Betti base derived P-stereogenic phosphine-diamidophosphite ligands with a single atom spacer and their application in asymmetric catalysis

Abstract

A set of hybrid P-stereogenic phosphine-diamidophosphite ligands based on the Betti base backbone has been synthesized. The ligands possess five chiral centers including the P-chirality in both the phosphorus atoms. The synthesis involves the incorporation of a P-chiral P–N synthon with a stereochemically defined P-chiral diamidophosphite as a coupling partner. The new ligands were applied in Rh-catalyzed asymmetric hydrogenation of several dehydroamino acids and in the Pd-catalzyed asymmetric allylic substitution of diphenyl allyl acetate. Moderate ees upto 74% in allylic substitution and excellent ees up to 99% were obtained in asymmetric hydrogenation using this new set of hybdrid PNP ligands.