Organophosphorus compounds. XX. Approaches to the synthesis of 2,3-Dihydro-1H-1,2-benzazaphospholes involving C-C and C-P ring closure

Abstract

Reaction of chloromethylphosphonic dichloride (9) with N-methylaniline gave N,N'-dimethyl-N,N'-diphenylchloromethylphosphonodiarnide (10) which upon treatment with aluminium chloride underwent intramolecular Friedel-Crafts alkylation to afford 1-methyl-2-(N'-methyl-N'-phenylamino)-2,3-dihydro-1N-l,2-benzazaphosphole 2-oxide(13a). Similarly, N-methyl-N-phenyl(ch1oromethy1)phenylphosphinamide (15) was cyclized to give 1-methyl-2-phenyl-2,3-dihydro-1H-1,2-benzazaphosphole2-oxide (1 3b).

Some unsuccessful approaches to this heterocyclic ring system are also reported.