A new synthesis of ethyl 2-methyl-4-oxocyclohex-2-enecarboxylate (Hagemann's ester) and its methyl and t-butyl analogues
作者:A. L. Begbie、B. T. Golding
DOI:10.1039/p19720000602
日期:——
Regioselective cyclisations of esters of 2-acetyl-5-oxohexanoic acid led to (i) alkyl 2-methyl-4-oxocyclohex-2-enecarboxylates (alkyl = But,Et or Me)(catalysed by pyrrolidinium acetate), (ii) esters of 4-pyrrolidino-2-methyl-cyclohexa-1,3-dienecarboxylic acid (in the presence of pyrrolidine), and (iii) alkyl 4-methyl-2-oxocyclohex-3-enecarboxylates (catalysed by hydrogen chloride).
导致(ⅰ)烷基-2-甲基-4-氧代环己基-2- enecarboxylates(烷基=卜的2-乙酰基-5-氧代己酸的酯的区域选择性环化吨等或Me)(由吡咯烷乙酸盐催化的),(II) 4-吡咯烷基-2-甲基-环己-1,3-二烯羧酸的酯(在吡咯烷存在下),和(iii)4-甲基-2-氧代环己基-3-烯基羧酸烷基酯(由氯化氢催化)。