23 research outputs found
Gold-Catalyzed Cyclization of 3â(2â˛-Azidoaryl)-1-arylpropargyl Carbonates or 3âAryl-1-(2â˛-azidoaryl)propargyl Carbonates to Produce Quinolines
A gold-catalyzed cyclization of 3-(2â˛-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-(2â˛-azidoaryl)Âpropargyl
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
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 imineâallenyl
imine isomerization/aza-DielsâAlder 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 3â(2â˛-Azidoaryl)-1-arylpropargyl Carbonates or 3âAryl-1-(2â˛-azidoaryl)propargyl Carbonates to Produce Quinolines
A gold-catalyzed cyclization of 3-(2â˛-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-(2â˛-azidoaryl)Âpropargyl
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
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 imineâallenyl
imine isomerization/aza-DielsâAlder 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 3â(2â˛-Azidoaryl)-1-arylpropargyl Carbonates or 3âAryl-1-(2â˛-azidoaryl)propargyl Carbonates to Produce Quinolines
A gold-catalyzed cyclization of 3-(2â˛-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-(2â˛-azidoaryl)Âpropargyl
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 3âCyclopropylideneprop-2-en-1-ones via CâP ĎâBond Cleavage
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 featureî¸a highly selective
cleavage of CâP Ď bonds in phosphines
Hydroxyphosphinylation Reaction of 3âCyclopropylideneprop-2-en-1-ones via CâP ĎâBond Cleavage
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 featureî¸a highly selective
cleavage of CâP Ď bonds in phosphines
Free vibration analysis of composite cylindrical shells with non-uniform thickness walls
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
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
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