Efficient stereospecific synthesis of diamide analogs of phosphatidylcholine starting from 1-(4'-methoxyphenyl)-sn-glycerol

Full text of DOI:10.1021/jo961422n

8706
J . Org. Chem. 1996, 61, 8706-8708
Sch em e 1. Syn th esis of Dia m id e An a logs of
Efficien t Ster eosp ecific Syn th esis of
Dia m id e An a logs of P h osp h a tid ylch olin e
Sta r tin g fr om
P h osp h a tid ylch olin e (1)
1-(4′-Meth oxyp h en yl)-sn -glycer ol
Hoe-Sup Byun and Robert Bittman*
Department of Chemistry and Biochemistry, Queens College
of The City University of New York,
Flushing, New York 11367-1597
Received J uly 25, 1996
Amide analogs of diacylglycerophosphocholines are of
1
interest as inhibitors of phospholipase A2 and as poten-
tial anti-HIV2 and antitumor agents.3 Synthetic amide-
linked lipids have been used to investigate the influence
of lipid structure on lipid movement in bilayer mem-
branes.4,5 Low-yielding achiral syntheses of 1,2-bis-
(acylamino)-1,2-dideoxy-sn-glycerophosphocholine (1) have
been reported starting from 2,3-dibromopropanol,2 2,3-
dibromopropionic acid,5,6 and L-asparagine.6 We report
here an efficient chiral synthesis of 1 starting from
readily available 1-(4′-methoxyphenyl)-sn-glycerol (2);7 2′,
the enantiomer of 2, afforded 2,3-diamido-1-propanol
(4c′), which can be converted into the enantiomer of 1.
Resu lts a n d Discu ssion
In t r od u ct ion of Tw o Am id e Gr ou p s in t o sn -
Glycer ol Der iva tive 2. In order to synthesize optically
active diamide analogs of phosphocholine we chose 1-(4′-
methoxyphenyl)-sn-glycerol (2) as the starting material.
The protected glycerol 2 was prepared by asymmetric
dihydroxylation7a of allyl 4-methoxyphenyl ether using
AD-mix supplemented with potassium persulfate.7b Glyc-
erol 2 was converted to the dimesylate by using meth-
anesulfonyl chloride in the presence of pyridine (Scheme
1). The dimesylate was subjected to a SN2 reaction in a
suspension of sodium azide in DMF. The diazide was
converted to the long-chain diamide by the reduction of
azide groups with triphenylphosphine-water8 followed
by in-situ acylation of the resulting diamine with an
excess of 4-nitrophenyl stearate, 4-nitrophenyl palmitate,
or 4-nitrophenyl caprylate in THF to give diamide 3.
Recrystallization of 3 in THF-acetone provided pure
diamidopropyl aryl ether 3 in 68-76% overall yield from
glycerol 2.
into the glycerol backbone of 3, the 4-methoxyphenyl
group was removed by using CAN.7b,9 The removal of
the 4-methoxyphenyl group by CAN is usually carried
out in CH3CN-H2O solution.7b,9 Due to the poor solubility
of diamidopropyl aryl ether 3 in this solvent system, it
was necessary to carry out the deprotection in another
solvent. We found that CHCl3-MeOH 1:1 was a suitable
solvent system for this purpose in the presence of 3 equiv
of CAN. The removal of the 4-methoxyphenyl group
provided 2,3-diamidopropanol 4 in 73-89% yield.
In ser tion of th e P h osp h och olin e Moiety in to
Dia m id op r op a n ol 4. It has been reported that phos-
phorylation reactions of rac-diamidopropanol 4 by using
â-bromoethyl phosphodichloridate or 2-chloro-1,3,2-dioxa-
phospholane followed by introduction of the quaternary
N+Me3 salt provide rac-1,2-bis(acylamino)-1,2-dideoxy-
glycerophosphocholines 1 in only about 12%6 and 40%2
yields, respectively. Instead, we chose to phosphitylate
3 using commercially available ethylene chlorophos-
phite.10 Our procedure, in which the phosphocholine
moiety is inserted into diamidopropanol 4 by use of
trivalent phosphorus, provided a higher yield (65-70%
overall yield from 4) than those obtained with penta-
valent phosphorus.
Dep r otection of th e 4-Meth oxyp h en yl Gr ou p .
After the desired diamido groups had been introduced
* To whom correspondence should be addressed. Tel.: (718) 997-
3279. Fax: (718) 997-3349. E-mail: bittman@qcvaxa.acc.qc.edu.
(1) (a) Yu, L.; Deems, R. A.; Hajdu, J .; Dennis, E. A. J . Biol. Chem.
1990, 265, 2657-2664. (b) Dijkman, R.; Dekker, N.; De Haas, G. H.
Biochim. Biophys. Acta 1990, 1043, 67-74. (c) Dijkman, R.; Cox, R.;
Van den Berg, L.; Verheij, H. M.; De Haas, G. H. Biochim. Biophys.
Acta 1994, 1212, 50-58.
(2) J ia, C.; Haines, A. H. J . Chem. Soc., Perkin Trans. 1 1993, 2521-
2523.
(3) Marx, M. H.; Piantadosi, C.; Noseda, A.; Daniel, L. W.; Modest,
E. J . J . Med. Chem. 1988, 31, 858-863.
(4) Kan, C.-C.; Bittman, R.; Hajdu, J . Biochim. Biophys. Acta 1991,
1066, 95-101.
(5) Moss, R. A.; Li, J .-M.; Kotchevar, A. T. Langmuir 1994, 10,
3380-3382.
(6) Sunamoto, J .; Goto, M.; Iwamoto, K.; Kondo, H.; Sato, T. Biochim.
Biophys. Acta 1990, 1024, 209-219.
(7) (a) For a recent review, see: Kolb, H. C.; VanNieuwenhze, M.
S.; Sharpless, K. B. Chem. Rev. 1994, 94, 2483-2547. (b) Byun, H.-S.;
Kumar, E. R.; Bittman, R. J . Org. Chem. 1994, 59, 2630-2633.
(8) For a review about the Staudinger reaction, see: Gololobov, Y.
G.; Zhmurova, I. N.; Kasukhin, L. F. Tetrahedron 1981, 37, 437-472.
(9) Vilche`ze, C.; Bittman, R. J . Lipid Res. 1994, 35, 734-738.
(10) Erukulla, R. K.; Byun, H.-S.; Bittman, R. Tetrahedron Lett.
1994, 35, 5783-5784.
S0022-3263(96)01422-3 CCC: $12.00 © 1996 American Chemical Society

Notes
J . Org. Chem., Vol. 61, No. 24, 1996 8707
the reaction mixture was concentrated to give a residue that
was dissolved in CHCl3 and filtered through a pad of silica gel
(elution with CHCl3) to remove triphenylphosphine oxide. The
1,2-diaminopropyl 4′-methoxyphenyl ether was eluted with
CHCl3-CH3OH-NH4OH 65:35:8, concentrated, and then re-
acted with 4-nitrophenyl caprylate. The product was purified
by column chromatography on silica gel (elution with CHCl3-
Exp er im en ta l Section
Gen er a l Meth od s. Melting points are uncorrected. 1H NMR
and 13C NMR spectra were recorded in CDCl3 at 400 and 100
MHz, respectively. FAB HRMS were obtained at Michigan State
University. Optical rotations were measured in a cell of 1-dm
pathlength. TLC was carried out with silica gel GF (250 µm)
glass plates from Analtech (Newark, DE) and silica gel 60
aluminum sheets from EM Separations (Gibbstown, NJ ). The
compounds were visualized by heating with phosphorus spray,
iodine chamber, and/or short-wavelength UV light. For flash
chromatography, silica gel 60 (230-400 ASTM mesh) was used
(purchased from Aldrich). Solvents were dried as follows: CH2-
Cl2 was distilled from CaH2; C6H6 was washed with concentrated
H2SO4 and water, dried over CaCl2, and then distilled over
sodium metal; and pyridine and DMF were dried by refluxing
over BaO followed by distillation just before use. 1- and 3-(4′-
methoxyphenyl)-sn-glycerol (2 and 2′)7b and 4-nitrophenyl es-
ters11 were prepared by the methods described earlier.
MeOH 50:1) to give 3c as a white solid: mp 97-98 °C; [R]25
D
+19.89° (c 2.0, CHCl3); 1H NMR δ 6.89 (d, 1H, J ) 6.7 Hz), 6.85-
6.78 (m, 4H), 6.69 (bs, 1H), 4.30 (bs, 1H), 4.06-4.03 (dd, 1H, J
) 3.8, 9.6 Hz), 3.86-3.84 (dd, 1H, J ) 6.4, 9.6 Hz), 3.75 (s, 3H),
3.70-3.62 (m, 1H), 3.46-3.42 (m, 1H), 2.19 (t, 4H, J ) 7.6 Hz),
1.62-1.60 (m, 4H), 1.25 (s, 16H), 0.88 (t, 6H, J ) 6.6 Hz); 13C
NMR δ 175.11, 174.22, 154.10, 152.31, 115.38, 114.63, 67.85,
55.62, 49.88, 41.33, 36.65, 36.50, 31.64, 29.73, 29.21, 29.16, 28.97,
28.81, 25.75, 25.64, 22.55, 14.00; HRMS (FAB, MH+) m/ z calcd
for C26H45N2O4 449.3379, found 449.3377.
(S)-2,3-Dioctan am idopr opyl 4-Meth oxyph en yl Eth er (3c′).
The compound was prepared in 66% yield from 3-(4′-meth-
oxyphenyl)-sn-glycerol (2′) by the procedure described above: mp
(R)-2,3-Dioctadecan am idopr opyl 4′-Meth oxyph en yl Eth er
(3a ). To a solution of 1-(4′-methoxyphenyl)-sn-glycerol (2, 1.0
g, 5.0 mmol) and pyridine (2.0 mL, 25 mmol) in 20 mL of CH2-
Cl2 was added methanesulfonyl chloride (0.80 mL, 10.4 mmol)
at -10 °C. After being stirred for 4 h at 0 °C, the mixture was
diluted with EtOAc and washed with water, 10% aqueous
NaHSO4 solution, saturated aqueous NaHCO3 solution, and
water. The solvents were removed in vacuo to give the crude
dimesylate as a white solid. The crude dimesylate was dissolved
in 30 mL of DMF, and sodium azide (3.25 g, 50.0 mmol) was
added. The reaction mixture was stirred at 90 °C for 24 h. The
product was extracted with EtOAc and concentrated to give a
crude diazide. The colored impurity was removed by dissolving
the crude diazide in 20 mL of hexane-EtOAc 10:1 and filtering
the solution through a pad of silica gel, which was rinsed with
100 mL of hexane-EtOAc 10:1. The filtrate was concentrated
under reduced pressure to give the diazide as a colorless oil. To
the solution of the diazide in wet THF were added triphen-
ylphosphine (2.63 g, 10 mmol) and 4-nitrophenyl stearate (3.78
g, 10 mmol) at the same time. After the reaction mixture was
stirred for 24 h at rt and was refluxed for 2 h, it was diluted
with acetone and cooled to -20 °C. The product was collected
by filtration and purified by recrystallization in THF-acetone
three times to give 2.77 g (76%) of diamidopropyl aryl ether 3a
99-100 °C; [R]25 -20.98° (c 2.0, CHCl3).
D
(R)-2,3-Diocta d eca n a m id o-1-p r op a n ol (4a ). To a solution
of diamidopropyl ether 3a (2.19 g, 3.0 mmol) in 300 mL of
CHCl3-CH3OH 1:1 was added CAN (5.48 g, 10.0 mmol), and
the mixture was stirred overnight at rt. The reaction mixture
was diluted with CHCl3 and was washed with aqueous 10% Na2-
SO3 solution and brine. The product was purified by recrystal-
lization in MeOH twice, followed by column chromatography on
silica gel (elution with CHCl3-MeOH 50:1), to give 1.66 g (89%)
of diamidopropanol 4a 12 as a white solid (elution with CHCl3-
CH3OH 50:1): mp 115-117 °C; IR (KBr) 3436, 3295, 1637 cm-1
;
1H NMR δ 6.72 (d, 1H, J ) 6.1 Hz), 6.30 (bs, 1H), 4.31 (bs, 1H),
4.11-4.18 (m, 1H), 3.42-3.76 (m, 4H), 2.18 (t, 4H, J ) 7.3 Hz),
1.63-1.77 (m, 4H), 1.25 (s, 56H), 0.88 (t, 6H, J ) 5.9 Hz); 13C
NMR δ 175.24, 174.39, 55.69, 49.90, 41.62, 36.73, 36.59, 32.11,
31.94, 31.77, 30.32, 30.08, 29.73, 29.70, 29.68, 29.55, 29.39, 29.33,
29.29, 26.31, 25.80, 25.70, 22.87, 22.71, 14.14; HRMS (FAB,
MH+) m/ z calcd for C39H79N2O3 623.6090, found 623.6109.
(R)-2,3-Dih exa d eca n a m id o-1-p r op a n ol (4b). The com-
pound was prepared in 83% yield from diamidopropyl ether 3b12
by the procedure described above: mp 112-114 °C (rac-4b lit.2
mp 110-112.5 °C); 1H NMR δ 6.89 (d, 1H, J ) 6.2 Hz), 6.71 (bs,
1H), 4.31 (bs, 1H), 4.03-4.09 (m, 1H), 3.43-3.81 (m, 4H), 2.18
(t, 4H, J ) 7.3 Hz), 1.63-1.77 (m, 4H), 1.25 (s, 48H), 0.88 (t,
6H, J ) 5.9 Hz); 13C NMR δ 175.23, 174.40, 55.69, 49.90, 41.62,
36.73, 36.59, 32.11, 31.94, 31.77, 30.32, 30.08, 29.73, 29.70, 29.68,
29.55, 29.39, 29.33, 29.29, 26.31, 25.80, 25.70, 22.87, 22.71, 14.14;
HRMS (FAB, MH+) m/ z calcd for C27H71N2O3 567.5465, found
567.5455.
as a white solid: mp 108-110 °C; [R]25 +15.82° (c 1.4, CHCl3);
D
IR (KBr) 3460, 1623 cm-1; H NMR δ 6.88-6.80 (m, 4H), 6.71
1
(d, 1H, J ) 6.1 Hz), 6.28 (bs, 1H), 4.30 (m, 1H), 4.09-4.06 (dd,
1H, J ) 3.8, 9.6 Hz), 3.88-3.85 (dd, 1H, J ) 6.4, 9.6 Hz), 3.78
(s, 3H), 3.69-3.61 (m, 1H), 3.41-3.46 (m, 1H), 2.36 (t, 4H, J )
7.3 Hz), 1.63-1.77 (m, 4H), 1.25 (s, 56H), 0.88 (t, 6H, J ) 5.9
Hz); 13C NMR δ 175.26, 174.42, 154.23, 152.30, 115.42, 114.73,
67.69, 55.69, 49.90, 41.62, 36.73, 36.59, 32.11, 31.94, 31.77, 30.32,
30.08, 29.73, 29.70, 29.68, 29.55, 29.39, 29.33, 29.20, 26.31, 25.80,
25.70, 22.87, 22.71, 14.15; HRMS (FAB, MH+) m/ z calcd for
(R)-2,3-Diocta n a m id o-1-p r op a n ol (4c). The compound was
prepared in 73% yield from diamidopropyl ether 3c by the
procedure described above: mp 102-103 °C; [R]25D +3.06° (c 5.0,
CHCl3); 1H NMR δ 6.98 (bs, 1H, D2O exchangeable), 6.76 (d,
1H, J ) 6.7 Hz, D2O exchangeable), 3.87 (bs, 1H), 3.69-3.65
(m, 1H), 3.58-3.47 (m, 2H), 3.30-3.24 (m, 1H), 3.14 (bs, 1H,
D2O exchangeable), 2.23 and 2.19 (t, 4H, J ) 7.3 Hz), 1.63-
1.77 (m, 4H), 1.25 (s, 16H), 0.88 (t, 6H, J ) 5.9 Hz); 13C NMR δ
176.02, 174.28, 61.35, 51.56, 39.57, 36.61, 36.89, 31.68, 29.23,
29.19, 28.99, 25.75, 25.61, 14.07; HRMS (FAB, MH+) m/ z calcd
for C19H39N2O3 343.2961, found 343.2961.
C
46H85N2O4 729.6509, found 729.6512.
(R)-2,3-Dih exa d eca n a m id op r op yl
4′-Met h oxyp h en yl
Eth er (3b). The compound was prepared in 73% yield from
1-(4′-methoxyphenyl)-sn-glycerol (2) and 4-nitrophenyl palmitate
by the procedure described above: mp 113-115 °C; [R]25
D
+14.78° (c 1.4, CHCl3); 1H NMR δ 6.77-6.88 (m, 4H), 6.70 (d,
1H, J ) 6.1 Hz), 6.28 (bs, 1H), 4.30 (m, 1H), 4.09-4.06 (dd, 1H,
J ) 3.8, 9.6 Hz), 3.88-3.85 (dd, 1H, J ) 6.4, 9.6 Hz), 3.76 (s,
3H), 3.71-3.64 (m, 1H), 3.43-3.48 (m, 1H), 2.19 (t, 4H, J ) 7.6
Hz), 1.63-1.59 (m, 4H), 1.25 (s, 48H), 0.88 (t, 6H, J ) 6.6 Hz);
13C NMR δ 175.23, 174.40, 154.22, 152.29, 115.41, 114.72, 67.69,
55.69, 49.90, 41.62, 36.73, 36.59, 32.11, 31.94, 31.77, 30.32, 30.08,
29.73, 29.70, 29.68, 29.55, 29.39, 29.33, 29.29, 26.31, 25.80, 25.70,
22.87, 22.71, 14.14; HRMS (FAB, MH+) m/ z calcd for C42H77N2O4
673.5883, found 673.5878.
(S)-2,3-Diocta n a m id o-1-p r op a n ol (4c′). The compound
was prepared in 70% yield from diamido ether 3c′ by the
procedure described above: mp 101-102 °C; [R]25D -2.63° (c 5.0,
CHCl3).
(R)-1,2-Bis(st ea r oyla m in o)-1,2-d eoxyp h osp h a t id ylch o-
lin e (1a ). To a solution of diamidopropanol 4a (623 mg, 1.0
mmol) and N-ethyl-N,N-diisopropylamine (0.50 mL, 3.59 mmol)
in 50 mL of CH2Cl2 was added ethylene chlorophosphite (0.6
mL, 3.44 mmol) at 0 °C. After the mixture was stirred for 24 h,
bromine (6.72 mmol of a stock solution in CCl4) was added at 0
°C. After 10 min, the solvent was removed under reduced
pressure. The residue was dissolved in 39 mL of CH3CN/2-
PrOH/CHCl3 (5:5:3), and 21 mL of 45% aqueous trimethylamine
was added at rt. After 24 h, the solvents were removed, the
residue was dissolved in THF-H2O 9:1, and the solution was
(R)-2,3-Diocta n a m id op r op yl 4′-Meth oxyp h en yl Eth er
(3c). The compound was prepared in 68% yield from 1-(4′-
methoxyphenyl)-sn-glycerol (2) and 4-nitrophenyl caprylate by
the procedure described above except for the following variation.
It was necessary to remove triphenylphosphine oxide after
reduction of the diazide by triphenylphosphine in THF-H2O
because the Rf values of 3c and triphenylphosphine oxide
coincide (elution with CHCl3-MeOH 10:1). After the reduction,
(12) The solubility of the compounds in CHCl3 was poor; therefore,
the optical rotations could not be measured.
(11) Hassner, A.; Alexanian, V. Tetrahedron Lett. 1978, 4475-4478.

8708 J . Org. Chem., Vol. 61, No. 24, 1996
Notes
passed through a TMD-8 ion exchange column. The fractions
containing the product were pooled and concentrated, giving
crude diamidophospholipid 1a . The product was purified by
column chromatography on silica gel (elution with CHCl3-CH3-
OH-H2O 65:25:4). Removal of silica gel by filtration through a
Metricel filter followed by lyophilization from C6H6 provided 575
mg (73%) of pure 1,2-diamido-1,2-deoxyphosphatidylcholine 1a
NMR δ 175.49, 174.71, 64.00, 58.95, 53.91, 39.70, 36.14, 35.00,
31.57, 29.43, 29.21, 29.06, 29.00, 25.91, 25.51, 25.44, 22.32, 13.69;
HRMS (FAB, MH+) m/ z calcd for C40H83N3O6P 732.6020, found
732.6016.
Ack n ow led gm en t. This work was supported by
National Institutes of Health Grant No. HL-16660. We
thank the mass spectrometry facility at Michigan State
University for the HR-FAB MS. We gratefully acknowl-
edge support from the National Science Foundation
(CHE-9408535) for funds for the purchase of the 400-
MHz NMR spectrometer.
as a white solid; IR (KBr) 3436, 1637, 1243 cm-1; [R]25 +1.06°
D
(c 2.5, CHCl3-MeOH 1:1); 1H NMR (CDCl3-CD3OD) δ 7.34 (bs),
6.85 (d, J ) 6.8 Hz), 4.15-3.25 (m, 9H), 3.24 (s, 9H), 2.28-2.15
(m, 4H), 1.63-1.77 (m, 4H), 1.25 (s, 56H), 0.88 (t, 6H, J ) 5.9
Hz); 13C NMR δ 176.08, 175.35, 64.50, 58.17, 54.44, 50.38, 40.26,
36.70, 36.65, 32.16, 29.93, 29.80, 29.66, 29.59, 29.39, 29.33, 29.29,
25.91, 25.70, 22.90, 22.71, 14.19; HRMS (FAB, MH+) m/ z calcd
for C44H91N3O6P 788.6645, found 788.6696.
Su p p or tin g In for m a tion Ava ila ble: 1H- and 13C-NMR
spectra (18 pages). This material is contained in libraries on
microfiche, immediately follows this article in the microfilm
version of the journal, and can be ordered from the ACS; see
any current masthead page for ordering information.
(R)-1,2-Bis(p a lm itoyla m id o)-1,2-d eoxyp h osp h a tid ylch o-
lin e (1b). The compound was prepared in 65% yield from
diamidopropanol 4b by the procedure described above: [R]25
D
1
+2.14° (c 2.5, CHCl3-MeOH 1:1); H NMR δ 7.32 (bs), 6.84 (d,
J ) 6.8 Hz), 4.16-3.20 (m, 9H), 3.25 (s, 9H), 2.29-2.16 (m, 4H),
1.64-1.78 (m, 4H), 1.25 (s, 48H), 0.88 (t, 6H, J ) 5.9 Hz); 13C
J O961422N