In order to develop new methyl substituted chiral building blocks which are useful for the synthesis of methyl branched natural products, the enantioselective bioreduction of an exo- methylene to a methyl group was investigated. 4-Acetoxy-2-methylene-1-butanol 3 was prepared from itaconic acid over four steps and converted to the chiral alcohol (R)-4-acetoxy- 2-methyl-1-butanol 4, by growing cells of Pseudomonas putida. The bioconversion ...