49642-47-9Relevant articles and documents
Substrate-modifier but not catalyst-modifier: Heterogeneous hydrogenation of C=O and C=C using cinchonidine
Solladié-Cavallo,Marsol,Hoernel,Garin
, p. 4741 - 4744 (2001)
Literature results and our own, concerning hydrogenation of ethyl pyruvate and 2-methyl pentenoic acid over Al2O3-supported platinum and palladium using cinchonidine (CD), indicate that CD activates pyruvate (through enol formation) and modifies the unsaturated acid (salt formation), but not the catalyst, and that CD may even poison the catalyst (palladium more than platinum). Therefore, the modifier's properties must fit the substrate's properties and not be a catalyst poison, the best sequence for addition of the reactants being: first a mixture of substrate/CD and then the supported Pt and/or Pd catalyst.
Enantioselective rearrangement coupled with water addition: Direct synthesis of enantiomerically pure saturated carboxylic acids from α,β-unsaturated aldehydes
Winkler, Till,Groeger, Harald,Hummel, Werner
, p. 961 - 964 (2014/05/06)
A novel type of organic synthesis enabling a direct one-pot transformation of α,β-unsaturated aldehydes into saturated carboxylic acids is described. As sole reagent water is required, which is integrated completely in the product. This tandem process proceeds under perfect atom economy, and consists of two coupled redox biotransformations without the need of external co-substrates for cofactor regeneration. The initial reduction of the C=C double bond of an α,β-unsaturated aldehyde is catalyzed by an NADPH-dependent ene reductase, leading to the formation of the saturated aldehyde and NADP+. The aldehyde intermediate is then oxidized to the corresponding carboxylic acid, thus regenerating NADPH for the next catalytic cycle. When using prochiral α,β-unsaturated aldehydes as substrates the corresponding carboxylic acids are formed enantioselectively with up to >99 % ee as demonstrated, e.g., for the transformation of citral to (S)-citronellic acid. Making a splash with citral: The direct one-pot transformation of α,β-unsaturated aldehydes to saturated carboxylic acids using only water proceeds with perfect atom economy. This tandem process involves two redox biotransformations without need of additional external co-substrates for cofactor regeneration. With, for example, citral as prochiral α,β-unsaturated aldehyde, transformation to (S)-citronellic acid proceeds with >99 % conversion and >99 % ee.
Enantioselective hydrogenation of α,β-unsaturated carboxylic acids on Pd nanocubes
Chen, Chunhui,Zhan, Ensheng,Ta, Na,Li, Yong,Shen, Wenjie
, p. 2620 - 2626 (2013/09/24)
Pd nanocubes of 6-19 nm in size were synthesized using a seeded growth method and examined for enantioselective hydrogenation of α,β- unsaturated carboxylic acids. It was found that the Pd nanocubes had two types of active sites on the planes and at the edges, respectively. Small nanocubes having a higher edge/plane ratio were more active in enantioselective hydrogenation of α,β-unsaturated carboxylic acids, but afforded a lower enantioselectivity because their sharp edges could not offer stable adsorption of the chiral modifier and the reaction intermediates. In contrast, large nanocubes with a higher fraction of flat planes provided a higher enantioselectivity but a much lower activity.
Synthesis and absolute configuration of (S)-(+)-chichimol ketone: the defensive secretion of walking stick Agathemera elegans
Espinoza-Moraga, Marlene,Cornejo-Morales, Roxana,Santos, Leonardo Silva
body text, p. 1062 - 1064 (2009/09/30)
The first enantioselective synthesis of chichimol ketone (4-methyl-1-hepten-3-one) is described and the absolute configuration of the main semiochemical compound is determined as having an (S)-configuration. The synthesis features the use of a ruthenium c
