Enantiomerically enriched preparation of enolizable β-keto amides. Diastereoselective α-acylation and subsequent aminolysis of 2-acyl-3-phenyl-l-menthopyrazoles
作者:Choji Kashima、Iwao Fukuchi、Katsumi Takahashi、Akira Hosomi
DOI:10.1016/0040-4020(96)00550-9
日期:1996.7
After deprotonation with LDA, 2-acyl-3-phenyl-l-menthopyrazoles (13) were diastereomerically α-acylated to give N-(3-phenyl-l-menthopyrazolyl) β-keto amides (14–19). The subsequent amides were converted into the corresponding N-alkyl amides (21–24) retaining their enantiomeric enrichment on the α-position. These are the first examples of enolizable β-keto acid derivatives having only one chiral center
用LDA去质子化后,2-酰基-3-苯基-升-menthopyrazoles(13)的非对映体α -酰化,得到N-(3-苯基升-menthopyrazolyl)β酮酰胺(14-19)。随后的酰胺被转化为相应的N-烷基酰胺(21-24),使它们的对映体富集在α位。这些是在α位仅具有一个手性中心的可烯醇化的β-酮酸衍生物的第一个实例。这些手性β-酮酰胺在干燥的苯中出奇地稳定,并且它们的光学不对称性在室温下几乎保留了两周而没有任何差向异构化。