Metal-free, 2-MeTHF mediated C(sp)-H functionalization of alkynes with anilines to access diaryl 1,2-diketones bearing lower E-factors

A metal-free and efficient oxidative C(sp)-H functionalization of alkynes has been developed for the synthesis of 1,2-diketones. A composite of tert-butyl nitrite and ascorbic acid effectively promoted the oxidative addition of a phenyl radical generated from aniline to terminal alkynes producing α-diketones. The one-pot strategy involves 2-methyltetrahydrofuran (2-MeTHF) as a useful alternative reaction medium for oxidative diketonation. Furthermore, the protocol provides a novel route to symmetrical and unsymmetrical substituted 1,2-diketones from easily accessible reactants. Notably, environmentally benign reagents, greener and renewable solvents, a broad range of substrates, large-scale synthesis, lower E-factors, practical applications, radical pathways and mild conditions are the promising features of the present method.