A regioselective synthesis of β-lactones; Bromolactonization of 2-substituted-1-cyclohexenyl-1-acetic acid

Bromolactonization of 2-substituted-1-cyclohexenyl-1-acetic acids with 1,3-dibromo-5,5-dimethylhydantoin (DBH) and potassium tertiary butoxide (t-BuOK) in anhydrous DMF was found to proceed in a highly regioselective manner. The reaction predominantly resulted in the formation of β-lactones (greater than 96%).