Domino Synthesis of Functionalized Cyclic Acetals From Organic Carbonates

Abstract

We report a method for the base-mediated transformation of ether-tethered acrylic ester-based cyclic carbonates into functionalized cyclic acetals. The protocol builds on the use of hydroxyalkyl-substituted cyclic carbonates that undergo an oxa-Michael addition reaction in the presence of alkyl propiolates thereby forging (E)-configured acrylic ether intermediates. The scope of the reaction involves the use of both five- and six-membered cyclic carbonates, and correspondingly, both five- and six-membered cyclic acetals can be prepared. The amount of reagents, the purification method, and the type of ester substrate all contribute to the efficiency of the transformation. Mechanistic control reactions point at the intermediacy of an alkoxide that induces an intramolecular Michael addition onto the acrylic double bond following alkoxide-mediated formation of both an alcohol and ester in the final product. These functional groups, among others, further enable easy diversification of acetal-based synthons.