Copper-Catalyzed Oxysulfenylation of Enolates with Sodium Sulfinates: A Strategy To Construct Sulfenylated Cyclic Ethers

Abstract

A new copper-catalyzed oxysulfenylation reaction of enolates with sodium sulfinates has been disclosed. A series of sulfenylated heterocycles including four- and seven-membered cyclic ether were obtained in mild to good yields. This reaction is proposed to go through a radical process, and the sulfur radical (RS(•)) may be a reactive species.

Copper-catalysed regioselective sulfenylation of indoles with sodium sulfinates

“…We screened different reductants such as Na 2 SO 3 , Na 2 S and (C 2 H 5 O) 2 POH, and found that they were less efficient ( table 1 , entries 2–4). Without the reductant, the yield was increased up to 82% due to DMF being a reductive solvent [ 41 ] ( table 1 , entry 5). Other additives such as bases (Na 2 CO 3 , NaOH) or acids (HOAc, TsOH) adversely affected the reaction ( table 1 , entries 6–9).…”

Deep Eutectic Solvents as Reaction Media for the Palladium‐Catalysed C−S Bond Formation: Scope and Mechanistic Studies

“…Also a radical process can take place in this new reaction media (Table ), affording the corresponding disulfide (entries 1 and 2). If a hydroxy‐functionalized alkene is added, the double bond reacts with the radical thiol with a subsequent cyclization to afford products 8 c – 8 e (entries 3–5) . Another radical‐mediated reaction is the synthesis of 8 f from phenylpropiolic acid catalysed by phosphoric acid …”

Copper(I) Bromide‐Dimethyl Sulfide‐Catalyzed Direct Sulfanylation of 4‐Hydroxycoumarins and 4‐Hydroxyquinolinones with Arylsulfonylhydrazides and Selective Fluorescence Switch‐ On Sensing of Cadmium(II) Ion in Water

“…Based on previously reported studies and these experimental results, a plausible mechanistic pathway is presented in Scheme for the formation of 3a and 5a through the sulfanylation reaction . The reaction is first initiated by Cu(I)‐catalyzed aerobic oxidation to give intermediates thiosulfonate 6 and disulfide 7 via intermediates 8 and 9 through redox decomposition . The copper catalyst then reacts with 6 or 7 to form copper(III) complex 10 , which undergoes DABCO‐mediated transmetallation at the 3‐position of 4‐hydroxycoumarins or 4‐hydroxyquinolinones to form another intermediate copper(III) complex 11 .…”