Cycloadditions. Part II. A steric effect in the 1,3-dipolar addition of 2-diazopropane to methyl but-2-ynoate
作者:A. C. Day、R. N. Inwood
DOI:10.1039/j39690001065
日期:——
5-methoxycarbonyl-3,3,4-trimethyl-3H-pyrazole being obtained in the ratio 6 : 1. In contrast, methyl propiolate behaves normally with 2-diazopropane, giving solely 3,3-dimethyl-5-methoxycarbonyl-3H-pyrazole. The preference for reverse addition to methyl but-2-ynoate is attributed to steric factors in the transition states for cycloaddition.
Cyclopropenes electrophiles : Reactions du morpholino-1 cyclohexene avec quelques esters GEM- DI methylcyclopropeniques; Acces a des analogues halopyrethriques (1).
作者:M. Franck-Neumann、M. Miesch、H. Kempf
DOI:10.1016/s0040-4020(88)90030-0
日期:1988.1
Electrophilic cyclopropene esters react with 1-morpholino cyclohexene to give various products depending on the second substituent of the cyclopropene double bond. Enamine alkylation is observed -but not always- as well as different formal cycloaddition reactions.