8-(2-Benzothiazolyl)-1,4-dioxaspiro[4.5]decan-8-ol → 4-(Benzothiazol-2-yl)-4-hydroxycyclohexan-1-one

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Reaktionsschritte

A solution of 4-(benzothiazol-2-yl)-1,1-ethylenedioxy-4-hydroxycyclohexane (1.0 g, 3.4 mmol) in acetic acid (40 mL) and conc. HCl (10 mL) was heated at 80° C. for 2 h with stirring. The volume was reduced on a rotary evaporator and the remaining solution was carefully neutralized with saturated sodium hydrogen carbonate solution and then extracted with diethyl ether (3×50 mL). The organic layers were combined, washed with water (2×50 mL) and dried over magnesium sulphate. Removal of the solvent under vacuum gave the product 4-(benzothiazol-2-yl)-4-hydroxycyclohexan-1-one (0.618 g) as an off white solid (73%); mp 134° C.; 1H NMR (CDCl3) δ 8.00 (1H, m, benzothiazole H-4/7), 7.91 (1H, m, benzothiazole H-4/7), 7.49 (1H, m, benzothiazole H-5/6), 7.41 (1H, m, benzothiazole H-5/6), 3.66 (1H, s, OH), 2.97–2.85 (4H, m, cyclohexanone CH2), 2.53–2.34 (4H, m, cyclohexanone CH2); IR (KBr disc) 2913, 1690, 1505, 1427, 1312, 1198, 889, 768 cm−1; MS (AP+) 248 (M++1), 230 (M++1—H2O); Anal. (C13H13NO2S) C, H, N.

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