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Chiral Aldehyde (chiral + aldehyde)
Selected AbstractsDiastereoselective Additions of Chiral Vinylzinc Reagents to ,-Chiral Aldehydes.CHEMINFORM, Issue 24 2004James A. Marshall Abstract For Abstract see ChemInform Abstract in Full Text. [source] Gianfranco Cainelli, Paola Galletti, Silvia Pieraccini, Arianna Quintavalla, Daria Giacomini, Gian Piero Spada, "Chiral aldehydes in hydrocarbons: Diastereoselective nucleophilic addition, NMR, and CD spectroscopy reveal dynamic solvation effects,"Chirality(2004) 16(1) 50,56CHIRALITY, Issue 4 2004Article first published online: 16 MAR 200 The original article to which this Erratum refers was published in Chirality (2004) 16(1) 50,56 Correction to the article: "Chiral Aldehydes in Hydrocarbons: Diastereoselective Nucleophilic Addition, NMR, and CD Spectroscopy Reveal Dynamic Solvation Effects" by Gianfranco Cainelli, Paola Galletti, Silvia Pieraccini, Arianna Quintavalla, Daria Giacomini, and Gian Piero Spada, Chirality 16:50,56, 2004. [source] Regioselective and Enantioselective Hydroformylation of DialkylacrylamidesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Abstract Dimethylacrylamide can be hydroformylated with very high chemo- and regioselectivity. Asymmetric hydroformylation of this substrate is possible, provided steps are taken to minimise racemisation of the aldehyde products, and this work demonstrates the effect of various conditions and variables on racemisation. Using the Landis diazaphospholane ligands up to 68% ee can be realised under very mild conditions. Other dialkylacrylamides were also hydroformylated under mild conditions giving similar or better enantioselectivities, including the Weinreb amide of acrylic acid (71% ee), and the asymmetric hydroformylation of diethylacrylamide producing the chiral aldehyde with up to 82% ee. [source] Dependence of the wittig reaction mechanism on the environment and on the substituents at the aldehyde group and at the phosphonium ylideINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2010Giuliano Alagona Abstract The B3P86/6-31G* mechanistic results for the Wittig reaction of acetaldehyde, CH3CHO, in vacuo and in tetrahydrofuran (THF) solution in the IEF-PCM framework, with an unsubstituted trimethylphosphonium or triphenylphosphonium ylide, that is Me3PCH2 or Ph3PCH2, have been compared to those recently obtained at the same levels for the reaction of Ph3PCH2 with a bulky chiral aldehyde, (2S,3R)-2,4-dimethyl-3-pyrrol-1-yl-pentanal [TCA (DOI: 10.1007/s00214-009-0521-4)], here named sys for short. The two model systems show distinct, but similar, behaviors that however differ from the large system one. In particular, betaine-type intermediates are not located in vacuo when Me3PCH2 is used, while only a gauche betaine is obtained using Ph3PCH2; the relevant barriers are anyway smaller than those found for sys. Conversely, in THF, the concerted and stepwise mechanisms are both represented and show TS1/TSb barriers, which are negligibly small for sys. Thus, in contrast to assessed literature, models with methyl groups in place of phenyl rings and branched aldehyde chains show a different behavior from realistic systems and prevent inferring general rules from their use, suggesting to resort to Ph3PCH2 whose results in vacuo and in THF are closer to sys. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Towards the Synthesis of Highly Functionalized Chiral ,-Amino Nitriles by Aminative Cyanation and Their Synthetic ApplicationsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2006Luca Bernardi Abstract The cyanobis(dibenzylamino)borane-mediated transformation of chiral aldehydes into the corresponding ,-amino nitriles is described. Starting from these compounds short synthetic routes can be envisaged for obtaining diastereomerically pure functionalized 1,2-diamines and hydroxylated ,-amino acids that are of interest as core key units of biologically active substances or as potential ligands for asymmetric catalysis. The stereochemical outcome of the aminative cyanation reaction is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Modular Chiral Bidentate Phosphonites: Design, Synthesis, and Application in Catalytic Asymmetric Hydroformylation ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2008Baoguo Zhao Dr. Abstract A new class of C2 -symmetric chiral bidentate phosphonite ligands has been synthesized in moderate to good yields from readily available starting materials. Application of these air-stable chiral phosphonites in the RhI -catalyzed asymmetric hydroformylation of styrene derivatives, vinyl acetate, and allyl cyanide afforded the corresponding chiral aldehydes with high regio- and enantioselectivities under mild reaction conditions. The modular nature of the ligands allows fine-tuning of the selectivities through judicious modifications of the substituents on the ligand backbone. X-ray structural analysis of the catalyst precursor suggested that the steric hindrance caused by the protruding remote substituents of the ligands into the vicinity of the metal center might be an important factor for the enantio-control of the reaction, whereas the sense of asymmetric induction can be rationalized on the basis of a trigonal-bipyramidal transition state diagram. [source] | ||||||||||