title: Chemoselective, regioselective, and E/Z-diastereoselective synthesis of 2-alkylidenetetrahydrofurans by sequential reactions of ambident dianions and monoanions.
abstract: A number of novel beta-ketoesters were prepared by regioselective alkylation reactions of simple beta-ketoester dianions. The cyclization of the dianions of these 1,3-dicarbonyl derivatives with 1-bromo-2-chloroethane afforded a variety of 2-alkylidenetetrahydrofurans with very good regioselectivity and E/Z-diastereoselectivity. These products were deprotonated to give novel ambident carbanions. The alkylation of these carbanions with alkyl halides proceeded with very good regioselectivity and E/Z-diastereoselectivity and allowed a convenient synthesis of a great variety of new 2-alkylidenetetrahydrofurans.
authors.affiliation: Institut für Chemie und Biochemie der Ernst-Moritz-Arndt-Universität Greifswald, Soldmannstrasse 16, 17487 Greifswald, Germany. peter.langer@uni-greifswald.de
authors.forename: Peter
authors.initials: P
authors.lastname: Langer
authors.forename: Esen
authors.initials: E
authors.lastname: Bellur