Cobalt(II)-Catalyzed Aerobic Oxidation of Terminal-Capped Alkynyl α-Cyano Alkanone Systems. An Oxygen-Mediated Radical Chain Reaction

A new N-hydroxyphthalimide (NHPI)/Co(II)-catalyzed protocol, mechanistically involving a sequence of α-hydrogen abstraction, 5-exo-dig cyclization, oxygen capture, hydrogen transfer, and 1,4-dehydration, has been developed to facilitate aerobic oxidation of aryl-, silyl-, and alkyl-capped alkynyl α-cyano alkanone systems to the corresponding highly functionalized products in an effective manner, thus turning this novel chain reaction, originally occurring spontaneously in low yields, into a practical methodology.

Tandem cyclization of α-cyano α-alkynyl aryl ketones induced by tert-butyl hydroperoxide and tetrabutylammonium iodide

The radical cascade protocol of the α-cyano α-TMS/aryl-capped alkynyl aryl ketones promoted by tert-butyl hydroperoxide under catalysis with tetrabutylammonium iodide in refluxing benzene has been developed, leading to the construction of a variety of highly functionalized [6,6,5] tricyclic frameworks in an efficient manner.