2-Hydroxy-3-methylbutyric acid (2-hydroxyisovaleric acid) is a metabolite found in the urine of patients with phenylketonuria methylmalonic acidemia propionic acidemia 3-ketothiolase deficiency isovaleric acidemia 3-methylcrotonylglycemia 3-hydroxy-3-methylglutaric acidemia multiple carboxylase deficiency glutaric aciduria ornithine transcarbamylase deficiency glyceroluria tyrosinemia type I galactosemia and maple syrup urine disease.

Quercetin 3,5,7,3,4-pentamethyl ether is a natural product.

2,6-Dimethylpiperidines are chemical compounds with the formula C5H8(CH3)2NH. Three stereoisomers exist: the achiral (R,S)-isomer and the chiral (R,R)/(S,S) enantiomeric pair. Dimethylpiperidines are derivatives of the heterocycle piperidine, wherein two hydrogen atoms are replaced by methyl groups.