PEG-mediated recyclable borylative coupling of vinyl boronates with olefins

Publication date: August 2019Source: Journal of Catalysis, Volume 376Author(s): Jakub Szyling, Jędrzej Walkowiak, Tomasz Sokolnicki, Adrian Franczyk, Kinga Stefanowska, Mateusz KlarekAbstractThis paper reports on the first green and sustainable repetitive batch borylative coupling of vinyl boronates with olefins by the effective immobilization of the [Ru(CO)Cl(H)(PCy3)2] catalyst in poly(ethylene glycols) with different molecular weights (Mw = 600–2000) and ending groups (OH, OMe, OSiMe3) or in biphasic poly(ethylene glycols)/supercritical CO2 (PEGs/scCO2) systems. Within this process, (E)-alkenyl boronates were obtained with high yields and excellent stereo-, regioselectivities. The best strategies permitted to carry out cross-coupling of vinyl boronates with styrene for up to 8–16 repetitive batches respectively, by applying 2 or 4 mol% of Ru-catalyst. The described methods enable the reuse of the TM-catalyst and solvents and the reduction or elimination of the use of volatile organic solvents and metal content in the final products, and obtain high cumulative TON values (up to 440). The biphasic systems also allowed the simplification of the separation procedure by effective product extraction in CO2 stream.Graphical abstract

Source: Journal of Catalysis - July 22, 2019 Category: Chemistry Source Type: research