The donor profiles of cyclopropanone acetals 1 and 2 were examined in the reactions with electron acceptors (TCNE, DDQ, chloranil, and 1-cyanonaphthalene). With TCNE under nonirradiating conditions, an exclusive 2+ 2 cycloaddition took place stereospecifically with monosubstituted acetals la-c but nonstereospecifically with disubstituted acetals ld, e. With quinones, a ringopening of the cyclopropane and its coupling with the quinone took place ...
