Synthesis of α,ß-unsaturated ketones through nickel-catalysed aldehyde-free hydroacylation of alkynes.

α,ß-Unsaturated ketones are common feedstocks for the synthesis of fine chemicals, pharmaceuticals, and natural products. Transition metal-catalysed hydroacylation reactions of alkynes using aldehydes have been recognised as an atom-economical route to access α,ß-unsaturated ketones through chemoselective aldehydic C-H activation. However, the previously reported hydroacylation reactions using rhodium, cobalt, or ruthenium catalysts require chelating moiety-bearing aldehydes to prevent decarbonylation of acyl-metal-hydride complexes. Herein, we report a nickel-catalysed anti-Markovnikov selective coupling process to afford non-tethered E-enones from terminal alkynes and S-2-pyridyl thioesters in the presence of zinc metal as a reducing agent. Utilization of a readily available thioester as an acylating agent and water as a proton donor enables the mechanistically distinctive and aldehyde-free hydroacylation of terminal alkynes. This non-chelation-controlled approach features mild reaction conditions, high step economy, and excellent regio- and stereoselectivity.

Reductive Ni-catalysis for stereoselective carboarylation of terminal aryl alkynes.

Stereoselective dicarbofunctionalization of terminal aryl alkynes has been achieved through reductive Ni-catalysis. The exclusive regioselective and anti-addition selective alkylarylation of terminal alkynes is accomplished using alkyl iodide and aryl iodide as electrophilic coupling partners in the presence of NiBr2 as the catalyst and Mn as an inexpensive reductant.