Hall and Co-workers

Intramolecular energy transfer between suitable fluorophores provides a highly efficient way of discriminating between saccharides based on the binding motif of the complex formed. 

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One of the best-known commercial instruments developed for organic carbon determinations is the Beckman total carbon analyser, which utilises an analysis scheme developed by Van Hall and co-workers [57,99]. This instrument works reasonably well in fresh water. It has become a standard instrument in pollution control and water treatment [103]. The Beckman instrument has not worked as satisfactorily for seawater because of the latter s high carbonate and low organic content. 

A large number of ferrocene cryptand-type molecules have been reported in the literature in the last ten years. Hall and co-workers, the initial pioneers of these cryptand systems (Beer etal., 1984 Bell and Hall, 1980 Hammond etal., 1986 Bell etal., 1983 Hall and Sharpe, 1990,1991 Hall etal., 1990a,b, 1991a,b,... 

Hall and co-workers have imaged overripe melons suffering from internal necrosis with both spin-echo and gradient-echo sequences at 2 T (86 MHz). 

Isomerization of cyclopropane was studied by Hall and co-workers (84, 103), who reported catalyst activity to increase with vacancy concentration. They postulated that the active site consisted of a vacancy and neighboring Al—OH group. Hydrogenation of ethylene at room temperature was found to increase with increase in catalyst reduction and irreversible hydrogen was apparently not involved in the reaction (104). 

The stereocontrolled synthesis of a-hydroxyakylated piperidines, a motif frequently encountered in natural products, represents a difficult synthetic challenge that was recently tackled by Hall and co-workers using the aza-variant of the Vaultier-Lallemand three-component reaction described in Scheme 12.14 [62]. One interesting feature of this reaction is the use of hydrazines, as masked amines, which allows the hetero-Diels-Alder reaction to operate on a normal electron demand manifold. Toure and Hall recently applied this powerful MCR to the asymmetric synthesis of (—)-methyl dihydropalustramate 192 [91], a degradation product and postulated biosynthetic precursor of (+)-palustrine (Scheme 12.27) [92]. 

Alternatively, the allylboration of aldehydes 200 with chiral allyl boronates 199a-d (conveniently prepared from camphorquinone in four steps) also provided the optically active homoallylic alcohols 201a-d with high ee in the presence of achiral Lewis acid catalysts. These boronates are relatively unreactive with aldehydes at low temperatures in the absence of Lewis acid catalyst. However, they furnish low to moderate ee for the allylation at higher temperatures. Hall and co-workers were able to increase the reactivity of the allyl boronates at low temperatures by the addition of strong Lewis acids such as Sc(OTf)3 and obtained the homoallylic alcohols with high ee at low temperatures (Equation 9) <2003JA10160>. 

A number of ferrocene cryptand molecules (66-74) ((29)—(31)) have been reported in the literature and it is only relatively recently that their electrochemical coordination properties have been disclosed. We have synthesized potassium-selective metallocene cryptands (72) (30) and (31) the electrochemistry of the former in the presence of K+ guest cations proved disappointingly irreversible (75). Hall and co-workers (76) have used cyclic voltammetry to investigate the coordination of... 

Thermolysis of C6H5N3 in (CH3)3CD produced aniline containing only 7% N—D, in spite of the fact that the tertiary position of isobutane is the most readily attacked one. Intermolecular insertion of arylnitrene in C—H bonds has been reported recently 63> in the thermolysis of phenylazide in alkane in yields up to 10%, along with aniline as the major product. Hall and co-workers 66> have shown that thermolysis of CeHs—N3 in optical active 2-phenylbutane led to 2-anilino-2-phenylbutane with 40% retention of optical activity they obtained further information on the nature of the insertion and hydrogen abstraction process from the thermolysis of ArN3 in mixed solvents. Aniline and N-cyclohexylaniline (ratio... 

The reversibility of the redox cycle involving and Oj was established for Fe by Boudart and co-workers (2) using Mossbauer spectroscopic techniques. They proposed that the oxygen was held between two Fe cations. Fu et al. (3) showed that Fe-Y acted as a redox catalyst for reactions of CO with NO, CO with Oj, and N2O with CO. The ability of Fe-Y to decompose NjO into its elements was established in the work of Hall and co-workers (4), who also showed that Fe-Mordenite was as active as Fe-Y, despite containing only 16% as much Fe as its Y-zeolite counterpart. This difference in catalytic activity was thought to result from differences in the environments of the Fe within the zeolite structures. The objective of the present study was to alter the cation environment and relate that environment to the catalytic activity this was accomplished by varying the silicon-to-aluminum ratio of Y-zeolite and by coexchanging Fe with Eu. 

Reduction of aromatic ketones. It has been generally assumed that metal ammonia reduction of aromatic ketones leads to alcohols, mainly because benzo-phenone (1) is reduced to diphenylmcthanol (2, benzhydrol) by sodium in liquid ammonia. However, Hall and co-workers report that aromatic ketones are reduced,... 

Another important example of the diflFerential adhesiveness which protein-dominated surfaces can display, is in the development of artificial skin especially for wound dressings and for temporary covers of extensive burns. C. W. Hall and co-workers 17) showed that relative tissue adhesion to mechanically identical velour fabrics constructed of various materials follows the order predicted by the critical surface tensions of construction material. 

Hall and co-workers have reported on the poisoning effect of ammonia on neopentane cracking over high-silica zeolites, i.e. H-ZSM-5,... 

Allylations of aldehydes and imines also constitute important carbon-carbon bond-forming reactions [14]. A range of metal-based Lewis acid catalysts have been reported. Hall and co-workers described the Bronsted acid-catalyzed allylation of aldehydes with allyl boronate (Equation 10.8) [15]. 

Chocolate makes a good NMR sample as it contains mobile and immobile phases and has a high proton density. Hall and co-workers have carried out a general survey of chocolate confectionery by MRI324 and have visualized the migration of liquid triacylglycerol by the same method.325 The use of NMR relaxation to assess chocolate has also been considered.326... 

In the selected instances of the observation of ring-opened products, copolymerization reactions, and the loss of dienophile stereochemistry in the [4 + 2] reactions of a,/3-unsaturated esters bearing an additional C-3 electron-withdrawing group as well as the lack of an observed rate dependency on the solvent polarity have led Hall and co-workers to conclude that such cycloadditions may proceed with the generation of biradical intermediates. However, such conclusions have been further cautioned by the detailed investigations of Hall and his co-workers in which they... 

In a series of papers Hall and co-workers have studied the oxidation of olefins over Pd and Pd-Au alloys, supported Ir," and unsupported Ag." The oxidation of ethylene over Pd and Pd-Au alloys produced the partial oxidation products acetic acid and acetic anhydride together with traces of ethylene oxide. Experiments with a reaction mixture containing [14-C]-acetaldehyde, in addition to ethylene and O2, showed that most of the radioactivity appeared in the acetic acid rather than the CO2. This was evi-... 

The hexachloroantimonate salts of unsubstituted imidoyl halides have been converted to the corresponding azides Boron trichloride complexes of N-substituted benzimidoyl chlorides are reported by Hall and co-workers... 

From computational studies, a related Ir(III)—Ir(V) cycle has also been proposed by Burgess, Hall, and co-workers for the hydrogenation of unfunctionalized aryl-substituted alkenes by using carbene oxazolines as chiral ligands (255). 

Hall and co-workers investigated line profiles of hyperfine structure components in I2 with a refined optical phase modulation/radiofrequency sideband technique using a saturating and a probe laser beam. 

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