SUPERACIDIC LOW-TEMPERATURE CYCLIZATION OF TERPENOLS AND THEIR ACETATES

The superacidic low-temperature cyclization of terpenols and their ace tates by fluorosulfonic acid represents a highly efficient chemo- and structurally selective and stereospecific process. Homoallylic alcohol s (alpha-isomers of cycloterpenols) are the products of cyclization of terpenols; the configuration of the hydroxymethyl group in the produc ts is predetermined by the configuration of the allylic double bond in aliphatic or partially cyclized precursors. The cyclization of terpen yl acetates yields monoacetates of fully cyclized diastereomeric prima ry-tertiary gamma-diols. Their stereochemistry also depends on the con figuration of the allylic double bond in the starting substrates.