Enantioselective Synthesis of Atropisomeric Biaryls using Biaryl 2,5‐Diphenylphospholanes as Ligands for Palladium‐Catalysed Suzuki‐Miyaura Reactions
Liam Byrne, Christian Sköld, Per‐Ola Norrby, Rachel H. Munday, Andrew R. Turner, Peter D. Smith
Abstract
Abstract Here we describe the development of biaryl 2,5‐diphenylphospholanes as a new class of C 2 ‐symmetric, monodentate ligands for asymmetric Suzuki‐Miyaura (ASM) reactions. Screening of a series of exemplary phospholanes led to the identification of two ligands that were used to prepare a range of atropisomeric biaryl and heterobiaryl products with good to excellent levels of enantioselectivity (up to 97:3 e.r.) under mild conditions. DFT studies suggest that the formation of a constraining ligand pocket and coordination of one of the biaryl methoxy groups in the optimised ligands to the metal centre is crucial for restricting conformational freedom in the bond‐forming step. magnified image