Carbanion Rearrangements. Collision-Induced Reactions of Enolate Negative Ions Derived From Dimethyl Succinates and Hexane-2,5-Dione

Abstract

Enolate ion MeOCOCHCH₂CO₂Me fragments through the intermediacy of two ion complexes [ MeOCO (CH₂=CHCO₂Me)] and [ MeO^-(O=C=CHCH₂CO₂Me)]. The major fragmentations produce CH₂=C=C( OMe )O-+HCO₂Me and O=C=CH- CH=C( OMe ). Similar ion complexes are formed from methyl-substituted succinates , but their fragmentations are often different from those outlined above: e.g. MeOCOC (Me)C(Me)₂CO₂Me - [ MeOCO (M₂C=CmeCO₂Me)] → CH₂(Me)C=C(Me)CO₂- Me+HCO₂Me. The corresponding enolate from hexane-2,s-dione (MeCOCHCH₂COMe) fragments through the acetyl anion complex [ MeCO (CH₂=CHCO₂Me)].