Synthesis of 6-Membered-Ring Fused Thiazine-Dicarboxylates and Thiazole-Pyrimidines via One-Pot Three-Component Reactions

A facile and efficient one-pot three-component reaction method for the synthesis of thiazine-dicarboxylates is reported. Reaction of an isocyanide and dialkyl acetylenedicarboxylate with 2-amino-4H-1,3-thiazin-4-one derivatives containing both an acidic proton and an internal nucleophile gave the products in good yields of 76–85%. The reactivity of dialkyl acetylenedicarboxylates was further tested in the synthesis of thiazole-pyrimidines where a two-component reaction of 2-aminothiazole with dialkyl acetylenedicarboxylates was successfully converted to a more efficient three-component reaction of a thiourea, α-haloketone and dialkyl acetylenedicarboxylate (DMAD/DEtAD) to give thiazole-pyrimidines in good yields of 70–91%.

Visible Light Mediated, Catalyst Free, One-Pot Convenient Synthesis of Dihydropyridines

: A simple, efficient and green protocol has been developed for the synthesis of polysubstituted dihydropyridines via one-pot, four-component reaction of aldehydes, arylamines, dialkyl acetylenedicarboxylate, and malononitrile. The reaction was proceeded at room temperature in the absence of catalyst in aqueous ethyl lactate under visible light irradiation. The main advantages of the present approach are mild reaction condition, high yield, no column chromatography, clean reaction profile, environmentally friendly and sustainable from the economic point of view

Green Synthesis of 4H-pyran Derivatives Using Fe3O4-MNPs as Efficient Nanocatalyst: Study of Antioxidant Activity

Aims & Objective: In this work, pyran derivatives were synthesized via a multicomponent reaction of ninhydrin, α-haloketones, dialkyl acetylenedicarboxylate, and triphenylphosphine in the presence of iron oxide magnetic nanoparticles (Fe3O4-MNPs) as efficient nanocatalyst in ethanol at room temperature. Materials & Methods: The biosynthesis of Fe3O4-MNPs was performed by Clover Leaf water extract. In addition, antioxidant activity was examined for the prepared compounds employing DPPH radical scavenging and ferric reduction activity potential (FRAP) experiment and comparing results with synthetic antioxidants (TBHQ and BHT). Results: Compound 5b showed excellent radical trapping activity and good reducing activity relative to standards (BHT and TBHQ). Conclusion: Some advantages of this procedure are: the workup of reaction is easy and the products can be separated easily by filtration. Fe3O4-MNPs display a good improvement in the yield of the product and showed significant reusable activity.

ZnBr2 Functionalized Ionic Liquid: An Efficient Solvent and Catalyst for the Facile Synthesis of 1-Benzamino-1,4-Dihydropyridine

Ionic liquids (ILs) are mostly composed of organic cations and organic/inorganic anions. One of the most important class of ILs are imidazolium ILs. The hydrophilicity and hydrophobicity of ILs are regularly influenced by length of alkyl side chain of cation. According to this effect, better hydrophilicity comes from a shorter alkyl side chain and on the contrary, better hydrophobicity comes from a lengthier alkyl side chain of cation. Typical ILs have exceptional properties. Most ILs are stable at about 300 °C in the liquid state at normal conditions. Due to the exceptional properties of ILs, they have been used in diverse industries including batteries and fuels. As solvents, ILs have been employed in many chemical fields. Solubilities of ILs with organic/inorganic species are completely satisfactory. Here, by N-methyl imidazole (Im), 1,3-dibromopropane, triethanolamine (TEA), and ZnBr2, new ionic liquid (TEA-Im-Zn) was synthesized and used as catalyst and solvent in the synthesis of functionalized 1-benzamino-1,4-dihydropyridine using aromatic aldehydes, malononitrile, triethylamine, arylamine and dialkyl acetylenedicarboxylate.

Intramolecular Diels–Alder and [3+2] Cycloaddition Reactions in the One-Pot Synthesis of Epoxypyrrolo[3,4-g]indazoles

A one-pot approach for the synthesis of epoxypyrrolo[3,4-g]indazoles is presented. The first step was initiated by a three-component reaction of an isocyanide, a dialkyl acetylenedicarboxylate, and 2-furancarboxylic acid, and led to 1,3-dioxoepoxyisoindole, followed by the addition of hydrazonoyl chloride through a [3+2]-cycloaddition reaction in the second step. The key step in the formation of final compound involves a bicyclization strategy through intramolecular Diels–Alder­ (IMDA) reaction.

Reaction Between 7-Hydroxy Coumarin, Alkyl Isocyanides and Dialkyl Acetylenedicarboxylate: Synthesis of 4H-Chromenes and 1-Azabuta-1,3-dienes

The reactive intermediate generated by the addition of <em>tert</em>-butyl and 1,1,3,3-tetramethyl butyl isocyanide to dialkyl acetylenedicarboxylate was trapped by 7-hydroxycoumarin to produce highly functionalized 4<em>H</em>-chromenes in fairly good yields. When the reaction is performed with cyclohexyl isocyanide, 1-azabuta-1,3-dienes were obtained.