Catalytic CN Bond Alkynylation of N‐Benzylic Sulfonamides with Terminal Alkynes

Abstract

A new cross-coupling reaction of N-benzylic sulfonamides with terminal alkynes for the synthesis of internal alkynes is reported. In the presence of 5 mol% of (Tf) 2 NH/Bi(OTf) 3 (1∶1), a broad range of N-benzylic sulfonamides react smoothly with arylacetylenes to afford structurally diverse internal alkynes in moderate to excellent yields. We reasoned that vinyl cations could be formed by the regioselective attack of terminal alkynes with benzyl cations generated in situ from N-benzylic sulfonamides under acidic conditions, which then eliminated to form a carbon-carbon triple bond.

Brønsted Acid-Catalyzed Reactions of Trifluoroborate Salts with Benzhydryl Alcohols

“…Furthermore, a direct C–H functionalization of benzylic position using DDQ and either CuOTf or Fe­(OTf) 2 is also known. Moreover, FeCl 3 -catalyzed direct nucleophilic substitutions of ethers using carbon nucleophiles and the cross-coupling of N -benzylic sulfonamides with terminal alkynes in the presence of catalytic amounts of Bi­(OTf) 3 and (Tf) 2 NH have been reported. More recently, a direct metal-catalyzed dehydrative coupling of diarylmethanols to synthesize bis-benzylic secondary alkylacetylenes has gained attention due to its atom economy .…”

Sodium iodide-mediated synthesis of vinyl sulfides and vinyl sulfones with solvent-controlled chemical selectivity

“…Sulfinic acids are readily accessible and have been widely used as sulfur sources in medicinal chemistry. 17 Moreover, sulfinic acids can be reduced to disulfides, which are active intermediates that can be used as sulfenylating agents. So we envisioned that sulfinic acids might be served as potential sulfur sources to react with alcohols under certain reaction conditions.…”