A modular approach to a new class of phosphinohydrazones and their use in asymmetric allylic alkylation reactions

A group of five phosphino hydrazones with a pendant binaphthyl unit as a chiral modifier has been synthesized from non-racemic 2,2'-bis(bromomethyl)-1,1'-binaphthyl and 3,3'-diiodo-2,2'-bis(bromomethyl)-1,1'-binaphthyl as the key intermediates. Their efficiency as chiral ligands in palladium-catalyzed allylic alkylation reactions has been investigated showing up to 95% ee under optimized conditions. X-ray diffraction structures of mono- and dimeric Pd complexes are also reported. (C) 2010 Elsevier Ltd. All rights reserved.