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Put a label on it: Carbon dioxide with H2 is shown to be an efficient and selective methylation reagent for aromatic and aliphatic amines (see scheme; acac=acetylacetonate, triphos = 1,1,1‐tris(diphenylphosphanylmethyl)ethane). A variety of functionalized amines including 13C‐labelled drugs were obtained with good yields and functional‐group tolerance.

Formation of C-C bonds from CO2 is a much sought after reaction in organic synthesis. To date, other than C-H carboxylations using stoichiometric amounts of metals, base, or organometallic reagents, little is known about C-C bond formation. In fact, to the best of our knowledge no catalytic methylation of C-H bonds using CO2 and H2 has been reported. Described herein is the combination of CO2 and H2 for efficient methylation of carbon nucleophiles such as indoles, pyrroles, and electron-rich arenes. Comparison experiments which employ paraformaldehyde show similar reactivity for the CO2/H2 system.

Triiron dodecacarbonyl allows for the selective reduction of esters into the corresponding ethers. This protocol has a wide substrate scope. In addition, cholesteryl pelarogonate has been reduced under the reaction conditions with an excellent yield.

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Aromatic ketones are enantioseletively hydrogenated in alcohols containing [RuX{(S,S)-Tsdpen}(eta(6)-p-cymene)] (Tsdpen=TsNCH(C(6)H(5))CH(C(6)H(5))NH(2); X=TfO, Cl) as precatalysts. The corresponding Ru hydride (X=H) acts as a reducing species. The solution structures and complete spectral assignment of these complexes have been determined using 2D NMR ((1)H-(1)H DQF-COSY, (1)H-(13)C HMQC, (1)H-(15)N HSQC, and (1)H-(19)F HOESY). Depending on the nature of the solvents and conditions, the precatalysts exist as a covalently bound complex, tight ion pair of [Ru(+)(Tsdpen)(cymene)] and X(-), solvent-separated ion pair, or discrete free ions. Solvent effects on the NH(2) chemical shifts of the Ru complexes and the hydrodynamic radius and volume of the Ru(+) and TfO(-) ions elucidate the process of precatalyst activation for hydrogenation. Most notably, the Ru triflate possessing a high ionizability, substantiated by cyclic voltammetry, exists in alcoholic solvents largely as a solvent-separated ion pair and/or free ions. Accordingly, its diffusion-derived data in CD(3)OD reflect the independent motion of [Ru(+)(Tsdpen)(cymene)] and TfO(-). In CDCl(3), the complex largely retains the covalent structure showing similar diffusion data for the cation and anion. The Ru triflate and chloride show similar but distinct solution behavior in various solvents. Conductivity measurements and catalytic behavior demonstrate that both complexes ionize in CH(3)OH to generate a common [Ru(+)(Tsdpen)(cymene)] and X(-), although the extent is significantly greater for X=TfO(-). The activation of [RuX(Tsdpen)(cymene)] during catalytic hydrogenation in alcoholic solvent occurs by simple ionization to generate [Ru(+)(Tsdpen)(cymene)]. The catalytic activity is thus significantly influenced by the reaction conditions.

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