Coupling of Two Different Alkynes to Give 1,3-Enynes

Coupling of Two Different Alkynes to Give 1,3-Enynes


C–C cross-coupling reactions are often used in organic synthesis. However, they usually require prefunctionalized reactants, which leads to a higher number of reaction steps and reduces efficiency. A high efficiency is particularly important in large-scale reactions, such as in the chemical and pharmaceutical industry.

Keary M. Engle, The Scripps Research Institute, La Jolla, CA, USA, and colleagues have developed a selective, catalytic method for the cross-coupling of internal and terminal alkynes to give 1,3-enynes that does not require prefunctionalized building blocks. The team used internal alkynes with a donor group (DG)—such as alcohols, amines, or amides—and different terminal alkynes as coupling partners, Pd(dba)2 (dba = dibenzylideneacetone) as the catalyst together with a phosphinoimidazoline ligand, and ammonium acetate as an additive.

The desired 1,3-enynes were obtained in generally good yields and with high regio-and stereoselectivities. To demonstrate the scalability of the reaction, the team performed a model reaction with a propargyl alcohol on a gram scale, obtaining a yield of 94 %.



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