Herein, we present the α-selective Giese reaction between pyranosyl/furanosyl bromides and dehydroalanine analogues, which provides access to a library of highly valuable α-C-glycosyl alanines. The key C-glycosyl radical is generated through photocatalysis by either the new generation copper(I) complex [(DPEPhos)(bcp)Cu]PF₆ or [Ru(bpy)₃](BF₄)₂. The reactions proceed smoothly, affording the desired α-C-glycosyl alanines in up to 99% yield when diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate [Hantzsch ester (HE)] is used as an additive. N,N-Diisopropylethylamine (DIPEA) has been selected as a reductant in both protocols. A mechanistic study by means of transient absorption spectroscopy unveils a halogen-atom transfer (XAT) process in C-glycosyl radical formation.

Indole-decorated glycine derivatives are prepared through an environmentally benign cross-dehydrogenative coupling between N-aryl glycine analogues and indoles (yield of ≤81%). Merging heterogeneous organocatalysis and photocatalysis, C-H functionalization has been achieved by selective C-2 oxidation of N-aryl glycines to afford the electrophilic imine followed by Friedel-Crafts alkylation with indole. The sustainability of the process has been taken into account in the reaction design through the implementation of a metal-free recyclable heterogeneous photocatalyst and a green reaction medium. Scale-up of the benchmark reaction (gram scale, yield of 69%) and recycling experiments (over seven runs without a loss of efficiency) have been performed to prove the robustness of the protocol. Finally, mechanistic studies were conducted employing electron paramagnetic resonance spectroscopy to unveil the roles of the photocatalyst and oxygen in the formation of odd-electron species.

Water remediation with biomass derivatives has attracted attention for its sustainable impact on the earth. Chemical procedures for new adsorbent and active biomaterials must be implemented to remove organic pollutants more efficiently. Herein, we obtained a sustainable, environmentally, and low‐cost biochar from bamboo Dendrocalamus giganteus (BBC, B400) by thermal treatment at 400 °C without physical and chemical pre‐ and post‐treatments. By electron paramagnetic resonance (EPR), we determined the quantification and ageing of persistent free radicals (PFRs, 10¹⁶–10¹⁹ spins/g) present in BBC over time. We demonstrated the removal efficiency (R %) of B400 against methylene blue (MB) aqueous solutions without and with different concentrations of H₂O₂ using a novel B400‐packed column‐flow system. Results demonstrated that the MB removal efficiency via physical adsorption and chemical degradation strongly depended on the concentration of carbon‐centred PFRs and their stability over time. Collectively, a reduced concentration of PFRs and their full passivation by proper treatments led to a remarkable loss of MB removal efficiency, thus evidencing that a PFR‐mediated radical degradation mechanism was predominant in the MB removal process. Experiments with t‐butanol alcohol (TBA) on aged B400 as a radical scavenger of the hydroxyl radical (⋅OH) have evidenced the critical role of PFRs in generating reactive oxygens species (ROSs) in solution, which catalysed the oxidative degradation of MB. Kinetics studies carried out on removal efficiency data vs time by all experiments established that the MB removal profiles of fresh B400 were best described by a pseudo‐second order (PSO) kinetic model, thus suggesting that chemical mechanisms such as electron transfer reactions and PFRs‐mediated degradation were the main contributors to MB removal. On the contrary, MB removal profiles of aged B400 with reduced or insignificant content of PFRs best fitted kinetic models, which describe physical absorption and diffusional nor radical processes, which led to a lower removal efficiency. These findings will be helpful for potential pilot and large‐scale experiments to remove a wide range of contaminants in water.

Within the realm of organic synthesis, photocatalysis has blossomed since the beginning of the last decade. A plethora of classical reactivities, such as selective oxidation of alcohol and amines, redox radical formation of reactive species in situ, and indirect activation of an organic substrate for cycloaddition by EnT, have been revised in a milder and more sustainable fashion via photocatalysis. However, even though the spark of creativity leads scientists to explore new reactions and reactivities, the urgency of replacing the toxic and critical metals that are involved as catalysts has encouraged chemists to find alternatives in the branch of science called organocatalysis. Unfortunately, replacing metal catalysts with organic analogues can be too expensive sometimes; however, this drawback can be solved by the reutilization of the catalyst if it is heterogeneous. The aim of this review is to present the recent works in the field of heterogeneous photocatalysis, applied to organic synthesis, enabled by continuous flow. In detail, among the heterogeneous catalysts, g-CN, polymeric photoactive materials, and supported molecular catalysts have been discussed within their specific sections, rather than focusing on the types of reactions.