One-step synthesis of bisphosphine monoxide ligands via PdI 2-catalysed oxidation

Abstract

Bisphosphine monoxides are an emerging class of monophosphine ligands that have found their use in many enantioselective protocols, especially in the field of asymmetric C-H functionalization, yet their synthesis is usually multistep and chemically-wasteful. This report shows a one-step modified protocol based on Grushin’s mono-oxidation of axially chiral bisphosphine ligands to form axially chiral bisphosphine monoxide ligands with biphenyl and 1,1’-binaphthyl scaffolds, by changing the reaction conditions as well as careful monitoring of the reaction progress by NMR spectroscopy. The modified protocol provides a quick way to prepare a series of chiral bisphosphine monoxide ligands for ligand screening in asymmetric methodological researches.