Catalytic and highly regiospecific carbon-carbon bond formation at alpha-position of Michael acceptor by palladium complex

Activated olefins react with allyl acetates and Bu3SnH in the presence of a catalytic amount of a palladium catalyst to afford the corresponding products which construct a new C-C bond selectively at the alpha-position of Michael acceptors.     

Novel synthesis of L-ribose from D-mannono-1,4-lactone

[reaction: see text] D-Mannono-1,4-lactone was efficiently converted into L-ribose in eight steps. A key step of this synthesis is the cyclization of a gamma-hydroxyalkoxamate under Mitsunobu conditions. It is noteworthy that the O-alkylation product was obtained in 94% yield and that none of the N-alkylation product was detected in this cyclization.     

Polyaddition reaction of pseudoxazolones with dimercaptans

Polymers having thioether, thiolester, and amide linkages in each repeating unit of a polymer main chain were prepared by the polyaddition reaction of pseudoxazolones (2-isopropylidene-4-alkyl-3-oxazolin-5-ones) and dimercaptans. The polymers had inherent viscosities in a range of 0.08–0.22 and gave transparent films by solution casting.     

Experimental evaluation of the ξ-function for an atmospheric argon plasma near 104 K

The ξ-functions for an atmospheric argon plasma have been evaluated within an accuracy of ±9% over the visible region (400–800 nm) at several temperatures in the 10⁴ K region. The plasma has been produced by a low-voltage, high-current arc jet and its parameters have been determined by using a recently published value for the atomic transition probability.     

Synthesis of 6-aminobenzo[b]naphtho[2,1-d]thiophene

6-Aminobenzo[b]naphtho[2,1-d]thiophene has been prepared by two different routes, one, a one-pot synthesis.     

Contraction of supramolecular double-threaded dimer formed by alpha-cyclodextrin with a long alkyl chain

A double-threaded dimer bearing a long substituent part and a large stopper group has been prepared and showed a conformational change with increased solvent polarity. [structure: see text]     

Kinetic study of radical polymerization of dialkyl fumarates using electron spin resonance spectroscopy

The radical polymerization of dialkyl fumarates (DRF) bearing various ester alkyl groups was kinetically studied. The propagation and termination rate constants were determined using electron spin resonance (ESR) spectroscopy. The introduction of the bulky ester alkyl groups such as a tert-butyl group decreased the termination rate constant as expected. However, it has also been revealed that the bulky groups promote propagation despite the steric repulsion. The propagation rate and mechanism are discussed in relation to the propagation manner, i.e., tacticity of the polymer. © 1996 John Wiley & Sons, Inc.