Chiral bis(oxazoline) and pyridyl alcoholate dioxo-molybdenum(VI) complexes: synthesis, characterization and catalytic examinations

• Type: Article in International Scientific Journal
• Date: 2001

Authors

Kuhn, FE (Author) Other; Santos, AM (Author) Other; Lopes, AD (Author) Other; Goncalves, IS (Author) Other; Rodriguez Borges, JE (Author) FCUP; Pillinger, M (Author) Other; Romao, CC (Author) Other

Journal

Title: Journal of Organometallic Chemistry

Vol. 621

Pages: 207-217

ISSN: 0022-328X

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 72 Citations

Scopus - 74 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-000-W9N

DOI: 10.1016/s0022-328x(00)00774-9

Abstract (EN): A group of chiral molybdenum(VI) complexes comprising MoO2Cl2L**, MoO2Cl(THF)L* and MoO2L2* [L**=chiral bis(oxazoline) and L* = chiral 2'-pyridyl alcoholate] have been prepared in good yields by reaction of the solvent substituted complex MoO2Cl2(THF)(2) with one or two equivalents of chiral ligand. Optically active aminoalcohols (L*) were obtained by reaction of the appropriate organolithium compound with (-)-menthone, (+)-8-phenylisomenthone, (-)-8-phenylmenthone. (+)-camphor and (-)-thujone. The molybdenum complexes were characterized by multinuclear NMR (H-1, C-13, O-17, Mo-95) spectroscopy, IR spectroscopy and elemental analysis. Mo-95-NMR data reflected the donor capability of the organic ligands, whereas H-1-NMR and IR data were comparatively indifferent to the changes in the Lewis base ligand. The complexes were evaluated as catalysts for the asymmetric epoxidation of trans-beta -methylstyrene by tert-butylhydroperoxide. The bis(oxazoline) complexes showed good catalytic activity but had low optical yields. Complexes of the type MoO2Cl(THF)L* (L* = chiral 2'-pyridyl alcoholate) also exhibited high catalytic activity and enantiomeric excesses of up to 23%. The corresponding MoO2L2* alcoholate complexes were considerably less active with comparable optical yields.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11