Glaser Coupling
Hay Coupling

The Glaser Coupling is a synthesis of symmetric or cyclic bisacetylenes via a coupling reaction of terminal alkynes. Mechanistically, the reaction is similar to the Eglinton Reaction; the difference being the use of catalytic copper(I), which is reoxidized in the catalytic cycle by oxygen in the reaction medium.

The related Hay Coupling has several advantages as compared with the Glaser Coupling. The copper-TMEDA complex used is soluble in a wider range of solvents, so that the reaction is more versatile.

A recent modification enables the production of a range of unsymmetrical 1,3-diynes:

L. Su, J. Dong, L. Liu, M. Sun, R. Qiu, Y. Zhou, S.-F. Yin, J. Am. Chem. Soc., 2016, 138, 12348-12351.

A valuable alternative is the Cadiot-Chodkiewicz Coupling which also allows the preparation of asymmetric bisacetylenes.

Recent Literature

Efficient Copper(II) Acetate Catalyzed Homo- and Heterocoupling of Terminal Alkynes at Ambient Conditions
K. Balaraman, V. Kesavan, Synthesis, 2010, 3461-3466.

Phase Separation As a Strategy Toward Controlling Dilution Effects in Macrocyclic Glaser-Hay Couplings
A.-C. Bédard, S. K. Collins, J. Am. Chem. Soc., 2011, 133, 19976-19981.

lycosyl Triazole Ligand for Temperature-Dependent Competitive Reactions of Cu-Catalyzed Sonogashira Coupling and Glaser Coupling
N. Mishra, S. K. Singh, A. S. Singh, A. K Agrahari, V. K. Tiwari, J. Org. Chem., 2021, 86, 17890-17895.

Recyclable Polystyrene-Supported Copper Catalysts for the Aerobic Oxidative Homocoupling of Terminal Alkynes
S. Yan, S. Pan, T. Osako, Y. Uozumi, Synlett, 2016, 27, 1232-1236.

One-Pot Formation and Derivatization of Di- and Triynes Based on the Fritsch-Buttenberg-Wiechell Rearrangement
T. Luu, Y. Morisaki, N. Cunningham, R. R. Tykwinski, J. Org. Chem., 2007, 72, 9622-9629.

End-Cap Stabilized Oligoynes: Model Compounds for the Linear sp Carbon Allotrope Carbyne
T. Gibtner, F. Hampel, J.-P.Gisselbrecht, A. Hirsch, Chem. Eur. J., 2002, 68, 408-432.