Copper Acetate Aerobic Oxidative Synthesis of Pyrido[1,2-a]benzimidazoles from Aminopyridines and Phenylboronic Acids

Abstract

Pyrido[1,2-a]benzimidazoles, which show interesting and potentially useful biological activities, have drawn extensive attention from chemists. A straightforward copper acetate-oxidative one-pot synthesis of these compounds from 2-aminopyridines and phenylboronic acids through C–N bond formation and C–H bond activation was developed as a simple and convenient method.

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

“…On the other hand, such heterocyclic moieties present in bioactive compounds, or their synthetic intermediates may eventually play the role of a directing group, thus providing an opportunity for convenient and straightforward transformations based on metal-mediated C-H activation [314]. Many methods potentially useful for the synthesis or modification of bioactive compounds based on copper-promoted activation of C-H bonds in (hetero)arenes have been reported in the last years, including methods for the formation of C-C [304][305][306][307][308][309][310][311][312], C-X [315][316][317][318][319], C-N [305,[320][321][322][323][324], C-O [325][326][327][328][329][330], and C-S [324,331,332] bonds. Some of these methods are highlighted herein.…”

“…The copper-mediated C-H activation for C-N bond formation is useful in the synthesis of N-containing heterocycles commonly encountered in bioactive compounds, such as pyrido[1,2a]benzimidazoles [320], 1H-indazoles and 1H-pyrazoles [322], among others. For instance, a method for the modification of 6-anilinopurine nucleosides through copper-mediated C(sp 2 )-H activation and intramolecular amination was reported to synthesize modified nucleosides, which are useful scaffolds in the design of antiviral drugs.…”

Simple inorganic base promoted polycyclic construction using mucohalic acid as a C3 synthon: synthesis and AIE probe application of benzo[4,5]imidazo[1,2-a]pyridines

“…Now, many methods have been developed for the preparation of benzo[4,5]imidazo[1,2- a ]-pyridines. Generally, intramolecular or intermolecular tandem C–N coupling/annulation reactions catalyzed by the transition-metal Pd 12 or Cu 13 are the main methods. The oxidative C–H cyclic amination reaction promoted by hypervalent iodine( iii ) or other strong oxidants has provided an alternative synthetic strategy.…”