A solvent-free and catalyst-free reaction of o-aminobenzophenone with aryl isothiocyanates: expedient access to congested 4-phenyl-4-hydroxyquinazolin-2-thione derivatives†

An efficient method to construct 4-phenyl-4-hydroxyquinazolin-2-thiones via solvent-free and catalyst-free addition of o-aminobenzophenone with aryl isothiocyanates under thermal conditions has been developed, providing new congested 4-phenyl-4-hydroxyquinazolin-2-thiones in practically quantitative yields via simple purification by filtration/recrystallization. Extension of these conditions to o-aminoacetophenone in place of o-aminobenzophenone led to 4-methylenequinazoline-thione as a result of a subsequent dehydration reaction.