Hemin-catalyzed biomimetic oxidative phenol-indole [3 + 2] reactions in aqueous media was written by Fu, Yu;Yu, Qile;Zhang, Yulong;Gao, Zhonghong;Wu, Yuzhou;Zhong, Fangrui. And the article was included in Organic & Biomolecular Chemistry in 2019.Reference of 1146-43-6 This article mentions the following:
A hemin/H2O2 catalytic system for oxidative phenol-indole [3 + 2] coupling in aqueous solution was developed, enabling benign synthesis of valuable benzofuroindolines under sustainable conditions. Mechanistic studies revealed the dual role of iron porphyrin responsible for both phenol oxidation and Lewis acid activation, which differs from the well-explored chem. of hemin in carbene and nitrene insertion reactions. A preliminary experiment with cytochrome c showed that the turnover of iron porphyrin was amenable for a macromol. setting with remarkable efficiency (∼13,300 TON). In the experiment, the researchers used many compounds, for example, N-(4-Hydroxyphenyl)-4-methylbenzenesulfonamide (cas: 1146-43-6Reference of 1146-43-6).
N-(4-Hydroxyphenyl)-4-methylbenzenesulfonamide (cas: 1146-43-6) belongs to amides. Compared to amines, amides are very weak bases and do not have clearly defined acid–base properties in water. On the other hand, amides are much stronger bases than esters, aldehydes, and ketones. Amides are not in general accessible by the direct condensation of amines with carboxylic acids for two reasons: first, both components are readily deactivated by a transfer of a proton from the acid to the amine and second, the hydroxy unit on the carbonyl of the acid is a relatively poor leaving group. Nevertheless, the formation of five- and six-membered rings is often surprisingly simple provided that other factors can be brought into play to assist in the condensation.Reference of 1146-43-6
Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics