Configuration of Enolates of β-Ketocarboxylic Acid Esters — Carbocation-Carbanion Salts

✍ Scribed by Meier, Herbert ;Buß, Monika ;Adam, Martin

• Book ID: 102365933
• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 252 KB
• Volume: 1996
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199619961227

✦ Synopsis

Abstract

Deprotonation of (Z)‐ or (E)‐3‐hydroxy‐2,3‐dimesitylpropenoic acid methyl ester (1a) with tetrakis(dimethylamino)‐methane (3) led to stable salt (E)‐2a, which belongs to a very rare species of salts that consist of a heteroatom‐stabilized carbocation and a heteroatom‐stabilized carbanion. An analogous guanidinium salt (E)‐2b was formed in the reaction of 3‐oxo‐2,3‐diphenylpropanoic acid methyl ester (1b) and 3. The molecular structures of these enolates were studied by NMR spectroscopy and an X‐ray analysis of (E)‐2a {MC[N(CH~3~)~2~]~3~} and compared with those of the corresponding alkali enolates.