Cobalt Used as a Novel and Reusable Catalyst: A New and One-Pot Synthesis of Isatin-Derived N,S-Acetals Using Substituted Isatins and Thiols

Abstract

The synthesis of isatin-derived N,S-acetals using cobalt as a recyclable heterogeneous catalyst in batch and continuous flow is reported for the first time. The present protocol produced high yields, which can be observed from the reaction between ketimines and thiols. Such reactions can also be applied to a gram-scale. In addition, the catalyst is recyclable, economically-viable, and nontoxic as well as easy to prepare. The remarkable features of this new methodology are high conversion and cleaner reaction profiles.

Highly Efficient Zn(L‐Pro)2 Catalyst for the Synthesis of 2‐Phenyl Benzimidazoles and 2‐Phenyl Benzothiazoles via Aerobic Oxygenation

“…Due to the wide variety of applications, a mild and environmentally friendly one‐pot synthesis of 2‐substituted benzothiazoles and benzimidazoles is required. Recently, our group reported the synthesis of dihydroquinazolin‐4(1H)‐ones, [45] pyrazole synthesis, [46] thio‐Michael addition reaction, [47] N, S‐acetals, [48] and Kabachnik‐Fields [49] using hybrid catalysts that are recyclable and eco‐friendly. In continuation of our reports, we present a simple, stable, cheap and one‐pot approach for the synthesis of 2‐substituted benzothiazoles and benzimidazoles utilizing Zn( L ‐Pro) 2 as an efficient and appropriate catalyst in ethanol at room temperature for 4–30 min as shown in Scheme 1.…”