(-)-Cedranediol boronic esters 3, a series of asymmetric homologation reagents were prepared from a new chiral director (-)- cedranediol 1 and boronic acids. 1 was easily synthesized by the dihydroxylation of (-)-α-cedrene 2 with OsO~4. Homologation of cedranediol boronic esters 3 with (dichloromethyl) lithium resulted in (R)-α-chloro boronic esters 4, with R/S-ratios over 25:1. It is easy to recover cedranediol for its boronic esters prone to rapid hydrolysis. The absolute configuration of cedranediol (R)-1-chloro-2- phenylethylboronate 4cR was determined by X-ray diffraction. The distortion of the five-membered 1, 3, 2-dioxaborolane ring of 4cR was found and discussed.

Key words: ASYMMETRY, HOMOLOGATION, CHIRAL REAGENT, X-RAY DIFFRACTION ANALYSIS