Enantioselective addition of organolithium reagents to imines mediated by C2-symmetric bis(aziridine) ligands

✍ Scribed by Pher G. Andersson; Fredrik Johansson; David Tanner

• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 888 KB
• Volume: 54
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(98)00675-9

✦ Synopsis

The C2-symmetric bis(aziridine) ligands 1 -5 have been screened in the enantioselective addition of organolithium reagents to imines. Ligand 1 (used in stoichiometric amounts) was found to be superior in terms of chemical yield and enantioselectivity, the best result being 90*70 yield and 89% e.e. in the addition of vinyllithium to imine 6a. Use of ligand 1 in substoichiometric amounts gave poorer yield and lower enantioselectivity. The enantioselectivity of the reaction was investigated as a function of substrate, reagent, stoichiometry and temperature, but no firm mechanistic conclusions could be drawn.

Preliminary results with deuterium-labelled methyllithium indicate complexation/exchange processes involving ligand, reagent and substrate.