N-hydroxypyridine-2(1H)-thione derivatives of carboxylic acids as activated esters. Part I. The synthesis of carboxamides

Article abstract of DOI:10.1016/0040-4020(96)00487-5

The reaction between an acyl derivative of N-hydroxypyridine-2(1H)- thione (a Barton PTOC ester) and either an amine (primary or secondary), or the corresponding sulfenamide, led to the formation of a carboxamide in a clean transformation requiring minimal work-up and purification. The reaction with a sulfenamide is particularly useful since the only by-product, an unsymmetrical disulfide, is of both synthetic and biological value. In sterically demanding cases, Barton PTOC esters were more reactive towards benzenesulfenamides than to the corresponding free amines.