexanes) to give lactone 17 (8.2 mg, 87%). TLC
3
0
1
that reported previously.
(50% ethyl acetate/hexanes, R
f
= 0.1): H NMR (400 MHz, CDCl
3
) d

J. Choi et al. / Bioorg. Med. Chem. 19 (2011) 580–587
585
9
.61 (d, J = 7.5 Hz, 1H), 6.76 (dd, J = 15.8, 4.3 Hz, 1H), 6.37 (ddd,
J = 15.8, 7.6, 1.7 Hz, 1H), 5.19–5.04 (m, 1H), 2.76–2.62 (m, 1H),
.55 (m, 1H), 2.18–2.05 (m, 1H), 2.06–1.87 (m, 2H), 1.83–1.64
1H), 5.62 (dd, J = 15.6, 6 Hz, 1H), 5.21 (m, 1H), 4.86 (d, 1H), 4.37
(m, 1H), 4.22 (m, 2H), 4.13 (dd, J = 12.4, 7.2 Hz, 2H), 4.07 (m, 1H),
3.64 (m, 2H), 3.47–3.59 (4H), 3.16 (br s, 9H), 2.27–2.36 (4H), 1.68
2
+
(
m, 1H). HRMS (TOF-MS/ESI): m/z calcd for C
8
H10NaO
3
(MNa ),
(m, 2H), 1.52–1.57 (4H), 1.16–1.26 (30H), 0.85 (t, J = 6.8 Hz, 3H).
77.0528; found, 177.0529. 1H NMR spectral data for 17 is in
13
1
3 3
C NMR (100 MHz, CD OD/CDCl = 1:2) 174.1, 173.4, 137.1,
28
agreement with that reported previously.
127.3, 101.6, 70.8, 70.6, 66.5, 63.8, 62.6, 61.5, 59.2, 54.0, 36.3,
6.2, 34.0, 33.9, 32.0, 29.7, 29.5, 29.4, 29.3, 29.2, 24.9, 22.7, 20.9,
3
+
4
.15. (E)-8,8-Diethoxy-5-oxooct-6-enoic acid (3b)
14.9, 13.9. HRMS (FAB): m/z calcd for C36H70NNaO11P (MNa ),
7
46.4584; found, 746.4584
The acid 3b was prepared using a solution of ester 14b
(
(
118.5 mg, 0.45 mmol) in PBS (pH 7.4, 50 mM, 8 mL) and methanol
1 mL) to increase solubility at room temperature. Porcine pancre-
4
.18. (E)-2-(5-Hydroxy-8-oxooct-6-enoyl)-1-palmitoyl-sn-
glycero-3-phosphatidylcholine (HOOA-PC, 1b)
atic lipase (PPL, type II, crude, 100 mg), then sodium chloride
20 mg) and calcium chloride (40 mg) were added. The pH of the
(
PPTS (4.6 mg, 18.4
ter 2b (11.1 mg, 15.3
O = 5:4:1 (2 mL), the resulting mixture was stirred for 4 h at
lmol) was added to a stirred solution of es-
reaction mixture was maintained at 7.0–7.2 by addition of sodium
hydroxide solution (0.1 N). After completion, solvents were evapo-
rated under reduced pressure, the residue extracted with chloro-
form/methanol (2:1, v/v), filtered, and dried using anhydrous
magnesium sulfate. Solvents were evaporated from the combined
organic extracts under reduced pressure and the residue purified
by flash chromatography on a silica gel column (chloroform/meth-
anol = 20:1) to give 3b (65 mg, 58%). TLC (chloroform/methanol/
l
mol) in tetrahydrofuran/acetone/
H
2
room temperature, and monitored by TLC for disappearance of
starting material. Upon completion, solvents were evaporated un-
der reduced pressure and the residue purified by flash chromatog-
raphy on a silica gel column (chloroform/methanol/H
2
O = 11:9:1,
= 0.18) to give 1b (8.4 mg, 85%). H NMR (400 MHz,
OD/CDCl = 1:2) d 9.53 (d, J = 8 Hz, 1H), d 6.93 (dd, J = 15.6,
.4 Hz, 1H). 6.29 (ddd, J = 15.6, 8, 1.6 Hz, 1H), 5.21 (m, 1H), 4.36
m, 2H), 4.11–4.26 (4H), 3.99 (m, 2H), 3.58 (m, 2H), 3.30 (s, 9H),
.39 (m, 2H), 2.31 (m, 2H), 1.57–1.77 (6H), 1.57 (m, 2H), 1.26
24H), 0.85 (t, J = 6.8 Hz, 3H). HRMS (FAB): m/z calcd for
1
TLC: R
CD
4
(
2
f
3
3
H
2
O = 80:19:1, R
J = 16.2, 4 Hz, 1H), 6.34 (dd, J = 16, 1.2 Hz, 1H), 5.05 (dd, J = 4.2,
.6 Hz, 1H), 3.63–3.69 (m, 2H), 3.50–3.56 (m, 2H), 2.69 (t,
J = 7.2 Hz, 2H), 2.43 (t, J = 6.8 Hz, 2H), 1.95 (tt, J = 7.2, 7.2 Hz, 2H),
= 0.51): 1H NMR (400 MHz, CDCl
) d 6.65 (dd,
f 3
1
(
1
1
.24 (t, J = 7.2 Hz, 6H). 13C NMR (100 MHz, CDCl
41.6, 131.6, 99.7, 61.8, 39.3, 33.2, 18.8, 15.4. HRMS (FAB): m/z
3
) 199.7, 179.2,
+
C
32
H61NO10P (MH ), 650.4033; found, 650.4030.
+
21 5
calcd for C12H O (MH ), 245.1389; found, 245.1382.
4
.19. Methyl 9-(chlorocarbonyl)octanoate (5c)
4
.16. (E)-2-(8,8-Diethoxy-5-oxooct-6-enoyl)-1-palmitoyl-sn-
Monomethyl azelate (500 mg, 2.4 mmol) was added dropwise
via syringe to a solution of oxalyl chloride (300 mg, 3.5 mmol,
.5 equiv) in benzene (3 mL). The reaction mixture was stirred
for 30 min at room temperature and then refluxed for 2 h, after
which time no acid starting material was detected by IR. Upon
completion, the solvent was evaporated under reduced pressure
glycero-3-phosphatidylcholine (18b)
1
1
-Methylimidazole (11.5
hlorobenzoylchloride (22.7 L, 0.16 mmol) were added to a solution
of acid 3b (31.7 mg, 0.16 mmol) and -2-lysophophatidylcholine
23.5 mg, 96 mol) in dry methylene chloride (4 mL). The resulting
lL, 0.14 mmol) and 2,6-dic-
l
L
(
l
and the residue purified by vacuum distillation to give 5c
mixture was stirred for 17 h at room temperature and monitored
by TLC for disappearance of the starting material. Solvents were then
evaporated under reduced pressure and the residue purified by flash
chromatography on a silica gel column (chloroform/methanol/
H
À1
(
1
2
491 mg, 90%). IR (film, cm ) 2943, 2861, 1811, 1733, 1462,
1
434, 1251, 1205. H NMR (400 MHz, CDCl
3
) d 3.66 (s, 3H), d
.87 (m, 2H), 2.30 (m, 2H), 1.65 (m, 2H), 1.60 (m, 2H), 1.35 (6H).
1
2
O = 16:9:1, TLC: R
f
= 0.34) to give 18b (25.6 mg, 74%). H NMR
(
(
(
(
(
400 MHz, CD OD/CDCl
3
3
= 1:2) d 6.64 (dd, J = 16.2, 4.0 Hz, 1H), 6.33
4.20. Methyl (E)-12,12-diethoxy-9-oxododec-10-enoate (14c)
dd, J = 16.0, 1.2, 1H), 5.21 (m, 1H), 5.04 (m, 1H), 4.39 (m, 1H), 4.25
m, 2H), 4.13 (dd, J = 12.0, 5.2 Hz, 2H), 4.00 (m, 2H), 3.61–3.69
4H), 3.49–3.57 (m, 2H), 3.30 (br s, 9H), 2.70 (t, J = 6.8 Hz, 2H), 2.37
t, J = 6.8 Hz,2H), 2.29 (t, J = 7.2 Hz, 2H), 1.89 (m, 2H), 1.57 (m, 2H),
The procedure was modified from that reported.21 1-Tributyl-
stannyl-3,3-diethoxy-prop-1-ene (4, 380 mg, 0.9 mmol) was added
dropwise via syringe to a solution of acyl chloride 5c (200 mg,
1
CDCl
6
2
.22 (30H), 0.85 (t, J = 6.8 Hz, 3H). 13C NMR (100 MHz, CD
3
OD/
= 1:2) 200.5, 174.1, 172.9, 141.8, 131.3, 99.8, 70.8, 66.5, 63.9,
2 2
0.9 mmol) and PdCl (MeCN) (2.3 mg, 9 lmol) in DMF (1.5 mL)
and the reaction mixture stirred first for 1 h in an ice bath and then
3 h at room temperature. Saturated aqueous sodium fluoride and
acetone were added to the brown-red reaction mixture to remove
tributyltin chloride. The mixture was extracted with ethyl acetate
3
2.6, 61.9, 59.3, 54.0, 39.2, 34.1, 33.2, 32.0, 29.8, 29.7, 29.6, 29.5,
9.4, 29.3, 29.2, 24.9, 22.7, 18.9, 14.9, 13.8. HRMS (FAB): m/z calcd
+
for C33
H
69NO11P (MH ), 722.4608; found, 722.4589.
(
3 Â 20 mL), followed by drying of the combined extracts over
4
.17. (E)-2-(5-Hydroxy-8,8-diethoxyoct-6-enoyl)-1-palmitoyl-
anhydrous sodium sulfate. Solvents were evaporated from the or-
ganic extracts under reduced pressure and the residue purified
by flash chromatography on a silica gel column (ethyl acetate/hex-
sn-glycero-3-phosphatidylcholine (2b)
Sodium borohydride (1.9 mg, 50
°C to a stirred solution of ester 18b (33.4 mg, 46
l
mol) was slowly added at
mol) in dry
anes = 7:93) to give 14c (171 mg, 60%). TLC (30% ethyl acetate/hex-
1
4
l
anes; R
f
= 0.51). H NMR (400 MHz, CDCl
3
) d 6.62 (dd, J = 16.1,
methylene chloride (1 mL) and methanol (2 mL). Once complete,
the reaction mixture was neutralized with acetic acid, solvents
were evaporated under reduced pressure, and the residue purified
4.3 Hz, 1H), 6.33 (dd, J = 16.1, 1.3 Hz, 1H), 5.04 (dd, J = 4.3, 1.3 Hz,
1H), 3.76–3.59 (m, 5H), 3.59–3.43 (m, 2H), 2.64 (t, J = 6.6 Hz, 2H),
2.34 (t, J = 7.2 Hz, 2H), 1.92 (p, J = 7.2 Hz, 2H), 1.20 (t, J = 7.2 Hz,
1
3
by flash chromatography on a silica gel column (chloroform/meth-
3
6H). C NMR (100 MHz, CDCl ) 200.8, 174.5, 141.1, 131.8, 99.8,
1
anol/H
2
O = 11:9:1, TLC: R
f
= 0.22) to give 2b (32.8 mg, 98%).
H
61.7, 51.7, 40.6, 34.3, 29.2, 25.09, 24.06, 15.54, 15.43. HRMS
+
NMR (400 MHz, CD
3
OD/CDCl
3
= 1:2) d 5.81 (dd, J = 15.6, 6 Hz,
31 5
(FAB): m/z calcd for C17H O (MH ), 315.2171; found, 315.2175.

5
86
J. Choi et al. / Bioorg. Med. Chem. 19 (2011) 580–587
4
.21. (E)-12,12-Diethoxy-9-oxododec-10-enoic acid (3c)
4.24. (E)-(9-Hydroxy-12-oxodec-10-enoyl)-1-palmitoyl-sn-
glycero-3-phosphatidylcholine (HODA-PC, 1c)
The acid was prepared using a solution of ester 14c (88.7 mg,
0
.28 mmol) in PBS (pH 7.4, 50 mM, 8 mL) and methanol (1 mL) to
PPTS (5.6 mg, 22.2
lmol) was added to a stirred solution of es-
increase solubility at room temperature. Porcine pancreatic lipase
type II, crude, 100 mg), sodium chloride (20 mg), and calcium
chloride (40 mg) were added. The pH of the reaction mixture was
maintained at 7.0–7.2 by addition of sodium hydroxide solution
ter 2c (14.5 mg, 18.6
l
mol) in tetrahydrofuran/acetone/H O =
2
(
5:4:1 (2 mL). The resulting mixture was stirred for 5 h at room
temperature and monitored by TLC for disappearance of starting
material. Upon completion, solvents were evaporated under re-
duced pressure and the residue purified by flash chromatography
(
0.1 N). Upon completion, solvents were evaporated under reduced
pressure, the residue extracted with chloroform/methanol (2:1,
v/v), filtered, and dried with anhydrous magnesium sulfate. Solvents
were evaporated from the combined organic extracts under reduced
pressureand theresiduepurifiedbyflashchromatography ona silica
on a silica gel column (chloroform/methanol/H
2
O = 11:9:1, TLC:
= 0.4) to give 1c (11.8 mg, 90%). H NMR (400 MHz, CD OD +
CDCl ) d 9.52 (d, J = 8 Hz, 1H), 6.91 (dd, J = 15.6, 4.8 Hz, 1H), 6.26
1
R
f
3
3
(ddd, J = 15.6, 8, 1.6 Hz, 1H), 5.20 (m, 1H), 4.38 (m, 1H), 4.31 (m,
gel column (chloroform/methanol = 15:1) to give 3c (56 mg, 67%).
1H), 4.22 (m, 2H), 4.14 (m, 1H), 3.97 (m, 2H), 3.58 (m, 2H), 3.30
1
TLC (chloroform/methanol/H
400 MHz, CDCl
1
3
2
1
2
O = 80:19:1,
R
f
= 0.70):
H
NMR
(s, 9H), 2.27–2.33 (4H), 1.57 (7H), 1.23–1.31 (31H), 0.85 (t,
+
(
3
) d 6.61 (dd, J = 16, 4.4 Hz, 1H), 6.33 (dd, J = 16,
.2 Hz, 1H), 5.04 (dd, J = 4.4, 1.2 Hz, 1H), 3.65–3.66 (m, 2H), 3.50–
.56 (m, 2H), 2.56 (t, J = 7.6 Hz, 2H), 2.33 (t, J = 7.2 Hz, 2H), 1.60 (m,
H), 1.30 (6H), 1.22 (6H). 13C NMR (100 MHz, CDCl
) 200.9, 179.8,
41.2, 131.8, 99.8, 61.7, 40.5, 34.2, 29.2, 29.1, 29.0, 24.8, 24.1, 15.4.
J = 6.8 Hz, 3H). HRMS (FAB): m/z calcd for C36
688.4548; found, 688.4583.
H67NO
9
P (MH ÀH
2
O),
3
Acknowledgment
+
28 5
HRMS (FAB): m/z calcd for C16H O (M ), 300.1937; found,
We are grateful for support of this work by National Institutes
of Health Grants RO1-GM021249, RO1-EY016813, and RO1-
HL053315.
3
00.1930.
4
.22. (E)-2-(12,12-Diethoxy-9-oxododec-10-enoyl)-1-palmitoyl-
sn-glycero-3-phosphatidylcholine (18c)
Supplementary data
1
-Methylimidazole (10.6
zoyl chloride (20.9 L, 0.14 mmol) were added to a solution of acid
c (20 mg, 0.06 mmol) and -lysophophatidylcholine (22 mg,
.04 mmol) in dry methylene chloride (4 mL). The resulting mixture
lL, 0.13 mmol) and 2,6-dichloroben-
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmc.2010.10.058.
l
3
0
L-a
References and notes
was stirred for 24 h at room temperature and monitored by TLC for
disappearance of starting material. The mixture was evaporated un-
der reduced pressure and the residue purified by flash chromatogra-
1.
Gu, X.; Sun, M.; Gugiu, B.; Hazen, S.; Crabb, J. W.; Salomon, R. G. J. Org. Chem.
003, 68, 3749.
2
phy on a silica gel column (chloroform/methanol/H
2
O = 16:9:1, TLC:
= 0.34) to give 18c (24.5 mg, 71%). H NMR (400 MHz, CD OD/
CDCl = 1:2) d 6.61 (dd, J = 16.1, 4.4 Hz, 1H), 6.32 (dd, J = 16.1,
.2 Hz, 1H), 5.20 (m, 1H), 5.04 (m, 1H), 4.39 (m, 1H), 4.23 (dt,
J = 11.8, 6.0 Hz, 2H), 4.13 (dd, J = 11.9, 6.8 Hz, 1H), 3.95 (m, 2H),
2. Sun, M.; Deng, Y.; Batyreva, E.; Sha, W.; Salomon, R. G. J. Org. Chem. 2002, 67,
1
3575.
R
f
3
3
4
.
.
Deng, Y.; Salomon, R. G. J. Org. Chem. 1998, 63, 7789.
Kaur, K.; Salomon, R. G.; O’Neil, J.; Hoff, H. F. Chem. Res. Toxicol. 1997, 10, 1387.
3
1
5. Sayre, L. M.; Sha, W.; Xu, G.; Kaur, K.; Nadkarni, D.; Subbanagounder, G.;
Salomon, R. G. Chem. Res. Toxicol. 1996, 9, 1194.
6
7
.
.
Podrez, E. A.; Poliakov, E.; Shen, Z.; Zhang, R.; Deng, Y.; Sun, M.; Finton, P. J.;
Shan, L.; Febbraio, M.; Hajjar, D. P.; Silverstein, R. L.; Hoff, H. F.; Salomon, R. G.;
Hazen, S. L. J. Biol. Chem. 2002, 277, 38517.
Podrez, E. A.; Poliakov, E.; Shen, Z.; Zhang, R.; Deng, Y.; Sun, M.; Finton, P. J.;
Shan, L.; Gugiu, B.; Fox, P. L.; Hoff, H. F.; Salomon, R. G.; Hazen, S. L. J. Biol. Chem.
3
.72–3.46 (6H), 3.26 (br s, 9H), 2.59 (t, J = 7.4 Hz, 2H), 2.30 (4H),
13
1
.58 (6H), 1.33–1.09 (36H), 0.85 (t, J = 6.8 Hz, 3H).
C NMR
(
100 MHz, CD
3
OD/CDCl = 1:2) 200.9, 174.1, 173.6, 141.5, 141.1,
3
1
3
2
7
31.9, 99.8, 68.3, 67.0, 62.6, 62.1, 61.9, 57.5, 54.0, 40.5, 35.6, 34.2,
4.1, 32.0, 29.7, 29.6, 29.4, 29.3, 29.1, 29.0, 28.9, 24.9, 24.8, 23.9,
2.7, 17.7, 14.9, 13.9. HRMS (FAB): m/z calcd for C40
78.5229; found, 778.5124.
2002, 277, 38503.
8. Podrez, E. A.; Byzova, T. V.; Febbraio, M.; Salomon, R. G.; Ma, Y.; Valiyaveettil,
M.; Poliakov, E.; Sun, M.; Finton, P. J.; Curtis, B. R.; Chen, J.; Zhang, R.;
Silverstein, R. L.; Hazen, S. L. Nat. Med. 2007, 13, 1086.
+
H
77NO11P (M ),
9.
Ashraf, M. Z.; Kar, N. S.; Chen, X.; Choi, J.; Salomon, R. G.; Febbraio, M.; Podrez,
E. A. J. Biol. Chem. 2008, 283, 10408.
4
.23. (E)-2-(9-Hydroxy-12,12-diethoxydodec-10-enoyl)-1-
10. Subbanagounder, G.; Deng, Y.; Borromeo, C.; Dooley, A. N.; Berliner, J. A.;
Salomon, R. G. Vasc. Pharmacol. 2002, 38, 201.
palmitoyl-sn-glycero-3-phosphatidylcholine (2c)
1
1
1. Watson, A. D.; Leitinger, N.; Navab, M.; Faull, K. F.; Horkko, S.; Witztum, J. L.;
Palinski, W.; Schwenke, D.; Salomon, R. G.; Sha, W.; Subbanagounder, G.;
Fogelman, A. M.; Berliner, J. A. J. Biol. Chem. 1997, 272, 13597.
2. Leitinger, N.; Tyner, T. R.; Oslund, L.; Rizza, C.; Subbanagounder, G.; Lee, H.;
Shih, P. T.; Mackman, N.; Tigyi, G.; Territo, M. C.; Berliner, J. A.; Vora, D. K. Proc.
Natl. Acad. Sci. U.S.A. 1999, 96, 12010.
Sodium borohydride (1.4 mg, 37
lmol) was slowly added at
4
°C to a stirred solution of ester 18c (24.5 mg, 31.4
l
mol) in dry
methylene chloride (1 mL) and methanol (2 mL). Upon completion,
the reaction mixture was neutralized with glacial acetic acid. Sol-
vents were evaporated under reduced pressure, and residue puri-
fied by flash chromatography on a silica gel column (chloroform/
13. Lee, H.; Shi, W.; Tontonoz, P.; Wang, S.; Subbanagounder, G.; Hedrick, C. C.;
Hama, S.; Borromeo, C.; Evans, R. M.; Berliner, J. A.; Nagy, L. Circ. Res. 2000, 87,
516.
1
1
1
4. Subbanagounder, G.; Watson, A. D.; Berliner, J. A. Free Radical Biol. Med. 2000,
methanol/H
2
O = 11:9:1, TLC: R
f
= 0.30) to give 2c (20.5 mg, 87%).
= 1:2) d 5.80 (dd, J = 15.6,
28, 1751.
1
5. Hoff, H. F.; O’Neil, J.; Wu, Z.; Hoppe, G.; Salomon, R. L. Arterioscler. Thromb. Vasc.
Biol. 2003, 23, 275.
6. Hollyfield, J. G.; Bonilha, V. L.; Rayborn, M. E.; Yang, X.; Shadrach, K. G.; Lu, L.;
Ufret, R. L.; Salomon, R. G.; Perez, V. L. Nat. Med. 2008, 14, 194.
H NMR (400 MHz, CD OD/CDCl
3
3
6
1
.4 Hz, 1H), 5.60 (dd, J = 15.6, 6.4 Hz, 1H), 5.21 (m, 1H), 4.86 (m,
H), 4.41 (m, 1H), 4.26 (m, 2H), 4.13 (dd, J = 12, 6.8 Hz, 1H), 4.04
(
(
(
7
3
1
8
m, 1H), 3.96 (m, 2H), 3.71–3.41 (6H), 3.18 (br s, 9H), 2.27–2.33
17. Kobayashi, Y.; Kishihara, K.; Watatani, K. Tetrahedron Lett. 1996, 37, 4385.
18. Taylor, E. C.; Chiang, C.-S. Synthesis 1977, 467.
4H), 1.58 (8H), 1.16–1.29 (36H), 0.85 (t, J = 6.8 Hz, 3H). 1 C NMR
3
1
2
9. Beaudet, I.; Parrain, J.; Quintard, J. Tetrahedron Lett. 1991, 32, 6333.
0. Lipshutz, B. H.; Ellsworth, E. L.; Dimock, S. H.; Reuter, D. C. Tetrahedron Lett.
1989, 30, 2065.
100 MHz, CD
3
OD/CDCl
1.4, 70.5, 66.5, 63.8, 62.7, 61.4, 59.2, 54.0, 40.3, 37.1, 34,2, 34.1,
2.0, 29.7, 29.6, 29.4, 29.3, 29.1, 29.0, 28.9, 24.9, 24.8, 22.7, 15.0,
3
= 1:2) 174.1, 173.6, 137.6 127.0, 101.7,
21. Parrain, J.; Beaudet, I.; Duchene, A.; Watrelot, S.; Quintard, J. Tetrahedron Lett.
1993, 34, 5445.
+
4.9, 13.9. HRMS (FAB): m/z calcd for C40H78NNaO11P (MNa ),
22. Rodriguez, A.; Nomen, M.; Spur, B.; Godfroid, J. Eur. J. Org. Chem. 1999, 2655.
02.5210; found, 802.5217.
23. Acharya, H. P.; Kobayashi, Y. Synlett 2005, 2015.

J. Choi et al. / Bioorg. Med. Chem. 19 (2011) 580–587
587
2
2
2
2
4. Gaffney, P. R.; Reese, C. B. J. Chem. Soc., Perkin Trans. 1 2001, 192.
5. Abell, A. D.; Morris, K. B.; Litten, J. C. J. Org. Chem. 1990, 55, 5217.
6. Micovic, I. V.; Ivanovic, M. D.; Piatak, D. M. J. Serb. Chem. Soc. 1988, 53, 419.
7. Uno, T.; Ku, J.; Prudent, J. R.; Huang, A.; Schultz, P. G. J. Am. Chem. Soc. 1996, 118,
28. Yeh, M. P.; Chuang, L.; Hsieh, Y.; Tsai, M. Chem. Commun. 1999, 805.
29. Gu, X.; Zhang, W.; Salomon, R. G. J. Am. Chem. Soc. 2007, 129, 6088.
30. Parrain, J.; Duchene, A.; Quintard, J. J. Chem. Soc., Perkin Trans.
187.
1
1990,
3
811.