The reaction of β-hydroxy acids with aldehydes

ß-Hydroxy acids react with various aldehydes in the presence of acidic materials to give spiro lactones in good yields. For example, 2-isopropyl-5-methyl-1,3-dioxaspiro[5,5]undecan-4-one was obtained in 90% yield from the reaction of 2-(1'-hydroxycyclohexyl)propionic acid and isobutyraldehyde.