Asymmetric Induction Predicated on Chelation Control

Hydration of formaldehyde four-membered versus six-membered transition state structures [7] 

Still conducted pioneering investigations on the use of chelate-controlled reactions of carbanions in additions to ketones for the stereoselective syntheses of simple vicinal diols. The results demonstrate that Mg Il) is superior to Li(I) for the formation of chelates (Equation 4) [64]. Surprisingly, THF proved to be the optimal solvent in the additions and provided 52 in 100 1 di Of additional interest is the observation that only a minor temperature dependence was observed in the addition reactions with substrate 51, including MEM as a protecting group. 

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