Optimised conditions are reported for Suzuki-Miyaura couplings between N-tosyl-2-bromo-benzylamines and -phenethylamines with vinylboronic acids, using pre-mixes of catalyst, ligand and base, leading to the corresponding 2-tosylaminomethyl- and 2-tosylaminoethyl-styrenes in generally excellent yields, using microwave excitation at 100 °C. 相似文献
Blood–tissue partition coefficients indicate how a chemical will distribute throughout the body and are an important part of any pharmacokinetic study. They can be used to assess potential toxicological effects from exposure to chemicals and the efficacy of potential novel drugs designed to target certain organs or the central nervous system. In vivo measurement of blood–tissue partition coefficients is often complicated, time-consuming, and relatively expensive, so developing in vitro systems that approximate in vivo ones is desirable. We have determined such systems for tissues such as brain, muscle, liver, lung, kidney, heart, skin, and fat.
Results
Several good (p < 0.05) blood–tissue partition coefficient models were developed using a single water–solvent system. These include blood–brain, blood–lung, blood–heart, blood–fat, blood–skin, water–skin, and skin permeation. Many of these partition coefficients have multiple water–solvent systems that can be used as models. Several solvents—methylcyclohexane, 1,9-decadiene, and 2,2,2-trifluoroethanol—were common to multiple models and thus a single measurement can be used to estimate multiple blood–tissue partition coefficients. A few blood–tissue systems require a combination of two water–solvent partition coefficient measurements to model well (p < 0.01), namely: blood–muscle: chloroform and dibutyl ether, blood–liver: N-methyl-2-piperidone and ethanol/water (60:40) volume, and blood–kidney: DMSO and ethanol/water (20:80) volume.
Conclusion
In vivo blood–tissue partition coefficients can be easily estimated through water–solvent partition coefficient measurements.
We have fabricated a bandgap-guiding hollow-core photonic crystal fiber (PCF) capable of transmitting and compressing ultrashort pulses in the green spectral region around 532 nm. When propagating subpicosecond pulses through 1 m of this fiber, we have observed soliton-effect temporal compression by up to a factor of 3 to around 100 fs. This reduces the wavelength at which soliton effects have been observed in hollow-core PCF by over 200 nm. We have used the pulses delivered at the output of the fiber to machine micrometer-scale features in copper. 相似文献
Selenocyclisations of the homoallylic sulfonamides [e.g., 26, 28 and 30] using phenylselanyl halides lead exclusively to β-selanyl-pyrrolidines [e.g., 27, 29 and 31] by an overall 5-endo-trig pathway, but with considerable variations in the stereochemical outcome, depending upon the substituents and the precise conditions used. Subsequent oxidative eliminations lead smoothly to the corresponding 3-pyrrolines and thence to poly-hydroxylated pyrrolidines. 相似文献
The crystal structure of Aurivillius phase ferroelectric Bi2WO6 has been studied in detail as a function of temperature by using high-resolution powder neutron diffraction. In agreement with an earlier study, a transition from space group P2(1)ab to B2cb occurs at about 660 degrees C. This transition corresponds to the loss of one octahedral tilt mode within the perovskite-like WO4 layer of the structure. A second, reconstructive, phase transition occurs around 960 degrees C, corresponding to the ferroelectric Curie point; in contrast to previous suggestions, the structure of this high-temperature phase contains layers of stoichiometry WO4, with WO6 octahedra sharing edges and corners, and with the fluorite-like Bi2O2 layers remaining essentially unchanged. This structure is closely related to that of the ambient temperature phase of lanthanide-doped derivatives, for example, Bi0.7Yb1.3WO6 recently reported. This phase-transition behaviour is in stark contrast to that of other members of the Aurivillius family, such as SrBi2Ta2O9 and Bi4Ti3O12, which retain the archetypal Aurivillius connectivity at all temperatures. 相似文献
A comparative study of the carbonyl-ene reaction between a range of 1,1'-disubstituted or trisubstituted alkenes and ethyl trifluoropyruvate catalyzed by Lewis acid-platinum group metal complexes of the type [M{(R)-BINAP}]2+ (M = Pt, Pd, Ni; BINAP is 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) revealed subtle but significant differences in their reactivity. For instance, the palladium-based Lewis acid [Pd{(R)-BINAP}]2+ catalyzes the ene reaction between methylene cycloalkane to afford the expected alpha-hydroxy ester in good yield and excellent diastereo- and enantioselectivity. In contrast, under the same conditions, the corresponding [M{(R)-BINAP}]2+ (M = Pt, Ni) catalyzes isomerization of methylene cycloalkane and the ene reaction of the resulting mixture of methylene cycloalkane and 1-methylcycloalkene at similar rates to afford a range of -hydroxy esters in high regioselectivity, good diastereoselectivity, and good to excellent enantioselectivity. In addition, [Pt{(R)-BINAP}]2+ also catalyzes postreaction isomerization of the ene product as well as consecutive ene reactions to afford a double carbonyl-ene product. The sense of asymmetric induction has been established by single-crystal X-ray crystallography, and a stereochemical model consistent with the formation of (S)-configured -hydroxy ester has been proposed; the same model also accounts for the observed exo-diastereoselectivity as well as the level of diastereoselectivity. 相似文献
Palladium complexes of 2-pyridyldiphenylphosphine anchored on polystyrene, polymethylmethacrylate and styrene-methylmethacrylate copolymer form highly active heterogeneous catalysts for the alkoxycarbonylation of terminal alkynes with activities approaching those obtained under homogeneous conditions. 相似文献