Isolation and Reactivity of Arylnickel(II) Complexes in Nickel-Catalyzed Borylation of Aryl Fluorosulfates.

Aryl fluorosulfates have emerged as versatile SuFExable substrates, harnessing the reactivity of the S-F bond. In this study, we unveil their alternative synthetic utility in nickel-catalyzed borylation via C-O bond activation. This method highlights mild reaction conditions, a broad substrate scope, and moderate functional group tolerance, rendering it a practical and appealing approach for synthesizing a diverse array of aryl boronate esters. Furthermore, computational analysis sheds light on the reaction pathways, uncovering the participation of LNi(0) and LNi(II)ArX species. This insight is supported by the 31P NMR reaction monitoring along with isolation and single-crystal X-ray structural elucidation of well-defined arylnickel(II) intermediates obtained from the oxidative addition of aryl fluorosulfates. A comprehensive investigation, merging experimental and computational approaches, deepens our understanding of the alternative reactivity of SuFExable substrates.

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.