Premium
Highly Enantioselective Ferrocenyl Palladacycle‐Acetate Catalysed Arylation of Aldimines and Ketimines with Arylboroxines
Author(s) -
Schrapel Carmen,
Frey Wolfgang,
Garnier Delphine,
Peters René
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201605244
Subject(s) - enantioselective synthesis , aldimine , imine , chemistry , transmetalation , aryl , stereocenter , catalysis , reagent , combinatorial chemistry , organic chemistry , medicinal chemistry , alkyl
Benzylic N ‐substituted stereocenters constitute a frequent structural motif in drugs. Their highly enantioselective generation is hence of technical importance. An attractive strategy is the arylation of imines with organoboron reagents. Chiral Rh complexes have reached a high level of productivity for this reaction type. In this article we describe that an electron rich Pd II catalyst also performs well in the arylation of aldimines, comparable to the best Rh catalysts. The ferrocenyl palladacycle‐acetate catalyst allows for a broad substrate scope and very high enantioselectivities. Commonly observed side reactions like aryl–aryl homocouplings and imine hydrolysis could be blocked. Mechanistic studies implicate that a) the acetate ligand is crucial for transmetallation, b) the active catalyst is most likely a palladacycle‐OAc monomer, c) the rate limiting step is probably the product release. By added KOAc the arylation could also be applied to ketimines.