New simple synthesis of N-acylpyrazolidines and N-arylsulfonyl-2-pyrazolines

Photocatalytic Generation of Nitrenes for Rapid Diaziridination

A blue LED, an organic photocatalyst (rose bengal), and the Lewis acid like oxidant PhI(OAc)₂ were utilized to generate nitrene intermediates through reactions of 1,2-diols and aliphatic amines under mild reaction conditions. A versatile and rapid diaziridination strategy was established to construct functionalized 1,2-disubstituted diaziridines, diaziridines with chiral substituents, and 1,2,3-trisubstituted analogues with excellent reaction rates, yields, and stereoselectivities. Control and labeling experiments to elucidate the mechanism of this elegant metal-free photocatalyzed cyclization reaction were performed.

Silver(I)-catalyzed facile synthesis of pyrazoles from propargyl N-sulfonylhydrazones

A silver(I)-catalyzed facile formation of pyrazoles from propargyl N-sulfonylhydrazones has been disclosed. During the reaction, a migration of sulfonyl groups (Ts, Ms) was observed. Good functional group compatibility was observed under mild reaction conditions (at room temperature for 3-5 h). This methodology allows for the efficient and regioselective synthesis of 1,3- and 1,5-disubstituted and 1,3,5-trisubstituted pyrazoles.