Chiral bis(oxazoline) complexes. Synthesis, structure and applications in catalytic phospho-transfer

A number of complexes have been prepared and characterised which contain [3aS-[2(3 ` aR*,8 ` aS*),3a,8a]]-methylene-bis[3a,8a-dihydro-8H-indeno[1,2-d]oxazole (BOX-H) and [3aS-[2(3 ` aR*,8 ` aS*),3a,8a]]-2,2 `-(2,6-pyridinediyl)bis[3a,8a-dihydro-8H-indeno[1,2-d]oxazole (Py-BOX) ligand frameworks. Single crystal X-ray analyses are reported on five compounds including one of the ligands themselves. The reported complexes have been examined as catalyst precursors in the catalytic phospho-transfer reaction between diorgano-H-phosphonate and benzaldehyde. In this context, we find the complexes to favour competitive hydrolysis of starting diorgano-H-phosphonates to monoorgano-H-phosphonic acids rather than nucleophilic addition to a carbonyl substrate. (C) 2001 Elsevier Science Ltd. All rights reserved.