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- Title
Highly Functionalized Cyclopentane Derivatives by Tandem Michael Addition/Radical Cyclization/Oxygenation Reactions.
- Authors
Holan, Martin; Pohl, Radek; Císařová, Ivana; Klepetářová, Blanka; Jones, Peter G.; Jahn, Ullrich
- Abstract
Densely functionalized cyclopentane derivatives with up to four consecutive stereocenters are assembled by a tandem Michael addition/single-electron transfer oxidation/radical cyclization/oxygenation strategy mediated by ferrocenium hexafluorophosphate, a recyclable, less toxic single-electron transfer oxidant. Ester enolates were coupled with α-benzylidene and α-alkylidene β-dicarbonyl compounds with switchable diastereoselectivity. This pivotal steering element subsequently controls the diastereoselectivity of the radical cyclization step. The substitution pattern of the radical cyclization acceptor enables a switch of the cyclization mode from a 5- exo pattern for terminally substituted olefin units to a 6- endo mode for internally substituted acceptors. The oxidative anionic/radical strategy also allows efficient termination by oxygenation with the free radical 2,2,6,6-tetramethyl-1-piperidinoxyl, and two CC bonds and one CO bond are thus formed in the sequence. A stereochemical model is proposed that accounts for all of the experimental results and allows the prediction of the stereochemical outcome. Further transformations of the synthesized cyclopentanes are reported.
- Subjects
CYCLOPENTANE; CYCLOPENTANE derivatives; ORGANIC compound derivatives; CHEMICAL derivatives; BICYCLOPENTANE
- Publication
Chemistry - A European Journal, 2015, Vol 21, Issue 27, p9877
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201500424