Base-promoted elimination reactions of (E)- and (Z)-arylaldehyde O-benzoyloximes. Effects of stereochemistry, β-aryl group and base-solvent on the nitrile-forming transition states

Sang Yong Pyun,Bong Rae Cho,Eric Scriven

doi:10.3998/ark.5550190.0011.709

Abstract

Base-promoted elimination reactions of (E)- and (Z)-arylaldehyde O-benzoyloximes. Effects of stereochemistry, β-aryl group and base-solvent on the nitrile-forming transition states

Highlights

Base-promoted elimination reactions forming C=C bonds have been extensively investigated for more than 50 years.[1,2,3,4,5,6,7] The results of the structure-reactivity relationships studies have led to a qualitative understanding of the relationship between the reactant structure and the transition state structure
The results reveal a wide variation of the transition state structures ranging from E2-central to E1cb mechanism
The structure-reactivity parameters permitted a mapping of the transition state for these reactions on the More-O’Ferrall-Jencks reaction coordinate energy diagram. These results provided a complete picture of the transition state differences for the syn- and anti-eliminations forming nitriles

Summary

Introduction

Base-promoted elimination reactions forming C=C bonds have been extensively investigated for more than 50 years.[1,2,3,4,5,6,7] The results of the structure-reactivity relationships studies have led to a qualitative understanding of the relationship between the reactant structure and the transition state structure. The transition state with greater extent of proton transfer than Nα-OC(O)Ar bond cleavage would move slightly toward the right as depicted by a shift from A to B on the energy diagram, resulting in a small increase in kH/kD (vide supra).[28] On the other hand, the kH/kD values for 2 decreased with the same variation of the leaving group.

Results

Conclusion