Pd/Cu-Catalyzed Vinylation of Terminal Alkynes with (2-Bromoethyl)diphenylsulfonium Triflate

Abstract

The potential of (2-bromoethyl)diphenylsulfonium triflate to be a powerful vinylation reagent was determined by the Sonogashira cross-coupling reactions with terminal alkynes. The vinylation proceeded smoothly at 25 °C under Pd/Cu catalysis to afford a variety of 1-and 2-unsubstituted 1,3-enynes in moderate to excellent yields. This protocol represents the first application of (2haloethyl)diphenylsulfonium triflate as a CHCH 2 transfer source in organic synthesis.

A Cascade Sonogashira Cross‐Coupling‐Substitution‐Elimination Reaction for the Synthesis of Linear Conjugated Dienynes

“…[8,9] The versatility of 1,3-enynes allows to prepare propargyl cyclopropanes, [10] allenes, [11,12] and to perform [2 + 2] cycloadditions. [13] Figure 1 shows that various methods have been developed in the past few decades for the synthesis of enynes, including: a cross-coupling reaction of 1-alkynes with vinyl iodides catalyzed by CuI/N,N-dimethylglycine to afford conjugated enynes in a palladium-and phosphine-free catalytic system for the Sonogashira-type coupling reaction (Figure 1a); [14] the coupling reaction of vicinal-diiodoalkenes with conjugated carboxylic esters catalyzed by nonstoichiometric PdHAP (Figure 1b); [15] the crosscoupling reaction of alkynylmagnesium reagents under iron catalysis by the acceleration effect of lithium salts (Figure 1c); [16] a single-step synthesis of enyne derivatives through Pd- catalyzed arylalkynylation of aryl iodides, internal alkynes, and alkynylsilanes (Figure 1d); [17] an efficient CspÀ Csp 2 coupling reaction of alkynyl bromides and alkenyl boronic acids catalyzed by CuFe 2 O 4 nanoparticles (Figure 1e); [18] a Co(OAc) 2 / triphos catalyst system for the selective cross-dimerization reaction between aryl or alkenyl alkynes and aliphatic alkynes (Figure 1f); [19] and a recent vinylation reaction of terminal alkynes with bromosulfonium triflate compounds catalyzed by palladium and copper (Figure 1g); [20] among others. [21] However, to the best of our knowledge, these methods involve the coupling of two unsaturated units or, when aiming to synthesize terminal enynes, expensive, dangerous and noneasily available acetylene gas (Figure 1f), except for the last example (Figure 1g).…”

Tetrabutylammonium Bromide (TBAB)-Promoted, Pd/Cu-Catalyzed Sonogashira Coupling of N-Tosyl Aryltriazenes

“…Recently, extension of the substrate scope in Sonogashira coupling has attracted increasing interest. In fact, the aryl/vinyl counterparts in Sonogashira coupling have been greatly extended from the traditional highly reactive (hetero)­aryl (pseudo)­halides to aryl chlorides and fluorides, as well as unconventional alternatives, such as diaryliodonium salts, aryldiazonium salts, diarylsulfoxides, arylammonium salts, tetraarylphosphonium salts, arylsulfonium salts, nitrobenzenes, carboxylic acids and derivatives, and boronic acids (Scheme ). In particular, the alkyl version of the protocol has also been achieved .…”

Palladium-Catalyzed Cyanation of Aryl Sulfonium Salts

“…Lastly, neutral sulfur fragments eliminated from sulfonium salts are less toxic to metal catalysts. Many studies about the functionalization of aryl sulfonium salts via C–S bond activation catalyzed by transition metal have been reported, such as arylation, alkenylation, alkynylation, alkoxycarbonylation, carboxylation, borylation, amination, etc. (Scheme B) .…”