- Dynamic kinetic resolution of amines by using palladium nanoparticles confined inside the cages of amine-modified MIL-101 and lipase
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Dynamic kinetic resolution (DKR) of amines is an important strategy for the synthesis of chiral drugs and their building blocks; however, improving the matchability of metal-catalyzed racemization and enzymatic resolution is still a task. In this paper, P
- Xu, Sen,Wang, Meng,Feng, Bo,Han, Xinchen,Lan, Zijie,Gu, Huajun,Li, Hexing,Li, Hui
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- Facile one-pot synthesis of unsymmetrical ureas, carbamates, and thiocarbamates from Cbz-protected amines
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A novel one-pot synthesis of unsymmetrical ureas, carbamates and thiocarbamates from Cbz-protected amines has been developed. In the presence of 2-chloropyridine and trifluoromethanesulfonyl anhydride, isocyanates are generated in situ, which facilitate rapid reaction with amines, alcohols, and thiols to afford the corresponding ureas, carbamates and thiocarbamates in high yields.
- Kim, Hee-Kwon,Lee, Anna
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supporting information
p. 7345 - 7353
(2016/08/05)
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- Self-disproportionation of enantiomers of non-racemic chiral amine derivatives through achiral chromatography
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Efficient self-disproportionation of enantiomers of several non-racemic chiral amines was achieved through conversion to N-acetamides and subsequent MPLC using an achiral column. The MPLC of these non-racemic N-acetamide derivatives gave the chart having a clear boundary between two fractions. Thus, in the less polar fraction, remarkable enantiomer enrichment was observed (>99%ee), while the ee of more polar fraction was considerably reduced. The magnitude of the enantiomer enrichments and depletions strongly depended on substituent on the amino group.
- Nakamura, Tsuyoshi,Tateishi, Kaori,Tsukagoshi, Shiori,Hashimoto, Saori,Watanabe, Shotaro,Soloshonok, Vadim A.,Ace?a, José Luis,Kitagawa, Osamu
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experimental part
p. 4013 - 4017
(2012/07/14)
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- Stereoselective amination of chiral benzylic ethers using chlorosulfonyl isocyanate: Total synthesis of (+)-Sertraline
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The stereoselective amination of various chiral benzylic ethers using chlorosulfonyl isocyanate is developed, and the application of this method to the total synthesis of a potent antidepressant, (+)-sertraline, from readily available 1-naphthol is also described (Figure presented).
- Lee, Sang Hwi,Kim, In Su,Li, Qing Ri,Dong, Guang Ri,Jeong, Lak Shin,Jung, Young Hoon
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p. 10011 - 10019
(2012/02/05)
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- Facile preparation of protected benzylic and heteroarylmethyl amines via room temperature Curtius rearrangement
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A step-wise, room temperature procedure for acyl azide formation and the subsequent Curtius rearrangement of phenyl and heteroaryl acetic acids is described. We have developed a protocol for room temperature Curtius rearrangement in MeOH or CHCl3 that provides an improvement over standard conditions, avoiding the use of additives or heat. This room temperature optimization of the Curtius rearrangement prevents the formation of side products often observed with benzylic acids, allowing access to a variety of benzylic and heteroarylmethyl amines.
- Leathen, Matthew L.,Peterson, Emily A.
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supporting information; experimental part
p. 2888 - 2891
(2010/06/14)
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- 1,5-Asymmetric Induction in Squarate Cascades. Conformational Control of Helicity by Chiral Amino Substituants during Conrotatory Octatetraene Cyclization Prior to β-Elimination
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Both the sigmatropic and electrocyclic rearrangement pathways that can arise when a pair of alkenyl anions are added to a squarate ester have high stereochemical demands. The distinction is nontrivial. When cis addition occurs initially, the stereoinduction that materializes at this point is fully transmitted into the product (s). The more commonly observed trans addition exhibits fleeting stereochemical consequences because of rapid equilibration of the octatetraenyl intermediates. In this instance, product distribution is governed by the relative rates of conrotatory cyclization at this advanced stage. Herein reported is a complete dissection of a squarate cascade when a stereogenic center attached to an amino substituent effects 1,5-asymmetric induction prior to β-elimination of the entire fragment. Deuterium labeling permits a direct measure of the contrasting kinetic imbalances associated with the two possible modes of alkenyl anion addition. Furthermore, quantitative analysis of the partitioning experienced by the two helical octatetraenes is readily accomplished. This work constitutes the first example where a complete dynamic profile for these complex processes has been possible. The fact that long-range asymmetric induction has been instrumental in solving the mechanistic puzzle is noteworthy.
- Paquette, Leo A.,Tae, Jinsung
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p. 2022 - 2030
(2007/10/03)
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- Conversion of carbonimidodithioates to carbamates
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Carbonimidodithioates derived from primary amines or α-amino acid esters have been converted to N-benzyloxycarbonyl derivatives under mild conditions by treatment first with sodium benzyl alcoholate and then with water. N-Benzyloxycarbonyl α-amino acids have been generated from the methyl esters by alkaline hydrolysis or from the allyl esters by Pd0-catalysed de-allylation.
- Anbazhagan, Mariappan,Reddy, T. Indrasena,Rajappa, Srinivasachari
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p. 1623 - 1627
(2007/10/03)
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- New asymmetric synthesis of (-)-esermethole
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A new synthesis of (-)-esermethole, based on the asymmetric alkylation at C(3) of racemic 1,3-dimethyl-5-methoxyoxindole (3), is described. The chloroacetyl derivatives of (-)-menthol and (S)-N-methyl-(1-phenylethyl) amine were chosen as chiral alkylating agents and used under different reaction conditions (temperature, solvent and base). In particular, the latter reacted with 3 in toluene at 10°C, in the presence of t-butyllitium, giving (3S,1'S)-N-methyl-N-(1'-phenylethyl)-1,3-dimethyl-5-methoxyoxindol-3-i lacetamide (10) with a 63% d.e.. This intermediate was easily separated from the undesired minor (3R,1'S) diastereomer (11) and converted to (-)-esermethole (99.6% e.e.) in two steps.
- Pallavicini,Valoti,Villa,Resta
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p. 363 - 370
(2007/10/02)
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- Homochiral Amine Synthesis by Baker's Yeast Resolution of a β-Keto Amide: 1-Phenylethylamine
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Preliminary investigation of the resolution potential of baker's yeast reduction of β-keto amides has been carried out with 1-phenylethylamine.Enantiomeric excess was determined by direct comparison of resolved enantiomers with derivatives prepared from c
- Hudlicky, T.,Gillman, Gene,Andersen, Catherine
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p. 281 - 286
(2007/10/02)
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- Improved Chiral Derivatizing Agents for the Chromatographic Resolution of Racemic Primary Amines
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Several 4- and/or 5-aryl-substituted 2-oxazolidones have been prepared and studied as chiral derivatizing agents (CDA) for the chromatographic resolution of chiral primary amines via diastereomeric allophanates.The diastereomeric allophanates derived from either racemic primary amines and cis-4,5-diphenyl-2-oxazolidone-3-carbamyl chloride or racemic isocyanates and cis-4,5-diphenyl-2-oxazolidone show sufficient NMR chemical shift differences and chromatographic separability that this heterocyclic system should prove to be a very useful CDA for the chromatographic resolution and determination of the absolute configuration of a variety of chiral primary amines.The diastereomeric allophanates are readily hydrolyzed to return both chiral components of the allophanates in excellent yield.Both solution and adsorbed conformations of these allophanates are discussed in reference to the determination of the absolute configuration of the allophanates (and hence of the chiral primary amine) from the senses of NMR nonequivalence between and chromatographic elution order of the diastereomers.
- Pirkle, William H.,Simmons, Kirk A.
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p. 2520 - 2527
(2007/10/02)
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