Glaser coupling

<h2 id="modifications">Modifications</h2>
<h3>Eglinton reaction</h3>

<p>In the related Eglinton reaction two terminal alkynes are coupled by a copper(II) salt such as <a href="/facts/Cupric_acetate/F67RaWKA">cupric acetate</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p>

2
          
          R
          
            −
          
          
          
            ≡
          
          
          
            −
          
          H
          
            
              →
              
                
                  pyridine
                
              
              
                
                  
                    
                      Cu
                      
                        
                          (
                          OAc
                          )
                        
                        
                          2
                        
                        
                          
                        
                      
                    
                    
                  
                
              
            
          
          R
          
            −
          
          
          
            ≡
          
          
          
            −
          
          
          
            ≡
          
          
          
            −
          
          R
        
      
    
    {\displaystyle {\ce {2R-\!{\equiv }\!-H->[{\overset {}{\ce {Cu(OAc)2}}}][{\ce {pyridine}}]R-\!{\equiv }\!-\!{\equiv }\!-R}}}

<p>The oxidative coupling of alkynes has been used to synthesize a number of <a href="/facts/Natural_product/J4RsVhmP">natural products</a>. The stoichiometry is represented by this highly simplified scheme:<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>
</p>

<p>Such reactions proceed via <a href="/facts/Metal-alkyne_complex/fmpXxdfI">copper(I)-alkyne</a> complexes.
</p><p>This methodology was used in the synthesis of <a href="/facts/Cyclooctadecanonaene/DDcINCl6">cyclooctadecanonaene</a>.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Another example is the synthesis of <a href="/facts/Diphenylbutadiyne/k9vFkpIe">diphenylbutadiyne</a> from <a href="/facts/Phenylacetylene/xT34BdYq">phenylacetylene</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a>
</p>
<h3>Hay coupling</h3>
<p>The Hay coupling is variant of the Glaser coupling. It relies on the <a href="/facts/TMEDA/fC8RDdxs">TMEDA</a> complex of <a href="/facts/Copper(I)_chloride/L8RgsAhF">copper(I) chloride</a> to activate the terminal alkyne. Oxygen (air) is used in the Hay variant to oxidize catalytic amounts of Cu(I) to Cu(II) throughout the reaction, as opposed to a stoichiometric amount of Cu(II) used in the Eglington variant.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> The Hay coupling of <a href="/facts/Trimethylsilylacetylene/qV4QG62p">trimethylsilylacetylene</a> gives the butadiyne derivative.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a>
</p>
<h2 id="scope">Scope</h2>
<p>In 1882 <a href="/facts/Adolf_von_Baeyer/5wRNhT9H">Adolf von Baeyer</a> used the method to prepare 1,4-bis(2-nitrophenyl)butadiyne, en route to <a href="/facts/Indigo_dye/aqC7umcC">indigo dye</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a>
</p><p>Shortly afterwards, Baeyer reported a different route to indigo, now known as the <a href="/facts/Baeyer%25E2%2580%2593Drewson_indigo_synthesis/sw5nnRIT">Baeyer–Drewson indigo synthesis</a>.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Cadiot%25E2%2580%2593Chodkiewicz_coupling/nJGvQ6Kk">Cadiot–Chodkiewicz coupling</a> - Another alkyne coupling reaction catalysed by copper(I).</li>
<li><a href="/facts/Sonogashira_coupling/oUdV3f2g">Sonogashira coupling</a> - Pd/Cu catalysed coupling of an alkyne and an aryl or vinyl halide</li>
<li><a href="/facts/Castro%25E2%2580%2593Stephens_coupling/Y5VI2bGC">Castro–Stephens coupling</a> - A cross-coupling reaction between a <a href="/facts/Copper(I)_acetylide/SJeUHJQJ">copper(I) acetylide</a> and an aryl halide</li>
<li><a href="/facts/Fritsch%25E2%2580%2593Buttenberg%25E2%2580%2593Wiechell_rearrangement/zbR3ND43">Fritsch–Buttenberg–Wiechell rearrangement</a> - can also form diynes</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Glaser, Carl (1870). "Untersuchungen über einige Derivate der Zimmtsäure" [Studies on some derivatives of cinnamic acid]. Annalen der Chemie und Pharmacie (in German). 154 (2): 137–171. doi:10.1002/jlac.18701540202. <a href="https://zenodo.org/record/1427297" target="_blank">https://zenodo.org/record/1427297</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Glaser, C. (1869). "Beiträge zur Kenntniss des Acetenylbenzols". Berichte der Deutschen Chemischen Gesellschaft. 2 (1): 422–424. doi:10.1002/cber.186900201183. <a href="https://zenodo.org/record/1424978" target="_blank">https://zenodo.org/record/1424978</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Eglinton, G.; Galbraith, A. R. (1959). "Macrocyclic Acetglenic Compounds. Part I. cyclo-Tetradeca-1:3-diyne and Related Compounds". J. Chem. Soc.: 889. doi:10.1039/JR9590000889. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Eglinton, G.; McRae, W. Adv. Org. Chem. 1963, 4, 225. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>K. Stöckel and F. Sondheimer (1974). "[18]Annulene". Organic Syntheses. 54: 1. doi:10.15227/orgsyn.054.0001. <a href="http://www.orgsyn.org/demo.aspx?prep=cv6p0068" target="_blank">http://www.orgsyn.org/demo.aspx?prep=cv6p0068</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>I. D. Campbell and G. Eglinton (1965). "Diphenyldiacetylene". Organic Syntheses. 45: 39. doi:10.15227/orgsyn.045.0039. <a href="/wiki/Organic_Syntheses" target="_blank">/wiki/Organic_Syntheses</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Hay, Allan S. (1962). "Oxidative Coupling of Acetylenes. II". The Journal of Organic Chemistry. 27 (9): 3320–3321. doi:10.1021/jo01056a511. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Graham E. Jones, David A. Kendrick, Andrew B. Holmes (1987). "1,4-Bis(trimethylsilyl)buta-1,3-diyne". Organic Syntheses. 65: 52. doi:10.15227/orgsyn.065.0052.{{cite journal}}:  CS1 maint: multiple names: authors list (link) <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Baeyer, Adolf (1882). "Ueber die Verbindungen der Indigogruppe". Berichte der Deutschen Chemischen Gesellschaft. 15 (1): 50–56. doi:10.1002/cber.18820150116. <a href="https://zenodo.org/record/1425250" target="_blank">https://zenodo.org/record/1425250</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>Johansson Seechurn, Carin C. C.; Kitching, Matthew O.; Colacot, Thomas J.; Snieckus, Victor (21 May 2012). "Palladium-Catalyzed Cross-Coupling: A Historical Contextual Perspective to the 2010 Nobel Prize". Angewandte Chemie International Edition. 51 (21): 5062–5085. doi:10.1002/anie.201107017. PMID 22573393. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
</ol>

Glaser coupling open-in-new

Glaser coupling