Palladium‐Catalyzed Dehydrogenative Coupling Reaction of Terminal Alkynes with Unactivated Alkenes

Abstract

Terminal alkynes having a bulky substituent dehydrogenatively couple with unactivated terminal alkenes with catalysis of palladium. The terminal sp carbon forms a bond with the internal sp2 carbon of the alkene regioselectively to produce branched, conjugated 1,3‐enynes with wide functional group tolerance.

Cross‐Dehydrogenative Alkynylation: A Powerful Tool for the Synthesis of Internal Alkynes

“…Aliphatic terminal alkynes did not work under the reaction conditions. Recently, the C−H alkynylation of inactivated aliphatic terminal alkenes with triisopropylsilylethyne to form branched 1,3‐enynes was also achieved with a palladium catalyst . When the activated alkenes (alkyl acrylates) were used, linear ( E )‐1,3‐enynes were generated under similar reaction conditions …”

Ruthenium‐Catalyzed Oxidative Cross‐Coupling of Alkenes with Triisopropylsilylacetylene

“…In 2018, Murakami et al. reported palladium‐catalyzed oxidative cross coupling of terminal alkynes with unactivated alkenes [10c] . The reaction resulted in branched 1,3‐enynes as the major products, along with linear 1,3‐enynes and 1,4‐enynes as a mixture of Z / E isomers.…”

Palladium‐Catalyzed C−H Alkynylation of Unactivated Alkenes

“…[3] Nonetheless, the stereoselectivity challenge remains even for such metal-mediated coupling reactions, especially for tri-and tetrasubstituted olefins, because the problem of stereocontrol is relegated to the stereoselective synthesis of the required functionalized olefin precursors. [4,5] Thus, novel methods for the stereo-and regioselective synthesis of conjugated, highly substituted enynes are desirable. Herein, we report convenient access to 1,3-enynes from cis-olefins in a stereo-and regioselective manner through palladium-catalyzed alkenyl C À H functionalization that proceeds through putative exo-metallacycles as intermediates (Scheme 1).…”