Nonactivated trienes and aryltrienes were cyclized into polycyclic compounds in good to excellent yields under bismuth triflate catalysis in a biomimetic fashion. The reaction showed broad applicability and allowed for the formation of functionalized bicyclic to tetracyclic structures from simple precursors in one pot. For some specific substrates, the cyclization was followed by a methyl shift as encountered in terpenoid biosynthesis.
Terpene Compounds as Drugs. II. Terpenyl Derivatives of Barbituric Acids and Normeperidine
Cycloisomerisation of polyenes such as diethyl geranylprenylmalonate [(E)‐1 a], diethyl geranylphenylmalonate [(E)‐2 a] and diethyl cinnamylgeranylmalonate [(E,E)‐3 a] catalysed by bismuth triflate was studied from experimental and theoretical viewpoints. Several intermediates were isolated and characterised, and calculated transition‐state structures are proposed for the three reactions. The diastereoselectivity