Chiral β-Aminophosphine Oxides via Bicyclic Guanidine-Mediated Phospha-Michael Reaction

Significance

A chiral bicyclic guanidine catalyst is used to mediate the reaction of diaryl phosphine oxides and nitrostyrenes to yield chiral β-aminophosphine oxides in high yields and enantioselectivities. Different aromatic groups on the phosphine oxides have been screened, with di(1-naphthyl) phosphine oxide giving the best results. The optical purity of the products could be further improved by recrystallization. In the case of trisubstituted nitroolefins, even very good diastereo­meric ratios were observed. The reduction of both the nitro group and the phosphine oxide is exemplified in the paper.