A process for upgrading to essentially 100% enantiomeric excess the optical purity of an organoborane intermediate represented by the formulae: IcpBHR* or Icp.sub.2 BR* wherein Icp is isopinocampheyl and R* is a unsubstituted or substituted, acyclic or cyclic alkyl having from 4 to 30 carbon atoms, comprising the steps of hydroborating cis-alkene, a trans-alkene or a tertiary-alkene with monoisopinocampheylborane or diisopinocampheylborane, obtaining a solid organoborane and recrystallizing the solid organoborane to obtain an enantiomeric excess of essentially 100% ee of said organoborane.