Recent Advances for Synthesis of Oxazole Heterocycles via C‐H/C‐N Bond Functionalization of Benzylamines

Abstract

The five membered heteroaromatic oxazole motifs and their scaffolds exhibit significant pharmaceutical and biological applications. Remarkably, the high efficiency in the assembly of structurally diverse oxazole scaffolds via C(sp 3 )-H functionalization of benzylamines have attracted synthetic organic chemists.In this review, the different synthetic strategies from benzylamines as a new emerging substrate via CÀ H/CÀ N bond functionalization towards oxazole synthesis are discussed in detail. Moreover, it highlights substrate scope along with the reaction mechanism involved during the reaction.

One-Pot N-α-C(sp3)–H Bond Functionalisation Cascade for the Synthesis of Polysubstituted Imidazoles

“…From the above experimental results and relevant literature, 59,70,74,[80][81][82][83][84] a possible mechanism for polysubstituted imidazole formation is summarised in Scheme 3. At first, oxidative addition of amine 1a in the presence of iron catalyst generates benzylimine (4) intermediate and FeCl 3 catalyst.…”

“…68 As well, the designing of different N-heterocycles with amines as a building block as an alternative route in organic transformations has had increased attention in recent years. 59,[69][70][71][72][73][74] Due to its utility of complex molecule construction in total synthesis, organic transformation via benzylic -C(sp 3 )-N bond functionalisation has emerged as a robust and fascinating tool for lead discovery through rapid preclinical research. 75 Also, organic transformations with aerobic/molec-ular oxygen as oxidant have become a delightful platform to generate innovative chemistry.…”

Iodine-Promoted Oxidative Cyclization of Methyl Azaarenes and α-Amino Ketones for One-Pot Synthesis of 2-Azaaryl-5-aryl Oxazoles

“…Classic methods for the synthesis of oxazoles include the Van Leusen synthesis, the Bredereck synthesis, and the Robinson synthesis . Recently, some practical strategies were developed for the synthesis of oxazoles, such as palladium/copper-catalyzed transformations, aerobic oxidative cyclization of enaminones, and visible-light photoredox-catalyzed cyclization (Scheme a) . Furthermore, iodine plays an important role in the synthesis of oxazole skeletons.…”