Synthesis of (±)-trans-2,5-Diisopropylborolane

The cyclic hydroboration of 2,7-dimethyl-2,6-octadiene (6) was studied. It was found that the stereochemical outcome of the reaction was dependent upon the solvent, temperature, time and the nature of the borane reagent. Pure racemic trans-2,5-diisopropylborolane (14) was isolated following selective complexation of the cis-2,5-diisopropylborolane (15) with 1-(2-hydroxyethyl)-pyrrolidine.