A new approach to ethyl (2R,3R)-2-t-butyldimethytsilyloxymethyl-3- hydroxy-2-methylbutanoate, a compound which is related to a synthetic intermediate of the side chain of furaquinocin D, is described. The characteristic feature of this compound is a quarternary chiral center and an adjacent secondary alcohol, both of which are in a stereochemically defined state, and the setup of these functionalities was achieved by a combination of stereoselective chemical and enzymatic reactions. The reduction of ethyl 2-hydroxymethyl-2-methyl-3-oxobutanoate with excess NaBH4 afforded (2R*,3R*)-(±)-hydroxy ester with a high diastereomeric excess. After protecting the primary hydroxy group as TBDMS ether, the optical resolution was achieved by lipase-catalyzed hydrolysis of the corresponding chloroacetate in a highly enantioselective manner.
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