Palladium‐Catalyzed Alkynylthiolation of Alkynes with Triisopropylsilylethynyl Sulfide

Abstract

Regio‐ and stereoselective addition of a silyl‐substituted alkynyl sulfide to various terminal alkynes proceeds in the presence of a palladium catalyst to give (Z)‐1‐thio‐1,3‐enynes, which are useful building blocks for the synthesis of polysubstituted 1,3‐enynes. Addition to internal alkynes also takes place under solvent‐free conditions (see scheme).

Palladium-Catalyzed Carbothiolation of Alkenes and Alkynes for the Synthesis of Heterocycles

“…Subsequently, we tested the reaction conditions for the intramolecular reaction with alkynes. The carbothiolation of these unsaturated moieties has been previously studied. − However, most methods are restricted to terminal alkynes, and protocols that employ substituted alkynes rely on the use of platinum or highly activated thiocyanates, whereas our reaction conditions could be extended to the synthesis of compounds 46 and 47 . These results highlight again the capability of the reported methodology for carbothiolation reactions.…”

“…Despite this challenge, various transition metal catalysts have proven to be competent in overcoming this issue. For example, completely atom-economical carbofunctionalizations of alkynes, such as carbo-halogenations (chlorination, − bromination, and iodination − ), carbocyanations, − and carbothiolations − have already been reported.…”

Transition-Metal-Catalyzed C–S, C–Se, and C–Te Bond Formations via Cross-Coupling and Atom-Economic Addition Reactions. Achievements and Challenges

“…Pd-catalyzed alkynylthiolation of alkynes with triisopropylsilylethynyl sulfide was reported. 981 The process was performed as a cis-addition to the triple bond of the alkyne with the breakage of the C−S bond and the formation of a C−C bond and a new C−S bond. Not limited to alkynes, other unsaturated molecules may also undergo Pd-catalyzed insertion into the C−S bond.…”

Palladium-Catalyzed Regio- and Stereoselective Carbothiolation of Terminal Alkynes with Azolyl Sulfides

“…Carbothiolation of alkynes has been regarded as the ideal approach to the highly substituted alkenyl sulfides in organic synthesis, which can generate carbon–carbon and carbon–sulfur bonds simultaneously . Regio- and stereoselective addition of various carbon–sulfur bonds to alkynes has been achieved by using transition metal catalysts: thioesterification, cyanothiolation, allylthiolation, alkenylthiolation, acylthiolation, iminothiolation, alkynylthiolation, and alkylthiolation. , Although only decarbonylative addition reaction of thioesters is known, the atom-economical arylthiolation across alkynes has yet to be disclosed to date because carbon–sulfur bonds in aryl sulfides tend to cause a reversible oxidative addition . While it was previously found that aryl sulfides underwent cross-coupling with organometallic reagents probably because of the high reactivity of the once formed oxidative adducts for subsequent transmetalation, arylthiolation of alkynes is unprecedented.…”