An iodine/DMSO system is introduced as an excellent catalyst in three‐component coupling reactions of tetrahydrobenzo[b]pyran synthesis. The reaction proceeds quickly under very mild reaction conditions.

Thiazole, a five-membered heterocyclic compound constitutes the skeleton of various commercially marketed drug candidates and the heart-core in a diverse range of entities of biological and medicinal interest. It is a versatile and essential component of natural products and medicinally significant heterocyclic compounds. The chemistry of thiazoles was widely developed in terms of anti-microbial, anti-cancer, anti-tubercular, anti-oxidant, anti-inflammatory, and other therapeutically active agents after the pioneering work of Hofmann and Hantzsch, Bogert and coworkers in 1887. Besides these, thiazole heterocycles are also useful as the constituents of several dyes and photographic materials. The present review encompasses and highlights the recent progress in the development of thiazole based heterocyclic compounds for various applications focusing it a scaffold of biological and medicinal interest. Graphical Abstract

Molecular iodine contributes significantly to organic transformations in synthetic organic chemistry. It works effectively due to its mild Lewis acidic character, ability as an oxidizing agent, good moisture stability, and easy availability.

An efficient zinc oxide nanoparticle catalyzed one‐pot, four‐component synthesis of 6‐amino‐3‐methyl‐5‐cyano‐4‐aryl‐1,4‐dihydropyrano[2,3‐c]pyrazoles from aromatic aldehyde, malononitrile, ethyl acetoacetate, and hydrazine hydrate in aqueous medium is described. Since water was employed as the reaction medium, it serves as a green route for the synthesis of pyrano[2,3‐c]pyrazoles. The advantages associated with the present protocol include nonchromatographic purification technique, use of recyclable heterogeneous nano‐ZnO catalyst in aqueous medium, and short reaction time. It combines successfully the synergistic effect of green chemistry with nanocatalysis.

One-pot, three-component condensation of benzil/benzoin, substituted aromatic aldehydes, and ammonium acetate in an ethanol–water (1:1, v/v) solvent system using sulfated tin oxide catalyst under reflux condition afforded corresponding 2,4,5-triaryl-1H-imidazoles in excellent yield. The remarkable advantages offered by this method include green and reusable catalyst, mild reaction conditions, fast reaction rate, and excellent yield of products. This novel methodology maintains atom economy and an environmentally friendly approach.