Electron Transfer Profile of Cyclopropanone Acetals in the Nonirradiated Reaction with Tetracyanoethylene, Chloranil, and Dicyanodichlorobenzoquinone
摘要:
The donor profiles of cyclopropanone acetals 1 and 2 were examined in the reactions with electron accepters (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 occurred. 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.
Electron Transfer Profile of Cyclopropanone Acetals in the Nonirradiated Reaction with Tetracyanoethylene, Chloranil, and Dicyanodichlorobenzoquinone
摘要:
The donor profiles of cyclopropanone acetals 1 and 2 were examined in the reactions with electron accepters (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 occurred. 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.