Organoboranes for synthesis—substitution with retention

Abstract

The facile reaction of olefins dienes and acetylenes with various hydroborating agents made a vast array of organoboranes readily available. Organoboranes tolerate many functional groups and are often formed in a stereosnecific manner. The boron atom in these organoboranes can be readily substituted with a variety of functional groups to give organic compounds under mild conditions such that organoboranes now appear to be among the most versatile internediates available for organic synthesis. Exploration of these substitution reactions revealed that the organoboranes transfer the alkyl group to essentially most of the other elements of synthetic and biological interest, including carbon, with complete maintenance of stereochemical integrity. Consequently, the organic groups that are formed stereospecifically by the hydroboration reaction can be readily incorporated into organic molecules. A recent development-preparation of optically pure organoborane intermediates-makes possible the synthesis of essentially any compound containing a chiral center in both optical isomers in essentially 100% optical purity. Thus, our research program has taken boranes from an exotic material of little interest to a reagent widely used in organic synthesis, greatly assisting chemists in overcoming synthetic difficulties. © 1987 IUPAC