- Cadiot-Chodkiewicz coupling
The Cadiot-Chodkiewicz coupling in
organic chemistry is acoupling reaction between a terminalalkyne and ahaloalkyne catalyzed by a copper(I) salt such ascopper(I) bromide and anamine base [Chodkiewicz, W. Ann. Chim. Paris 1957, 2, 819-869.] [Cadiot,P.; Chodkiewicz, W. In Chemistry of Acetylenes; Viehe, H. G., Ed.; Marcel Dekker: New York, 1969; pp 597-647.] . The reaction product is a di-acetylene or di-alkyne .The
reaction mechanism involvesdeprotonation by base of the acetylenic proton followed by formation of acopper(I) acetylide . A cycle ofoxidative addition andreductive elimination on the copper center then creates a new carbon carbon bond.Related couplings are the Glaser coupling and the Eglinton coupling.
Cadiot-Chodkiewicz coupling
In one study ["Synthesis of 1,4-Cyclohexadiene-Based Acetylenic Macrocycles with Cadiot-Chodkiewicz Coupling. Structure of a Tub-Shaped Tetrameric Container" Arkasish Bandyopadhyay, Babu Varghese, and Sethuraman Sankararaman
J. Org. Chem. ; 2006; 71(12) pp 4544 - 4548; (Article) DOI|10.1021/jo0605290] the Cadiot-Chodkiewicz coupling has been applied in the synthesis of acetylenemacrocycle s starting from "cis-1,4-diethynyl-1,4-dimethoxycyclohexa-2,5-diene". This compound is also the starting material for the dibromide through NBS andsilver nitrate :The coupling reaction itself takes place in
methanol withpiperidine , thehydrochloric acid salt ofhydroxylamine andcopper(I) bromide .Eglinton reaction
In the related Eglinton reaction [G. Eglinton and A. R. Galbraith, J. Chem. Soc., 889 (1959).] two terminal alkynes are coupled directly a copper(II) salt such as
cupric acetate . This procedure was used in the synthesis ofcyclooctadecanonaene . Another example is the synthesis of diphenyldiacetylene fromphenylacetylene [OrgSynth | author = I. D. Campbell and G. Eglinton | title = Diphenyldiacetylene | collvol = 5 | collvolpages = 517 | year = 1973 | prep = cv5p0517]Glaser coupling
The Glaser coupling (1870) is by far the oldest acetylenic coupling and is based on cuprous salts like
copper(I) bromide and an additional oxidant like oxygen. The base in its original scope isammonia . [cite journal
title = Untersuchungen über einige Derivate der Zimmtsäure
author = Carl Glaser
journal = Annalen der Chemie und Pharmacie
volume = 154
issue =
pages = 137
year = 1870
url =
doi = 10.1002/jlac.18701540202] [cite journal
title = Beiträge zur Kenntniss des Acetenylbenzols
author = Carl Glaser
journal = Berichte der deutschen chemischen Gesellschaft
volume = 2
issue =
pages = 422–424
year = 1869
url =
doi = 10.1002/cber.186900201183]Hay coupling
The Hay coupling (1962) is another version of the Glaser coupling with the
TMEDA complex ofcopper(I) chloride [cite journal | title = Oxidative Coupling of Acetylenes. II | author = Allan S. Hay | journal =J. Org. Chem. | year = 1962 | volume = 27 | issue 9 | pages = 3320–3321 | doi = 10.1021/jo01056a511] .An example is the the coupling oftrimethylsilylacetylene [OrgSynth | title = 1,4-Bis(trimethylsilyl)buta-1,3-diyne | author = Graham E. Jones, David A. Kendrick, and Andrew B. Holmes | collvol = 8 | collvolpages = 63 | year = 1993 | prep = cv8p0063]References
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