The ring-opening reaction of epoxides 1b and 1c utilizing LiAlH4, have been studied within the Molecular Electron Density Theory (MEDT) at the B3LYP/6-31(d) computational level. The regioisomeric reaction paths including the two oxiranes cycles of epoxides 1b and 1c have been explored. DFT calculations show that the attack of the hydride ion H- is favorable on the carbon C-3 for the epoxide 1b, while this action is realized on carbon C-2 for the epoxide 1c in the highest conformity with the experimental outcomes. Furthermore, we have operated a docking calculation to examine the antibacterial activities of the products 1a-1f, further more we have performed a docking calculation to scrutinize the products 1-9 against SARS-CoV-2. Indeed, the docking results showed that alpha-himachalene (2) possess a higher affinity to the main protease. (C) 2021 Published by Elsevier B.V.