First direct discrimination of chiral phosphorus thionate (P=S) derivatives by multinuclear magnetic resonance spectroscopy in the presence of a chiral dirhodium complex†

Enantiomeric ratios of compounds with P=Se functionalities (phosphine selenides) can easily be determined by 1H, 13C, 31P, and 77Se NMR spectroscopic inspection of their diastereomeric complexes with (R)-Rh2(MTPA)4 (MTPA-H ≡ methoxytrifluoromethylphenylacetic acid; Mosher's acid). This is the first facile and rapid spectroscopic method for chiral recognition in this class of compounds. Whereas most complexation shifts Δδ are moderate or even negligible, significant signal dispersions Δν can be observed. Some rationalization for the adduct formation mode is presented. NMR spectral characteristics of the free P=Se compounds 1–5 are described. Chirality 14:407–411, 2002. © 2002 Wiley-Liss, Inc.