By‐Product‐Catalyzed Redox‐Neutral Sulfenylation/Deiodination/Aromatization of Cyclic Alkenyl Iodides with Sulfonyl Hydrazides

Abstract

A by‐product‐catalyzed redox‐neutral process has been established through tandem sulfenylation/deiodination/aromatization of cyclic alkenyl iodides with sulfonyl hydrazides. In the absence of external catalysts and additives a range of 4‐iodo‐1,2‐dihydronaphthalenes reacted with sulfonyl hydrazides to give structurally diverse 2‐naphthyl thioethers in good yields. Mechanistic studies showed that at an early stage sulfonyl hydrazides decomposed completely to thiosulfonates and disulfides and at a late stage the resulting thiosulfonates underwent tandem sulfenylation/deiodination/aromatization with 4‐iodo‐1,2‐dihydronaphthalenes involving a [1,5]‐sigmatropic hydrogen shift. Importantly, iodine was generated as a by‐product from 4‐iodo‐1,2‐dihydronaphthalenes upon heating and served as a catalyst for the decomposition of sulfonyl hydrazides and subsequent formation of 2‐naphthyl thioethers.magnified image

C3 Sulfenylation of N‐Heteroarenes in Water under Catalyst‐Free Conditions

“…On the basis of literature reports, and our above observations in the present work, a plausible reaction mechanism is proposed (Scheme ). In the presence of water, 2a disassociate into a sulfur anion and PhS + ( A ).…”

Mild and Regioselective Bromination of Phenols with TMSBr

“…Despite the wide applications of by‐products as a catalyst, additive, or reagent in tandem reactions, by‐product dimethyl sulfide generated from the oxidative bromination reaction of YBr/DMSO was generally disposed as toxic and smelly waste. With our continuous interest in regioselective halogenation and hydrogen chemistry, herein, we wish to report a mild and regioselective bromination of phenols with TMSBr (Scheme C).…”

Synthesis of Thioethers from Sulfonyl Chlorides, Sodium Sulfinates, and Sulfonyl Hydrazides

“…In 2016, Tian and co-workers 80 reported a redox-neutral process via tandem thiolation/deiodination/aromatization of cyclic alkenyl iodides with sulfonyl hydrazides (Scheme 32). Mechanistic studies showed that molecule iodine, as a byproduct, was generated from dihydronaphthalene iodide 50a upon heating and served as a catalyst for the decomposition of sulfonyl hydrazide and subsequent formation of 2naphthyl sulfide 50.…”