Microwave-assisted synthesis of s-triazino[2,1-b][1,3]benzoxazoles, s-triazino[2,1-b][1,3]benzothiazoles, and s-triazino[1,2-a]benzimidazoles

摘要

2-Amino-4-oxo-derivatives of s-triazino[2,1-b][1,3]benzoxazoles, s-triazino[2,1-b][1,3]benzothiazoles, and s-triazino[1,2-a]benzimidazoles were synthesized by carbonylation of 2-benzoxazolylguanidines, 2-benzothiazolylguanidines, and 2-benzimida-zolylguanidines with phenyl isocyanate under microwave irradiation (180 degrees C, 15 minutes). Using phenyl isothiocyanate instead of phenyl isocyanate under the same conditions led to the successful ring closure via thiocarbonylation of 2-benzoxazolylguanidines. However, the formation of 2-imino-4-phenylimino-s-triazino[2,1-b][1,3]benzothiazoles from 2-benzothiazolylguanidines was observed instead under microwave irradiation conditions.