THEORETICAL STUDIES ON E2 ELIMINATION-REACTIONS - EVIDENCE THAT SYN ELIMINATION IS ACCOMPANIED BY INVERSION OF CONFIGURATION AT THE CARBANIONIC CENTER

A theoretical treatment of the stereochemical course of alkene-forming elimination reactions is discussed. Based on frontier molecular orbital theory and ab initio molecular orbital calculations it is concluded that the feasibility of both syn and anti modes of elimination is enhanced by maximizing the overlap of the developing carbanionic orbital at Cβ with the Cα-leaving group σ* orbital. Furthermore, the less favored mode of syn elimination occurs by the concerted process of leaving-group expulsion at Cα and the concomitant inversion of configuration at Cβ. Copyright © 1979, American Chemical Society. All rights reserved.