Molecules 2001, 6
812
in water (100 mL), then extracted with dichloromethane (3 x 200 mL). The combined organic phases
were dried (MgSO4) and then concentrated under reduced pressure. The residue was purified by
chromatography on Kieselgel G (40 g) using chloroform - methanol (9:1) as eluent, which gave two
main fractions: (a) the less polar fraction contained colouress plates of 16β-hydroxyaspidospermidine
(6a) (1.24 g, 72.5%), m.p. 55°C; Anal. Found: C, 76.75; H, 9.05; N, 9.0; Calc. for C19H26N2O: C, 76.5;
H, 8.70; N, 9.0%; IR: νmax (CHCl3) 3420 (-OH), 3000-2705, 1600, 1480, 1460, 1312, 1250, 1030, 900,
and 630 cm -1; λ max (MeOH) 212, 244, 300; 1H-NMR: δ H (CDCl3, 400 MHz) 7.05 (2H, m, Ar-H), 6.7
(1 H, t, J=7 Hz), 6.55 (1H, d, J=7 Hz, Ar-H), 4.85 (1H, m, 16-H), 3.77 (1H, d, J=4 Hz, 2-H), 3-0.8
13
(17H, m), and 0.55 ppm (3H, t, J=7.5 Hz, -CH3); C-NMR: δC 150.37 (C-13), 136.01 (C-8), 127
(C-11), 123 (C-9), 118.4 (C- 10), 109.26 (C-12), 74.49 (C-21), 71.01 (C-2), 67.65 (C-16), 54.1 (C-7),
53.15 (C-3), 52.49 (C-5), 43.0 (C-6), 36.11 (C -20), 35.97 (C-17), 34.7 (C-15), 34.23 (C-19), 22.10
(C-14) and 7.75 ppm (CH3 ); MS: m/z (%) 298 (M+, 5.7), 254 (8.7), 144 (5.3), 138 (1.5), 130 (5.5) and
124 (100); (b) The more polar fraction corresponds to the second epimer, 16α-hydroxyaspido-
spermidine (6b) (212 mg, 12.3 % ), which was obtained as an amorphous solid; IR: ν
(CHCl3)
max
3400 cm-1(OH), 3000, 2940, 2860, 2700, 1605, 1480, 1460, and 670 cm -1; UV: λmax 212, 242 and 296
nm; 1H-NMR: δH (CDCl3, 300 MHz) 7.25-6.6 (4H, m, Ar-H ), 3.6 (1H, m, 16-H), 4 (1H, s, -OH), 3.5
(1H, m, H-2), 3.8-0.8 (16 H, m), 0.6 (3H, t, J=7 Hz, -CH3); MS: m/z (%) 298 (M+, 5.8), 249 (6.2), 168
(18.3), 144 (13.5), 138 (3.1), 130 (16.1) and 124 (100).
Na-Formyl-16β- formyloxyaspidospermidine (7a).
To a stirred solution of 16β-hydroxyaspidospermidine (6a) (121 mg, 0.4 mmol) in formic acid
(5.47 mL, 6.6 mg, 0.14 mol) at 0°C, acetic anhydride (0.54 mL, 59 mmol) was added dropwise over 10
minutes. The resulting reaction mixture was stirred at room temperature for 18 h and then concentrated
under reduced pressure. The residue was purified by chromatography on kieselgel G (20 g) with
dichloromethane/methanol (2%) as the eluent, to give the Na-formyl-16β-formyloxyaspidospermidine
7a (130 mg, 90.1 %) as colourless plates, m.p. 70-2 °C; Anal. Found: C, 71.4; H, 7.6; N, 8; HRMS
M+, m/z 354.19138; C21H26N2O3 requires C, 71.18; H, 7.34; M+, m/z 354.1913; IR:νmax (CHCl3) 3019,
2943, 2900, 2800, 2740, 1720, 1670, 1600, 1480, 1460, 1400, 1361 and 1180 cm-1; UV: λmax (MeOH)
210, 250, 282, 290, λ min 226, 270 nm; 1H-NMR: δH (CDCl3, 300 MHz), 8.9 (1H, s, -CHO), 8.6 (1H, s,
-CHO), 7.9 (dd, J=9.3 and 18 Hz, 12-H), 7.15-7 (3H, m, Ar-H), 5.75 (1H, m, 16-H), 4.6 (1H, d, J=5Hz,
2-H), 3 (2H, m), 2.4-0.8 (13H, m), and 0.7 (3H, t, J=6Hz, -CH3); 13C-NMR: δC 160.187, 160.35
(-NCHO), 160.05, 157.89, (-OCHO), 140.97 (C-13), 138.46 (C-8), 127.81, 127.62 (C-16), 124.79,
124.64 (C-11), 123.17, 122.28 (C -9), 116.153 (C- 10) 109.05 (C-12), 71.05, 70.29 (C-21), 70.14, 68.8
(C-2), 66.4,63.7 (C - 7), 53.32, 52.96 (C- 3), 51.89, 51.76 (C - 5), 41.11, 40.67 (C–6), 35.04, 34.94
(C-20), 34.84, 34.64 (C-17), 32.76, 32.15 (C-15), 27.9, 26.61 (C-19), 21.57, 21.46 (C-14) and 7.12,
6.95 (-CH3); MS: m/z (%) 354 (M+, 1.9), 326 (0.9), 325 (0.9), 282 (3.9), 144 (4.5), 130 (5.2), 124
(100) and 29 (CHO, 15.9).