synthesis and some transformations of 4-oxo-2-(β-ethoxyvinyl)-4H-1,3-benzoxazinium salts

A method was developed for the synthesis of 4-oxo-(-ethoxyvinyl)-4H-1,3-benzoxazinium salts by condensation of oxo-2-alkylbenzoxazinium salts by condensation of oxo-2-alkylbenzoxazinium salts with ethyl orthoformate. During hydrolysis and aminolysis, attack of the nucleophile is directed to the -carbon atom of the benzoxazinium salts. The previously unknown 2-formylmethylene-4-oxo-3,4-dihydro-2H-1,3-benzoxazines and their nitrogen derivatives were obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 322–327, March, 1977.