Dehydrogenative desaturation-relay via formation of multicenter-stabilized radical intermediates.

ABSTRACT: In organic molecules, the reactivity at the carbon atom next to the functional group is dramatically different from that at other carbon atoms. Herein, we report that a versatile copper-catalyzed method enables successive dehydrogenation or dehydrogenation of ketones, aldehydes, alcohols, ?,?-unsaturated diesters, and N-heterocycles to furnish stereodefined conjugated dienecarbonyls, polyenecarbonyls, and nitrogen-containing heteroarenes. On the basis of mechanistic studies, the copper-catalyzed successive dehydrogenation process proceeds via the initial ?,?-desaturation followed by further dehydrogenative desaturation of the resultant enone intermediate, demonstrating that the reactivity at ?-carbon is transferred through carbon-carbon double bond or longer ?-system to the carbon atoms at the positions ?, ?, and ? to carbonyl groups. The dehydrogenative desaturation-relay is ascribed to the formation of an unusual radical intermediate stabilized by 5- or 7,- or 9-center ?-systems. The discovery of successive dehydrogenation may open the door to functionalizations of the positions distant from functional groups in organic molecules.

SUBMITTER: Shang Y 

PROVIDER: S-EPMC5741636 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature