A new regio- and stereospecific asymmetric rearrangement was discovered during the asymmetric hydrolysis of the meso epoxy diesters dialkyl 5,6-epoxybicyclo[2.2.1]hept-2-ene-2,3-dicarboxylate, 3a-c, with pig liver esterase (PLE). The rearrangement quantitatively produces the optically active monoester 6-formyl-2-(alkoxycarbonyl)bicyclo[3.1.0]hex-2-ene-1-carboxylic acid, 6a-c. These rearranged products, 6a-c, have the same skeleton as 10, which was reported by Meinwald (J. Am. Chem. Sec, 1963, 85, 582). In contrast to the classical Meinwald rearrangement, this new rearrangement proceeds under slightly basic conditions efficiently. The reaction mechanism was investigated, and it is proposed to proceed via the cu-lactone-type intermediate 24, which was formed by intramolecular Michael addition of the carboxylate anion generated by the enzymatic hydrolysis.