A P,N ligand with central and axial chiral elements: synthesis and application in allylic alkylation

Abstract

Two epimers of 4-({5-[(diphenylphosphino)methyl]-2,2-dimethyl-1,3-dioxolan-4-yl}methyl)-4,5-dihydro-3 H-dinaphtho[1,2- e:2′,1′- c]azepine were prepared starting from (2 S,3 S)-4-amino-2,3- O-isopropylidenebutane-1,2,3-triol and ( R)- and ( S)-binaphthol. These ligands, in association with Pd(0) gave enantioselectivities up to 89% ( S) and 36% ( R) ee for the ( S A ,4 S,5 R) and the ( R A ,4 S,5 R) ligands in the alkylation of racemic 1,3-diphenylprop-2-enyl acetate with dimethyl malonate, showing that the binaphthyl moiety is the most important structure in the enantioselective creation of the new stereogenic center.