title: Synthesis of functionalized 2-alkylidenetetrahydrofurans by cyclization of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with epoxides.
abstract: The Lewis acid mediated cyclization of epoxides with 1,3-bis(trimethylsilyloxy)-1,3-butadienes, electroneutral equivalents of 1,3-dicarbonyl dianions, results in the formation of 2-alkylidenetetrahydrofurans with a great variety of substitution patterns and functional groups. This includes the synthesis of 2,3'-bifuranylidenes and 7-oxabicyclo[4.3.0]nonanes. The cyclization of dienes with functionalized epoxides containing base-labile groups proceeds with good chemoselectivity. In all reactions, good regio- and E diastereoselectivities are observed. Based on the stereoselectivities observed for reactions of 1,2-disubstituted epoxides, a working hypothesis for the mechanism of the reaction is suggested.
authors.affiliation: Institut für Organische Chemie, der Georg-August-Universität Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany. planger@uni-goettingen.de
authors.forename: Peter
authors.initials: P
authors.lastname: Langer
authors.forename: Holger
authors.initials: H
authors.lastname: Armbrust
authors.forename: Tobias
authors.initials: T
authors.lastname: Eckardt
authors.forename: Jörg
authors.initials: J
authors.lastname: Magull