A new quinazoline-containing axially chiral ligand for asymmetric catalysis

The rationale behind the design of an axially chiral quinazoline-containing phosphinamine ligand, 2-phenyl-Quinazolinap, is described. Its synthesis had two metal-catalysed couplings as the key steps. Enantiopure ligand was obtained after resolution and afforded up to 66% enantiomeric excess tee) in Pd-catalysed allylic alkylation. eta(3)-Allyl Pd complexes were investigated by H-1 NMR in an attempt to explain the sense of enantioselection observed, which was opposite to that of related ligands. Rhodium-catalysed enantioselective hydroboration of a variety of substituted styrenes was achieved with excellent conversions, good regioselectivities and ee values of up to 91% with 2-phenyl-Quinazolinap as the ligand. (C) 2000 Elsevier Science Ltd All rights reserved.