5-Hydroxypent-2-enenitriles as precursors toward dihydropyranones, dienenitriles and functionalized naphthalenes

5-Hydroxypent-2-enenitriles were found to be precursors toward several classes of compounds with synthetic and biological interests. To be specific, upon treatment with sulfuric acid in dichloromethane and depending on the configuration of the C–C double bond and the nature of substituents attached on the C–C double bond, 5-hydroxypent-2-enenitriles could afford 5,6-dihydropyran-2-ones, 2,4-dienenitriles, or functionalized naphthalenes through intramolecular Pinner reaction, β-elimination or intramolecular Friedel–Crafts reaction, respectively.