ORGANOBORANES IN SYNTHESIS AND ANALYSIS
Organoboranes which are important for preparative purposes include triethylborane, alkyldiboranes and in particular diethylborylpivalate and bis- (ethylpivaloyloxy) diboroxane (BEPDIB). — Several new boron-specific applications of organoboranes in synthesis of organic compounds will be given. Tri- and tetrasubstituted (Z/E) -alkenes are sometime obtained highly selectively on reaction of heteroatom containing electrophiles with substituted 1-alkinyl- borates. — Versatile aldol-additions and both homo- and mixed condensations of ketones and certain aldehydes can be carried out with the help of organoboranes — Stereoselective formation of erythro- and threo-ketoles can be performed using the easily obtainable vinyloxyboranes. — Separations, purifications and selective O-derivatisations of polyhydroxy compounds are possible via O-ethylboranediyl derivatives. The O-ethylboron protective groups are useful for the NMR-spectroscopic identification of polyalcohols, saccharides and their derivatives.