Generation of (Z)-β-alkenyl alkylsulfones via a copper-catalyzed decarboxylative alkylsulfonylation

Abstract

A copper-catalyzed three-component reaction of N-tosyl acrylamides, 1,4-diazabicyclo[2.2.2]octane-sulfur dioxide and phenyliodine(III) dicarboxylates is developed. This transformation using phenyliodine(III) dicarboxylates as alkyl radical precursors and N-tosyl amidyl as the weakly coordinating directing group provides diverse (Z)-β-alkenyl alkylsulfones in moderate to good yields through direct C(sp²)–H alkylsulfonylation. This decarboxylative alkylsulfonylation from sulfur dioxide under copper catalysis proceeds efficiently, and the weak nitrogen coordination provides excellent regio- and stereoselectivities. Moreover, the synthetic practicability of this transformation is demonstrated through a gram-scale synthesis. A plausible radical participating mechanism through weak-coordinating-group-oriented direct C(sp²)–H alkylsulfonylation is proposed.