title: Asymmetric synthesis of 2-alkenyl-1-cyclopentanols via tin-lithium exchange and intramolecular cycloalkylation.
abstract: [reaction: see text] We report a method for the synthesis of chiral cyclopentanes using tin-lithium exchange and cycloalkylation reactions. The sec-butyllithium/(-)-sparteine-mediated deprotonation of an alkyl carbamate and subsequent substitution furnishes a highly enantioenriched stannane as a stable carbanion equivalent. It was transformed into suitable cyclization precursors, which underwent tin-lithium exchange and stereoselective cycloalkylation when reacted with n-butyllithium, giving highly enantioenriched cyclopentanes in very good yields. A kinetic resolution was observed with a higher substituted stannane.
authors.affiliation: Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, D-48149 Münster, Germany.
authors.forename: Guido
authors.initials: G
authors.lastname: Christoph
authors.forename: Dieter
authors.initials: D
authors.lastname: Hoppe