A new, base-free high turnover number (TON) catalyst for hydrogenation of simple and functionalized amides is prepared by reacting [Ru(η3-C3H5)(Ph2P(CH2)2NH2)2]BF4 and BH4− under hydrogen.
1,10-phenanthroline is grafted to indium tin oxide (ITO) and titanium dioxide nanoparticle (TiO) semiconductors by electroreduction of 5-diazo-1,10-phenanthroline in 0.1 M HSO. The lower and upper potential limits (-0.20 and 0.15 V, respectively) were set to avoid reduction and oxidation of the 1,10-phenanthroline (phen) covalently grafted at C5 to the semiconductor. The resulting semiconductor-phen ligand (ITO-phen or TiO-phen) was air stable, and was bonded to Ru- or Ir- by reaction with cis-[Ru(bpy)(CHCN)] (bpy = 2,2'-bipyridine) or cis-[Ir(ppy)(CHCN)] (ppy = ortho-C metalated 2-phenylpyridine) in CHCl and THF solvent at 50 °C. Cyclic voltammetry, X-ray photoelectron spectroscopy, solid-state UV-vis, and inductively coupled plasma-mass spectrometry all confirmed that the chromophores SC-[(phen)Ru(bpy)] and SC-[(phen)Ir(ppy)] (SC = ITO or TiO) formed in near quantitative yields by these reactions. The resulting photoanodes were active and relatively stable to photoelectrochemical oxidation of hydroquinone and triethylamine under neutral and basic conditions.
The organic carbazole−cyanobenzene push−pull dye 1,2,3,5tetrakis(carbazol-9-yl)-4,6-dicyanobenzene was derivatized and attached to carbon or indium-doped tin oxide (ITO) electrodes by simple diazonium electrografting. The surface-bound dye is active and stable for the visible light photosynthetic isomerization of a wide range of functionalized stilbene and cinnamic acid derivatives. Up to 87,000 net turnovers were obtained for the isomerization of trans-stilbene. The isomerizations can be carried out in air with a 33% reduction in the rate. The ITO photoelectrodes are also active and stable toward photo-oxidations under basic and acidic conditions.
High-throughput screening and lab-scale optimization were combined to develop the catalytic system trans-RuCl((S,S)-skewphos)((R,R)-dpen), 2-PrONa, and 2-PrOH. This system hydrogenates functionalized α-phenoxy and related amides at room temperature under 4 atm H pressure to give chiral alcohols with up to 99% yield and in greater than 99% enantiomeric excess via dynamic kinetic resolution.
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