Synthesis of δ-Lactones from Glutaraldehyde

A novel and general synthesis of δ-lactones from glutaraldehyde is described. The dialdehyde is first reacted with an alkyl or substituted alkyl Grignard reagent to afford a δ-hydroxyaldehyde in good yield. These aldehydes exist preferentially in the cyclic hemiacetal form (δ-lactols). Oxidation of the latter compounds to give δ-lactones is readily achieved with silver oxide or bromine. The δ-lactols and δ-lactones serve as intermediates for the total synthesis of steroids.