A GENERAL MECHANISTIC SCHEME FOR INTRAMOLECULAR ELECTROCHEMICAL HYDROCYCLIZATIONS - MECHANISM OF THE ELECTROREDUCTIVE CYCLIZATION OF OMEGA-KETO-ALPHA,BETA-UNSATURATED ESTERS

A systematic procedure is suggested for formulating possible mechanism s by which electrochemical hydrocyclization and dehydrocyclization can occur. A combination of linear sweep voltammetry (LSV) and chemical a nd electrochemical arguments can be used to reduce the mechanistic pos sibilities to a small set or even a unique mechanism. The procedure is applied to the reductive cyclization of omega-keto-alpha,beta-unsatur ated esters. Of the several hundred mechanistic possibilities for this process, the combination of LSV and chemical arguments can reduce the list to four; preparative-scale electrolysis of a specially designed substrate permits assignment of a unique mechanism, the e-P-d-c-p path , at low concentrations of electroactive substance.