CuI‐catalyzed, one‐pot synthesis of 3‐aminobenzofurans in deep eutectic solvents

Synthesis of Benzofuran Derivatives via a DMAP-Mediated Tandem Cyclization Reaction Involving ortho-Hydroxy α-Aminosulfones

An efficient cascade cyclization strategy was developed to synthesize aminobenzofuran spiroindanone and spirobarbituric acid derivatives utilizing 2-bromo-1,3-indandione, 5-bromo-1,3-dimethylbarbituric acid, and ortho-hydroxy α-aminosulfones as substrates. Under the optimized reaction conditions, the corresponding products were obtained with high efficiency, exceeding 95% and 85% yields for the respective derivatives. This protocol demonstrates exceptional substrate versatility and robust scalability up to the Gram scale, establishing a stable platform for the synthesis of 3-aminobenzofuran derivative. The successful synthesis paves the way for further biological evaluations with potential implications in scientific research.

A Comprehensive Review on Benzofuran Synthesis Featuring Innovative and Catalytic Strategies

Benzofurans have intrigued both pharmaceutical researchers and chemists owing to the medicinal usage of their derivatives against copious disease-causing agents (i.e., bacteria, viruses, and tumors). These heterocyclic scaffolds are pervasively encountered in a number of natural products and drugs. The ever-increasing utilization of benzofuran derivatives as pharmaceutical agents persuaded the chemists to devise novel and facile methodological approaches to assemble the biologically potent benzofuran nucleus. This review summarizes the current developments regarding the innovative synthetic routes and catalytic strategies to procure the synthesis of benzofuran heterocycles with their corresponding mechanistic details, reported by several research groups during 2021-2023.

A sustainable avenue for the synthesis of propargylamines and benzofurans using a Cu-functionalized MIL-101(Cr) as a reusable heterogeneous catalyst

A heterogeneous copper-catalyzed A3 coupling reaction of aldehydes, amines, and alkynes for the synthesis of propargylamines and benzofurans has been developed. Here, the modified metal-organic framework MIL-101(Cr)-SB-Cu complex was chosen as the heterogeneous copper catalyst and prepared via post-synthetic modification of amino-functionalized MIL-101(Cr). The structure, morphology, thermal stability, and copper content of the catalyst were determined by FT-IR, PXRD, SEM, TEM, EDX, TGA, XPS, and ICP-OES. The catalyst shows high catalytic activity for the aforementioned reactions under solvent-free reaction conditions. High yields, low catalyst loading, easy catalyst recovery and reusability with not much shrink in catalytic activity, and a good yield of 82% in gram-scale synthesis are some of the benefits of this protocol that drove it towards sustainability.

Deep Eutectic Solvents as à-la-Carte Medium for Transition-Metal-Catalyzed Organic Processes

Our society is facing a tremendous challenge to become more sustainable in every sphere of life. Regarding the chemical industry, one of the most significant issues to be addressed is the use of volatile organic compounds (VOCs) as solvents because they are petrol-derived and most of them are toxic and flammable. Among the possible solutions, deep eutectic solvents (DESs) have emerged as sustainable alternatives to VOCs in organic catalyzed transformations and other fields. The advantages of these new reaction media are not only related to their more benign physical and chemical properties and, for most of them, their renewable sources but also due to the possibility of being recycled after their use, increasing the sustainability of the catalyzed process in which they are involved. However, their use as media in catalytic transformations introduces new challenges regarding the compatibility and activity of known catalysts. Therefore, designed catalysts and "à-la-carte" DESs systems have been developed to overcome this problem, to maximize the reaction outcomes and to allow the recyclability of the catalyst/media system. Over the last decade, the popularity of these solvents has steadily increased, with several examples of efficient metal-catalyzed organic transformations, showing the efficiency of the catalysts/DES system, compared to the related transformations carried out in VOCs. Additionally, due to the inherent properties of the DES, unknown transformations can be carried out using the appropriated catalyst/DES system. All these examples of sustainable catalytic processes are compiled in this review.

An Efficient and Versatile Deep Eutectic Solvent-Mediated Green Method for the Synthesis of Functionalized Coumarins

Herein, we report a green and efficient synthetic route for the construction of diverse functionalized coumarins in good-to-excellent yields (60-98%) via the Pechmann condensation. The optimized synthetic route involves a biodegradable, reusable, and inexpensive deep eutectic solvent (DES) of choline chloride and l-(+)-tartaric acid in a ratio of 1:2 at 110 °C. Interestingly, phloroglucinol and ethyl acetoacetate, upon reaction, furnished the functionalized coumarin (20) in 98% yield within 10 min. On the other front, the same DES at relatively lower reaction temperature (90 °C) was found to provide the bis-coumarins in decent yields (81-97%) within 20-45 min. Moreover, this particular method was found to be quite effective for large-scale coumarin synthesis without noteworthy reduction in the yields of the desired products. Noticeably, in this versatile approach, the DES plays a dual role as solvent as well as catalyst, and it was effectively recycled and reused four times with no significant drop-down in the yield of the product.