Detailed conformational analysis of 1-phenyl-1H-4,5-dihydro-2,4-benzod
iazepines using X-ray structures, nuclear Overhauser experiments, vari
able-temperature H-1 NMR, and MacroModel (MULTIC) reveals a rapid equi
librium between axial and equatorial comformations for the free base o
f 2. The DCl salt of 2 and 1-methyl-1-phenyl analog 3, however, prefer
the axial conformation.