Electron Transfer Profile of Cyclopropanone Acetals in the Nonirradiated Reaction with Tetracyanoethylene, Chloranil, and Dicyanodichlorobenzoquinone

Article abstract of DOI:10.1021/jo00103a043

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 1a-c but nonstereospecifically with disubstituted acetals 1d,e.With quinones, a ring-opening of the cyclopropane and its coupling with the quinone took place to give the C (cyclopropane)-O (quinone) adduct 9 (with chloranil) or 10 (with DDQ), the latter of which underwent the elimination of a phenol to produce unsaturated esters 5 and 6.In addition, the intervention of the C (cyclopropane)-C (quinone) adduct 14 (with chloranil) or 15 (with DDQ), both as the precursor of 5 and 6, was also postulated.With 1-cyanonaphthalene, under photolysis, the cis/trans isomerization of 1 and 2 occured.The results provided evidences that cyclopropanone acetals, in general, are prone to function as donors.The mechanism of the reaction with quinones, in particular, was investigated in detail.