Treat me gently: for a selective synthesis of the unusually sensitive cyclophanic α-pyrone neurymenolide A, the chosen catalysts must be able to distinguish between six different sites of unsaturation, without scrambling any of the skipped π systems. This challenge was met with a new gold-catalyzed pyrone synthesis in combination with a molybdenum-catalyzed ring-closing alkyne metathesis.
Hybrid nanoparticles with a silica core and grafted poly(methyl methacrylate) (PMMA) or poly(n-butyl methacrylate) (PBMA) chains were prepared via activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) at room temperature under high pressure. Due to enhanced propagation rate constant and reduced termination rate constant for polymerizations conducted under high pressure, the rate of polymerization was increased, while preserving good control over polymerization when compared to ATRP under ambient pressure. Molecular weights of greater than 1 million were obtained. The PMMA and PBMA brushes exhibited "semi-diluted" or "diluted" brush architecture with the highest grafting densities ≈0.3 chain·nm(-2).
A three-component
Pd-catalyzed difunctionalization of internal
and terminal alkynes with iodoperfluoroalkanes and boronic acids is
reported here. Under low catalyst loading and mild reaction conditions,
perfluoroalkylated tri- and tetrasubstituted olefins were obtained
in very good yields and in excellent regio- and stereoselectivities.
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