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A synthetic approach to dibenzofurotropone derivatives 1 has been developed through the palladium-catalyzed cyclization of (2-bromoaryl)(3-arylfuran-2-yl)methanones 2 via the activation of arylic C–H bonds. Compounds 2 were easily prepared from the palladium-promoted acyl migration and cyclization of (Z)-pent-2-en-4-yn-1-yl acetates 3 in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), followed by oxidative decarbonylation and oxidation with O2. Ten new tropone compounds are reported and these compounds show absorption in the UV-vis region and emission in the visible region.

The reaction of (Z)-5-phenyl-1,3-di-p-tolylpent-2-en-4-yn-1-ol (1) with trimethylsilyl chloride in dichloromethane at ambient temperature gave a dimeric ether compound 2 in 30% yield. Subsequently, heating 2 in toluene under refluxing temperature rendered the title compound quantitatively. The structure of this tricyclic-fused compound was characterized using NMR, mass spectroscopy, and X-ray crystallography. This unique linear tricyclic fused furan framework is reported for the first time.

A series of 3-hydroxy-fluorene-2-carboxylate compounds were prepared from Michael addition of acetoacetate to 2-benzylideneindan-l-one followed by Robinson annulation and aromatization. In this reaction, we were able to isolate two Robinson annulation products and characterize them. This sequential reaction could proceed without the isolation of intermediates to give the desired products directly in reasonable yields.

A Hantzsch-type strategy for the synthesis of 2,3,5,6-tetrasubstituted pyridines via an oxidative coupling of β-enamine carbonyl compounds with rongalite was developed. This method employs rongalite as a C1 unit for the assembly of a pyridine ring at C-4 position, offering a facile method for the preparation of substituted pyridine derivatives with a broad functional group tolerance. In particular, this method allows us to prepare terpyridine derivatives, which are important ligands or structural fragments for catalysts and 3D metal–organic frameworks.