Catalytic asymmetric reactions via p-allylpalladium complexes coordinated with chiral monophosphine ligands
نویسنده
چکیده
Chiral monophosphines (MOPs), whose chirality is due to biaryl axial chirality, are prepared from enantiometrically pure 2,2%-dihydroxy-1,1%-binaphthyl and 3,3%-dihydroxy-4,4%-biphenanthryl. The representatives are 2-(diphenylphosphino)-2%-methoxy1,1%-binaphthyl (MeO–MOP and 3-(diphenylphosphino)-3%-methoxy-4,4%-biphenanthryl (MOP–phen). The palladium complexes coordinated with the MOP ligands are highly effective catalysts for catalytic asymmetric allylic substitution reactions, where chelating bisphosphine ligands cannot be used because of their low catalytic activity or low selectivity towards the desired reaction pathway. The catalytic asymmetric reactions are: (1) asymmetric reduction of allylic esters with formic acid (93% ee). (2) Regioand enantioselective alkylation of allyl esters (87% ee). © 1999 Elsevier Science S.A. All rights reserved.
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