19 research outputs found
Isolation and characterization of iridium(III) and iridium(V) complexes of 2-(arylazo)pyridine and studies of amine fusion reactions at the coordinated diazo-ligand
No full textAsymmetric Synthesis of Tetrahydrofurans through Palladium(0)-Catalyzed [3 + 2]-Cycloaddition of Vinylcyclopropanes with Ketenes
Full text linkIn this article we describe a new asymmetric synthesis of highly substituted tetrahydrofurans through a Pd(PPh3)4-catalyzed formal [3 + 2]-cycloaddition of donor-acceptor cyclopropanes and ketenes. The desired structural motif was formed in moderate to excellent yields (42-84% for 16 examples), with excellent Z:E isomer diastereoselectivity (≥19:1 for 16 examples), and with good to excellent enantioselectivity in all cases examined (83-97% ee for 6 examples). The synthetic utility of the products was illustrated by a number of diastereoselective transformations into reduced tetrahydrofurans and spirocyclic tetrahydrofuran-barbiturate derivatives. ©</p
Asymmetric Synthesis of Tetrahydrofurans through Palladium(0)-Catalyzed [3 + 2]-Cycloaddition of Vinylcyclopropanes with Ketenes
No full textIn
this article we describe a new asymmetric synthesis of highly
substituted tetrahydrofurans through a Pd(PPh3)4-catalyzed formal [3 + 2]-cycloaddition of donor–acceptor
cyclopropanes and ketenes. The desired structural motif was formed
in moderate to excellent yields (42–84% for 16 examples), with
excellent Z:E isomer diastereoselectivity
(≥19:1 for 16 examples), and with good to excellent enantioselectivity
in all cases examined (83–97% ee for 6 examples). The synthetic
utility of the products was illustrated by a number of diastereoselective
transformations into reduced tetrahydrofurans and spirocyclic tetrahydrofuran-barbiturate
derivatives
Self-assembly of multiferroic core-shell particulate nanocomposites through DNA-DNA hybridization and magnetic field directed assembly of superstructures
No full textMultiferroic composites of ferromagnetic and ferroelectric phases are of importance for studies on mechanical strain mediated coupling between the magnetic and electric subsystems. This work is on DNA-assisted self-assembly of superstructures of such composites with nanometer periodicity. The synthesis involved oligomeric DNA-functionalized ferroelectric and ferromagnetic nanoparticles, 600 nm BaTiO3 (BTO) and 200 nm NiFe2O4 (NFO), respectively. Mixing BTO and NFO particles, possessing complementary DNA sequences, resulted in the formation of ordered core-shell heteronanocomposites held together by DNA hybridization. The composites were imaged by scanning electron microscopy and scanning microwave microscopy. The presence of heteroassemblies along with core-shell architecture is clearly observed. The reversible nature of the DNA hybridization allows for restructuring the composites into mm-long linear chains and 2D-arrays in the presence of a static magnetic field and ring-like structures in a rotating-magnetic field. Strong magneto-electric (ME) coupling in as-assembled composites is evident from static magnetic field H induced polarization and low-frequency magnetoelectric voltage coefficient measurements. Upon annealing the nanocomposites at high temperatures, evidence for the formation of bulk composites with excellent cross-coupling between the electric and magnetic subsystems is obtained by H-induced polarization and low-frequency ME voltage coefficient. The ME coupling strength in the self-assembled composites is measured to be much stronger than in bulk composites with randomly distributed NFO and BTO prepared by direct mixing and sintering
Self-assembly of multiferroic core-shell particulate nanocomposites through DNA-DNA hybridization and magnetic field directed assembly of superstructures
No full textHydrido iridium(III) complexes of azoaromatic ligands. Isolation, structure and studies of their physicochemical properties
No full textAsymmetric Synthesis of Tetrahydrofurans through Palladium(0)-Catalyzed [3 + 2]-Cycloaddition of Vinylcyclopropanes with Ketenes
No full textIn
this article we describe a new asymmetric synthesis of highly
substituted tetrahydrofurans through a Pd(PPh3)4-catalyzed formal [3 + 2]-cycloaddition of donor–acceptor
cyclopropanes and ketenes. The desired structural motif was formed
in moderate to excellent yields (42–84% for 16 examples), with
excellent Z:E isomer diastereoselectivity
(≥19:1 for 16 examples), and with good to excellent enantioselectivity
in all cases examined (83–97% ee for 6 examples). The synthetic
utility of the products was illustrated by a number of diastereoselective
transformations into reduced tetrahydrofurans and spirocyclic tetrahydrofuran-barbiturate
derivatives
Catalytic stereoselective synthesis of cyclopentanones from donor–acceptor cyclopropanes and in situ-generated ketenes†
No full text<jats:p>Diastereoselective and enantiospecific (3 + 2)-cycloaddition of <jats:italic>in situ</jats:italic>-generated ketenes with donor–acceptor cyclopropanes to give cyclopentanones is realised.</jats:p>
Mechanistic Investigations of the Pd‐Catalyzed Hydrogenolysis of Ketene Heterodimer β‐Lactones
No full textAsymmetric Synthesis of Tetrahydrofurans through Palladium(0)-Catalyzed [3 + 2]-Cycloaddition of Vinylcyclopropanes with Ketenes
No full textIn
this article we describe a new asymmetric synthesis of highly
substituted tetrahydrofurans through a Pd(PPh3)4-catalyzed formal [3 + 2]-cycloaddition of donor–acceptor
cyclopropanes and ketenes. The desired structural motif was formed
in moderate to excellent yields (42–84% for 16 examples), with
excellent Z:E isomer diastereoselectivity
(≥19:1 for 16 examples), and with good to excellent enantioselectivity
in all cases examined (83–97% ee for 6 examples). The synthetic
utility of the products was illustrated by a number of diastereoselective
transformations into reduced tetrahydrofurans and spirocyclic tetrahydrofuran-barbiturate
derivatives
