Recent Progress in Iodine‐Catalysed C−O/C−N Bond Formation of 1,3‐Oxazoles: A Comprehensive Review

Abstract

Over the last few decades, iodine has been a stellar catalyst for numerous organic transformations such as CÀ H activation, hetero-annulation and coupling reactions. In heterocyclic chemistry, iodine is primarily an economical and eco-friendly catalyst that fascinates the construction of CÀ O/CÀ N bonds via oxidative, radical, and electrophilic pathways. Several novel Iodine-catalyzed methodologies have been reported, presenting advances in heterocyclic synthesis with regioselectivity, wide substrate scope and excellent yields. Furthermore, feasible protocols implemented to get oxazole annulation in literature have an enormous impact on new synthetic applications. Therefore, this literature analysis comprises advancements in the field of iodine-mediated 1,3-oxazole synthesis since 1998. For the ease of the readers, the reported methodologies have been categorised based on iodine functioning in reactions with insight into the reaction mechanisms and highlights.

Advances in the synthetic strategies of benzoxazoles using 2-aminophenol as a precursor: an up-to-date review

“…They are one of the most favorable moieties in terms of synthetic aspects as they have a vast substrate scope and chemoselectivity. 41 They are generally prepared by the condensation of 2-aminophenol with acids and their derivatives, 42 oxidative coupling, 43 or other different methodologies. 44 In the past few decades, a generous amount of research has been done on the synthesis and biological activity of benzoxazole derivatives.…”

Tf2O-Mediated Direct Synthesis of 4-Sulfenylated Oxazoles from β-Keto Sulfoxides and Nitriles

“…On the other hand, the Pummerer reaction generally involved the addition of a nucleophile to the thionium ion, and the overall process represented a powerful tool for the construction of heterocyclic compounds . Inspired by recent reports utilizing nitriles as precursors of an oxazole moiety − and our continuous interest in the transformation of thiophenols, we herein developed a Tf 2 O-catalyzed direct and general synthesis of 4-sulfenylated oxazoles from β-keto sulfoxides and nitriles via stabilized α-carbonyl cation intermediate (Scheme e).…”