Synthesis of new BINAP-based aminophosphines and their ³¹P-NMR spectroscopy.

BINAP aminophosphines are prevalent N,P-bidentate, chiral ligands for asymmetric catalysis. While modification via the BINAP-nitrogen linkage is well explored and has provided a diverse body of derivatives, modification of the other substituents of the phosphorous center is another avenue in generating new congeners of this important class of chiral ligands. Herein reported are new BINAP aryl aminophosphines with electron rich or deficient substituents on the aryl rings. This scalable synthesis converted readily available starting material, (S)-BINOL, to a key intermediate (S)-NOBIN, from which the final chiral aminophosphines were prepared via a palladium-catalyzed, phosphonylation reaction. The aryl substituents are able to modify the electronic properties of the phosphorous center as indicated by the range of ³¹P-NMR shifts of these new ligands. A computational analysis was performed to linearly quantitate contributions to the ³¹P-NMR shifts from both resonance and field effects of the substituents. This correlation may be useful for designing and preparing other related aminophosphines with varying ligand properties.

Mechanistic investigations of multidentate organocatalyst-promoted counterion catalysis for fast and enantioselective aza-Morita-Baylis-Hillman reactions at ambient temperature.

Kinetic experiments were performed on the catalytic cycle of a trifunctional organocatalyst-promoted counterion catalysis of asymmetric aza-Morita-Baylis-Hillman reactions. The catalysis was found to be first order in the trifunctional catalyst with the Michael addition as the rate-limiting step. Temperature variation changed the rate of catalysis but not the enantioselectivity of the reaction.