Synthesis of pyrazolone derivatives. XXXI. Asynmetric synthesis of 3a-alkyl-3,3a,4,5,6,7-hexahydro-2H-indazol-3-ones.
作者:ISOO ITO、TAISEI UEDA、TOSHIHISA ASANO、NORIICHI ODA
DOI:10.1248/cpb.26.1328
日期:——
The reaction of pimelyl dichloride and (-)-menthol gave (-)-(1R, 2S, 5R)-dimethyl pimelate (I), which was cyclized by the Dieckmann reaction to give (-)-(1R, 2S, 5R)-menthyl 2-oxocyclohexanecarboxylate (II). Alkylation of II gave (-)-(1R, 2S, 5R)-menthyl 1-alkyl-2-oxocyclohexanecarboxylates (IIIa-c), which were condensed with hydrazine hydrate in ethanol to give 3a-alkyl-3, 3a, 4, 5, 6, 7-hexahydro-2H-indazol-3-ones (Va-c). The compounds (Va, b) were found to be optical active. The condensation of ethyl 2-oxocyclohexanecarboxylate with (-)-(1R, 2S, 5R)-methyl carbazate (VII) gave (-)-(1R, 2S, 5R)-menthyl 3-hydroxy-4, 5, 6, 7-tetrahydro-2H-indazole-2-carboxylate (IX), whose reaction with benzyl bromide gave (-)-(1R, 2S, 5R)-menthyl 1-benzyl-3-oxo-2, 3, 4, 5, 6, 7-hexahydro-1H-indazole-2-carboxylate (X) and (-)-(1R, 2S, 5R)-menthyl 3a-benzyl-3-oxo-3, 3a, 4, 5, 6, 7-hexahydro-2H-indazole-2-carboxylate (XI). The hydrolysis of XI gave Va. However, the compound Va obtained by this method did not show optical rotation.
将二氯嘧啶与(-)-薄荷醇反应,得到(-)-(1R, 2S, 5R)-二甲基嘧啶酸酯(I),通过迪克曼反应使其环化,得到(-)-(1R, 2S, 5R)-薄荷基 2-氧代环己烷羧酸酯(II)。将 II 烷基化后得到(-)-(1R, 2S, 5R)-1-烷基-2-氧代环己烷羧酸孟酯(IIIa-c),在乙醇中与水合肼缩合后得到 3a-烷基-3, 3a, 4, 5, 6, 7-六氢-2H-吲唑-3-酮(Va-c)。发现这些化合物(Va,b)具有光学活性。2-oxocyclohexanecarboxylate 与 (-)-(1R, 2S, 5R)-methyl carbazate (VII) 缩合得到 (-)-(1R, 2S, 5R)-menthyl 3-hydroxy-4, 5, 6, 7-tetrahydro-2H-indazole-2-carboxylate (IX),其与溴化苄反应得到 (-)-(1R、2S,5R)-1-苄基-3-氧代-2,3,4,5,6,7-六氢-1H-吲唑-2-甲酸孟酯(X)和(-)-(1R,2S,5R)-3a-苄基-3-氧代-3,3a,4,5,6,7-六氢-2H-吲唑-2-甲酸孟酯(XI)。XI 的水解产物是 Va。然而,用这种方法得到的化合物 Va 并未显示出光学旋转。