-Glycosylcrotylboronates for the Synthesis of Glycomimetics.

The stereoselective synthesis of - and - isomers of a - crotylpinacolboronate Ni-promoted reactions on an allylic acetate and a diene precursor, respectively, is described. The - and - isomers reacted with 1,2--isopropylidene glyceraldehyde in the presence or absence of ()- and ()- TRIP catalysts, to give predominantly 3,4- and 3,4- crotylation products, respectively, with moderate to high facial selectivity. These products were transformed to biologically relevant --disaccharides.