ADDITION COMPOUNDS OF ALKALI METAL HYDRIDES XVIII. REACTION OF TRIALKYLBORANES WITH t-BUTYLLITHIUM. A GENERAL CONVENIENT METHOD FOR THE PREPARATION OF LITHIUM TRIALKYBOROHYDRIDES

Article abstract of DOI:10.1016/S0022-328X(00)83693-1

The reaction of t-butyllithium with representative trialkylboranes possessing widely differing steric requirements was examined.This reaction occurs rapidly in ether solvents, even at -78 deg C, with formation of the corresponding lithium trialkylborohydride in quantitative yield.This synthesis is highly general, accomodating even strongly hindered trialkylboranes such as tris(trans-2-methylcyclopentyl)borane and trisiamylborane.The only by-product is isobutylene, which is generally innocuous and easily removed.The lithium trialkylborohydrides were characterized byhydride analyses, infrared spectra, and 11B NMR spectra.The formation of the trialkylborohydrides appears to be due to kinetic, rather than thermodynamic, factors.This reaction provides a highly general, facile, and quantitative route to the lithium trialkylborohydrides.