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Abstract: 1-Vinylpyrrole-2-carbaldehydes and 1-vinyl-4,5-dihydrobenzo[g]indole-2-carbaldehyde were synthesized in 56–91% yields from their 1-vinyl derivatives by a modified Vilsmeier–Haack reaction. A low temperature (−78°C) is required to avoid removal of the N-vinyl group, whereas at elevated temperature (reflux in 1,2-dichloroethane) the latter process leads to direct conversion of 1-vinylpyrroles to pyrrole-2-carbaldehydes. [Copyright &y& Elsevier]

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (C H⋯O) and moderate (N H⋯N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Transition metal-free cross-coupling of pyrroles with acyl(bromo)acetylenes in a solid Al 2 O 3 medium. • Addition of propargylamine to acylethynylpyrroles. • One-put synthesis of pyrrolyl-pyridines from acylethynylpyrroles and propargylamine. Abstract Acylethynylpyrroles, available via the transition metal-free coupling of pyrroles with acylhaloacetylenes are readily annelated with propargylamine in a one-pot step-wise procedure: catalyst-free heating (60–65 °C, 6–16 h) in DMSO and then keeping for 2.5 h with CuI at the same temperature. The products are pyrrolyl-pyridines isolated in good to excellent yields (56–94%). It is experimentally shown that dehydrogenation of intermediate dihydropyridine moiety is not resulted from the oxidation with DMSO (Me 2 S was not detected) or air (argon blanket) and is likely associated with the CuI catalysis. [ABSTRACT FROM AUTHOR]

Abstract: A new highly synthetically potent series of bifunctional pyrroles, 1-vinylpyrrole-2-carbonitriles, were synthesized from readily available 1-vinylpyrrole-2-carbaldehyde oximes by two methods: (1) reaction with acetylene (KOH/DMSO, 70°C, 10min, yields 58–67%) and (2) reaction with acetic anhydride (90–100°C, 5h, yields 83–93%). Starting from 2-phenyl-1-vinylpyrrole, the one-pot synthesis of the corresponding 1-vinyl-2-carbonitrile was accomplished directly by successive treatment with a DMF/(COCl)2 complex, NH2OH·HCl/NaOAc, and acetic anhydride (yield 58%). [Copyright &y& Elsevier]

• Hitherto unknown N -allenylpyrrole-2-carbaldehydes have been synthesized. • Mild formylating complex DMF/(COCl) 2. • Promising synthons for fine organic synthesis. Hitherto unknown N -allenylpyrrole-2-carbaldehydes were synthesized via the formylation of readily available N -allenylpyrroles under the action of the mild formylating complex DMF/(COCl) 2. The reaction selectively proceeds in the case of pyrroles with electron-withdrawing substituents to afford the products in good to excellent yields. For pyrroles bearing electron-donating substituents, the reaction proceeds in a cascade manner to deliver unusual complex products, the structure of which was confirmed by X-ray diffraction analysis. The target N -allenylpyrrole-2-carbaldehydes represent promising synthons for organic synthesis. [ABSTRACT FROM AUTHOR]

Abstract: Indoles are cross-coupled with 1-benzoyl-2-bromoacetylene on Al2O3 at room temperature under base and solvent-free conditions to afford 3-(2-benzoylethynyl)indoles in 22–76% yields, thus representing the first examples of direct ethynylation of the indole nucleus. [Copyright &y& Elsevier]