Formation and reactions of chloro-methoxy- and -(2-methylpropoxy)-carbene

Chloro-methoxy- and -(2-methylpropoxy)-carbene are formed from 3-chloro-3-methoxy- and 3-(2-methylpropoxy)-diazirine, respectively. In the absence of carbene traps they fragment to give carbon monoxide and either methyl chloride or alkene and HCl. They add readily to electron-poor alkenes to give cyclopropanes, and react with alcohols to give alkyl formates. The influence of substituents on the reactivity of carbenes is discussed, and the reaction of alkoxychlorocarbenes with alcohols is related to the mechanism of base-catalysed halogenoform hydrolysis.