Rhodium (I1) acetate, or trifluoroacetate-catalyzed decomposition of 1-diazo-2- (trialkylsiloxy~ propenes with electron-withdrawing groups at the 1-position results in the formation of highly reactive cyclopropenes. These cyclopropenes contain both donor and acceptor substituents on the alkene and are very susceptible to ring opening and fragmentation reactions. Nevertheless, when appropriately functionalized with bulky ...