Formation and X-Ray Crystal Structure of 5,6-Dihydro-1-hydroxy-5,5-dimethyl-1-phenyl-3-phenylamino-1H-pyrrolo[1,2-a][1,5]benzodiazepin-2(4H)-one

The reaction of 2,3-dihydro-2,2,4-trimethyl-1H-1,5-benzodiazepine (1) with (Z)-N-(benzoylmethylene)aniline N-oxide in anhydrous benzene at room temperature gave 5,6-dihydro-1-hydroxy-5,5-dimethyl-1-phenyl-3-phenylamino-1H-pyrrolo[1,2-a][1,5]benzodiazepin-2(4H)-one (2), accompanied by several by-products. The structure of compound (2), the first example of a tetrahydropyrrolo[1,2-a][1,5]benzodiazepine derivative, was established by an X-ray crystallographic analysis. A mechanism for its formation is suggested.