Isovaleryl coenzyme A, an intermediate of the leucine catabolism. It is synthesized from β-methylbutyric acid by the action of enzyme acyl CoA synthetase. The conversion of isovaleryl-CoA to methylcrotonyl-CoA is catalyzed by the enzyme isovaleryl-CoA dehydrogenase in leucine catabolism pathway. The enzyme isovaleryl-CoA oxidase also calalyzes this conversion in fatty acid β-oxidation pathway.