The di-copper-substituted ﾎｳ-Keggin-type silicotungstate TBA4[ﾎｳ-H2SiW10O36Cu2(ﾎｼ-1,1-N3)2] (I, TBA = tetra-n-butylammonium) could act as an efficient reusable homogeneous catalyst for the aerobic oxidative alkyne homocoupling. Various kinds of structurally diverse terminal alkynes including arom., heteroarom., aliph., double bond-contg., silylacetylene, propargylic alc., and propargylic amine derivs. could selectively be converted into the corresponding diynes in the presence of I. The catalytic activity of I was much higher than those of the mono-copper-substituted silicotungstate, monomeric copper complexes, and simple copper salts, showing that the di-copper core in I plays an important role in the present alkyne homocoupling. The reaction mechanism involving the formation of the di-copper(II)-alkynyl intermediate, reductive elimination of a diyne, and re-oxidn. of reduced copper species by O2 has been proposed. [on SciFinder(R)]
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