Novel heterocycles. Synthesis of the 2,4,3-benzodiazaphosphepine ring system

Novel alkyl (1,2,4,5-tetrahydro-3H-2,4,3-benzodiazaphosphepin-3-yl)carbamate-P-oxides ( 7 ) were synthesized by cyclization of the corresponding dichlorophosphinylcarbamates ( 5 ) with α,α'-diamino-o-xylene ( 6 ). A steric limitation in the synthesis of analogs is discussed.