Anodic oxidation of carbamates using organothio groups as electroauxiliaries

Abstract

Three methods for the preparation of α-organothio carbamates were developed: 1. (1) the treatment of the anion of carbamates with α-halo sulfides, 2. (2) the base-catalyzed reaction of carbamates with aldehydes followed by the acid-catalyzed reaction with thiols, and 3. (3) the treatment of imines with methyl chloroformate followed by the reaction with thiols in the presence of an amine. The oxidation potentials of α-organothio carbamates were found to be much less positive than those of the corresponding carbamates. The anodic oxidation of α-organothio carbamates resulted in the facile cleavage of the carbon-sulfur bond and the selective introduction of nucleophiles such as methanol, allylsilanes, silyl enol ethers, trimethylsilylcyanide, and arenes onto the carbon to which the organothio group has been attached. These results indicate that organothio groups serve as effective electroauxiliaries in the anodic oxidation of carbamates.