cs500130y_si_001.pdf (1.44 MB)
Copper-Catalyzed Regioselective Formation of Tri- and Tetrasubstituted Vinylboronates in Air
journal contribution
posted on 2014-05-02, 00:00 authored by Yannick
D. Bidal, Faïma Lazreg, Catherine S. J. CazinThe
first “in air” copper-catalyzed method for the
selective synthesis of tri- and tetrasubstituted vinylboronate derivatives
is presented. Three different variants of the borylation of internal
alkynes (α-hydroboration, β-hydroboration, and carboboration)
are described using a single catalyst: [Cu(Cl)(IMes)] (IMes = N,N′-bis-[2,4,6-(trimethyl)phenyl]imidazol-2-ylidene)
without taking any precaution to avoid the presence of air. Bis(pinacolato)diboron
was used to afford β-hydroborated products in the presence of
methanol. Adding instead another electrophile allowed the formation
of tetrasubstituted vinylboronate species. Finally, the α-products
were obtained using pinacolborane as the boron source. All compounds
were obtained in high yield with excellent regioselectivity at low
catalyst loading (0.04–2 mol %). The protocol constitutes a
very convenient route to access these highly valuable molecules.
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Keywords
electrophileRegioselectivepresenceAirTheborylationregioselectivityTetrasubstituted VinylboronatesloadingmolaccessmethanolpinacolboranemethodsynthesisTrimoleculecompoundhydroborationvariantBisformationcatalysttetrasubstituted vinylboronate derivativeshydroboratedtetrasubstituted vinylboronate speciestriIMecarboborationalkyneFormationboron sourceprecautionCu
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