An efficient method for the synthesis of disubstituted thioureas via the reaction of N,N′-di-Boc-substituted thiourea with alkyl and aryl amines under mild conditions

An efficient method for the synthesis of disubstituted thioureas via the reaction of N,N′-di-Boc-substituted thiourea 5 with alkyl and aryl amines under mild conditions has been developed. In the presence of NaH as a base, trifluoroacetic anhydride (TFAA) reacted with 5 providing intermediate 6, which then reacted with amines giving thioureas 7 in excellent yields. This reaction conditions tolerated other functional groups such as amide, ester, enol ether and hydroxyl groups.