An efficient, highly versatile and simple protocol was developed for the synthesis of xanthones and thio-xanthones via an intermolecular catalytic coupling of 2-substituted benzaldehydes and various phenols under ligand free conditions by using nano-CuFe 2 O 4 as a catalyst and K 3 PO 4 as a base in DMF sol-vent at 80 0 C in air. The reaction proceeds smoothly with a wide range of starting materials and furthermore, the explored copper ferrite catalyst is air-stable, inexpensive, magnetically separated, recyclable and reusable up to four cycles.

Highly efficient and facile methodology has been developed for the ring opening reaction of spiro‐epoxy oxindoles with electron rich arenes in presence of molecular iodine. These reactions can be carried out easily under mild reaction conditions to afford functionalized 2‐indolinone derivatives in excellent yields.

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3,3′-Di-indolylmethane derivatives are important biologically active compounds possessing anti-cancer properties. Hence, development of synthetic routes to these are of great interest to organic chemists. In the present communication we report a high-yield method using mild reaction conditions and short reaction times for the synthesis of 3,3′-di-indolylmethane derivatives. The method involved reactions of indole and substituted indoles with C,N-disubstituted nitrones in the presence of acid catalysts, with the utilisation of microwave irradiation techniques. Reactions of indole, 2-methyl indole and 2-phenyl indole were performed with ten different C,N-diaryl- and C-aryl-N-methyl- nitrones in dichloromethane solution in the absence and presence of acid catalysts, viz. ytterbium triflate, p-toluene sulphonic acid and Montmorillonite clay K-10. Reaction times varied between 2 to 18 minutes. In general, yields of the catalysed reactions were above 75%. The products were characterised spectroscopically, including two-dimensional NMR studies. The microwave irradiation technique enhanced reaction rates by a significant amount. Ytterbium triflate proved to be the best catalyst, giving clean reactions, without formation of by-products, in high yields. The structure and conformation of 3,3′-di-indolyl-phenylmethane were computed. GRAPHICAL ABSTRACT: We report a high-yield method using mild reaction conditions and short reaction times for the synthesis of 3,3′-di-indolylmethane derivatives, involving reactions of indole and substituted indoles with C, N-disubstituted nitrones in the presence of acid catalysts using microwave irradiation.

A broad spectrum of substituted phenols and thiophenol (IVb) can be used in the title reaction with o‐substituted benzaldehydes.