Oxidative coupling of acetylenes

The synthesis can be conducted both in solution and without solvents. The reaction in solvent (e.g., methanol, ethanol, dioxane, dimethylformamide) is recommended for volatile 1,3-diynes and amines in this case the pyrroles are purer and the yield is higher. With disubstituted diacetylenes, ammonia and primary alkyl- and arylamines produce 1,2,3-trisubstituted pyrroles under the same conditions (65CB98 71MI1). Since disubstituted diacetylenes are readily obtained by oxidative coupling of acetylenes (98MI2), this reaction provides a preparative route to a wide range of pyrroles. 

Oxidative Couplings of Acetylenic Compounds - General Introduction... 

Eastmond, R. Walton, D. R. M. 1968 The protection of terminal ethynyl groups in the oxidative couplings of acetylenes. Chem. Commun. 204—205. 

The oxidative coupling of acetylenes, reported originally by Glaser and subsequently modified by others, has played a major role in the development of polyacetylene chemistry. The reaction has been reviewed comprehensively, and these reviews should be consulted for details and lists of earlier references -... 

Scheme 7.2 The active site for the oxidative coupling of acetylene to furan over UO. The unit bulk structure of P-UO contains five U atoms (three are sixfold coordinated) only one is represented in the scheme for simplicity. U atoms can accommodate up to eight hgands and the adsorption of two acetylene molecules can occur on a single sixfold coordinated U atom. Oxidative coupling proceeds with the following reaction stoichiometry 2C2H2-rU03 C H O-rUO. The square indicates an O vacancy. The out-of-plane oxygen (represented by O) is incorporated into the C. intermediate to form furan...

Oxidative coupling of acetylenes /-Butylamine. Cupric acetate, anhydrous. Cuprous chloride. 

Intramolecular oxidative coupling of acetylenes (1, 159 4, 105). Two recent syntheses of the first known bicychc annulenes (1) analogous to naphthalene involved this reaction in two steps. These substances are relatively... 

Oxidative coupling of acetylenic compounds proceeds more eflBciently in the solid state than in water. In this procedure, powedered cuprous aryl acetylide and CUCIJ.2H2O was kept for 3 hr to give the coupled product in 40-75% yield (Scheme 35), compared to 10-30% in water. 

Cupric acetate pyridine Macrocyclic polyacetylenes Oxidative coupling of acetylene derivatives s. lA, 770 (CHsCOO)2Cu CsHsN... 

The cyclization of thienyl-substituted diacetylenes with hydrogen sulfide or sodium sulfide is also a very successful method for the synthesis of oligothiophenes. The key point here is the synthesis of the precursor diynes. Symmetrical diacetylenes can be obtained by the oxidative coupling of acetylenes with copper(I) or copper(II) salts ( Glaser, Hay, or Eglington coupling ). The synthesis of unsymmetric diynes proceeds best via the Cadiot-Chodkiewicz procedure in which an acetylene is reacted with an acetylic halide in the presence of copper(I) salts [117]. Therefore, thienyl-substituted acetylenes and bromoacetylenes are important starting materials. 

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