Mesityltriphenylbismuthonium tetrafluoroborate as an efficient bismuth(V) oxidant: remarkable steric effects on reaction rates and chemoselectivities in alcohol oxidation

In the presence of N,N,N′,N′-tetramethylguanidine, mesityltriphenylbismuthonium tetrafluoroborate oxidizes primary and secondary alcohols to aldehydes and ketones, respectively, under mild conditions. In this reaction, the mesityl ligand exclusively abstracts an α-hydrogen to afford mesitylene and triphenylbismuthane as side products. A remarkable steric effect has also been exhibited in the chemoselective oxidation between primary and secondary alcohols.