The supramolecular hydrogen-bonded self-assembled resorcinarene hexameric capsule promotes the ring closing isomerization of cannabidiol through encapsulation of the intermediate carbocation species formed by protonation with HCl. The confinement effect imparted by the capsule steers product selectivity towards the uncommon products D8-iso-THC, D4(8)-iso-THC, together with the hydrated 8-hydroxy-iso-HHC