Acid-Catalyzed Rearrangement of Propella-ε-lactones

Article abstract of DOI:10.1021/jo00334a020

The acid-catalyzed rearrangement of <5.3.2>- and <5.4.2>propella-ε-lactones 9 and 10 in boiling acetic acid takes place readily to afford the 1,2-disubstituted cyclopentene 21 and cyclohexene 26 as the major products, respectively, while such lactone ring cleavage of the <4.3.2>- and <4.4.2>propella-δ-lactones 1 and 2 does not occur at all under similar conditions.The remarcable distinction in reactivity in the acid-catalyzed rearrangement between the ε-lactones and the δ-lactones is attributed to the effect of lactone ring size.