Vol. 26, No. 11, 2015
Teixeira et al.
2285
(20), 92 (17), 91 (25), 82 (42), 81 (100), 80 (11), 79 (49), 78
(19), 77 (45), 70 (27), 69 (57), 66 (17), 65 (14), 55 (17), 54
(27), 53 (29), 51 (21), 41 (22), 40 (12). *These assignments
could be reversed.
1:1 v/v); m.p. 112.9-113.4 °C; IR (film) νmax / cm-1 2969,
1769, 1385, 1189, 1001, 853; 1H NMR (300 MHz, CDCl3)
d 1.15-1.38 (m, 4H, H5, H6, H8 and H8’), 1.45-1.67 (m, 2H,
H5’ and H6’), 2.24-2.28 (m, 1H, H4), 2.42 (tdd, 1H, J 8.7,
3.6, 1.3 Hz, H3a), 2.51 (dt, 1H, J 8.7, 1.3 Hz, H7a), 2.65-2.69
(1H, m, H7), 3.89 (dd, 1H, J 9.5, 3.8 Hz, H3’), 4.43 (dd,
1H, J 9.5, 9.0 Hz, H3); 13C NMR (75 MHz, CDCl3) d 27.1
(C5)*, 27.8 (C6)*, 33.4 (C8), 40.5 (C7), 41.7 (C3a), 42.6
(C4), 48.0 (C7a), 72.9 (C3), 179.6 (C1); MS m/z (%) 152
([M]+, 14), 93 (19), 91 (11), 85 (10), 81 (10), 80 (100), 79
(72), 78 (11), 77 (20), 68 (17), 67 (39), 66 (86), 64 (15), 54
(14), 53 (13), 51 (10), 41 (27), 40 (10). *These assignments
could be reversed.
(3aS,4R,5R,6S,7S,7aS)- and (3aR,4S,5S,6R,7R,7aR)-5,6-
epoxyhexahydro-4,7-methanoisobenzofuran-1(3H)-one (5)
Epoxide 5 was obtained (137.5 mg) in 83% yield
by reaction of lactone 3 (150 mg, 1.0 mmol) with 70%
MCPBA (346.8 mg, 2.0 mmol), by following the same
procedure described for lactone 4: white solid; TLC Rf =
0.30 (hexane:ethyl acetate 1:1 v/v); m.p. 112.9-113.4 °C;
IR (film) νmax / cm-1 2969, 1769, 1385, 1189, 1001, 853;
1H NMR (300 MHz, CDCl3) d 0.87 (dm, 1H, J 11.2 Hz,
H8), 1.42 (dquint, 1H, J 11.2, 1.9 Hz, H8’), 2.57 (sl, 1H,
H4), 2.61 (ddt, 1H, J 8.9, 3.6, 1.9 Hz, H3a), 2.65-2.70 (m,
1H, H7a), 3.94 (sl, 1H, H7), 3.16 (d, 1H, J 4.4 Hz, H5),
3.26 (d, 1H, J 4.4 Hz, H6) 3.97 (dd, 1H, J 9.7, 3.6 Hz,
H3’), 4.49 (dd, 1H, J 9.7, 8.9 Hz, H3); 13C NMR (75 MHz,
CDCl3) d 21.3 (C8), 39.1 (C3a), 41.6 (C7), 43.2 (C4), 45.6
(C7a), 50.5 (C5), 50.9 (C6), 71.4 (C3), 177.3 (C1); MS m/z
(%) 93 (21), 91 (27), 82 (92), 81 (100), 79 (34), 77 (43),
66 (12), 65 (11), 54 (22), 53 (21), 51 (18), 41 (15), 40 (9).
(3aR,4R,5S,6S,7S,7aS)- and (3aS,4S,5R,6R,7R,7aR)-
5,6-dichlorohexahydro-4,7-methanoisobenzofuran-
1(3H)-one (8a) and (3aR,4R,5R,6R,7S,7aS)- and
(3aS,4S,5S,6S,7R,7aR)-5,6-dichlorohexahydro-4,7-
methanoisobenzofuran-1(3H)-one (8b)
Chlorine was bubbled for 20 min into a solution
of lactone 3 (537.1 mg, 3.58 mmol) dissolved in
dichloromethane (20 mL). The chlorine was produced by
adding concentrated HCl to a two-neck round-bottom flask
containing MnO2 under vigorous stirring. The progress of
the reaction was checked by TLC, and the mixture was
stirred until all the substrate was fully consumed. The
solvent was evaporated and the pure product was obtained
after column chromatography packed with silica-gel using
hexane:diethyl ether 1:1 as eluent to give 0.2761 g (35%
yield) of 8a and 0.0575 g (7% yield) of 8b.
(3aR,4R,7S,7aS)- and (3aS,4S,7R,7aR)-hexahydro-4,7-
methanoisobenzofuran-1(3H)-one (6)
To a 25 mL round-bottom flask were added compound 2
(0.1024 g, 0.68 mmol), ethanol (10 mL) and Pd/C 10%
(7.3 mg). The resulting mixture was stirred under hydrogen
atmosphere for 1 h.After the solvent evaporation the residue
was purified by column chromatography with silica-gel using
hexane:ethyl acetate 1:1 as eluent to give 73.1 mg of 6 (70%
yield): white solid; TLC Rf = 0.63 (hexane:ethyl acetate 1:1
v/v); m.p. 64.8-65.6 °C; IR (film) νmax / cm-1 2961, 2881,
Data for compound 8a
Colorless oil; TLC Rf = 0.37 (hexane:ether 1:1 v/v);
IR (film) νmax / cm-1 2981, 2913, 1769, 1485, 1385, 1273,
1189, 1052, 1009, 945, 812, 776, 689, 641, 480; 1H NMR
(300 MHz, CDCl3) d 1.55-1.64 (m, 1H, H8), 2.00 (dquint,
1H, J 12.1, 1.6 Hz, H8’), 2.53-2.58 (m, 1H, H4), 2.70 (d,
1H, J 8.9 Hz, H7a), 2.86 (sl, 1H, H7), 3.20 (tdd, 1H, J 8.9,
3.7, 1.6 Hz, H3a), 3.74 (t, 1H, J 3.0 Hz, H6), 3.97 (dd, 1H,
J 9.7, 3.7 Hz, H3’), 4.24 (dd, 1H, J 4.0, 3.0 Hz, H5), 4.56
(t, 1H, J 9.7 Hz, H3); 13C NMR (75 MHz, CDCl3) d 30.4
(C8), 33.6 (C3a), 45.6 (C7a), 49.3 (C4), 49.6 (C7), 66.5
(C6), 67.4 (C5), 71.6 (C3), 177.3 (C1); MS m/z (%) 224
([M+4]+, 0.22), 222 ([M+2]+, 1.21), 220 ([M]+, 1.70), 141
(12), 105 (29), 91 (25), 80 (100), 79 (52), 78 (11), 77 (23),
66 (38), 65 (42), 63 (19), 53 (17), 52 (15), 51 (44), 50 (15),
49 (10), 41 (15), 40 (13).
1
1761, 1485, 1381, 1172, 1069, 997; H NMR (300 MHz,
CDCl3) d 1.50-1.63 (m, 6H, H5, H6, H8 and H8’), 2.34-2.40
(m, 1H, H4), 2.64-2.69 (m, 1H, H7), 2.80-3.92 (m, 1H, H3a),
2.98 (dd, 1H, J 11.2, 5.7 Hz, H7a) 4.21-4.34 (m, 2H, H3 and
H3’); 13C NMR (75 MHz, CDCl3) d 21.5 (C5)*, 25.4 (C6)*,
39.8 (C7), 40.3 (C4), 41.9 (C8/C3a), 46.7 (C7a), 68.4 (C3),
178.8 (C1); MS m/z (%) 93 (13), 91 (12), 85 (40), 80 (33),
79 (31), 77 (15), 68 (12), 67 (32), 66 (100), 65 (10), 53 (9),
41 (19). *These assignments could be reversed.
(3aS,4R,7S,7aR)- and (3aR,4S,7R,7aS)-hexahydro-4,7-
methanoisobenzofuran-1(3H)-one (7)
Product 7 was obtained (197.8 mg, 1.30 mmol) in 92%
yield by reaction of lactone 3 (0.2132 mg, 1.42 mmol)
and Pd/C 10% (14.2 mg) under hydrogen atmosphere, by
using the same procedure described for the synthesis of
lactone 6: white solid; TLC Rf = 0.30 (hexane:ethyl acetate
Data for compound 8b
Colorless oil; TLC Rf = 0.31 (hexane:ether 1:1 v/v);
IR (film) νmax / cm-1 2975, 2911, 1769, 1485, 1385, 1189,