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4.6. Spiro[1-bromo-4-l-menthyloxy-5-oxo-6-oxa-bicyclo[3.1.0]hexane-2,30 -(40-diphenylmethoxy-50 -l-
menthyloxybutyrolactone)] 8a
Purification by flash chromatography (petroleum ether:EtOAc, 98:2) gave 8a (0.62 g, 84%) as a white
solid: Rf 0.51 (10% EtOAc–petroleum ether, 30–60°C); mp 154–155°C (white plates, from petroleum
ether, 30–60°C); [α]D20=−127.1 (c 1.110, CHCl3); UV (λmax, CHCl3): 288.6 (lg ε 1.795), 275.4 (lg ε
1
1.826), 258.4 (lg ε 2.543), 252.9 (lg ε 2.561) nm; IR (KBr, cm−1): 3066, 1789, 1129, 921; H NMR
(200 MHz, CDCl3): δ 0.66 (3H, d, J=7.2 Hz), 0.69 (3H, d, J=6.8 Hz), 0.74 (3H, d, J=6.8 Hz), 0.78
(3H, d, J=7.2 Hz), 0.82 (3H, d, J=6.8 Hz), 0.86 (3H, d, J=6.8 Hz), 1.02–1.34 (10H, m), 1.34–1.47 (2H,
m,), 1.52–1.80 (4H, m), 1.87–2.11 (2H, m), 3.05 (1H, s), 3.19 (1H, ddd, J=10.2, 4.08 Hz), 3.29 (1H,
ddd, J=10.2, 4.08 Hz), 4.86 (1H, s), 5.20 (1H, s), 5.33 (1H, s), 5.50 (1H, s),7.34 (10H, m); 13C NMR
(45 MHz, CDCl3): δ 15.5, 15.6, 20.6, 20.8, 21.9, 22.0, 22.7, 23.1, 24.7, 25.4, 31.1, 31.2, 33.9, 34.0,
34.3, 38.3, 38.6, 38.7, 39.5, 47.1, 47.2, 76.5, 78.5, 82.3, 86.1, 97.0, 100.7, 126.4, 127.3, 128.1, 128.6,
129.0, 140.7, 167.8, 169.0; EIMS m/z: 736 (M+, 6), 669, 664, 632, 261 (C15H17O+4 , 100); anal. calcd for
C41H53O7Br: C, 66.75; H, 7.24; found: C, 67.02; H, 7.47. The structure of 8a was confirmed by X-ray
crystallography (Fig. 2).
4.7. Spiro[1-bromo-4-l-menthyloxy-5-oxo-6-oxa-bicyclo[3.1.0]hexane-2,30 -(40-benzyloxy-50-l-
menthyloxybutyrolactone)] 8b
Purification by flash chromatography (petroleum ether:EtOAc, 98:2) gave 8b (0.46 g, 70%) as a white
solid: Rf 0.86 (15% EtOAc–petroleum ether, 30–60°C); mp 120–122°C (white plates, from petroleum
ether, 30–60°C); [α]D20=−138.8 (c 0.77, CHCl3); UV (λmax, CHCl3): 264.0 (lg ε 1.555), 258.1 (lg ε
1
1.663), 252.3 (lg ε 1.387) nm; IR (KBr, cm−1) 3068, 1790, 1131, 921; H NMR (200 MHz, CDCl3): δ
0.73 (3H, d, J=7.2 Hz), 0.75 (3H, d, J=6.8 Hz), 0.78 (3H, d, J=6.8 Hz), 0.86 (3H, d, J=7.2 Hz), 0.91
(3H, d, J=6.8 Hz), 0.96 (3H, d, J=6.8 Hz), 1.18–1.46 (6H, m), 1.51–1.98 (6H, m), 1.99–2.19 (6H, m),
3.03 (1H, s), 3.45 (2H, ddd, J=10.2, 4.10 Hz), 3.53 (1H, s), 4.56 (2H, dd, J=10.66 Hz), 5.57 (1H, s), 5.64
(1H, s), 7.34 (5H, m); 13C NMR (45 MHz, CDCl3): δ 15.6, 15.6, 20.7, 20.8, 22.1, 22.2, 22.8, 23.2, 24.8,
25.4, 31.3, 31.4, 34.3, 34.0, 34.1, 38.3, 38.5, 39.0, 39.8, 47.3, 47.3, 73.2, 76.6, 78.4, 81.6, 99.9, 100.0,
128.5, 128.8, 128.9, 136.0, 167.8, 168.7; EIMS m/z: 562, 430, 137, 94, 91, 83, 55, 43, 41 (C3H+5 , 100);
anal. calcd for C35H49O7Br: C, 63.53; H, 7.46; found: C, 63.55; H, 7.57.
4.8. Spiro[1-bromo-4-l-menthyloxy-5-oxo-6-oxa-bicyclo[3.1.0]hexane-2,30 -(40-α-methylbenzyloxy-50 -
l-menthyloxybutyrolactone)] 8c
Purification by flash chromatography (petroleum ether:EtOAc, 98:2) gave 8c (0.67 g, 88%) as a pale
yellow oil: Rf 0.50 (10% EtOAc–petroleum ether, 30–60°C); [α]D20=−159.5 (c 0.70, CHCl3); UV (λmax
,
C2H5OH): 215.9 (lg ε 2.35) nm; IR (KBr, cm−1): 3060, 1784, 1123, 933; 1H NMR (200 MHz, CDCl3):
δ 0.64 (3H, d, J=7.2 Hz), 0.70 (3H, d, J=6.8 Hz), 0.74 (3H, d, J=6.8 Hz), 0.74–1.02 (27H, m), 1.19–1.79
(24H, m), 1.89–2.23 (12H, m), 2.06 (6H, s), 2.93 (1H, s), 3.08 (1H, s), 3.20 (2H, ddd, J=10.30, 10.30,
4.12 Hz), 3.58 (2H, ddd, J=10.3, 10.3, 4.1 Hz), 3.64 (1H, s), 3.69 (1H, s), 4.43 (2H, m), 4.97 (1H, s),
5.31 (1H, s), 5.72 (1H, s), 5.87 (1H, s), 7.23–7.44 (10H, m); 13C NMR (45 MHz, CDCl3): δ 15.2, 15.4,
15.6, 20.4, 20.5, 20.6, 20.7, 21.9, 22.00, 22.1, 22.2, 22.5, 22.6, 22.9, 23.1, 24.4, 24.5, 25.1, 30.8, 31.1,
33.8, 34.00, 34.0, 37.7, 38.1, 38.4, 38.6, 38.3, 38.6, 38.9, 39.3, 47.0, 47.2, 47.3, 75.9, 76.3, 78.1, 79.3,
79.6, 80.5, 96.6, 100.2, 101.0, 125.7, 126.2, 126.4, 127.5, 128.2, 128.4, 128.5, 128.6, 128.8, 140.5, 141.6,