A practical synthesis of aryl sulfones via cross-coupling of sulfonyl hydrazides with aryltriazenes using copper/ionic liquid combination

Recent advances in the chemistry of aryltriazene

Triazene is one of the most versatile building blocks in organic synthesis. Generally, it is viewed as a safe equivalent of diazonium salt, thus immediately finding numerous applications in preparative chemistry and medicinal chemistry. Besides, it can be used as a removable directing group in C-H functionalization or play a smart role as a precursor for aryl cation/radical generation. In this review, we will highlight recent noteworthy developments in this field.

Easy access to α-carbonyl sulfones using cross-coupling of α-aryl-α-diazoesters with sulfonyl hydrazides

A facile synthesis of α-carbonyl sulfones has been accomplished by the cross-coupling of α-aryl-α-diazoesters with sulfonyl hydrazides in the presence of CuI and DBU. The reaction employs inexpensive and bench stable sulfonyl hydrazides as a sulfonyl source, and facilitates the migratory insertion with α-aryl-α-diazoesters under mild reaction conditions.

Copper-Catalyzed Thiolation of Hydrazones with Sodium Sulfinates: A Straightforward Synthesis of Benzylic Thioethers

A facile and sustainable protocol for the thiolation of hydrazones with sodium sulfinates has been developed in the presence of CuBr₂ and DBU in DMF to afford diverse benzylic thioethers. Control experiments reveal a radical pathway involving a thiyl radical as a key intermediate.

Base-promoted synthesis of diarylsulfones from sulfonyl hydrazines and diaryliodonium salts

An efficient and concise method for the synthesis of diverse substituted sulfones was developed with high selectivity. Using n-PrOH as the solvent, diaryl sulfones are formed even on a gram scale via metal-free coupling from sulfonyl hydrazines with symmetrical or unsymmetrical diaryliodonium salts.

Iodine-catalyzed thioallylation of indoles using Bunte salts prepared from Baylis-Hillman bromides

Metal-free iodine-catalyzed regioselective thioallylation of indoles has been accomplished at room temperature using Bunte salts prepared from Baylis-Hillman bromides. The resulting multi-functional C3 thioallylated indoles exhibit ample structural diversity and good functional group tolerance.

Iodine-Catalyzed Synthesis of 3-Arylthioindoles Employing a 1-Aryltriazene/CS2 Combination as a New Sulfenylation Source

A practical approach for the regioselective synthesis of 3-arylthioindoles has been accomplished using a combination of 1-aryltriazene/CS₂ as a new sulfenylation source. The methodology employs molecular iodine as a catalyst and is compatible with a variety of structurally diverse reactants.

Brønsted and Lewis acid adducts of triazenes

Spectroscopy and crystallographic data show that triazenes are protonated at N1 position.