A new quinazoline-containing axially chiral ligand for asymmetric catalysis

✍ Scribed by Mary McCarthy; Patrick J Guiry

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 94 KB
• Volume: 19
• Category: Article
• ISSN: 0277-5387
• DOI: 10.1016/s0277-5387(99)00403-9

✦ Synopsis

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 (ee) in Pd-catalysed allylic alkylation. h 3 -Allyl Pd complexes were investigated by 1 H 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.