The preparation and resolution of 2-phenyl-Quinazolinap, a new atropisomeric phosphinamine ligand for asymmetric catalysis

The preparation and resolution of an axially chiral quinazoiine-containing phosphinamine ligand is described. The biaryl linkage was formed in a Pd-ca talysed coupling of 4-chloro-2-phenylquinazoline 10 with 2-methoxyl-naphthy lboronic acid 11. Demethylation of the product ether 12 afforded alcohol 13 which was converted into the corresponding triflate 14 by treatment with t rifluoromethanesulphonic anhydride. An Ni-catalysed phosphinylation gave th e required phosphinamine ligand 9 as a racemate. Diastereomeric palladacycl es 16, formed from 9 and (+)-di-mu-chlorobis[(R)-dimethyl(1-(1-naphthyl)eth yl)aminato-C-2,N]dipalladium(II) 15 were separated to give diastereomerical ly pure materials. An X-ray crystal structure of the (R,R)-16 palladacycle was determined and is discussed. Displacement of the resolving agent by rea ction with 1,2-bis(diphenylphosphino)ethane gave enantiopure 2-phenyl-Quina zolinap 9, a new atropisomeric phosphinamine ligand for asymmetric catalysi s. (C) 1999 Elsevier Science Ltd. All rights reserved.