GENERATION AND REACTIONS OF NOVEL COPPER CARBENOIDS THROUGH A STOICHIOMETRIC REACTION OF COPPER METAL WITH GEM-DICHLORIDES IN DIMETHYL-SULFOXIDE

Copper metal and such gem-dichlorides as ɑ,ɑ-dichloro acid esters, la-e, diphenyldichloromethane, 2, benzal chloride, 3, 1,1-dichloroacetone, 4, l,l-dichloro-2-butene, 5, and carbon tetrachloride, 6, were found toundergo a stoichiometric reaction in dimethyl sulfoxide (DMSO) under a mild condition to produce copper carbenoid intermediates via a,a-elimination of dichlorides along with the formation of CuCl2(DMSO)2. Thus, 1 and 2 gave substituted olefins via a carbenoid coupling reaction. From 5 and 6, reaction products via the oxygen abstraction from DMSO were produced together with dimethyl sulfide; 3 and 4 were found to cause both types of reactions. The carbenoid intermediates formed from 1 did not cause cyclopropanation reaction with cyclohexene in contrast to the conventional carbalkoxy carbenoid generated by a decomposition reaction of ethyl diazoacetate. Also the carbenoid coupling reaction was completely inhibited by the addition of triphenylphosphine, which was contrastive to the formation of phosphonium ylide with a carbenoid from ethyl diazoacetate. © 1990, American Chemical Society. All rights reserved.