Cherniak-unicorn reaction

The Tscherniak-Einhorn reaction is a name reaction in organic chemistry, which was first introduced in 1901 by Joseph Tscherniak for the condensation of N- hydroxymethylphthalimide with various aromatic compounds and expanded in 1905 by Alfred Einhorn for the condensation of N- hydroxymethylchloracetamide and benzoic acid or cinnamic acid .

Overview reaction

This reaction describes an acid catalyzed electrophilic aromatic amidoalkylation using an N -hydroxymethylamide or N -hydroxymethylimide. The N -hydroxymethylamides or N -hydroxymethylimides are also known as Tscherniak-Einhorn reagents. This reaction is catalyzed by strong acids such as 85-100% sulfuric acid , p -toluenesulfonic acid , methanesulfonic acid and trifluoroacetic acid.

The N -hydroxymethylamides can be prepared by condensing the corresponding amides with aqueous formaldehyde solution in dioxane in the presence of sodium hydroxide .

Reaction mechanism

In the first step, the N -hydroxymethylamide is protonated by an acid . After splitting off water, a mesomeric-stabilized cation is formed, which reacts with the aromatic in the sense of an electrophilic aromatic substitution.

application

This reaction is used for the production of some alkaloid derivatives.

literature

Harold E. Zaugg, Ann M. Kotre, Jean E. Fraser: Tscherniac-Einhorn reaction. I. Equilibria in solutions of N- (hydroxymethyl) phthalimide in strong sulfuric acid . In: The Journal of Organic Chemistry . tape 34 , no. January 1 , 1969, doi : 10.1021 / jo00838a004 (English).

Harold E. Zaugg, Robert W. DeNet, Jean E. Fraser, Ann M. Kotre: Tscherniac-Einhorn reaction. II. Kinetics and mechanism . In: The Journal of Organic Chemistry . tape 34 , no. 1 , January 1969, p. 14 , doi : 10.1021 / jo00838a005 (English).

Individual evidence

↑ Alfred Einhorn, Eduard Bischkopff, Bruno Szelinski, Gustav Schupp, Eduard Spröngerts, Carl Ladisch, Theodor Mauermayer: About the N-methylol compounds of the acid amides [first treatise.] In: Justus Liebig's Annalen der Chemie . tape 343 , no. 2-3 , 1905, pp. 207 , doi : 10.1002 / jlac.19053430207 .
↑ ^a ^b ^c ^d Tscherniac-Unicorn Reaction . In: Comprehensive Organic Name Reactions and Reagents . Wiley, 2010, ISBN 978-0-470-63885-9 , pp. 2807-2811 , doi : 10.1002 / 9780470638859.conrr629 .
↑ Tscherniac-Unicorn reaction. illumina-chemie.de, May 11, 2013, accessed on February 23, 2019 .

[1] Alfred Einhorn, Eduard Bischkopff, Bruno Szelinski, Gustav Schupp, Eduard Spröngerts, Carl Ladisch, Theodor Mauermayer: About the N-methylol compounds of the acid amides [first treatise.] In: Justus Liebig's Annalen der Chemie . tape 343 , no. 2-3 , 1905, pp. 207 , doi : 10.1002 / jlac.19053430207 .

[:0-2] Tscherniac-Unicorn Reaction . In: Comprehensive Organic Name Reactions and Reagents . Wiley, 2010, ISBN 978-0-470-63885-9 , pp. 2807-2811 , doi : 10.1002 / 9780470638859.conrr629 .

[3] Tscherniac-Unicorn reaction. illumina-chemie.de, May 11, 2013, accessed on February 23, 2019 .