Reaction of Triphenylphosphine Radical Cation with 1,3-Dicarbonyl Compounds : Electrochemical One-Step Preparation of Dioxomethylenetriphenylphosphoranes

概要

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Electrochemical oxidation of Ph_3P (1) in MeCN in the presence of 1,3-dicarbonyl compounds, R^1COCH_2COR^2 (3), with HCIO_4 as the supporting electrolyte resulted in the formation of the phosphonium salts, Ph_3P^+-CH(COR^1)COR^2 ClO_4^- (4), provieded that R^1 and/or R^2 is a phenyl group. On the other hand, electrolysis in CH^2Cl^2 with 2,6-lutidinium perhlorate gave the phosphoranes, Ph_3P=C(COR^1)COR^2 (5), directly from 1 and 3 in fair to excellent yields : in this case, R^1 or R^2 need not necessarily be a phenyl group. Thus, the electrolysis is shown to be a convenient method to perpare 5 in a single step. Plausible processes for the formation of 4 and 5 are proposed, involving the reaction of electrochemically generated Ph_3P^+・with the enol form of 3 as the keystep.
社団法人日本薬学会の論文
1988-02-25