To expand the versatility of asymmetric hydroboration, we plan to synthesize a wide variety of chiral hydroborating agents and to study the factors governing the asymmetric induction in the hydroboration of various prochiral olefins including substituted heterocyclic olefins. The recently developed method of enhancing the optical purity of mono- and diisopinocampheylalkylboranes to essentially 100% enantiomerically pure boronic esters and their conversion to optically pure lithium monoalkylborohydrides opens possibilities for preparing a variety of chiral boranes in essentially 100% enantiomeric purity. From these chiral borane reagents, we can synthesize practically any enantiomer units, both (+)- and (-)-isomers, which are of interest to biochemical and pharmaceutical research in 100% optical purity. We propose to explore the synthesis and utility of chiral allyldialkylboranes, a new reagent, containing a variety of representative substituents in the allylic moiety. The condensation of these allylboranes with carbonyl compounds will provide valuable methodology for the control of absolute and relative stereochemistry in acyclic systems as required in the synthesis of biologically active systems. The utility of various chiral organoborane intermediates will be explored for the stereospecific and asymmetric reductions of prochiral carbonyl compounds and imine derivatives.
| Joshi, N N; Srebnik, M (1989) Resolution of rac-1,2-halohydrins by chiral complexation gas chromatography. J Chromatogr 462:458-60 |
