Synthetic studies on calyculin a: a convenient asymmetric synthesis of anti-vicinal diols

anti-Vicinal diols have been prepared with excellent relative and absolute stereocontrol via the reaction of aldehydes with B-{3-[(diisopropylamino)dimethylsilyl]allyl}diisopinocampheylborane in THF and diethyl ether and work-up using potassium fluoride, potassium hydrogen carbonate and hydrogen peroxide in aqueous methanol. Absolute stereoselectivities of reactions were determined by conversion of four product diols into bis[(R)-α-methoxy-α-(trifluoromethyl)phenylacetate] esters. The reactions are relevant to the synthesis of the marine phosphatase inhibitor calyculin A.