Structural diversity in phosphoramidate’s chemistry: Syntheses, spectroscopic and X-ray crystallography studies

Novel phosphorus compounds of bisphosphoramidate, phosphoramidate and phosphoric triamide derivatives were synthesized using the starting materials PCl5 and POCl3. The products were then characterized by 1H, 13C, 31P, 19F NMR, IR spectroscopy and CHN elemental analysis. It is noticeable that the reaction of 4-aminobenzamide with PCl5 in different molar ratios yields different products, bisphosphoramides and phosphoric triamides. Moreover, we were taken by surprise that the interaction of POCl3 with the first-type aromatic amines gave bisphosphoramidates with P–N–P linkages that exhibited 2J(P,P) ≈ 20.0 Hz in the 31P NMR spectra. In fact, two simple one-pot pathways are presented here for the synthesis of new bisphosphoramidates, and to the best of our knowledge these are the first instances of bisphosphoramidates that have been obtained up until now. The structures of compounds I (4-OCH3–C6H4–CH2–C9H13–NH2Cl), 34 and 44 were further determined by X-ray crystallography. All of these structures produced three dimensional polymeric chains through strong- and weak hydrogen bonds. The presence of chiral aminoacidester moieties in the phosphoric triamides lead to chiral molecules that showed two sets of signals for the two groups. Interestingly, in phosphoric triamides containing cyanoacetamide moieties, the existence of aromatic amine substituents on the P atoms created central chiral phosphorus atoms, i.e. the two aromatic groups revealed two sets of peaks in the 1H and 13C NMR spectra, while compounds with aliphatic moieties did not display this effect.

A series of various novel phosphorus compounds of bisphosphoramidates, phosphoramidates, and phosphoric triamides were synthesized and characterized. Some interesting and unusual phenomena are noted in this study.Figure optionsDownload as PowerPoint slide