Use of dipyridyldithiocarbonate (DPDTC) as an environmentally responsible reagent leading to esters and thioesters under green chemistry conditions

A new, green esterification and thioesterification method has been developed based on the intermediacy of in situ-generated 2-thiopyridine esters derived from dipyridyldithiocarbamate (DPDTC). Both are formed from initial treatment of the corresponding carboxylic acid with DPDTC under neat conditions, followed by introduction of the alcohol or thiol, together with catalytic amounts of an activating group, in concentrated EtOAc or under aqueous micellar conditions. These 1-pot processes generate high yields of esters and thioesters, avoid use of traditional coupling agents, and lead to minimal waste creation as both the EtOAc and the thiol by-product are easily recycled. A new, green esterification and thioesterification method has been developed based on the intermediacy of in situ-generated 2-thiopyridine esters derived from dipyridyldithiocarbamate (DPDTC).