Volume 58, Issue 11 pp. 3579-3583
Communication

Transfer Hydrocyanation of α- and α,β-Substituted Styrenes Catalyzed by Boron Lewis Acids

Patrizio Orecchia

Patrizio Orecchia

Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany

These authors contributed equally to this work.

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Dr. Weiming Yuan

Dr. Weiming Yuan

Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany

These authors contributed equally to this work.

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Prof. Dr. Martin Oestreich

Corresponding Author

Prof. Dr. Martin Oestreich

Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany

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First published: 09 January 2019
Citations: 64

Graphical Abstract

Acid-free! Bench-stable cyclohexa-1,4-diene-based hydrogen cyanide (HCN) surrogates are reported to engage in transfer hydrocyanation of alkenes upon treatment with certain boron Lewis acids. The success also depends on the equilibrium position between the intermediate isocyano- and cyanoborate isomers. Tertiary nitriles are obtained with exclusive Markovnikov selectivity.

Abstract

A straightforward gram-scale preparation of cyclohexa-1,4-diene-based hydrogen cyanide (HCN) surrogates is reported. These are bench-stable but formally release HCN and rearomatize when treated with Lewis acids. For BCl3, the formation of the isocyanide adduct [(CN)BCl3] and the corresponding Wheland complex was verified by mass spectrometry. In the presence of 1,1-di- and trisubstituted alkenes, transfer of HCN from the surrogate to the C−C double bond occurs, affording highly substituted nitriles with Markovnikov selectivity. The success of this transfer hydrocyanation depends on the Lewis acid employed; catalytic amounts of BCl3 and (C6F5)2BCl are shown to be effective while B(C6F5)3 and BF3⋅OEt2 are not.

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