In this study, we report the development of an environmentally friendly artificial Vitreoscilla hemoglobin (VHb) for the synthesis of 3-amino-[1,2,4]-triazole and [4,3-a]pyridine. We employed a strategy that combines porphyrin substitution with axial ligand mutations to create a highly active VHb oxidase containing cobalt protoporphyrin IX (Co(ppIX)), while simultaneously introducing double mutations (H85Y, P54C). This artificial enzyme catalyzes the cyclization desulfurization reaction of the corresponding 2-hydrazinopyridine and isothiocyanate in PBS containing 10% DMSO (v/v) under aerobic conditions at room temperature. This method addresses the limitations of catalytic activity observed in natural hemoglobin and provides a novel pathway for the green synthesis of nitrogen-containing heterocycles. Furthermore, the porphyrin ligand substitution strategy broadens the application scope of artificial metalloenzymes in non-natural reactions.
The design and construction of efficient, low-cost, eco-friendly noble-metal-free metal–organic framework (MOF) catalysts for CO2 conversion under mild conditions are appealing for green and sustainable chemistry but remain extremely challenging. Herein, two new two-dimensional (2D) FeII-MOFs (1 and 2) were successfully synthesized. MOF 1 could be used as a heterogeneous catalyst for achieving three diverse CO2 conversions: (1) carboxylation reaction of terminal alkynes with CO2; (2) cycloaddition reaction of epoxides with CO2; and (3) carboxylative cyclization of propargylic amines with CO2. In these three diverse conversions, MOF 1 not only exhibited excellent catalytic activity and substrate tolerance and exceptionally high yield but also showed high recyclability and repeatability, exhibiting excellent catalytic activity after ten cycles. Furthermore, the mechanisms of the three reaction types were discussed in detail. This work provides a strategy for the conversion of CO2 into a variety of high value-added chemicals.
A unique core–shell structure electrocatalyst was prepared for electrocatalytic nitrate reduction (ECNO3R) into ammonia. CuCo2O4 spinel oxide nanosheets were grown on carbon cloth (CC), and a CoFe layered double hydroxide (CoFe-LDH) honeycomb was subsequently electroplated on each CuCo2O4 nanosheet. Compared with CoFe-LDH directly grown on CC, this core–shell structure has a much larger electrochemically active surface area with more catalytic sites and also provides better contact between the catalytic sites and the nitrate substrates. This therefore enhanced the effective conversion of a wide concentration range of nitrate into ammonia. Meanwhile, the nitrate removal rate, ammonia selectivity and faradaic efficiency (FE) are all larger than 90% at a nitrate concentration lower than 500 mg L−1. After 14 times repeated stability tests, the FE retained 86%–91% of the initial value, and the ammonia yield did not decline significantly. The isotope tracing and blank comparison experiments verified that the ECNO3R was not contaminated by any external nitrogen sources. Both density functional theory and X-ray photoelectron spectroscopy confirmed the synergistic catalytic effect between CuCo2O4 and CoFe-LDH. Moreover, active hydrogen (*H) was not involved in the ECNO3R. This work provides an effective and green way to transform nitrate pollutants into valuable ammonia.
The atom transfer radical addition (ATRA) of alkyl halides enables efficient simultaneous C–C and C–halogen bond formation in a single step. However, the development of mild, cost-effective ATRA protocols for the reaction of bicyclic alkenes with functionalized haloalkanes remains a significant challenge and underexplored. Herein, we report visible-light-mediated ATRA haloalkylation of bicyclic alkenes using functionalized haloalkanes. This catalytic system operates under mild and peroxide-free conditions, enabling the construction of haloalkylated bicyclic frameworks in a complete atom-economy across diverse substrates with generally good stereoselectivities. Scalability studies and downstream derivatizations of the products underscore the synthetic utility of the present haloalkylation protocol. Additionally, mechanistic studies including in-depth DFT calculations, have clarified the reaction pathway and origin of stereoselectivity.
The development of sustainable methods for peptide modification and sulfur incorporation remains a central challenge in chemical biology and catalysis. Here, we first report a visible-light-promoted, metal-free carbamoylation strategy that enables the direct synthesis of thiocarbonyl amino acid and peptide derivatives from DHP-tagged amino acids and peptides. This transformation proceeds via a photocatalytic radical process that forms C–S bonds efficiently under mild, biocompatible conditions. The method features a broad substrate scope and high functional group tolerance, delivering over 50 examples in up to 98% yield. Mechanistic studies support the generation of carbamoyl radicals from 4-carbamoyl-DHP precursors, followed by selective coupling with thiolations to furnish the corresponding thiocarbonyl products. The reaction operates smoothly at room temperature, employs green solvents, and can be readily scaled up without loss of efficiency. Furthermore, this protocol enables the late-stage functionalization of amine-containing drugs, natural products, and proteins, providing a general and sustainable platform for peptide diversification.
This review provides a comprehensive overview of optimization strategies for the synthesis of poly(hydroxyurethane)s (PHUs) via the most common route: cyclic carbonate (CC) aminolysis with amines. PHUs represent a sustainable alternative to conventional polyurethanes, eliminating toxic isocyanates and allowing the use of bio-based monomers. Despite these advantages, their broader industrial adoption is limited by slow polymerization kinetics, modest molecular weights, side reactions, and scalability challenges. Key factors affecting the reaction are examined, including the structure and substituents of CCs and amines, reaction conditions (temperature, time, molar ratios), solvent selection, and the use of plasticizers to mitigate hydrogen bonding limitations. Special attention is given to catalytic approaches, including fundamental catalysts, ionic liquids, dual catalysis, and catalyst-free methods. Strategies to control regioselectivity, side reactions and the influence of solvent choice are also discussed. The potential of bio-based materials for sustainable PHU production is also highlighted. Finally, perspectives are provided on enhancing PHU reactivity and advancing industrial scalability.
An environmentally friendly transition metal-free strategy for the α,β-C(sp3)–H dehydrogenative diazotization of piperidines has been developed. This method employs aryl diazonium salts as dual-function reagents (electrophile functionalization reagent and hydride acceptor) and proceeds efficiently at room temperature under ambient air, eliminating the need for transition metals, stoichiometric external oxidants, and harsh conditions. Featuring broad substrate scope, simple operation, and remarkable step economy, this protocol establishes a green and sustainable profile for constructing C–N bonds, providing facile access to valuable piperidine derivatives with reduced environmental impact.

