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Ruthenium-catalyzed asymmetric homogeneous hydrogenation (AHH) is used as the key step of a multi-kilogram scale synthesis of an enantiomeric fluoropiperidine. The AHH of a tetrasubstituted β-fluoroenamide is carried out under mild conditions using a Ru/Josiphos catalyst with high ee (98%).

Suitable as highly effective polymerization catalysts is the new class of donor/acceptor metallocenes in which the rotation of the two pi ligands is restricted through the formation of a dative D(+)-->A(-) bond (see picture). Specifically optimized substitution patterns yield excellent properties for the synthesis of high-melting, highly crystalline thermoplastic materials, amorphous thermoplastic materials with high glass transition temperatures as well as polyolefin elastomers with low glass T(g).

Hexafluorophosphoric acid promotes 1,3,4-oxadiazolium hexafluorophosphate formation from N′-acyl-N-aroyl-N-arylhydrazides or N′-acyl-N-acyl-N-arylhydrazides under mild conditions. These 1,3,4-oxadiazolium hexafluorophosphates can be treated with cyanamide in propan-2-ol in the presence of triethylamine to generate 1,5-disubstituted 3-amino-1H-1,2,4-triazoles in good yields. This safe and scalable protocol displays a broad scope with respect to N-substitutions and N′-acyl protecting groups.

3-Thiabicyclo-[3,3,0]-oct-5-en-7-ones have been prepared by intramolecular Pauson-Khand reaction on allylpropargylsulfide cobalt complexes in benzene with dimethylsulfoxide as promoter and dimethylsulfide in 65-80% yield.

Department of Chemistry and Division of Molecular Engineering and Chemistry, Korea University, Seoul 136-701, KoreaReceived September 16, 2004Key Words : Pauson-Khand reaction, Propargyl aldehyde dicobalt hexacarbonyl, Asymmetric addition,Bis(homoallyl)zincThe preparation of the optically active secondary prop-argyl alcohols has been a subject of intensive researches.