A one-step method for covalent bond immobilization of biomolecules on silica operated in aqueous solution.

A simple, one-step method for covalent bond immobilization of biomolecules on silica operated in water is described. In the approach, an NHS-ester linked methallylsilane is utilized as a bifunctional linker to couple the biomolecule to the silica surface. Weak organic acid such as acetic acid activates the silica surface enough to react with bifunctional linker without destroying activity of biomolecule.

Hydrogen-bonding-driven enantioselective resolution against the Kazlauskas rule to afford γ-amino alcohols by Candida rugosa lipase.

Most lipases resolve secondary alcohols in accordance with the "Kazlauskas rule" to give the R enantiomers. In a similar manner to other lipases, Candida rugosa lipase (CRL) exhibits R enantioselectivity towards heptan-2-ol, although the enantiomeric ratio (E) is low (E=1.6). However, unexpected enantioselectivity (i.e., S enantioselectivity, E=58) of CRL towards 4-(tert-butoxycarbonylamino)butan-2-ol, which has a similar chain length to heptan-2-ol, has been observed. To develop a deeper understanding of the molecular basis for this unusual enantioselectivity, we have conducted a series of molecular modeling and substrate engineering experiments. The results of these computational and experimental analyses indicated that a hydrogen bond between the Ser450 residue and the nitrogen atom of the carbamate group is critical to stabilize the transition state of the S enantiomer.

Microwave-assisted, rhodium(III)-catalyzed N-annulation reactions of aryl and α,ß-unsaturated ketones with alkynes.

New Rh(III)-catalyzed, one-pot N-annulation reactions of aryl and α,ß-unsaturated ketones with alkynes in the presence of ammonium acetate have been developed. Under microwave irradiation conditions, the processes lead to rapid formation of the respective isoquinoline and pyridine derivatives with efficiencies that are strongly dependent on the steric nature of the aryl ring and enone substituents. By employing this protocol, a variety of isoquinoline and pyridine derivatives were prepared in high yields. In addition, a new one-pot approach to the synthesis of pyridines, involving four-component reactions of ketones, formaldehyde, NH(4)OAc, and alkynes, has been uncovered. This process takes place through a route involving initial aldol condensation of the ketone with formaldehyde to generate a branched α,ß-unsaturated ketone that then undergoes Rh(III)-catalyzed N-annulation with NH(4)OAc and the alkyne

A method for highly efficient catalytic immobilisation of glucose oxidase on the surface of silica.

A simple, mild and convenient method has been developed for catalytic immobilisation of glucose oxidase (GOx), chemically modified to contain pendant methallylsilyl groups, on an untreated silica surface.

A method for the synthesis of pyridines from aldehydes, alkynes and NH4OAc involving Rh-catalyzed hydroacylation and N-annulation.

A new method for regiocontrolled pyridine synthesis has been developed involving sequential Rh(I)-catalyzed chelation-assisted hydroacylation of alkynes with aldehydes followed by Rh(III)-promoted N-annulation of the resulting α,ß-enones with another alkyne and NH(3).