First direct discrimination of chiral phosphine selenide (P=Se) derivatives by multinuclear magnetic resonance spectroscopy in the presence of a chiral dirhodium complex

Abstract

Enantiomeric ratios of compounds with P=Se functionalities (phosphine selenides) can easily be determined by (1)H, (13)C, (31)P, and (77)Se NMR spectroscopic inspection of their diastereomeric complexes with (R)-Rh(2)(MTPA)(4) (MTPA-H identical with 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 Delta(delta) are moderate or even negligible, significant signal dispersions Delta(nu) 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.