2,2-Dimethylbutanoyl chloride is a reagent that is used in the synthesis of 4α,5-Dihydro Simvastatin (D450010). 4α,5-Dihydro Simvastatin is an impurity in the synthesis of Simvastatin (S485000), a synthetic derivative of a fermentation product of Aspergillus terreus. A competitive inhibitor of HMG-CoA reductase. A synthetic analog of Lovastatin. Antilipemic. Simvastatin, the drug, is sold under the trade name Zocor.