A one‐pot, three‐component synthesis of 3‐arylsulfonylated thioflavones has been developed. The reactions were carried out without using any catalysts or additives. The desired products were obtained through intramolecular radical cyclization. This process provides an alternative route for the synthesis of thioflavone derivatives, which have been found in various bioactive compounds.

We developed a novel method for direct C3 carbamoylation of 2H-indazoles using oxamic acids as carbamoyl radical sources. In the presence of ammonium persulfate, carbamoyl radicals were generated from oxamic acids, then used for further reactions with 2H-indazoles to afford the desired products. The reaction proceeds under metal-and catalyst-free conditions. This simple process allows for the efficient synthesis of C3 carbamoylated 2H-indazoles, which are important scaffolds in organic synthesis.Indazoles, nitrogen-containing heterocycles, are important scaffolds in organic synthesis and have been found in many biologically active compounds. [1] 2H-Indazoles are of particular interest, as they have recently been confirmed to exhibit many significant biological activities, including antitumor and antiinflammatory properties (Figure 1). [2] While there have been no shortage of attempts to synthesize indazole scaffolds, many studies on the synthesis of 2H-indazoles have some limitations due to their thermodynamically less favored properties. [3] Direct functionalization of 2H-indazoles at the C3 position has been particularly challenging because of low reactivity at that site. [4] Nevertheless, direct C3 functionalization of 2H-indazoles remains a target worth pursuing, as it would provide an efficient route for the synthesis of various 2H-indazole derivatives. Very recently, some remarkable breakthroughs concerning C3 functionalization of 2H-indazoles through acylation, [4c,5] arylation, [4d,6] alkylation, [5b] alkenylation, [7] trifluoromethylation, [8] selenylation, [9] and phosphorylation, [10] have been achieved using pioneering approaches, including visible-light-mediated reactions (Scheme 1, I). [11,12] While a number of different approaches to the synthesis of C3 functionalization of 2Hindazoles have been developed, successful direct C3 carbamoylation of 2H-indazoles is comparatively rarely reported (Scheme 1, II). Carbamoylation is one of the most efficient methods to introduce an amide motif into a molecule. [13] Carbamoylation reactions provide rapid CÀ H carbamoylated heterocycles that would typically otherwise be synthesized from conventional amide-coupling reactions, which require the use of prefunctionalized starting compounds and wasteful coupling reagents. [14] Amide motifs have been found in many natural products, pharmaceuticals, and specialized materials, and amide-functionalized N-heterocycles are important scaffolds in medicinal chemistry. 2H-indazoles containing amide motifs also demonstrate biological properties (Figure 1).With this in mind, the development of a direct and efficient method for the carbamoylation of 2H-indazoles that relies on simple processes would be significant. We envisioned that direct C3 carbamoylation of 2H-indazoles might be possible [a] V.

A one‐pot, three‐component synthesis of 3‐(arylsulfonyl)benzothiophenes was developed. The reaction did not require any catalysts or additives. The desired products were obtained via an intramolecular radical cyclization. Acetic acid was employed as the solvent and a quencher for side reactions involving methyl radicals. Moreover, inexpensive potassium metabisulfite was used as a sulfur dioxide surrogate. This process provides more opportunities for synthesizing benzothiophene derivatives, which are found in many bioactive compounds.