2.5. 2 Cyanation of Epoxides
Buch
Herausgeber: van Leeuwen, P. W. N. M.
Titel: C-1 Building Blocks in Organic Synthesis 2
Untertitel: Alkenations, Cross Couplings, Insertions, Substitutions, and Halomethylations
Print ISBN: 9783131751218; Online ISBN: 9783132064515; Buch-DOI: 10.1055/b-003-125817
1st edition © 2014. Thieme. All rights reserved.
Georg Thieme Verlag KG, Stuttgart
Fachgebiete: C1-bildende Blöcke in der organischen Synthese
Science of Synthesis Reference Libraries
Übergeordnete Publikation
Titel: Science of Synthesis
DOI: 10.1055/b-00000101
Typ: Mehrbändiges Werk
Abstract
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Opening of epoxides with cyanide yields β-cyanohydrins (β-hydroxy nitriles), which are synthetically versatile intermediates that can be readily converted into a wide array of new functional groups. During the ring-opening reaction two contiguous stereocenters are generated, which can be controlled in several ways. When the reaction is performed without activation, terminal epoxides can be opened such that attack will take place at the least hindered carbon atom. Addition of a hard Lewis acidic catalyst will lead to activation of the epoxide, due to coordination to the epoxide oxygen atom, allowing the use of electronically and sterically more demanding substrates. Furthermore, ligands surrounding the metal of the catalyst can direct to which position of the epoxide attack will take place. If enantiopure ligands are used, meso-epoxides can be desymmetrized, resulting in the formation of a single enantiomer of the β-hydroxy nitrile product.
Schlüsselwörter
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