β-Deprotonation by lithium di-isopropylamide. Vinyl carbanions from oxygen heterocycles in the synthesis of carboxylic acids in the benzofuran, flavone, and coumarin …

…, FM Dean, MA Jones, DA Smith, RS Varma

Index: Costa, Ana M. B. S. R. C. S.; Dean, Francis M.; Jones, Michael A.; Smith, Dennis A.; Varma, Rajender S. Journal of the Chemical Society, Chemical Communications, 1980 , # 24 p. 1224 - 1226

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Abstract

Lithium di-isopropylamide at–70° C can remove the α-proton from benzofuran in the absence of activating groups and the β-proton if such groups are present; in flavone and 4- methoxycoumarin β-deprotonation occurs readily and the carbanions are easily carboxylated giving acids not previously accessible, while in 2, 6-dimethylchromone β- deprotonation is kinetically favoured allowing 3-acylation to be achieved separately from ...