This paper describes the synthesis and characterization of alkylidene pentamethylcyclopentadienyl imido tungsten(VI) complexes via a-hydrogen abstraction processes from suitable alkyl derivatives. Reaction of WCp*Cl4 with one equivalent of NH2R (R= Bu, 2,6-Me2–C6H3), two equivalents of NEt3 and subsequent oxidation with PCl5 affords the pentamethylcyclopentadienyl imido tungsten derivatives, WC...

Tungsten NArR alkylidene complexes have been prepared that contain the electron-withdrawing ArR groups 2,4,6-X3C6H2 (ArX3, X = Cl, Br), 2,6-Cl2-4-CF3C6H2 (ArCl2CF3), and 3,5-(CF3)2C6H3 (Ar(CF3)2). Reported complexes include W(NArR)2Cl2(dme) (dme = 1,2-dimethoxyethane), W(NArR)2(CH2CMe3)2, W(NArR)(CHCMe3)(OTf)2(dme), and W(NArR)(CHCMe3)(ODBMP)2 (DBMP = 4-Me-2,6-(CHPh2)C6H2). The W(NArR)(CHCMe3)(...

15-Alkylidene andrographolide derivatives were specific alpha-glucosidase inhibitors. Semi-synthetic studies of these derivatives led to new alpha-glucosidase inhibitors. Their alpha-glucosidase inhibitory activity was evaluated. Bioactivity results indicated that most of the derivatives were excellent alpha-glucosidase inhibitors. Among them, 6c displayed the best alpha-glucosidase inhibitory ...

[reaction: see text] A template containing two secondary dialkylammonium ion recognition sites for encirclement by olefin-bearing dibenzo[24]crown-8 derivatives has been used to promote olefin cross metatheses with ruthenium-alkylidene catalysts. For monoolefin monomers, the rates of metatheses and yields of the dimers are both amplified in the presence of the template. Likewise, for a diolefin...

Theoretical descriptions of alkylidene chalcogen difluorides have been performed on their planar (1-3) and bent (4-6) conformations. The planar T-shaped conformations were the most stable ones, from the calculations performed (Gaussian-G2 and B3LYP/6-311+G). The bonding nature of the T-shaped (C(2)(v)()) structures has also been analyzed by means of the atoms in molecules (AIM) theory and elect...

Depending on the substitution pattern and the solvent, the gold-catalyzed cyclization of alk-4-yn-1-ones affords different oxygen heterocycles under mild reaction conditions. Alkynones with one substituent at C-3 undergo a 5-exo-dig cycloisomerization to substituted furans , whereas a 6-endo-dig cyclization to 4H-pyrans is observed with substrates bearing two substituents at C-3. In alcoholic s...

In earlier papers we studied direct limits (G,K) = lim −→ (Gn,Kn) of two types of Gelfand pairs. The first type was that in which the Gn/Kn are compact riemannian symmetric spaces. The second type was that in which Gn = Nn ⋊ Kn with Nn nilpotent, in other words pairs (Gn,Kn) for which Gn/Kn is a commutative nilmanifold. In each we worked out a method inspired by the Frobenius–Schur Orthogonalit...

This paper is concerned with the control of nonlinear pure-feedback systems with unknown nonlinear functions. This problem is considered di/cult to be dealt with in the control literature, mainly because that the triangular structure of pure-feedback systems has no a/ne appearance of the variables to be used as virtual controls. To overcome this di/culty, implicit function theorem is 0rstly exp...

The two quotes above suggest alternate ideas about the sources of happiness. The first (written around AD 180) is nn Aristotelian notion. Happiness is a way of living, not a state. The second quote (written some 1500 years later) suggests ideas about the sources of happiness perhaps more akin to the way that we tend to view [hem today. Happiness is about conviviality, warmth. food (and perhaps ...