Described herein are the scope and limitations using Tp*Rh(PPh(3))(2) as a catalyst for alkyne hydrothiolation with alkyl thiols. In general, catalytic hydrothiolation proceeds in high yields and with high regioselectivity for a wide range of alkynes and thiols. A variety of functional groups were well-tolerated, including nitriles, amines, halogens, ethers, esters and silanes, although strongly coordinating groups were found to be incompatible with hydrothiolation. Both sterically encumbered alkynes and thiols were successful in hydrothiolation. Electron rich alkynes react more rapidly than electron deficient alkynes. Overall, this hydrothiolation protocol provides convenient access to a variety of functionalized branched alkyl vinyl sulfides.

Using recently developed methodology for the regioselective formation of branched alkyl vinyl sulfides, we report a convenient route to 1,1-disubstituted olefins. We demonstrate that n-propanethiol successfully undergoes catalytic alkyne hydrothiolation with both aryl and aliphatic alkynes using Tp*Rh(PPh3)2 as the catalyst. The resulting vinyl sulfides undergo Kumada cross-coupling to afford the desired disubstituted alkene. Both two-step and one-pot procedures are reported.

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Alkenes Q 0083Synthesis of 1,1-Disubstituted Olefins via Catalytic Alkyne Hydrothiolation/Kumada Cross-Coupling. -One-pot and two-step procedures afford disubstituted alkenes. The one-pot procedure affords slightly higher yields. -(SABARRE, A.; LOVE*, J.; Org. Lett. 10 (2008) 18, 3941-3944; Dep. Chem., Univ. British Columbia, Vancouver, B. C. V6T 1Z1, Can.; Eng.) -R. Steudel 04-055

Thioethers P 0430Synthesis of 1,1-Disubstituted Alkyl Vinyl Sulfides via Rhodium-Catalyzed Alkyne Hydrothiolation: Scope and Limitations. -The Rh catalyst (RHB) efficiently promotes the addition of thiols to various alkynes. Reaction of terminal alkynes generally proceeds with excellent regioselectivity yielding the branched adducts. The propiolate (VI), however, gives the linear isomers. Some functional groups such as halides, nitriles, amines, and esters are tolerated but strongly coordinating ones like 2-pyridine and carboxylic acids prevent the addition. -(YANG, J.; SABARRE, A.; FRASER, L. R.; PATRICK, B. O.; LOVE*, J. A.; J. Org. Chem. 74 (2009) 1, 182-187; Dep. Chem., Univ. British Columbia, Vancouver, B. C. V6T 1Z1, Can.; Eng.) -Jannicke 18-056