Asymmetric Synthesis of 2-Methyl Cyclohexane Carboxylic Acids by Heterogeneous Catalysis: Mechanistic Aspects

Бессон, М.; Delbecq, Françoise; Gallezot, P.; Neto, Samuel; Pinel, Catherine

doi:10.1002/(sici)1521-3765(20000317)6:6<949::aid-chem949>3.0.co;2-h

Cited by 43 publications

(16 citation statements)

References 10 publications

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“…This stringent requirement is also present in other technological sectors such as fragrances, flavours and agrochemicals. There are a number of different approaches which have been used to create heterogeneous chiral catalysts including: immobilising chiral transition metal complexes at surfaces [2]; attaching chiral auxiliaries to the reactant to induce an asymmetry in the surface reaction [3]; creating intrinsically chiral surfaces in which asymmetric configurations of the reactive surface are displayed [4]; and, finally, adsorbing chiral molecules at achiral solid surfaces to induce asymmetry [5]. The work discussed here directly impinges on the last case, where there are several successful examples of introducing enantioselectivity to heterogeneous reactions by modifying surfaces via the adsorption of chiral organic molecules.…”

Section: Introductionmentioning

confidence: 99%

Assembly of Chiral Amino-Acids at Surfaces from a Single Molecule Perspective: Proline on Cu(110)

et al. 2011

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We present a molecule-by-molecule mapping of an amino-acid monolayer on a Cu(110) surface in which individual molecular configuration, bonding and adsorption footprints are identified. This detailed mapping provides direct evidence that the (4 9 2) structures of enantiopure and racemic proline are governed by a strict heterochiral adsorption footprint template. For the racemic system this has an interesting consequence, namely that it leads to a 2-D random solid solution, a situation that is rarely encountered in 3-D.

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Section: Introductionmentioning

confidence: 99%

Assembly of Chiral Amino-Acids at Surfaces from a Single Molecule Perspective: Proline on Cu(110)

et al. 2011

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“…Di-tert-butyl (2S,4E)-4-[(dimethylamino)methylidene]-5-oxopyrrolidine-1,2-dicarboxylate (4) was prepared from 1 following the literature procedures [5c, 10,11].…”

Section: Methodsmentioning

confidence: 99%

“…Herein, we report the result of this study -a simple parallel solution-phase pyroglutamic acid (1) following the literature procedures [5c, 10,11]. Thus, acid-catalysed esterification of (S)-pyroglutamic acid (1) with tert-butyl acetate gave tert-butyl pyroglutamate (2) [10], which was N-acylated with Boc 2 O in acetonitrile in the presence of catalytic amounts of 4-dimethylaminopyridine (DMAP) to afford di-tert-butyl (2S)-5-oxopyrrolidine-1,2-dicarboxylate (3) [11]. Finally, heating of 3 with one equivalent of tert-butoxy-bis(dimethylamino)methane (Bredereck s reagent, TBDMAM) furnished di-tert-butyl (2S,4E)-4-[(dimethylamino)-methylidene]-5-oxopyrrolidine-1, 2-dicarboxylate (4) in 70 % yield over three steps [5c] (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Parallel Solution-phase Synthesis of (2S,4E)-4-(Arylaminomethylidene)pyroglutamic Acids

Svete

Grošelj²,

Baškovč³

et al. 2010

Zeitschrift Für Naturforschung B

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A library of twelve N(4 )-substituted di-tert-butyl (2S,4E)-4-arylaminomethylidene-5-oxopyrrolidine-1,2-dicarboxylates 6/6 a -l were prepared in 47 -90 % yield by parallel acid-catalysed treatment of di-tert-butyl (2S,4E)-4-[(dimethylamino)methylidene]-5-oxopyrrolidine-1,2-dicarboxylate (4) with anilines 5a -j, ethyl glycinate (5k), and ethyl β -alaninate (3l). Acidolytic deprotection of compounds 6a -c, e -j afforded the corresponding (2S,4E)-4-arylaminomethylidene-5-oxopyrrolidine-2-carboxylic acids 7a -c, e -j in 39 -99 % yield. The configuration around the C=C double bond in the enaminones 6 and 7 was determined by NMR spectroscopy.

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“…The resulting substrate possesses two most stable conformations, as calculated by molecular modeling with a very small energy difference (1 kJ mol −1 ) and a very large interconversion barrier (>1000 kJ mol −1 ), which indicated that there is no possible interconversion between these two conformers [112]. X-ray structural analysis of the substrate indicated that only one conformer was effectively present.…”

Section: Diastereoselective Hydrogenation Of Aromatic Ringsmentioning

confidence: 95%

Diastereoselective Catalysis

Бессон

Pinel

2008

Handbook of Heterogeneous Catalysis

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IntroductionA reaction is referred to as stereoselective when a substrate S, which may yield a series of stereoisomer products (P 1 , P 2 , . . . P n ) gives preferentially -or even exclusively -one of these. Today, the preparation of stereoisomeric compounds is generating tremendous academic and industrial interest. Especially, the synthesis of enantiopure chiral compounds is becoming increasingly important in the production of pharmaceuticals, agrochemicals, fragrances, and flavor substances. Among the different methods used to prepare pure enantiomers, asymmetric catalysis plays an important role, particularly hydrogenation. Currently, two types of asymmetric hydrogenation with solid catalysts are utilized, namely enantioselective and diastereoselective synthesis.In enantioselective hydrogenation, one enantiomer of a chiral product is formed preferentially from a prochiral precursor, the stereoselectivity being induced by a chiral catalyst. Immobilization of very selective metal-ligand complexes and modification of active metals by an adsorbed chiral organic molecule (chiral modifier) have been extensively studied [1]. In some cases, high enantioselectivities approaching 98% enantiomeric excess (e.e.) have been obtained with modified supported metal catalysts. The numerous investigations devoted to the understanding of the mechanism have been summarized in several reviews [1][2][3][4][5]. The most effective catalysts are Ni-tartaric acid, Pt-cinchona, Pd-cinchona and, to a lesser extent, Rh-cinchona systems. The field of reaction types is still limited to a narrow range of asymmetric hydrogenations.The other frequently used catalytic strategy for the synthesis of pure enantiomers is based on diastereoselective hydrogenation. This involves the selective formation of one diastereoisomer by creating a new stereogenic center in a chiral molecule. In this approach, the reaction consists of three simple steps. First, a covalent bond between the prochiral substrate and a chiral moiety (chiral auxiliary) is formed. Then, the diastereoselective hydrogenation is performed over various noble metal catalysts, leading stereoselectively to a new chiral center. This step does not require a chiral catalyst, but the stereogenic center in the chiral auxiliary is able to induce the stereoselectivity. The desired molecule can finally be obtained by selective cleavage of the chiral auxiliary from the product which can be recycled.

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Asymmetric Synthesis of 2-Methyl Cyclohexane Carboxylic Acids by Heterogeneous Catalysis: Mechanistic Aspects

Cited by 43 publications

References 10 publications

Assembly of Chiral Amino-Acids at Surfaces from a Single Molecule Perspective: Proline on Cu(110)

Assembly of Chiral Amino-Acids at Surfaces from a Single Molecule Perspective: Proline on Cu(110)

Parallel Solution-phase Synthesis of (2S,4E)-4-(Arylaminomethylidene)pyroglutamic Acids

Diastereoselective Catalysis

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