Metal and Metal Oxide Nanoparticles: A Lever for C–H Functionalization

Abstract

The past decade has seen the development of a new reactivity concept, exploiting the ubiquity of C−H bonds. The direct activation of this bond type brings forth a straightforward way for the derivatization of organic molecules. Consequently, the design of metal catalyzed C−H bond functionalization reactions has become a flourishing area in organic synthesis. Thus, this review focuses on molecular transformation of "unactivated" C(sp 3 )−H and C(sp 2 )−H bonds present in feedstock and readily available hydrocarbons into valuable chemicals by nanoparticle-leveraged C−H activation, resulting in more sustainable approaches for industrial applications. The distinctive reactivity properties of these nanoentities lead to remarkable reactivity specificities depending on the type of surface sites and the structure dynamics, directly impacting the process selectivity.

Recent developments on nano-ZnO catalyzed synthesis of bioactive heterocycles

“…In 2013, they developed a simple protocol for the efficient synthesis of 1,8-dioxooctahydroxanthene derivatives (53) via a one-pot pseudo three-component condensation between various aldehydes (5) and dimedone (16) in the presence of catalytic amount of ZnO-nanoparticles at 90 °C under solvent-free conditions [113] (Scheme 7). The optimized reaction conditions also worked satisfactorily in synthesizing a variety of N-aryl-1,8-dioxodecahydroacridine derivatives (54) in one-pot when the reaction was carried out in presence of aromatic amines (20) with excellent yield of 70-91% within just 5-25 min (Scheme 7). After completion of reaction, nano-ZnO was successfully recovered and recycled for five successive runs with little loss in the catalytic activity.…”

“…A simple, efficient one-pot, four-component condensation of aldehydes (5) (18) of the four component reaction they also synthesized a series of 2-aminohexahydroquinolines (20) under the same optimized reaction conditions. After completion of the reaction, the catalyst was recovered and reused four times without any significant loss in catalytic activity.…”

“…In recent past, among the other nano catalysts, metal oxides such as ZnO, CuO, SiO 2 , CeO 2 , Fe 3 O 4 , CaO, In 2 O 3 ZrO 2 , etc. in nano form, have drawn considerable attention as efficient, environmentally sustainable, heterogeneous catalysts and have found immense applications in various organic transformations that include C-H funtionalizaion [20], synthesis of 2-aminobenzimidazoles, Fig. 1 Some of the marketed drugs containing heterocycles 2-aminobenzothiazoles, benzoxazoles [21], tetrahydrobenzofurans [22], α-aminophosphonate [23], bis-2,3-dihydroquinazolin-4(1H)-ones [24], 1,4-substituted 1,2,3-triazoles [25], xanthenes [26], pyrano [2,3-d]pyrimidines, 4H-chromenes, and dihydropyrano [3,2-c]chromenes [27], substituted pyridines [28], quinoxalin-2-amine [29] and many more [30,31].…”

Introduction of Ag/CuO/MCM‐48 as an efficient catalyst for the one‐pot synthesis of novel pyran‐pyrrole hybrids

“…Metal‐based catalysts, heterogeneous catalysts containing metal/metal oxides, have been broadly implemented in manifold chemical reactions, for example hydrogenation, C–H functionalization, C–C coupling reactions and heterocyclic synthesis . During the past decade, bimetallic nanocatalysts have attracted the attention of many chemists.…”

Tailoring of Hetero–oligophenylene Stabilized Nanohybrid Materials: Potential Tandem Photo‐Promoted Systems for C–C and C–X Bond Formation Reactions via C‐H Activation

“…[3a-d] Development of novel photo-promoted systems which could harvest clean, cost effective and abundant solar energy to carry out CÀH functionalization reactions is one of the best approaches in this direction. [4] As a result, a variety of photo-promoted systems based on various plasmonic metals such as silver and gold have been developed [5] and efforts are being made to develop new, less expensive and efficient photo-promoted systems. Recently from our lab, we reported several photo-promoted ensembles which could efficiently harvest solar radiations for carrying out a variety of reactions.…”