4-(Pyrrolidin-1-yl)pyridine-catalyzed deconjugative esterification of 2-cyclohexylideneacetic acids afforded isopropyl 2-(cyclohex-1-enyl)acetate by employing 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as a coupling reagent. On the other hand, 4-(pyrrolidin-1-yl)pyridine-catalyzed esterification with 1,3-dicyclohexylcarbodiimide was not accompanied by deconjugation and gave isopropyl 2-cyclohexylideneacetate.
A facile synthetic approach to β,γ-unsaturated esters by deconjugative esterification of α,β-unsaturated carboxylic acids with alcohols in the presence of 1,3-dicyclohexylcarbodiimide (DCC), Me3N·HCl, and Me2NEt is described. The one-pot synthesis was effectively improved under microwave irradiation.