Superacidic cyclization of higher terpenoid acids and their esters

The superacidic cyclization of aliphatic and partially cyclized C₁₅–C₂₅ terpenoid acids and their esters proceeds structure-selectively and stereospecifically, affording -isomers of completely cyclized epimeric ,-unsaturated acids or esters; the configuration of their carboxylic or ester groups is predetermined by the configuration of the double bond conjugated with the carboxyl or ester groups in the starting compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2507–2513, December, 1995.