ETUDE DE L'ACTION DE L'OXYDE DU TRICHLOROPHOSPHINE SUR LES AMIDINES N-BENZIMIDAZOL-2-YL: SYNTHESE DES [1,2-a] BENZIMIDAZOLO-1,3,5,2-TRIAZAPHOSPHORINE-2-OXYDES [STUDY OF THE ACTION OF TRICHLOROPHOSPHINE OXIDE ON N-BENZIMIDAZOL-2-YL AMIDINES: SYNTHESIS OF [1,2-a] BENZIMIDAZOLO-1,3,5,2-TRIAZAPHOSPHORINE-2-OXIDES]