Transposition oxy-cope assistee par le trifluoroacetate mercurique en quantite stoechiometrique et en quantite catalytique

Abstract

Tertiary 1,5-hexadien-3-ols are transformed at room temperature into δ-ethylenic ketones in 35-90%, yields under two sets of conditions: treatment with one molar equivalent of mercuric trifluoroacetate followed by demercuration of the intermediate α-mercuro ketone with sodium borohydride; and treatment with 0.2 molar equivalent of t of lithium trifluoroacetate or trifluorométhansulfonate. The reactions are highly stereoselective, the E isomer of the ketone forming 80-95% of the product. The highest selectivity was observed under the second conditions.