Superparamagnetic copper ferrite nanoparticles catalyzed aerobic, ligand-Free, regioselective hydroboration of alkynes: Influence of synergistic effect
•Hydroboration of terminal and internal alkynes.•High catalytic activity due to synergistic effect.•Low-Catalyst copper loading with four times recycle.•High functional-group tolerance, Ligand-Free, and environmental-friendly.
We discovered a general and comprehensive approach for the regioselective hydroboration of terminal and internal alkynes to synthesize vinylboronates using inexpensive and magnetically separable copper ferrite nanoparticles at low catalyst loading using Bis(pinacolato)diboron in the absence of ligand and additives, under mild and greener conditions. A diverse range of functional groups was tolerated in the reaction, including allene and enones, and the corresponding boronates were obtained in high yields under air. Moreover, the assynthesized alkenylboronates were used as precursors to prepare wide variety of vinylorgano chalcogenides regioselectively, in high yields. The present protocol enable the conversion of CspH bonds to make Csp2B bonds via activation of BB bond, followed by formation of Csp2Se (Te or S) bonds via activation of Se (Te or S)- Se (Te or S) bonds in a regioselective manner. Deuterium isotope labeling studies showed that the proton source of vinyl boronate stem from the solvent employed.
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Journal: Applied Catalysis A: General - Volume 519, 5 June 2016, Pages 78–84