title: Electrophilic aromatic prenylation via cascade cyclization.
abstract: To gain access to prenylated hexahydroxanthenes, tandem cascade cyclization-electrophilic aromatic substitution reactions have been studied on substrates bearing allylic and propargylic substituents. Both BF3·OEt2and TMSOTf can be used to initiate this reaction sequence, resulting in different ratios of the C-2 and C-6 substitution products. Even though allylic transposition is observed in some cases, the results of a crossover experiment are consistent with an intramolecular reaction sequence. Taken together, these studies now allow preparation of either the C-2 or C-6 prenylated hexahydroxanthene products.
authors.affiliation: Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294 USA.
authors.forename: John G
authors.initials: JG
authors.lastname: Kodet
authors.affiliation: Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294 USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Topczewski
authors.affiliation: Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294 USA.
authors.forename: Kevyn D
authors.initials: KD
authors.lastname: Gardner
authors.affiliation: Department of Chemistry, University of Iowa, Iowa City, Iowa 52242-1294 USA.
authors.forename: David F
authors.initials: DF
authors.lastname: Wiemer
keywords: Cationic; Cyclization; Electrophilic aromatic substitution; Prenylation; Tandem reactions