Dual Macrolactonization/Pyran-Hemiketal Formation via Acylketenes: Applications to the Synthesis of (-)-Callipeltoside A and a Lyngbyaloside B Model System

摘要

Acylketenes (Scheme 1, 2) are often employed as electro-philes to trap alcohols to construct β-ketoesters (4) via the transient enols (3) produced by concerted addition of the hydroxylic nucleophile (Scheme 1). Thermolysis of 1,3-dioxin-4-one derivatives (1) is the most common method used for the generation of 2. Boeckman and co-workers pioneered the application of these reactive species in the synthesis of complex molecules such as macrocyclic lactones and lactams, which can be constructed by intramolecular reactions of hydroxy- or amino-containing acylketenes.