Enantiomerically divergent pathways in Tsuji-Trost reactions: exploiting the structural differences between β-acyloxy-o-(diphenylphosphino)benzamides and β-amido-o-(diphenylphosphino)benzoates
摘要:
Using a single chiral scaffold, (1R,2S)-norephedrine, a series of monophosphine ligands have been prepared. The ligands prepared, beta-acyloxy-(o-diphenylphosphino)amides and beta-amido-(o-diphenylphosphino)esters, give rise to enantiomerically divergent products in the Tsuji-Trost asymmetric allylic reaction. The phosphinoamides afforded the best enantioselectivities and favored the (S)-enantiomer of the product. In contrast the phosphinoesters afforded lower enantioselectivities and favored the (R)-enantiomer. A mechanistic rationale for this observation is proposed. (C) 2016 Elsevier Ltd. All rights reserved.