title: Tuning ligand structure in chiral bis(phosphite) and mixed phosphite-phosphinite PCP-palladium pincer complexes.
abstract: A range of chiral resorcinol bis(phosphite) and phosphite-phosphinite ligands were produced and their propensity to form palladium PCP-pincer complexes examined. The ease of base-assisted C-H palladation of the ligands falls in the order bis(phosphinite) > phosphite-phosphinite > bis(phosphite). The catalytic activity of the complexes in the asymmetric allylation of benzaldehyde with allyl tributyltin was examined and it was found that, contrary to expectations, ligands with 3,3'-disubstituted BINOL residues show poorer activity and stereoselectivity than unsubstituted BINOL analogues. In addition the order of activity of the pincer complexes was established as bis(phosphite) > phosphite-phosphinite > bis(phosphinite). Crystal structures of representative examples of a 3,3'-disubstituted BINOL, mono- and bis(phosphite) ligands based on 2,4-di-tert-butyl resorcinol and Pd complexes of two of the chiral complexes are presented.
authors.affiliation: School of Chemistry, University of Bristol, Cantocks Close, Bristol, UK BS8 1TS. r.bedford@bristol.ac.uk
authors.forename: Robin B
authors.initials: RB
authors.lastname: Bedford
authors.forename: Yu-Ning
authors.initials: YN
authors.lastname: Chang
authors.forename: Mairi F
authors.initials: MF
authors.lastname: Haddow
authors.forename: Claire L
authors.initials: CL
authors.lastname: McMullin