Syntheses and structural study of phospholidines derived from aromatic amides

The preparation and structural study in solution by ¹H, ¹³C and ³¹P NMR spectroscopy of 2-dimethylamine-N-acetylbenzoxazaphospholidine 1b, 2-dimethylamine-N-acetylbenzo diazapbospholidine 2b, 2-dimethyl-N,N′-diacetylbenzoxazaphospholidine 3b, bis-[(2-dimethylamine)-N,N′-(benzoxazaphospholidine)]-1,2-ethane 4b, bis-[(2-dimethylamine)-N,N′-(benzoxazaphospholidine)]oxalyl 5b. The reaction of compounds 1b-5b with BH₃DMS afforded the corresponding P - BH₃ adducts without reducing the heterocycles, 1c-5c were also studied by ¹¹B NMR. The solid state structure determined by x-ray diffraction analysis of 1b and 3b shows phosphorus atoms with 45% of sp³ character and with the NMe₂ group in axial position.