Iron Nitrate-Mediated Selective Synthesis of 3-Acyl-1,2,4-oxadiazoles from Alkynes and Nitriles: The Dual Roles of Iron Nitrate.

A direct strategy for the selective synthesis of 3-acyl-1,2,4-oxadiazoles from alkynes and nitriles has been developed under iron(III) nitrate-mediated conditions. The mechanism includes three sequential procedures: iron(III) nitrate-mediated nitration of alkynes leads to α-nitroketones, dehydration of α-nitroketones provides the nitrile oxides, and 1,3-dipolar cycloaddition of nitrile oxides with nitriles produces 3-acyl-1,2,4-oxadiazoles under iron-mediated conditions. Iron(III) nitrate plays dual roles in the nitration of alkynes and the activation of nitriles, while the formation of pyrimidine/isoxazole byproducts can be efficiently inhibited.

Synthesis of ( E)-ß-Selenovinyl Sulfones through a Multicomponent Regio- and Stereospecific Selenosulfonation of Alkynes with Insertion of Sulfur Dioxide.

A novel and practical method for the selenosulfonation of alkynes with the insertion of sulfur dioxide has been developed. A series of ß-(seleno)vinyl sulfones with high levels of regio- and stereoselectivity have been prepared. The key features of this reaction include a broad substrate scope, excellent functional-group tolerance, and amenability to scale-up synthesis. A plausible radical mechanism is proposed to illustrate this reaction.

A novel metal-free amidosulfenylation of alkenes leading to ß-azolyl sulfides.

A novel and environmentally benign method for C-S and C-N bond formation by the direct amidosulfenylation of alkenes has been developed under metal-free conditions. Various alkenes and azoles were transformed into the corresponding ß-azolyl sulfides in ionic liquids. The wide substrate scope, good functional group tolerance, and ease of operation make this reaction attractive for the synthesis of nitrogen- and sulfur-containing molecules.