The superacidic cyclization of aliphatic and partially cyclized C-10-C
-20 terpenylphenylsulfones proceeds structure-selectively and stereosp
ecifically, affording alpha- or mixtures of alpha- and gamma-isomers o
f completely cyclized terpenylphenylsulfones. The configuration of the
phenylsulfonylmethylene group in the cyclized products is predetermin
ed by the configuration of the allylic double bond in the starting com
pounds. (C) 1998 Elsevier Science Ltd. All rights reserved.