Guanidine and guanidinium salt catalyzed enantioselective phosphorus - carbon bond formation reactions

Abstract

The aim of this study is to develop guanidine and guanidinium salt-catalyezd highly enantioselective phosphorus-carbon bond formation reactions.<br>Chiral bicyclic guanidine was found to catalyze the phospha-Michael reactions between diaryl phosphine oxide and nitroalkenes, and moderate to high yields (up to 99%) and high enantioselectivities (up to 96%) were achieved. In most cases, the enantioselectivities of the phospha-Michael products could be increased to excellent level (>99%) by a single recrystallization. This reaction offered a direct methodology to prepare chiral N2-aminophosphine oxides and N2-aminophosphines. <br>Guanidinium catalysts were obtained in a single step from commerically available diamine. Using these catalysts, asymmetric phospha-Michael reaction has been developed with secondary phosphine oxides and H-phosphinates as P nucleophiles. A series of enantiomerically enriched N1-amino phosphine oxides and N1-amino phosphinates were prepared. H-phosphinates containg P-chiral center were obtained with high enantiopurities through kinetic resolution.