Two single-enantiomer (R and S) Amidophosphoesters

The compound (C6H5O)2P(O)[NHCH(CH3)(C6H5)] exists in previously published papers, with together its melting point, elemental analysis and selected mass spectrum peaks, and with no sign of the type of NHCH(CH3)(C6H5) fragment as R, S or racemic. Here, the crystal structures of (C6H5O)2P(O)[NH(+)CH(CH3)(C6H5)] and (C6H5O)2P(O)[NH(–)CH(CH3)(C6H5)] are reported. The compounds are named as diphenyl (R-(+)-α-methylbenzylamido)phosphate, (I), and diphenyl (S-(–)-α-methylbenzylamido)phosphate, (II). In both structures, the chiral one-dimensional hydrogen-bonded architectures, along [010], are built from NH…OP interactions; however, they are mirror images of each other. The assemblies of these compounds include the non-centrosymmetric graph-set motif C(4) and the compounds crystallize in the chiral space group P21. Figure 1 shows the assembly of the structure (II), for a typical example. For each molecule, the two C6H5O groups bonded to phosphorus are different in NMR media (monitored by 1H and 13C NMR). For both compounds, the phosphorus signal exactly appears at –0.81 ppm (DMSO-d6), in a calibrated condition (concentration, temperature).