An unprecedented protocol for the synthesis of 1,2,4-oxadiazoles from carbamates has been developed by employing nitriles as both substrates and solvents. This one-pot procedure achieves the formation of C═N bonds via TFA-mediated [3+2] annulation. A series of 1,2,4-oxadiazoles are synthesized in moderate to good yields.

A photoredox-mediated radical amidation ring-expansion sequence that enables the generation of all-carbon quaternary centers bearing a protected aminomethyl substituent is described. The methodology can be applied to both styrene and unactivated alkene substrates generating structurally diverse sp3 -rich amine derivatives in a concise manner.

Although they offer great potentials, the high reactivity and diverse pathways of radical chemistry pose difficult problems for applications in organic synthesis. In addition to the differentiation of multiple competing pathways, the control of various selectivities in radical reactions presents both formidable challenges and great opportunities. To regulate chemoselectivity and regioselectivity, as well as diastereoselectivity and enantioselectivity, calls for the formulation of conceptually new approaches and fundamentally different governing principles. Here we show that Co(II)-based metalloradical catalysis enables the radical chemoselective intermolecular amination of allylic C-H bonds through the employment of modularly designed D2-symmetric chiral amidoporphyrins with a tunable pocket-like environment as the supporting ligand. The reaction exhibits a remarkable convergence of regioselectivity, diastereoselectivity and enantioselectivity in a single catalytic operation. In addition to demonstrating the unique opportunities of metalloradical catalysis in controlling homolytic radical reactions, the Co(II)-catalysed convergent C-H amination offers a route to synthesize valuable chiral α-tertiary amines directly from an isomeric mixture of alkenes.

The annulation reactions of benzoamidyl radicals with alkenes were realized under visible light irradiation with fac-Ir(ppy)₃ as catalyst and N-aminopyridinium salts as benzoamidyl radical precursors. The reaction can deliver two distinct types of products: in the case of vinyl arenes, [3 + 2] annulation product dihydrooxazoles were yielded exclusively; when alkyl-substituted alkenes were used, on the other hand, it afforded [4 + 2] annulation product dihydroisoquinolinones. Factors determining the reaction consequence were elucidated by DFT calculations.