Alkyl Formates as Transfer Hydroalkylation Reagents and Their Use in the Catalytic Conversion of Imines to Alkylamines**

Easily accessible via a simple esterification of alcohols with formic acid, alkyl formates are used as a novel class of transfer hydroalkylation reagents, CO₂ acting as a traceless linker. As a proof-of-concept, their reactivity in the transfer hydroalkylation of imines is investigated, using a ruthenium-based catalyst and LiI as promoter to cleave the C−O σ-bond of the formate scaffold. Providing tertiary amines, the reaction displays a divergent regioselectivity compared to previously reported transfer hydroalkylation strategies.     

C---H bond activation of formate on clean and K-covered Ru(001): a theoretical study

An extended Hückel (EH) study is performed on the clusters representing a formate adsorbed on Ru(001) and on in order to investigate the effect of potassium on the selectivity of decomposition of formate on Ru(001). The adsorption geometry and the VSIP (valence state ionization potential) values of EH parameters are determined from ab initio calculations on small clusters. The EH calculation reproduces well the site preference of formate on each surface suggested from experiments. The C---H bond of formate, which is our focus in this study, is calculated to be almost the same on the two surfaces when the molecular plane of formate is perpendicular to the surface; but when the plane is tilted from the surface normal and thus the C---H bond approaches the surface, the C---H bond is weakened to a much higher extent on clean Ru(001) than on K-covered Ru(001). This is in good agreement with the experimental result that the presence of potassium changes the reaction pathway of the decomposition of formate on Ru(001) by suppressing C---H bond cleavage.     

Bismuth and mixed bismuth-lanthanide carboxylates as precursors for pure and Ln-promoted bismuth molybdate catalysts

Several bismuth(III) carboxylates (formate, acetate, propionate, oxalate, lactate) and the analogous tervalent lanthanum, samarium and praseodymium formates and acetates were synthesized and characterized in view of their use as precursors for the formation of bismuth- or lanthanide-based molybdate catalysts upon controlled thermal decomposition on MoO₃ support. Mixed Bi-Ln carboxylates were prepared and used in parallel as precursors for Ln-promoted bismuth molybdate catalysts. Both the nature of the lanthanide element and the calcination temperature were found to determine the formation of specific molybdate-type phases on the support. Detailed examination of these catalysts by X-ray diffraction and FTIR spectroscopy identified -M₂Mo₃O₁₂ phases in Bi- and Pr-containing samples calcined at 823 K, and hexamolybdate phases M₂Mo₆O₂₁ in La- or Sm-containing catalysts calcined at 973 K.     

Synthesis of 2,3,3a,9a‐Tetrahydro‐1H‐cyclopenta[b]quinoxaline‐1,3,4,9‐tetracarboxylate by Cyclization of 1,5‐Bis[(trimethylsilyl)oxy]penta‐1,4‐dienes with Quinoxalines

The cyclization of 1,5‐bis[(trimethylsilyl)oxy]penta‐1,4‐dienes with quinoxalines and chloroformates afforded 2,3,3a,9a‐tetrahydro‐1H‐cyclopenta[b]quinoxaline‐1,3,4,9‐tetracarboxylate.     

Vibrational properties and DFT calculations of formamidine-templated Co and Fe formates

Experimental Raman and IR spectra of [NH₂-CH-NH₂][M(HCOO)₃] (M = Co, Fe), containing formamidinium cations [NH₂-CH-NH₂]⁺ (FMD⁺) were recorded at room temperature. In order to assign the vibrational modes corresponding to the FMD⁺ cation, the three-parameter hybrid B3LYP density functional method has been used with the 6-311G(2d,2p) basis to derive the vibrational wavenumbers (harmonic and anharmonic), infrared intensities and Raman scattering activities of formamidine molecule and FMD⁺ cation. The performed calculations revealed that protonation should affect most significantly the ν(CH), ρ(NH₂), ω(NH₂) and τ(NH₂) modes, which are expected to shift towards higher wavenumbers after protonation.