Phenyliodonium Diacetate Mediated One-Pot Synthesis of Benzimidazoles and Quinazolinones from Benzylamines

Abstract

An efficient metal‐free, one‐pot protocol was developed for the synthesis of variety benzimidazole and quinazolinones in moderate to good yields. This protocol proceeds via oxidation of benzylamine, resulting in in‐situ aldehyde formation followed by the condensation with o‐phenylenediamine and o‐aminobenzamide to the corresponding N‐heterocycles using a mild oxidant phenyliodonium diacetate (PIDA). We describe a new strategy for C–N bond cleavage and formation in the absence of transition‐metal reagent or ligand under environmentally benign reaction conditions.

Oxidative Olefination of Benzylamine with an Active Methylene Compound Mediated by Hypervalent Iodine (III)

“…As the reaction time increased to 10 min the formation of imine 9 was observed ( δ = 3.85). [14b] Subsequently, the 1 H NMR spectrum after 20 min clearly shows a broad singlet at δ = 4.29 corresponding to –NH 2 of the addition product 10 as shown in Figure . It is noteworthy that the intensity of peak at δ = 3.92 decreases constantly.…”

Recent Advances in the Synthesis of Benzimidazole Derivatives from the Oxidative Coupling of Primary Amines

“…13 In 2016, Kamal and co-workers developed a metal-free one-pot protocol for the synthesis of 2-substituted benzimidazole derivatives which proceeds through the oxidation of benzylic amines using an inexpensive mild oxidant, (diacetoxyiodo)benzene (PIDA). 14 By heating 1.2 equivalents of both (diacetoxyiodo)benzene and benzylic amine together with 1 equivalent of the o-phenylenediamine at 80 °C for 4 hours in a mixture of DMSO and H 2 O (1:1 ratio) as the solvent, 2-substituted benzimidazoles were isolated in high yields ranging from 77 to 92%. The reaction mechanism involves the oxidative addition of (diacetoxyiodo)benzene with benzylamine substrate, followed by the formation of a benzaldimine inter-…”

“…Since 2012, new and more environmentally friendly strategies for the catalyst-free oxidative coupling of primary amines for the construction of the benzimidazole framework have been identified. [11][12][13][14][15] At the same time, significant progress has resulted from the discovery of selective catalytic systems that avoid using stoichiometric or excess amounts of specific oxidants, which adversely affect the economics as well as the ecofriendly nature of the reaction.…”

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

“…Benzothiazoles and benzimidazoles are both significant classes of heterocyclic compounds with a broad range of applications in medicine, agrochemicals, natural products, and functional materials for the pharmaceutical industry [3,5] . Particularly, benzothiazoles and benzimidazoles are five‐membered heterocyclic compounds having biological and therapeutic properties including antiulcer, antibacterial, antifungal, antihypertensive, [6] anticancer, [7,9] antiparasitic, [10,11] enzyme inhibition, [12] and anticonvulsant capabilities [13] . Benzothiazoles are useful as building blocks in the pharmaceutical industry for anticancer, [14] anti‐diabetic, [15] and anti‐Alzheimer's activities [16] .…”