Unsymmetrical salen ligands: Synthesis and use in chromium mediated asymmetric epoxidation

✍ Scribed by Adrian M. Daly; T. Cormac Dalton; Marie F. Renehan; Declan G. Gilheany

• Book ID: 104261273
• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 242 KB
• Volume: 40
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(99)00489-x

✦ Synopsis

Chiral non-racemic salen ligands with two different salicylidene moieties can be synthesised via trapping of the intermediate mono-salicylidene using (+)-O,O'-dibenzoyl-D-tartaric acid. The chromium complexes of these ligands can be used in asymmetric epoxidation of alkenes. The presence of triphenylphosphine oxide substantially raises the selectivity (ee) of the epoxidation.