A mechanistically designed cinchona alkaloid ligand in the osmium catalyzed asymmetric dihydroxylation of alkenes

A new ligand has been designed using dihydroquinine as the chiral controller for asymmetric dihydroxylation of alkenes. The purpose of this design of the ligand is to find out the transition state involved in the mechanism of asymmetric dihydroxylation, which may shed some light to differentiate between the hypothesis put forward by Sharpless' and Corey's groups. The present study supports the hypothesis proposed by Sharpless et al. and it appears that the L shaped cleft may be involved in governing the high selectivity of asymmetric dihydroxylation of alkenes.