Synlett

A novel strategy has been developed for the direct and regioselective ortho-acetoxylation of N-(2-benzoylphenyl)benzamides through C–H activation using a catalytic amount of Pd(OAc)2 (5 mol%) and a stoichiometric amount of PhI(OAc)2 in a mixture of acetic anhydride and acetic acid. By using this protocol, a new series of niclosamide derivatives was produced in good yields. This is the first report on the synthesis of niclosamide and its derivatives by means of C–H functionalization. This newly developed method offers several advantages such as high regioselectivity, operational simplicity, and good to excellent yields. It provides a short three-step process for the synthesis of niclosamide involving acid–amine coupling, ortho-acetoxylation through C–H activation, and deacylation.

Indolo[2,1-b]quinazolin-12(6H)-one derivatives are prevalent in many synthetic intermediates, pharmaceuticals, and organic materials. Herein, we developed a photoredox radical cascade cyclization reaction that uses visible light as the primary energy input to promote the reaction, leading to a series of indolo[2,1-b]quinazolin-12(6H)-one derivatives under oxygen conditions.

A practical method for the debenzylation of aryl benzyl ethers has been developed using easy-to-operate I2 and Et3SiH, as well as the green solvent ethyl acetate. Halo, methoxy, ester, and nitro groups on the benzene ring of the aryl benzyl ether are compatible with this debenzylation. Control experiments revealed that Et3SiI, generated in situ, might be the actual promoter of the procedure. This method does not require a separate desilylation reaction to obtain phenol products.

A simple and efficient method for the synthesis of symmetric 2,3,5,6-tetrasubstituted pyridines from enaminones and triethyl orthoformate, catalyzed by pyridinium p-toluenesulfonate, has been established in which triethyl orthoformate was applied as a carbon source. The procedure was smoothly executed, culminating in the synthesis of symmetrical 2,3,5,6-tetrasubstituted pyridines with moderate to exceptional yields across a diverse array of substrates.

Retrosynthesis refers to the process of deconstructing a target molecule step by step until simpler and commercially available synthetic precursors are identified to develop a valid synthetic pathway. As a powerful problem-solving tool, it has gradually been expanded to other fields of chemistry. The application of a ‘retrosynthesis mindset’ can be relevant beyond chemistry, such as in education, research management, and science advice. In this Letter, we discuss the concept of the retrosynthesis mindset and its implications within and beyond chemistry in the hope of highlighting a broader potential and encouraging the adoption of such a mindset to enhance problem solving and strategic planning across disciplines.1 Introduction2 Retrosynthesis Education3 Retrosynthesis Within and Beyond the Lab4 Conclusion

Retrosynthesis refers to the process of deconstructing a target molecule step by step until simpler and commercially available synthetic precursors are identified to develop a valid synthetic pathway. As a powerful problem-solving tool, it has gradually been expanded to other fields of chemistry. The application of a ‘retrosynthesis mindset’ can be relevant beyond chemistry, such as in education, research management, and science advice. In this Letter, we discuss the concept of the retrosynthesis mindset and its implications within and beyond chemistry in the hope of highlighting a broader potential and encouraging the adoption of such a mindset to enhance problem solving and strategic planning across disciplines.1 Introduction2 Retrosynthesis Education3 Retrosynthesis Within and Beyond the Lab4 Conclusion

A new synthetic approach has emerged for constructing 9H-pyrrolo[1,2-a]indole scaffolds by the reactions between indoles and chalcones under metal- and solvent-free conditions at 80 °C. The reaction occurs smoothly in the presence of a Brønsted acidic ionic liquid, 1-methyl-3-(4-sulfobutyl)-1H-imidazol-3-ium tosylate, as a catalyst, permitting the synthesis of the desired products with satisfactory yields. The developed protocol is applicable to the construction of biologically important pyrrolo[1,2-a]indole derivatives from easily accessible chalcones having various substituents. The process commences with Michael addition to chalcones, followed by annulations induced by the elimination of a water molecule, yielding the 9H-pyrrolo[1,2-a]indole scaffolds. Several control experiments were carried out to achieve a better understanding of the reaction pathway. The feasibility of recycling the catalyst was also demonstrated. This method produces water as the sole byproduct and represents a green synthetic protocol. The clean reaction, easily accessible reactants, and the metal- and solvent-free and environmentally friendly reaction conditions are the notable advantages of this procedure.

A new synthetic approach has emerged for constructing 9H-pyrrolo[1,2-a]indole scaffolds by the reactions between indoles and chalcones under metal- and solvent-free conditions at 80 °C. The reaction occurs smoothly in the presence of a Brønsted acidic ionic liquid, 1-methyl-3-(4-sulfobutyl)-1H-imidazol-3-ium tosylate, as a catalyst, permitting the synthesis of the desired products with satisfactory yields. The developed protocol is applicable to the construction of biologically important pyrrolo[1,2-a]indole derivatives from easily accessible chalcones having various substituents. The process commences with Michael addition to chalcones, followed by annulations induced by the elimination of a water molecule, yielding the 9H-pyrrolo[1,2-a]indole scaffolds. Several control experiments were carried out to achieve a better understanding of the reaction pathway. The feasibility of recycling the catalyst was also demonstrated. This method produces water as the sole byproduct and represents a green synthetic protocol. The clean reaction, easily accessible reactants, and the metal- and solvent-free and environmentally friendly reaction conditions are the notable advantages of this procedure.

We present a novel and cost-effective method for synthesizing biologically important α-keto esters in a single-step reaction. This approach involves a sequential cascade process within a single reaction vessel facilitated by t-BuOK, which promoted the cleavage of the sp2 C(O)–N bond of an isatin and the formation of a new N–C(sp2)(O) bond with benzoyl chloride. To the best of our knowledge, this is the first instance of the construction of an α-keto ester scaffold adjacent to an amide group through a one-pot process. In comparison to existing methods, our protocol offers several advantages: readily available starting materials, mild reaction conditions, a concise synthetic pathway, high sustainability, and excellent tolerance towards various functional groups. Given these strengths, we anticipate widespread use of this method in the synthesis of related α-keto ester scaffolds.

In this contribution, a speedy and direct approach for the synthesis of benzo[1,2,4]triazine derivatives via a copper-catalyzed intermolecular N-arylation of 2-iodoaniline and hydrazonoyl chlorides is described. The reaction proceeds in THF at room temperature with no need for any ligand. The use of simple and readily available starting materials, mild copper-catalytic reaction conditions, and good yields (72–92%) are remarkable specifications of this protocol.