The ring-opening reactions of (1aS,2S,6bR)-5-ethyl-2-hydroxyhexahydro-4H-oxireno[2,3-e]isoindole-4,6(5H)-dione were investigated under very mild and nonchelated conditions. C-2 selective ring-opening products were obtained with nucleophilic additions such as Cl-, Br- and N-3(-). The exact configuration of (3aS,4R,5R,6S,7aS)-5-chloro-2-ethyl-4,6-dihydroxyhexahydro-1H-isoindole-1,3(2H)-dione was determined by X-Ray diffraction analysis which was obtained from the reaction of epoxy alcohol with HCl . On the other hand, theoretical computations were carried out to explain the regioselectivity in the ring opening reaction of epoxy alcohols. The results showed that the ring-opening reaction of both epoxy alcohols proceeds in a kinetically controlled manner and regioselectivity occurs depending on the transition state. (c) 2022 Published by Elsevier B.V.