The asymmetric ruthenium-catalyzed reductive amination employing ammonia and hydrogen to primary amines is described. Here we demonstrate the capability of our catalyst to perform a chemo- and enantioselective process while using simple ammonia gas as a reagent, one of the most attractive and industrially relevant nitrogen sources. The presence of a catalytic amount of ammonium iodide was essential for obtaining good yields and enantioselectivities. The mechanism of this reaction was investigated by DFT and we found a viable pathway that also explains the trend and magnitude of enantioselectivity through the halide series in good agreement with the experimental data. The in-depth investigation of substrate conformers during the reaction turned out to be crucial in obtaining an accurate prediction of the enantioselectivity. Furthermore, we report the crystallographic data of the chiral [Ru(I)H(CO)((S,S)-f-binaphane)(PPh)] complex, which we identified as the most efficient catalyst in our investigation.

By using silver complexes with bulky ligands such as DavePhos or N-heterocyclic carbenes, propargylic alcohols are smoothly converted with CO2 into a unique class of unexplored cyclic alkylidene carbonates. These systems, for the first time, also achieve the direct carboxylative cyclization of primary propargylic alcohols. The silver-DavePhos catalyst is further applied for the bis-carboxylative cyclization of primary propargyl derivatives, thereby providing an effective route to a series of previously inaccessible and industrially relevant α-alkylidene cyclic carbonates.

Several vanadium(V) complexes with either dipic-based or Schiff base ligands were synthesized. The complexes were fully characterized by elemental analysis, IR, H,C, and V NMR spectroscopy, as well as mass spectrometry and X-ray diffraction. Furthermore, they were tested toward their catalytic deperoxidation behavior and a significant difference between 4-heptyl hydroperoxide and cyclohexyl hydroperoxide was observed. In the case of 4-heptyl hydroperoxide, the selectivity toward the corresponding ketone was higher than with cyclohexyl hydroperoxide. DFT calculations performed on the vanadium complex showed that selective decomposition of secondary hydroperoxides with vanadium(V) to yield the corresponding ketone and water is indeed energetically feasible. The computed catalytic path, involving cleavage of the O-O bond, hydrogen transfer, release of ketone/water, and finally addition of hydroperoxide, can proceed without the generation of radical species.

IntroductionNylon 6i so ne of the most widely used polymers and is produced on al arge industrial scale ( % 4million t/a). [1][2][3][4] This importantp olymer has aw ide range of applications, for example in the textile industry in the manufacture of yarn or as thin plastic film for packaging purposes. [2] On an industrial scale, the polymer is produced throughr ing-opening polymerization of e-caprolactam at high temperatures. [1,2,4] The required starting materialf or the synthesis of e-caprolactam is cyclohexanone that reacts with hydroxylamine in ac ondensation reaction to the correspondingc yclohexanone oxime and through an acid-catalyzed Beckmann rearrangement providing the desired ecaprolactam (Scheme 1). [4] The well-established industrial process to obtain cyclohexanone is the autoxidation of cyclohexane, either non-catalyzed or catalyzed by different transition metal compounds such as soluble cobalt catalysts. [5][6][7][8][9][10][11][12][13][14][15] The liquid-phaseo xidationo fc yclohexane is conducted at temperatures up to 130 8Cincombination with highpressures (125-165 8C, 8-15 bar). These conditions are appliedt os horten the retention time to avoid oxidative side reactions. For the same reason, the cyclohexane conversion is limited to 10-12 %p er cycle. [3] One common intermediate in the oxidation procedure is cyclohexyl hydroperoxide which further decomposest oam ixture of the In this study,k nown homogeneous and heterogeneous chromium(VI) catalysts ystems were investigated with respectt o the favored formation of cyclohexanone during the decomposition of cyclohexyl hydroperoxide (CHHP). The focus was on mechanistic studies using differents pectroscopic methods as well as DFT calculations to further optimize the reactionc onditions. As in previous decomposition studies, am echanism via the formation of am etal alkylperoxido intermediate is probable. In situ spectroscopics tudies revealed that in case of both the soluble and insoluble catalyst, the selectived ecomposition happens via an on-radical, non-redox mechanism at the Cr VI stage through the formation of ac yclohexylperoxychromium(-VI) complex.T he proposed mechanism is supported by thorough DFT calculations.

A cooperative methoxy transfer between orthosilicate esters and organotin oxides was developed for the synthesis of various N-alkyl and N-aryl carbamates from carbon dioxide in up to 97% isolated yield. The reaction is highly selective and Nalkylated amines are not observed. Density functional theory calculations of the reaction were performed and, together with NMR observations, a plausible mechanism featuring the catalytic regeneration of dialkyltin dialkoxide is proposed.

The influence of the ligand backbone on the enantioselectivity in the ruthenium-catalyzed direct asymmetric reductive amination of acetophenone with NH 3 and H 2 , using bidentate binaphthyl-substituted phosphine ligands, was investigated in a combined computational and experimental study. A model for the bite angle dependence of the enantiomeric excess (ee) when using diphosphines bearing binaphthyl-groups on the Patoms was developed. This revealed a significant potential for increasing the enantioselectivity, if ligands with a larger bite angle than the previously reported (S,S)-f-binaphane are used. Suitable backbone candidates were selected from more than one million structures provided by the Cambridge Structural Database (CCDC-CSD) and the most promising candidates were synthesized accordingly. Despite all efforts, an increase of the ee was not possible with this approach. The larger backbones resulted in the preference of different ligand coordination modes avoiding the formation of the more strongly enantiodiscriminant substrate pocket between the naphthyl wings.

Jubiläum: Mitte Februar fand die zehnte „CaRLa Winter School“ in Heidelberg statt. Bei der fünftägigen Veranstaltung tauschten sich 40 Doktoranden und Postdoktoranden mit 9 Professoren aus aller Welt und Vertretern der BASF über neue Erkenntnisse der homogenen Katalyse aus. Organisiert wurde die Konferenz von den Leitern des Catalysis Research Laboratorys, Thomas Schaub (BASF) und Stephen Hashmi (Universität Heidelberg).

Im Februar fand die elfte Catalysis Research Laboratory (CaRLa) Winter School am Deutsch‐Amerikanischen Institut in Heidelberg statt. Auf der einwöchigen, von der BASF finanzierten Veranstaltung tauschten sich 40 Doktoranden und Postdocs aus aller Welt mit neun Professoren und Forschern der BASF über homogene Katalyse und organische Synthese aus. Organisatoren der Konferenz sind die Leiter des Katalyseforschunglabors Thomas Schaub (BASF) und A. Stephen K. Hashmi (Universität Heidelberg). Die Universität Heidelberg und die BASF gründeten das Kooperationsprojekt im Jahr 2006; es soll für die Industrie relevante Forschung der homogenen Katalyse vorantreiben.