Titanocene bis-catecholborane, [Cp2Ti(HBcat)2], catalyzes the room temperature hydroboration of aryl carbonyl compounds and vinylphosphines by pinacolborane rapidly, cleanly and chemoselectively. Reactions produced alkoxyboronate esters and phosphanyl(organyl)boranes (POBs) at room temperature in moderate to high yields and short reaction times. Facile hydrolysis of alkoxyboronate esters over silica occurred cleanly to afford alcohols in good yields. The catalyst demonstrated a preference for C=O bonds over C=C bonds in both conjugated and non-conjugated enones. Kinetic studies of the catalytic hydroboration of a series of acetophenones showed that electron-poor substrates undergo the reaction faster than electron-rich substrates. This result is consistent with the proposed mechanism in which stronger ?-acids should undergo C=O bond cleavage more readily. Hydroboration of vinylphosphines yielded Anti-Markovnikov POBs which bonded to transition metal complexes via phosphorus alone.

Titanium(II)-catalyzed hydroboration of heteroatomic unsaturated substrates

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.