23 research outputs found

    Gold-Catalyzed Cyclization of 3‑(2′-Azidoaryl)-1-arylpropargyl Carbonates or 3‑Aryl-1-(2′-azidoaryl)propargyl Carbonates to Produce Quinolines

    No full text
    A gold-catalyzed cyclization of 3-(2′-azidoaryl)-1-arylpropargyl carbonates to generate substituted quinolines via a sequence of 3,3-rearrangement, 6-<i>endo</i>-trig cyclization and denitrogenation has been developed. Similar products could be obtained from 3-aryl-1-(2′-azidoaryl)­propargyl carbonates under different gold catalytic conditions via a sequential 6-<i>endo</i>-dig cyclization, denitrogenation, and 1,2-H shift process

    Chemo- and Regioselective Assembly of Polysubstituted Pyridines and Isoquinolines from Isocyanides, Arynes, and Terminal Alkynes

    No full text
    We have disclosed a general and efficient synthetic strategy for polysubstituted pyridines and isoquinolines with high chemo- and regioselectivity. In this methodology, 1-alkynyl imines act as the key compound to undergo a sequential alkynyl imine–allenyl imine isomerization/aza-Diels–Alder reaction/aromatization. In the first place, 1-alkynyl imines were formed in situ by a highly selective multicomponent reaction of isocyanides, arynes, and terminal alkynes and reacted with another molecule of arynes or terminal alkynes to furnish target heterocyclic products in a highly efficient and atom-economic manner. On the other hand, we attempted to prepare 1-alkynyl imines by other approaches to undergo a similar reaction sequence to afford polysubstituted pyridines and isoquinolines with a wider range. Different from the first approach, the second approach utilized the preprepared 1-alkynyl imines to introduce the related different substitutents into the final products: arynes or terminal alkynes bearing substituents different from those of 1-alkynyl imines have been successfully applied for the synthesis a wide variety of pyridines and isoquinolines with diversity

    Gold-Catalyzed Cyclization of 3‑(2′-Azidoaryl)-1-arylpropargyl Carbonates or 3‑Aryl-1-(2′-azidoaryl)propargyl Carbonates to Produce Quinolines

    No full text
    A gold-catalyzed cyclization of 3-(2′-azidoaryl)-1-arylpropargyl carbonates to generate substituted quinolines via a sequence of 3,3-rearrangement, 6-<i>endo</i>-trig cyclization and denitrogenation has been developed. Similar products could be obtained from 3-aryl-1-(2′-azidoaryl)­propargyl carbonates under different gold catalytic conditions via a sequential 6-<i>endo</i>-dig cyclization, denitrogenation, and 1,2-H shift process

    Chemo- and Regioselective Assembly of Polysubstituted Pyridines and Isoquinolines from Isocyanides, Arynes, and Terminal Alkynes

    No full text
    We have disclosed a general and efficient synthetic strategy for polysubstituted pyridines and isoquinolines with high chemo- and regioselectivity. In this methodology, 1-alkynyl imines act as the key compound to undergo a sequential alkynyl imine–allenyl imine isomerization/aza-Diels–Alder reaction/aromatization. In the first place, 1-alkynyl imines were formed in situ by a highly selective multicomponent reaction of isocyanides, arynes, and terminal alkynes and reacted with another molecule of arynes or terminal alkynes to furnish target heterocyclic products in a highly efficient and atom-economic manner. On the other hand, we attempted to prepare 1-alkynyl imines by other approaches to undergo a similar reaction sequence to afford polysubstituted pyridines and isoquinolines with a wider range. Different from the first approach, the second approach utilized the preprepared 1-alkynyl imines to introduce the related different substitutents into the final products: arynes or terminal alkynes bearing substituents different from those of 1-alkynyl imines have been successfully applied for the synthesis a wide variety of pyridines and isoquinolines with diversity

    Gold-Catalyzed Cyclization of 3‑(2′-Azidoaryl)-1-arylpropargyl Carbonates or 3‑Aryl-1-(2′-azidoaryl)propargyl Carbonates to Produce Quinolines

    No full text
    A gold-catalyzed cyclization of 3-(2′-azidoaryl)-1-arylpropargyl carbonates to generate substituted quinolines via a sequence of 3,3-rearrangement, 6-<i>endo</i>-trig cyclization and denitrogenation has been developed. Similar products could be obtained from 3-aryl-1-(2′-azidoaryl)­propargyl carbonates under different gold catalytic conditions via a sequential 6-<i>endo</i>-dig cyclization, denitrogenation, and 1,2-H shift process

    Hydroxyphosphinylation Reaction of 3‑Cyclopropylideneprop-2-en-1-ones via C–P σ‑Bond Cleavage

    No full text
    An unexpected hydroxyphosphinylation of 3-cyclopropylideneprop-2-en-1-ones with phosphines has been observed. This method provides a unique regio- and stereoselective synthesis of highly functionalized 1-dialkylphinyl-3-oxo-(1<i>Z</i>)-alkenyl cyclopropanols with important potentials. The reaction displays an unusual mechanistic featurea highly selective cleavage of C–P σ bonds in phosphines

    Hydroxyphosphinylation Reaction of 3‑Cyclopropylideneprop-2-en-1-ones via C–P σ‑Bond Cleavage

    No full text
    An unexpected hydroxyphosphinylation of 3-cyclopropylideneprop-2-en-1-ones with phosphines has been observed. This method provides a unique regio- and stereoselective synthesis of highly functionalized 1-dialkylphinyl-3-oxo-(1<i>Z</i>)-alkenyl cyclopropanols with important potentials. The reaction displays an unusual mechanistic featurea highly selective cleavage of C–P σ bonds in phosphines

    Free vibration analysis of composite cylindrical shells with non-uniform thickness walls

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    The paper proposes to characterize the free vibration behaviour of non-uniform cylindrical shells using spline approximation under first order shear deformation theory. The system of coupled differential equations in terms of displacement and rotational functions are obtained. These functions are approximated by cubic splines. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector which are spline coefficients. Four and two layered cylindrical shells consisting of two different lamination materials and plies comprising of same as well as different materials under two different boundary conditions are analyzed. The effect of length parameter, circumferential node number, material properties, ply orientation, number of lay ups, and coefficients of thickness variations on the frequency parameter is investigated

    PdCl<sub>2</sub>-Catalyzed Oxidative Cycloisomerization of 3-Cyclopropylideneprop-2-en-1-ones

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    A novel PdCl<sub>2</sub>-catalyzed oxidative cycloisomerization of 3-cyclopropylideneprop-2-en-1-ones, providing a facile synthesis of highly strained functionalized 2-alkylidenecyclobutanones via furan-fused cyclobutene intermediates, is reported. An interesting route to 2(3<i>H</i>)-furanones with a spiro-cyclopropane unit from the obtained 2-alkylidenecyclobutanones via a ring-contraction rearrangement reaction is also realized

    PdCl<sub>2</sub>-Catalyzed Oxidative Cycloisomerization of 3-Cyclopropylideneprop-2-en-1-ones

    No full text
    A novel PdCl<sub>2</sub>-catalyzed oxidative cycloisomerization of 3-cyclopropylideneprop-2-en-1-ones, providing a facile synthesis of highly strained functionalized 2-alkylidenecyclobutanones via furan-fused cyclobutene intermediates, is reported. An interesting route to 2(3<i>H</i>)-furanones with a spiro-cyclopropane unit from the obtained 2-alkylidenecyclobutanones via a ring-contraction rearrangement reaction is also realized
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