HIGHLY STEREOSELECTIVE ADDITION OF ORGANOLITHIUM REAGENTS TO CHIRAL OXAZOLINES - ASYMMETRIC SYNTHESIS OF 3-SUBSTITUTED ALKANOIC ACIDS AND 3-SUBSTITUTED LACTONES

Nucleophilic addition of organolithium reagents to chiral α, β-unsaturated oxazolines 3 furnishes the adducts 6 with a high degree of stereoselectivity. Hydrolysis of these adducts leads to 3-substituted alkanoic acids in >90% enantiomeric excess. A mechanism to account for this highly stereoselective process is advanced consistent with the observed facts. The method allows, by reversing the order of group introduction, a route to either enantiomer in high enantiomeric excess. Use of alkoxy-substituted chiral oxazolines provides a route to 3-substituted valerolactones and benzovalerolactones in >90% ee. © 1979, American Chemical Society. All rights reserved.