Heterogeneous catalytic approaches in C–H activation reactions

Abstract

This review summarizes the development of user-friendly, recyclable and easily separable heterogeneous catalysts for C–H activation during the last decade until December 2015.

Base‐Promoted Heterogeneous Reusable Copper Fluorapatite (CuFAP) Catalyzed Facile Synthesis of 1,2‐Diarylethanols via C(sp3)‐H Functionalization of Nitrotoluene

“…Owing to the potential utility of 1,2‐diarylethanol in the pharmaceutical, and organic synthesis as structural backbone, cost‐effective, sustainable, environmentally friendly synthesis of its structural units under mild reaction conditions by avoiding the use of costly ligands, precious metal catalysts, additives, prefunctionalized substrates, and toxic, hazardous reagents is still challenging and an active research area. The C−H functionalization has been continuously increasing interest among chemist/biologist, which provides a straightforward approach for the synthesis of complex scaffolds using cheap and readily available starting materials under milder reaction conditions by avoiding the use of prefunctionalized substrates and thus provides an environmentally benign and economically attractive approach. In this context, to the best of our knowledge, the synthesis of 1,2‐diarylethanol is not yet reported and/ or developed via sp 3 C−H functionalization using heterogeneous, recyclable, and eco‐friendly catalysts.…”

Definition of green synthetic tools based on safer reaction media, heterogeneous catalysis, and flow technology

“…Among the different approaches for the definition of catalytic methodologies, the use of insoluble catalysts that operate in a heterogeneous fashion is highly intriguing and also challenging [48][49][50][51][52][53]. Significant advantages may derive from the adoption of this strategy with the reduction of waste produced, provided that an easy recovery and reuse of the catalyst is achieved.…”

Continuous‐Flow Palladium‐Catalyzed Synthesis of Cyclohexanones from Phenols using Sodium Formate as a Safe Hydrogen Source

“…To define milder and more energy efficient one-step processes, the use of selectiveh omogeneous and heterogeneous catalysts hasb een investigated in the liquid phase and has resulted in many successful examples mainly based on single or mixed Pd, [3] Pt, [4] Ru, [5] Rh, [6] andN i [7] catalysts on different supports. [13] Following our interest in developing sustainable protocols based on the use of safe media, heterogeneous catalysis, [16] and the applicationo fflow technology, [17] we report herein our approacht owardst he definition of ac ontinuous-flow protocol by using commerciallya vailableP d/C for the catalyzed selective transfer hydrogenation of phenol to cyclohexanone in water by using sodium formate as ah ydrogen source.In ap reliminaryo ptimization study in batch, we investigated the best reaction conditions suitable for transfer to af low pro-Scheme1.Reactionsteps in at ypical phenol hydrogenation process. The chemical strategy to reduce phenol selectively is based on controlling the desorption of cyclohexanone from the catalyst surface beforef urther hydrogenation leads to cyclohexanol.…”

“…[8] Considering the commonly proposed mechanism for the hydrogenation of phenol on supported palladiumc atalysts, reductiono ccurs on the phenolate ion adsorbed on the support in proximity of the metal particles, which are responsible for the activation of hydrogen. [13] Following our interest in developing sustainable protocols based on the use of safe media, heterogeneous catalysis, [16] and the applicationo fflow technology, [17] we report herein our approacht owardst he definition of ac ontinuous-flow protocol by using commerciallya vailableP d/C for the catalyzed selective transfer hydrogenation of phenol to cyclohexanone in water by using sodium formate as ah ydrogen source. [9] The use of formic acid derivativesa sahydrogen sourcei n combination with ap alladium catalyst is ap romising, safe, and sustainable alternative to classic methods.…”

“…The chemical strategy to reduce phenol selectively is based on controlling the desorption of cyclohexanone from the catalyst surface beforef urther hydrogenation leads to cyclohexanol. [13] Following our interest in developing sustainable protocols based on the use of safe media, heterogeneous catalysis, [16] and the applicationo fflow technology, [17] we report herein our approacht owardst he definition of ac ontinuous-flow protocol by using commerciallya vailableP d/C for the catalyzed selective transfer hydrogenation of phenol to cyclohexanone in water by using sodium formate as ah ydrogen source. Formates are stable and nontoxic, and they can be obtainedf rom the processing of biomass.…”