A full account of the Pd-catalyzed intramolecular reactions of (E)-2,2-disubstituted 1-alkenyldimethylalanes with aryl triflates as an entry into polycarbocyclic structures displaying an ethyl−methyl-substituted all-carbon benzylic quaternary center is herein presented. It was found that the efficiency of the Pd-catalyzed carbon−carbon bond forming process is highly affected by the structure of the starting material, including tether length and aryl substitution pattern; substituting the position ortho to the triflate is mandatory to obtain a good yield of the carbocycle. Moreover, the formation of 1-ethyl-1-methylindanes is facile in comparison to the case for the analogous tetrahydronaphthalenes, for which the competing methyl cross-coupling reaction is equally competent. It was established through labeling studies that the carbon−carbon bond forming events are stereospecific and proceed though the intermediacy of a neopentylic sp3-gem-dimetallic palladio(II) dialkylaluminoalkane species, from which a 1,2-methyl migration from aluminum to carbon occurs. Intramolecular palladium-catalyzed reactions of 1-naphthyl triflates with (E)-2,2-disubstituted 1-alkenyldimethylalanes revealed two competing reaction pathways: arylation with sequential 1,2-alkyl migration from aluminum to carbon and intramolecular 1,2-diarylation, in which the catalytic cycle is terminated by direct arylation of the C(sp3)−Pd(II) bond. Factors such as tether length, additives, solvent polarity, and C−H···Pd interactions between the Pd(II) center and the hydrogen atom at the 8-position all influence not only the pathway taken by the (σ-aryl)palladium(II) complexes but also the subsequent reactivity of the (σ-alkyl)palladium(II) complexes.

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Two different methods to graft silica particles with poly(acrylic acid) (PAA) were studied. In the first method PAA was reacted with 1,1′‐carbonyldiimidazole to give functionalized PAA. The resulting activated carbonyl group reacted easily with 3‐aminopropyl‐functionalized silica at low temperatures. In the second method 3‐glycidoxypropyl‐functionalized silica particles were reacted directly with PAA by using magnesium chloride as a catalyst. Different molecular weights of PAAs were used in order to investigate the effect of molecular weight on grafting yields in both methods. The grafting yields were determined with thermogravimetric analysis (TGA). All products were also investigated with IR. The results showed that the yields of reactions performed at ambient temperature by using 1,1′‐carbonyldiimidazole‐functionalized PAA were the same as with a direct reaction of unfunctionalized PAA and 3‐aminopropyl‐functionalized silica performed at 153°C. Also in reactions between 3‐glycidoxypropyl‐functionalized silica and PAA the yields were satisfactory. Copyright © 2006 John Wiley & Sons, Ltd.

A stable, bioactive cellulose acetate (CA) surface was developed by functionalizing the surface with highly thermostable avidin form. The CA films were first functionalized with a mixture of 3-aminopropyltrimethoxysilane and tetraethoxysilane to introduce free amino groups onto the surface of CA films. Free amino groups were functionalized with glutaraldehyde to obtain an activated surface for covalent biomolecule immobilization. A genetically engineered, high-affinity biotin-binding protein chimeric avidin, ChiAVD(I117Y), was used for biofunctionalization of the surface. The chimeric avidin protein has an increased stability in chemically harsh conditions and at high temperature when compared to wt (strept)avidin. The biological activity, i.e., biotin-binding capacity, of the immobilized protein was probed by [(3)H]-biotin. The activity of the chimeric avidin on functionalized CA films was fully retained over the three months' study period. The biotin-binding capacity of the immobilized chimeric avidin was compared to that of immobilized streptavidin, chicken avidin, and rhizavidin and significant differences between proteins were detected. The developed material offers a valuable platform for the development of inexpensive in vitro diagnostics and also supports biosensing applications that are required to operate under demanding conditions.

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