Enantiomerically Pure 2-Bromo-2'-diphenylphosphinyl-1,1'-binaphthyl as a Monophosphorus Template for Electrophilic Functionalization in Chiral MOP-Type Ligand Synthesis

摘要

Pd-catalyzed monophosphinylation of(R)-2-bromo-2'-iodo-l,l'-binaphthyl with Ph_2P(O)H afforded(R)-2-bromo-2'-diphenylphosphinyl-l,l'-binaphthyl in good yield with excellent chemoselectivity and no observable racemization.Subsequent lithiation in the presence of excess thiosulfonate furnished an enantiomerically pure sulfenylation product,which was reduced to afford a chiral S-MOP ligand.Chiral ligand based on the l,1'-binaphthalene scaffold is one of the most successful ligands in transition-metal-catalyzed enantioselective processes.BINAP has been the leading ligand in this class.In addition,since the pioneering work of the 2-diphenylphosphino-2'-methoxy-1,1'-binaphthyl(MOP)ligand reported by Hayashi and Uozumi,1 non-C_2-symmetrical monophosphine analogues of BINAP have also proven to be excellent ligands for asymmetric catalysis.