Synthesis of Derivatives of Chlorophyll-a
J. Chin. Chem. Soc., Vol. 52, No. 5, 2005 999
was stirred at 0 °C for 15 minutes. This mixture was then
added to a solution of nickel chlorin 6a (94 mg, 0.14 mmol) in
dichloromethane (20 mL) with continuous stirring at 0 °C.
The final mixture was then warmed up to room temperature
and stirred for 18 hours. Saturated aqueous sodium carbonate
(100 mL) was then added, and the solution was stirred over-
night. The mixture was extracted with dichloromethane; the
combined organic layers were washed with water (3 ´ 200
mL) and dried over anhydrous sodium sulfate, and the sol-
vent was removed under vacuum. The resulting residue was
chromatographed on silica gel with hexane-ethyl acetate
(3:1) to give 7a as a dark green solid (79 mg, 78%); mp 156-
157 °C; UV-vis (CHCl3) lmax: 413 (1.00), 605 (0.27), 692
(0.62) nm; 1H NMR (300 MHz, CDCI3) d: 1.40 (t, J = 7.4 Hz,
3H, 8b-H), 1.43 (d, J = 7.6 Hz, 3H, 18-CH3), 1.82-2.46 (m,
4H, 17a+17b-H), 2.74 (s, 3H, CH3), 2.90 (s, 3H, CH3), 3.24
(s, 3H, CH3), 3.22-3.48 (m, 1H, 17-H), 3.57 (s, 6H, 2 ´
OCH3), 3.72 (q, J = 7.2 Hz, 2H, 8a-H), 3.90 (s, 3H, OCH3),
4.15 (d, J = 5.7, 1.9 Hz, 3a-H), 4.35-4.48 (m, 1H, 18-H), 4.42
(d, J = 19.3 Hz, 1H, 132-H), 4.45 (t, J = 5.7 Hz, 3b-H), 4.60 (d,
J = 19.3 Hz, 1H, 132-H), 5.79 (dd, J = 15.4, 7.8 Hz, 1H,
20b-H), 8.36 (d, J = 15.4 Hz, 20a-H), 8.58, 8.88 (s, each 1H,
meso-H), 9.69 (d, J = 7.8 Hz, 20c-H); IR (KBr) n: 1739-1670
(C=O), 1625 (C=C), 1573 (chlorin skeleton), 1450, 1368,
1298, 984 cm-1. Anal. Calcd for C39H42N4NiO6: C 64.93, H
5.87, N 7.77. Found C 64.73, H 5.69, N 7.52.
6c as a green solid (70%); mp 152-153 °C; UV-vis (CHCl3)
1
lmax: 417 (1.00), 435 (0.96), 606 (0.26), 712 (0.73) nm; H
NMR (300 MHz, CDCI3) d: 0.84 (t, J = 7.2 Hz, 3g-CH3), 1.41
(t, J = 7.5 Hz, 3H, 8b-H), 1.39-1.80 (m, 8H, 3c~e-H), 1.43 (d,
J = 7.4 Hz, 3H, 18-CH3), 1.82-2.49 (m, 6H, 3b-H+17a+17b-
H), 2.96 (s, 3H, CH3), 3.04 (s, 3H, CH3), 3.31 (s, 3H, CH3),
3.22-3.57 (m, 1H, 17-H), 3.59 (s, 3H, OCH3), 3.74 (q, J =
7.5 Hz, 2H, 8a-H), 4.42-4.61 (m, 1H, 18-H), 4.46 (d, J =
19.8 Hz, 1H, 132-H), 4.70 (d, J = 19.8 Hz, 1H, 132-H), 5.77
(dd, J = 15.8, 7.6 Hz, 1H, 20b-H), 8.46 (d, J = 15.8 Hz,
20a-H), 8.96, 9.28 (s, each 1H, meso-H), 9.74 (d, J = 7.6 Hz,
20c-H); IR (KBr) n: 1739-1666 (C=O), 1638 (C=C), 1566
(chlorin skeleton), 1442, 1340, 1274, 982 cm-1. Anal. Calcd
for C42H46N4NiO5: C 67.66, H 6.22, N 7.52. Found C 67.48,
H 6.03, N 7.79.
Nickel(II) 3-(1-hydroxylethyl)-20-formylvinyl-3-devinyl-
pyropheophorbide-a methyl ester (8a) and Nickel(II)
20-formylvinylpyropheophorbide-a methyl ester (9a)
These two compounds were obtained from the nickel
complex 6d as a green solid in 42% and 26% yield, respec-
tively. 8a: mp 168-171 °C; UV-vis (CHCl3) lmax: 413 (0.99),
432 (1.00), 605 (0.26), 687 (0.67) nm; 1H NMR (300 MHz,
CDCI3) d: 1.40 (t, J = 7.5 Hz, 3H, 8b-H), 1.42 (d, J = 6.5 Hz,
3H, 18-CH3), 1.79 (d, J = 6.5 Hz, 3a-CH3), 1.89-2.51 (m, 4H,
17a+17b-H), 2.93 (s, 3H, CH3), 2.79 (s, 3H, CH3), 3.26 (s,
3H, CH3), 3.26-3.48 (m, 1H, 17-H), 3.56 (s, 3H, OCH3), 3.72
(q, J = 7.5 Hz, 2H, 8a-H), 4.30-4.48 (m, 1H, 18-H), 4.39 (d, J
= 19.8 Hz, 1H, 132-H), 4.61 (d, J = 19.8 Hz, 1H, 132-H), 5.71
(dd, J = 16.0, 8.0 Hz, 1H, 20b-H), 8.39 (d, J = 16.0 Hz, 20a-
H), 8.92, 9.31 (s, each 1H, meso-H), 9.69 (d, J = 8.0 Hz, 20c-
H); IR (KBr) n: 1740-1670 (C=O), 1645 (C=C), 1566 (chlo-
rin skeleton), 1460, 1333, 1256, 989 cm-1. Anal. Calcd for
C37H38N4NiO5: C 65.60, H 5.65, N 8.27. Found C 65.34, H
5.41, N 8.04. 9a: mp 147-150 °C; UV-vis (CHCl3) lmax: 409
Nickel(II) 3-pentylcarbonyl-20-formylvinyl-3-devinyl-
pyropheophorbide-a methyl ester (7b)
This compound was obtained from the nickel complex
6b as a green solid (70%); mp 143-145 °C; UV-vis (CHCl3)
1
lmax: 416 (1.00), 436 (0.97), 605 (0.26), 712 (0.72) nm; H
NMR (300 MHz, CDCI3) d: 0.86 (t, J = 7.0 Hz, 3d-CH3), 1.43
(t, J = 7.5 Hz, 3H, 8b-H), 1.42-1.79 (m, 4H, 3c~d-H), 1.46 (d,
J = 7.4 Hz, 3H, 18-CH3), 1.88-2.48 (m, 6H, 3b-H+17a+17b-
H), 2.95 (s, 3H, CH3), 3.06 (s, 3H, CH3), 3.30 (s, 3H, CH3),
3.24-3.55 (m, 1H, 17-H), 3.59 (s, 3H, OCH3), 3.78 (q, J = 7.5
Hz, 2H, 8a-H), 4.43-4.60 (m, 1H, 18-H), 4.47 (d, J = 19.8 Hz,
1H, 132-H), 4.68 (d, J = 19.8 Hz, 1H, 132-H), 5.76 (dd, J = 15.8,
7.6 Hz, 1H, 20b-H), 8.44 (d, J = 15.8 Hz, 20a-H), 8.97, 9.26
(s, each 1H, meso-H), 9.72 (d, J = 7.6 Hz, 20c-H); IR (KBr) n:
1738-1669 (C=O), 1640 (C=C), 1568 (chlorin skeleton),
1440, 1344, 1270, 987 cm-1. Anal. Calcd for C40H42N4NiO5:
C 66.96, H 5.90, N 7.81. Found C 66.76, H 5.73, N 7.70.
1
(1.00), 604 (0.19), 694 (0.67) nm; H NMR (300 MHz,
CDCI3) d: 1.42 (d, J = 7.1 Hz, 3H, 8b-H), 1.45 (t, J = 7.3 Hz,
3H, 18-CH3), 1.82-2.45 (m, 4H, 17a+17b-H), 2.81 (s, 3H,
CH3), 2.91 (s, 3H, CH3), 3.25 (s, 3H, CH3), 3.54 (q, J = 7.5
Hz, 2H, 8a-H), 3.57 (s, 3H, OCH3), 3.60-3.78 (m, 1H, 17-H),
4.32-4.50 (m, 1H, 18-H), 4.45 (d, J = 20.0 Hz, 1H, 132-H),
4.62 (d, J=20.0 Hz, 1H, 132-H), 5.71-5.93 (m, 3H, 3b-H+20b-
H), 7.38-7.50 (m, 1H, 3a-H), 8.40 (d, J = 15.6 Hz, 1H, 20a-
H), 8.74, 8.92 (s, each 1H, meso-H), 9.70 (d, J = 7.8 Hz, 1H,
20c-H); IR (KBr) n: 1740-1668 (C=O), 1645 (C=C), 1570
(chlorin skeleton), 1455, 1323, 1241, 992 cm-1. Anal. Calcd
for C37H36N4NiO4: C 67.39, H 5.50, N 8.50. Found C 67.18, H
5.35, N 8.29.
Nickel(II) 3-heptylcarbonyl-20-formylvinyl-3-devinyl-
pyropheophorbide-a methyl ester (7c)
This compound was obtained from the nickel complex