Issue in Honor of Prof. Otto Meth-Cohn ARKIVOC 2000 (v) 779-797
3,3-Dimethoxy-5,7-dimethoxycarbonylbicyclo[2.2.2]oct-5-en-2-one (8b). A mixture of methyl vanillate(0.50 g, 2.7 mmol), DAIB (0.97 g, 3.0 mmol) and MA (2 mL) was reacted according to the general method, to give a pale yellow oil (0.60 g, 76%); 1H NMR [CDCl3] d 7.06 (1H, dd, J 2.0, 6.6Hz, H-6), 3.77 (1H, d, J 2.8Hz, H-4), 3.75 (3H, s, OCH3), 3.64 (3H, s, OCH3), 3.63 (1H, dd, J 1.7, 10.1Hz, H-1), 3.32 (3H, s, OCH3),
3.26 (3H, s, OCH3), 3.08 (1H, m, H-7), 2.36 (1H, td, J 2.9, 10.3Hz, H-8), 1.69 (1H, m, H-8); 13C NMR [CDCl3] d 200.2 (C), 173.2 (C), 164.5 (C), 138.5 (C), 135.8 (CH), 93.6 (C), 52.9 (CH), 52.5 (CH), 51.2 (CH), 50.7 (CH), 50.5 (CH), 39.6 (CH), 38.7 (CH), 25.2 (CH2); IR .max 2953, 1740, 1721, 1439, 1256, 1107, 1072, 774cm-1; TLC (ethyl acetate / hexane 2:8) RF 0.24; MS (EI, m/z) 270 (M+-CO), 211 (-CO2CH3), 151 (- HCO2CH3). 7-Acetyl-5-(benzothiazol-2-yl)-3,3-dimethoxybicyclo[2.2.2]oct-5-en-2-one (8c).
Compound 4 (0.50 g, 1.9 mmol), DAIB (0.69 g, 2.1 mmol) and MVK (2 mL) was reacted according to the general method, to give an off white solid (0.25 g, 37%); mp 159 °C; 1H NMR [CDCl3] d 8.01 (1H, dd, J 1.0, 7.4Hz, H-4’/7’), 7.83 (1H, dd, J 1.1, 7.2Hz, H-4’/7’), 7.50-7.34 (2H, m, H-5’,6’), 6.89 (1H, dd, J 1.7, 6.6Hz, H-6), 4.40 (1H, dd, J 2.8, 5.1Hz, H-4), 3.68 (1H, dd, J 1.7, 6.6Hz, H-1), 3.45 (3H, s, OCH3), 3.36 (3H, s, OCH3), 3.27 (1H, m, H-7), 2.54 (1H, ddd, J 3.1, 10.4, 13.2Hz, H-8), 2.17 (3H, s, COCH3), 1.76 (1H, ddd, J 2.8, 6.8, 13.0Hz, H-8); 13C NMR [CDCl3] d 205.8 (C), 200.4 (C), 164.9 (C), 153.8 (C), 141.3 (C), 135.3 (C), 128.5 (CH), 126.7 (CH), 126.2 (CH),
123.8 (CH), 122.0 (CH), 94.3 (C), 51.0 (CH), 50.7 (CH), 50.6 (CH), 48.3 (CH), 40.6 (CH), 28.7 (CH), 24.8 (CH2); IR .max 2944, 1730, 1709, 1433, 1360, 1096, 1071, 756cm-1; MS (ES, m/z) 358 (M++1), 326 ([M++1]-CH3OH); Anal. Calcd. for C19H19NO4S: C, 63.85; H, 5.36; N, 3.92. Found: C, 63.59; H, 5.35; N, 3.91. 5-(Benzothiazol-2-yl)-3,3-dimethoxy-7-(propionyl)bicyclo[2.2.2]oct-5-en-2-one (8d).
Compound 4 (0.50 g, 1.9 mmol), DAIB (0.69 g, 2.1 mmol) and EVK (2 mL) was reacted according to the general method, to give a white crystalline solid (0.25 g, 35%); mp 134 °C; 1H NMR [CDCl3] d 7.97 (1H, dd, J 1.4, 7.9Hz, H-4’/7’), 7.81 (1H, dd, J 1.3, 8.1Hz, H-4’/7’), 7.47-7.31 (2H, m, H-5’,6’), 6.87 (1H, d, J 1.6, 6.2Hz, H-6), 4.36 (1H, dd, J 2.8, 5.1Hz, H-4), 3.62 (1H, dd, J 1.7, 6.6Hz, H-1), 3.42 (3H, s, OCH3), 3.33 (3H, s, OCH3), 3.24 (1H, m, H-7), 2.51 (1H, m, H-8), 2.43 (2H, q, J 7.3Hz, CH2), 1.71 (1H, ddd, J 2.8, 6.8, 12.9Hz, H-8), 1.02 (3H, t, J 7.3Hz, CH3); 13C NMR [CDCl3] d
208.8 (C), 200.4 (C), 165.0 (C), 153.8 (C), 141.1 (C), 135.3 (C), 128.7 (CH), 126.6 (CH), 126.1 (CH), 123.8 (CH), 122.0 (CH), 94.3 (C), 51.0 (CH), 50.7 (CH), 47.3 (CH), 40.7 (CH), 34.7 (CH), 25.2 (CH2), 8.2 (CH); IR .max 2980, 1740, 1715, 1485, 1317, 1092, 1055, 764cm-1; MS (m/z) 372 (M++1), 340 ([M++1]-CH3OH); Anal. Calcd. for C20H21NO4S: C, 64.67; H, 5.70; N, 3.77. Found: C, 64.73; H, 5.69; N, 3.77. ISSN 1424-6376 Page 789 ©ARKAT USA, Inc
