Eder Joao Lenardao

The growing demand for green solvents to replace petroleum‐derived counterparts in organic synthesis has garnered significant attention, driven by the need for more sustainable production processes. In this context, organic carbonates (OCs) have emerged as prominent alternatives to toxic solvents that pose risks to human health and the environment. This review presents recent advances in the application of major dialkyl carbonates, namely dimethyl carbonate (DMC), diethyl carbonate (DEC), and propylene carbonate (PC), as solvents in organic synthesis. By discussing more than seventy papers from the past 6 years, we demonstrate the rising importance of this solvent class, which has transitioned from exotic adjuvants to essential components of modern synthetic methodologies. Through a compilation and analysis of the recent literature, this review aims to serve as a comprehensive resource for synthetic chemists, underscoring the potential of OCs to pave the way for safer and more sustainable synthesis.

A sustainable visible light-promoted protocol for preparing selenium- and sulfur-decorated 2,3-dihydrobenzofurans from 2-allylphenols and diorganyl dichalcogenides is reported. The reaction proceeds under blue LEDs irradiation (Kessil PR160L, λ_max = 440 nm) under mild conditions, in the absence of photocatalysts or oxidants, in accordance with the green chemistry principles. Eighteen derivatives were obtained, covering electron-rich, electron-deficient, and polycyclic systems, with yields from 20% to 96%. The method is operationally simple, scalable, and tolerant to diverse aryl substituents, although the presence of electron-withdrawing groups reduces its efficiency. This approach offers an ecofriendly alternative to conventional oxidative or photocatalyst-mediated strategies to prepare the target molecules, opening new opportunities for advancing organoselenium chemistry and exploring its potential in organic synthesis.

This work introduces a visible light-driven, oxidant-free synthesis of seleno-thiochromenones that yields potent dual COX-2/5-LOX inhibitors outperforming celecoxib.

The development of metal-free strategies for the synthesis of 1,2,3-triazoles has emerged as an important alternative to traditional copper-catalyzed methods. In this review, a comprehensive overview of DBU-driven azide-based [3 + 2] cycloaddition reactions (DBU: 1,8-diazabicyclo[5.4.0]undec-7-ene) for the construction of structurally diverse 1,2,3-triazoles is presented. The role of DBU as a strong, non-nucleophilic organocatalyst is highlighted, particularly in promoting enolate formation and enabling efficient cycloaddition under mild conditions. Key transformations, including azide-carbonyl cycloadditions, reactions with activated alkenes, and multicomponent/tandem processes, are systematically discussed. Mechanistic aspects, substrate scope, regioselectivity, and synthetic applications, especially in medicinal chemistry, are critically analyzed. Overall, this work consolidates current advances and underscores the potential of DBU‑mediated methodologies as sustainable and versatile tools for heterocycle synthesis.

The development of sustainable heterogeneous catalysts remains a significant challenge in green chemistry, particularly for reactions that are traditionally carried out under homogeneous conditions. In this context, we hypothesized that hybrid hydrogels formed by alginate (Alg) and iota‑carrageenan (ι-CAR) could provide a complementary set of carboxylate and sulfate functional groups capable of efficiently immobilizing Cu2+ ions and generating an active, reusable catalytic platform. To test this concept, Alg/ι-CAR microspheres were prepared by Ca2+ ionotropic gelation followed by Cu2+ ion exchange, and their structural, morphological, and thermal properties were thoroughly characterized. The Fourier transform infrared (FTIR), thermogravimetric analysis (TGA/DTG), X-ray diffraction (XRD), scanning electron microscopy with an energy-dispersive X-ray (SEM/EDX), and porosity analyses confirmed the successful incorporation of Cu2+ and revealed increased surface roughness and porosity after ion exchange, supporting the initial hypothesis of enhanced metal coordination within the hybrid matrix. The resulting Alg/ι-CAR-Cu2+ microspheres showed high catalytic activity in the Paal-Knorr synthesis of pyrroles, reaching 78% yield under mild conditions, and remained effective for up to three reuse cycles before gradual deactivation caused by partial Cu2+ leaching and surface densification. These findings demonstrate that the synergistic interactions between Alg and ι-CAR create a robust and efficient support for Cu2+ immobilization, highlighting the potential of biopolymer-based hybrid materials as sustainable heterogeneous catalysts for organic synthesis.

An approach has been developed for the direct synthesis of various selenium-functionalized benzo[4,5]imidazo[2,1-b][1,3]thiazine derivatives via the electrophilic cyclization reaction between 2-(methylthio)-1-(3-arylprop-2-yn-1-yl)-1H-benzo[d]imidazoles and diorganyl diselenides promoted by N-fluorobenzenesulfonimide (NFSI). This strategy is used to construct fused heterocyclic scaffolds based on selenium-functionalized 4H-benzo[4,5]imidazo[2,1-b][1,3]thiazines using NFSI as a stable and nonhazardous oxidizing agent in the presence of CH₃CN at 80 °C. The protocol allowed a broad substrate scope leading to the synthesis of 16 novel selenium-functionalized benzo[4,5]imidazo[2,1-b][1,3]thiazines in yields of up to 95%. Furthermore, control studies, including ¹H, ¹⁹F, and ⁷⁷Se NMR experiments, were conducted to identify intermediates, which contributed to the elucidation of the reaction mechanism.