Cationic Cyclization of (α-Furyl)-and (β-Furyl)methyl Derivatives of (±)-Limonene.-α-and β-Furylmethyl derivatives of (±)-limonene (IV), prepared from compound (I), undergo cyclization in acidic media to yield isomeric tricyclic furoterpenoids related to the metabolites of some marine organisms. -(MOISEENKOV, A. M.; LOZANOVA, A. V.; SURKOVA, A. A.; BUEVICH, A. V.; VESELOVSKII, V. V.; Izv.