Ruthenium-catalyzed cycloaddition of propargylic alcohols with phenol derivatives via allenylidene intermediates: catalytic use of the allenylidene ligand as the C(3) unit

Novel ruthenium-catalyzed cycloaddition of propargylic alcohols with 2-naphthols and phenols bearing electron-donating groups via allenylidene intermediates has been developed to give the corresponding 1H-naphtho[2,1-b]pyrans and 4H-1-benzopyrans, respectively, in moderate to excellent yields with complete regioselectivity.     

Phase-shifting interferometry with feedback control using heterodyne phase detection

A phase-shifting interferometer with feedback control using heterodyne phase detection was developed. A composite heterodyne phase detection method for obtaining feedback signals was proposed. Interference fringe stabilization and accurate pi/2 phase shifts under micrometer-order vibrations were successfully demonstrated using a digital high-speed lock-in amplifier.     

Amination of N-aryl prolinol via ring expansion and contraction: application to the chiral ligand for the catalytic asymmetric reaction

Chiral diaminophosphines 4 were prepared from (S)-prolinol-derived aminophosphine oxide 5 by bromination with ring expansion followed by amination with ring contraction and reduction, using trichlorosilane. In the presence of 4 as a ligand, palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (11) with a dialkyl malonate-BSA-LiOAc system was successfully carried out with good enantioselectivities (up to 98% ee).     

Ruthenium-catalyzed cycloaddition between propargylic alcohols and cyclic 1,3-dicarbonyl compounds via an allenylidene intermediate

Thiolate-bridged diruthenium complexes such as [Cp*RuCl(mu(2)-SR)(2)RuCp*Cl] (Cp* = eta(5)-C(5)Me(5); R = Me, (n)Pr, (i)Pr) and [Cp*RuCl(mu(2)-S(i)Pr)(2)RuCp*(OH(2))]OTf (OTf = OSO(2)CF(3)) promote the cycloaddition between propargylic alcohols and cyclic 1,3-dicarbonyl compounds to give either the corresponding 4,6,7,8-tetrahydrochromen-5-ones or 4H-cyclopenta[b]pyran-5-ones in high yields with complete regioselectivity. This catalytic cycloaddition provides a simple and one-pot synthetic protocol for a variety of substituted chromenones and cyclopenta[b]pyranones.     

Entrap-immobilization of biocatalysts on cellulose acetate-inorganic composite gel fiber using a gel formation ofcellulose acetate–metal (Ti, Zr) alkoxide

We developed a new entrap-immobilization method, using a gel formationof cellulose acetate and metal (Ti, Zr) alkoxide. Several biocatalysts(-galactosidase, -chymotrypsine, invertase, urease, lipase andSaccharomyces cereviciae) were successfullyentrap-immobilized on this composite gel fiber. The immobilization process wassimple and the resultant immobilized biocatalysts on the gel fiber were easy tohandle. It is considered that the biocatalysts are physically entrapped amongthe gel networks and distribute throughout the gel fiber. The gel fiber wasstable in phosphate buffer solution, electrolyte solution and organic solvent,because the gel formation was due to coordination interaction between celluloseand transition metal. Therefore, it can be applicable as a support for abiotransformation in various reaction media. We examined some enzyme reactionsand biotransformation using the immobilized biocatalysts on this gel fiber andevaluated this immobilization matrix in the reactions compared to the resultsobtained by the other immobilization method. The immobilized biocatalyst showedstable activity for repeated cycles and over a long period of time. Moreover,continuous reaction could be carried out in a column reactor packed with thisimmobilized biocatalyst.