反应详情

To benzothiazole (3.46 g, 25.6 mmol) dissolved in dry THF under a nitrogen atmosphere at −78° C. was added butyl lithium (17.1 mL of 1.5M solution, 1 equiv.) dropwise. The reaction mixture was stirred for 1 h then 1,4-cyclohexanedione mono-ethylene ketal dissolved in dry THF (15 mL) in one portion. The reaction mixture was stirred at −78° C. for a further 3 h then water (10 mL) was added. The mixture was warmed to room temperature and the white precipitate was collected on a filter, washed with water (2×20 mL) then dried under vacuum to give 4-(benzothiazol-2-yl)-1,1-ethylenedioxy-4-hydroxycyclohexane. The yield was 4.403 g (59%); mp 165° C.; 1H NMR (CDCl3) δ 8.05 (1H, m, benzothiazole H-4/7), 7.89 (1H, m, benzothiazole H-4/7), 7.47 (1H, m, benzothiazole H-5/6), 7.39 (1H, m, benzothiazole H-5/6), 4.02 (4H, s, ethylene 2×CH2), 3.16 (1H, s, OH), 2.41–2.31 (4H, m, cyclohexanone 2×CH2), 1.82–1.72 (4H, m, cyclohexanone 2×CH2); IR (KBr disc) 2897, 1501, 1437, 1368, 1038, 997, 764 cm−1; MS (AP+) 292 (M++1), 274 (M++1-H2O); Anal. (C15H17NO3) C, H, N.

1. stirringThe reaction mixture was stirred at −78° C. for a further 3 h
2. customthe white precipitate was collected on a filter
3. washwashed with water (2×20 mL)
4. customthen dried under vacuum