N-Substituted benzoxazolyl ureas and thioureas in Biginelli reaction promoted by trifluoromethane sulfonic acid: An efficient and convenient synthesis of substituted benzoxazolyl 3,4-dihydropyrimidine (1H)-(thio)-ones

An efficient synthesis of 3,4-dihydropyrimidine 2 (1H)-ones and thiones (3,4-DHPMs) core was prepared by one-pot three-component Biginelli condensation and which was catalyzed by trifluoromethane sulfonic acid. The classical Bignelli reaction has been extended by the use of N-substituted benzoxazolyl semicarbazides and thiosemicarbazides and this method has the advantage of excellent yields and short reaction times.