Renewable Molecular Flasks with NADH Models: Combination of Light-Driven Proton Reduction and Biomimetic Hydrogenation of Benzoxazinones

Using small molecules with defined pockets to catalyze chemical transformations resulted in attractive catalytic syntheses that echo the remarkable properties of enzymes. By modulating the active site of a nicotinamide adenine dinucleotide (NADH) model in a redox-active molecular flask, we combined biomimetic hydrogenation with in situ regeneration of the active site in a one-pot transformation using light as a clean energy source. This molecular flask facilitates the encapsulation of benzoxazinones for biomimetic hydrogenation of the substrates within the inner space of the flask using the active sites of the NADH models. The redox-active metal centers provide an active hydrogen source by light-driven proton reduction outside the pocket, allowing the in situ regeneration of the NADH models under irradiation. This new synthetic platform, which offers control over the location of the redox events, provides a regenerating system that exhibits high selectivity and efficiency and is extendable to benzoxazinone and quinoxalinone systems.     

CATALYTIC HYDROGENATION OF CARBON DIOXIDE TO C2+ ALCOHOLS OVER COPPER-COBALT SPINELS (I)

Several Cu-Co spinels were prepared for higher alcohol synthesis from CO2 and H2. They exhibited a promising potential for the reaction with a high selectivity to C2+ alcohols, but the selectivity decreased when KOH was introduced. XRD characterization showed that the addition of KOH destroyed the metallic Cu and Co cluster. Some results were discussed.     

海南粗榧新碱类似物芳环的反常氢化反应（英文）

报道了海南粗榧新碱类似物芳环的一种反常氢化反应，并提出了可能的反应机理。     

Catalytic Hydrogenation of Diacetyl Monoxime to Tetramethylpyrazine with the Soluble Transition Metal Catalysts

Tetramethylpyrazine(TMP)isausefulcompoundinfoodindustry'.InrecentyearsithasbeenfoundasanactiveingredientinChuanxi0ng(ligusticumwallichiifranch),whichisatraditionalChineseherb.NowTMPhasbeenwidelyusedinthetreatmentofpatientswithcerebralischemicdiseasesinChina2.OneoftheimportantmethodsforthepreParationoftetramethylpNazineistheselfcondensati0noftwomoleculesof2-aminobutanoneto2,5-dihydrotetramethlipyrazineandsubsequentoxidati0ntoTMP3.2-Aminobutanoneispreparedusuallyinsituviathereductionofthec…     

Hydrogenation of acetylene–ethylene mixtures on Pd catalysts: study of the surface mechanism by computational approaches. Metal dispersion and catalytic activity

The hydrogenation mechanism of acetylene–ethylene mixtures on Pd catalysts under different experimental conditions was studied by employing a time-dependent Monte Carlo approach set to use a fixed series of event probabilities. The dependence of the catalyst activity and selectivity on the sizes of the metal particles was simulated at microscopic level and the results, also refined by fitting procedures, suggested proper explanations for the apparent nonuniformity of the related experimental findings. The use of the steric hindrance parameter of the surface species and the available surface energy on the metallic catalyst sites was decisive for reproducing the experimental results. Received: 16 September 1999 / Accepted: 3 February 2000 / Published online: 2 May 2000