A convenient synthesis of polyfunctionally substituted heterocyclic systems derived from 4-methyl-2H-1,4-benzoxazin-3-one

Cycloaddition of 2-[(N-phenyl)thiocarboxamido-]-4-methyl-2H-1,4-benzoxazin- 3-one (2) to a,p-unsaturated compounds gave spiro pyridine derivatives. Rea ction of compound 2 with some halo compounds afforded thiazolidine derivati ves. 2-Ethoxymethylenyl-4-methyl-1,4-benzoxazine-3-thione underwent cycloco ndensation reactions with some bidentate reagents. Condensed tricyclic syst ems have been prepared through the reaction of 3-dicyanomethylenyl-4-methyl -2H-1,4-benzoxazine with the appropriate reagents.