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Relevant bibliographies by topics / Amine; Chiral auxiliary

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Academic literature on the topic 'Amine; Chiral auxiliary'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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Journal articles on the topic "Amine; Chiral auxiliary"

1

Ross, Günther, та Ivar Ugi. "Stereoselective syntheses of α-amino acid and peptide derivatives by the U-4CR of 5-desoxy-5-thio-D-xylopyranosylamine". Canadian Journal of Chemistry 79, № 12 (2001): 1934–39. http://dx.doi.org/10.1139/v01-186.

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Since 1961, the synthesis of α-amino acids derivatives by the four-component reaction of isocyanides (U-4CR) as a one-pot reaction has been developed. Only recently it was found that a variety of these α-amino acids compounds can be formed stereoselectively by the U-4CR using 1-amino-5-deoxy-5-thio-2,3,4-tri-O-isobutanoyl-β-D-xylopyranose as the amine component. The stereoselectivity inducing auxiliary 5-desoxy-5-thio-D-xylopyranosyl group of the so-formed products can be replaced selectively by hydrogen.Key words: stereoselective U-4CR, chiral amine component, amino carbohydrate, α-amino acid

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Morandini, Anna, Arianna Rossetti, and Alessandro Sacchetti. "Lipase-Catalyzed Kinetic Resolution of Alcohols as Intermediates for the Synthesis of Heart Rate Reducing Agent Ivabradine." Catalysts 11, no. 1 (2021): 53. http://dx.doi.org/10.3390/catal11010053.

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Ivabradine (Corlanor®), is a chiral benzocycloalkane currently employed and commercialized for the treatment of chronic stable angina pectoris and for the reduction in sinus tachycardia. The eutomer (S)-ivabradine is usually produced via chiral resolution of intermediates, by employing enantiopure auxiliary molecules or through preparative chiral HPLC separations. Recently, more sustainable biocatalytic approaches have been reported in literature for the preparation of the chiral amine precursor. In this work, we report on a novel biocatalyzed pathway, via a resolution study of a key alcohol i

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3

Nugent, Thomas C., Richard Vaughan Williams, Andrei Dragan, Alejandro Alvarado Méndez, and Andrei V. Iosub. "An investigation of the observed, but counter-intuitive, stereoselectivity noted during chiral amine synthesis via N-chiral-ketimines." Beilstein Journal of Organic Chemistry 9 (October 15, 2013): 2103–12. http://dx.doi.org/10.3762/bjoc.9.247.

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The default explanation for good to high diastereomeric excess when reducing N-chiral imines possessing only mediocre cis/trans-imine ratios (>15% cis-imine) has invariably been in situ cis-to-trans isomerization before reduction; but until now no study unequivocally supported this conclusion. The present study co-examines an alternative hypothesis, namely that some classes of cis-imines may hold conformations that erode the inherent facial bias of the chiral auxiliary, providing more of the trans-imine reduction product than would otherwise be expected. The ensuing experimental and computa

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Talsi, Evgenii P., Anna A. Bryliakova, Roman V. Ottenbacher, Tatyana V. Rybalova, and Konstantin P. Bryliakov. "Chiral Autoamplification Meets Dynamic Chirality Control to Suggest Nonautocatalytic Chemical Model of Prebiotic Chirality Amplification." Research 2019 (November 4, 2019): 1–9. http://dx.doi.org/10.34133/2019/4756025.

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Oxidative kinetic resolution of 1-phenylethanol in the presence of manganese complexes, bearing conformationally nonrigid achiral bis-amine-bis-pyridine ligands, in the absence of any exogenous chiral additives, is reported. The only driving force for the chiral discrimination is the small initial enantiomeric imbalance of the scalemic (nonracemic) substrate: the latter dynamically controls the chirality of the catalyst, serving itself as the chiral auxiliary. In effect, the ee of 1-phenylethanol increases monotonously over the reaction course. This dynamic control of catalyst chirality by the

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5

Katagiri, Toshimasa, Naomi Iguchi, Tomomi Kawate, Satoshi Takahashi, and Kenji Uneyama. "Trifluoromethylated amino alcohol as chiral auxiliary for highly diastereoselective and fast Simmons–Smith cyclopropanation of allylic amine." Tetrahedron: Asymmetry 17, no. 8 (2006): 1157–60. http://dx.doi.org/10.1016/j.tetasy.2006.04.031.

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Zimuwandeyi, Memory, Manuel A. Fernandes, Amanda L. Rousseau, and Moira L. Bode. "Total synthesis of ent-pavettamine." Beilstein Journal of Organic Chemistry 17 (June 10, 2021): 1440–46. http://dx.doi.org/10.3762/bjoc.17.99.

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Pavettamine, a plant toxin first isolated from Pavetta harborii in 1995, was previously identified as a polyamine with C2 symmetry and a 1,3-syn-diol moiety on a C10 carbon backbone – one of very few substituted polyamines to be isolated from nature. Its absolute configuration was later established by our first reported total synthesis in 2010. Herein we report the first total synthesis of the enantiomer of pavettamine, ent-pavettamine. The symmetrical structure of the molecule allows for the synthesis of a common C5 fragment that can be divergently transformed into two synthons for later conv

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7

Wosińska-Hrydczuk, Marzena, and Jacek Skarżewski. "2-Oxiranyl-pyridines: Synthesis and Regioselective Epoxide Ring Openings with Chiral Amines as a Route to Chiral Ligands." Heteroatom Chemistry 2019 (October 9, 2019): 1–12. http://dx.doi.org/10.1155/2019/2381208.

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New epoxides, derivatives of pyridine, 2,2′-bipyridine, and 1,10-phenanthroline, were synthesized from the respective α-methylazaarenes. The obtained racemic 2-oxiranyl-azaarenes along with styrene oxide and trans-stilbene oxide were submitted to the ring opening with chiral primary amines as a chiral auxiliary. The most effective reaction was run in the presence of Sc(OTf)3/diisopropylethylamine for 7 days at 80°C, affording a good yield of the amino alcohols. Except for styrene oxide which gave both α- and β-amino alcohols, the reactions led regioselectively to the corresponding diastereomer

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8

Pichler, Mathias, Johanna Novacek, Raphaël Robiette, et al. "Asymmetric syntheses of three-membered heterocycles using chiral amide-based ammonium ylides." Organic & Biomolecular Chemistry 13, no. 7 (2015): 2092–99. http://dx.doi.org/10.1039/c4ob02318h.

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9

Han, Jianlin, Ryosuke Takeda, Xinyi Liu, et al. "Preparative Method for Asymmetric Synthesis of (S)-2-Amino-4,4,4-trifluorobutanoic Acid." Molecules 24, no. 24 (2019): 4521. http://dx.doi.org/10.3390/molecules24244521.

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Enantiomerically pure derivatives of 2-amino-4,4,4-trifluorobutanoic acid are in great demand as bioisostere of leucine moiety in the drug design. Here, we disclose a method specifically developed for large-scale (>150 g) preparation of the target (S)-N-Fmoc-2-amino-4,4,4-trifluorobutanoic acid. The method employs a recyclable chiral auxiliary to form the corresponding Ni(II) complex with glycine Schiff base, which is alkylated with CF3–CH2–I under basic conditions. The resultant alkylated Ni(II) complex is disassembled to reclaim the chiral auxiliary and 2-amino-4,4,4-trifluorobutanoic aci

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Brittain, William D. G., Brette M. Chapin, Wenlei Zhai, et al. "The Bull–James assembly as a chiral auxiliary and shift reagent in kinetic resolution of alkyne amines by the CuAAC reaction." Organic & Biomolecular Chemistry 14, no. 46 (2016): 10778–82. http://dx.doi.org/10.1039/c6ob01623e.

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The Bull–James boronic acid assembly is used simultaneously as a chiral auxiliary for kinetic resolution and as a chiral shift reagent for in situ enantiomeric excess (ee) determination by <sup>1</sup>H NMR spectroscopy.

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Dissertations / Theses on the topic "Amine; Chiral auxiliary"

1

Cantrill, Alexander A. "Synthetic studies of N-diphenylphosphinyl aziridines." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243672.

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Buston, Jonathan Edward Hugh. "Asymmetric Meisenheimer rearrangements." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361334.

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Parr, Nigel. "Asymmetric #alpha#-amino acid synthesis." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302251.

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Kim, Shang U. "SYNTHETIC EFFORTS TOWARD FUMONISIN via AMINO ACID SCHIFF BASE METHODOLOGY." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193674.

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Synthetic efforts toward fumonisin analog were described. These are accomplished via amino acid Schiff base methodology. These efforts can be divided three major phases. First, tandem reductive alkylation with DIBAL/TRIBAL and different types of organo-lithium or Grignard nucleophiles provided threo-amino alcohol with excellent stereoselecitivites (2-27:1). The reductive alkylation utilized most hydrocarbon nucleophiles, e.g. alkyl-, vinyl-, alkenyl-, phenyl-, and dienyl-, and afforded high selectivites unless donor solvents (e.g. THF and Et2O) were used. Second, syntheses of the protected thr

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Mellem, Kevin T. "On the Development of Pseudoephenamine and Its Applications in Asymmetric Synthesis." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11227.

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Pseudoephedrine is well established as a chiral auxiliary in the alkylation of amide enolates to form tertiary and quaternary carbon stereocenters. However, due to its facile transformation into the illegal narcotic methamphetamine, pseudoephedrine is either illegal or highly regulated in many countries, which limits its use in academic and industrial settings. To address this issue, pseudoephenamine has been developed as a replacement for pseudoephedrine in organic synthesis. This new auxiliary suffers no regulatory issues and exhibits several practical advantages over pseudoephedrine, includ

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Kanazawa, Alice Misa. "Nouvelles synthèses de chaînes latérales du taxotère et du taxol et synthèses du (+ou-)- et (-)-homogynolide-A." Grenoble 1, 1994. http://www.theses.fr/1994GRE10008.

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Le taxol et le taxotere sont deux composes qui presentent des activites antitumorales assez remarquables contre plusieurs types de cancers. La synthese partielle en utilisant un produit naturel abondant et les chaines laterales correspondantes est la strategie de choix actuelle pour l'obtention de facon efficace de ces deux composes. Un des interets majeurs du laboratoire consiste a trouver de nouvelles methodes de synthese de ces chaines (surtout du taxotere) sous forme enantiomeriquement pure. Au cours de ce travail nous avons effectue, dans un premier temps, une synthese courte et directe (

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Ho, Pei-Hua, and 何珮華. "1.Pronounced Effects of Crystal Structures on Intramolecular Electron Transfer in Mixed-Valence Biferrocenium Cations: Structural, EPR, and 57Fe Mössbauer Characteristics2.Ferrocene Amine Derivative as Chiral Auxiliary in Regioselective Synthesis of." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/87247927787910826058.

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8

Lin, Kuan-Wen, and 林寬玟. "Asymmetric synthesis of Dihydroxyheliotridane employing Ketopinic amide as chiral auxiliary." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/55285214853657375733.

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Chang, Ya-Chun, та 張雅鈞. "Asymmetric Synthesis of (+)-α-Allokainic acid Employing Ketopinic Amide as Chiral Auxiliary". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8466q4.

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碩士<br>國立清華大學<br>化學系所<br>105<br>This thesis describes the application of imine 135 that derived from the condensation of ketopinic amide 168, a chiral auxiliary, and tert-butyl glycinate 171 in the synthesis of pyrrolidine alkaloids. Asymmetric Michael addition of imine 135 with α,β-unsaturated ester 149 afforded adduct 159 as a diastereomeric mixture (>20 : 1). Transamination of adduct 159, followed by cyclization provided lactam 179. The construction of C4 stereogenic center was achieved by aldol reaction of Boc-protected lactam 179 with activated acetone. Further functional group transformat

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李武哲. "Asymmetric Synthesis of (+)-α-Allokainic acid Employing Ketopinic Amide as Chiral Auxiliary". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/zhpkqp.

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碩士<br>國立清華大學<br>化學系<br>102<br>This study is the application of camphor derivatives ketopinic amide 126 as a chiral auxiliary in the synthesis of pyrrolidine alkaloids. Condensation of ketopinic amide 126 with tert-butyl glycinate (128) provided imine 109. Compound 119 could be obtained via asymmetric Michael addition of imine 109 with α,β-unsaturated ester 118. Hydrolysis of compound 119 to remove the chiral auxiliary followed by cyclization to afford lactam 120, and then via aldol reaction can construct the chiral center to provide compound 145 which can be an impor

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Book chapters on the topic "Amine; Chiral auxiliary"

1

Taber, Douglass. "Stereocontrolled Construction of Arrays of Stereogenic Centers." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0043.

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The Sharpless osmium-catalyzed asymmetric dihydroxylation is widely used. Lawrence Que, Jr. of the University of Minnesota designed (Angew. Chem. Int. Ed. 2008, 47, 1887) a catalyst with the inexpensive Fe that appears to be at least as effective, converting 1 to 2 in high ee. In an alternative approach, Bernd Plietker of the Universität Stuttgart used (J. Org. Chem. 2008, 73, 3218) chiral auxiliary control to direct dihydroxylation. The diastereomers of 4 were readily differentiated. Defined arrays of stereogenic centers can also be constructed by homologation. Armando Córdova of Stockholm University condensed (Tetrahedron Lett. 2008, 49, 803) dihydroxy acetone 6 with an in situ generated imine 5 to give the amino diol 8. In parallel work, Carlos F. Barbas III of Scripps/La Jolla described (Organic Lett. 2008, 10, 1621) a related addition to aldehydes. Magnus Rueping of University Frankfurt found (Organic Lett. 2008, 10, 1731) conditions for the addition of a nitro alkane such as 9 to the imine 10 to give 11. Keiji Maruoka of Kyoto University devised (J. Am. Chem. Soc. 2008, 130, 3728) a chiral amine that mediated the enantioselective iodination of aldehydes such as 12. Direct cyanohydrin formation delivered 13 in high de and ee. The epoxide 14 is readily prepared in high ee from crotyl alcohol. Barry M. Trost of Stanford University found (Organic Lett. 2008, 10, 1893) that 14 could be opened with 15, to give 16 with high regio- and diastereocontrol. Jérôme Blanchet of the Université de Caen Basse-Normandie optimized (Organic Lett. 2008, 10 , 1029) the amine 19 as a catalyst for the condensation of ketones such as 17 with the imine 18, to give 20. Michael J. Krische of the University of Texas has explored (J. Am. Chem. Soc. 2008, 130, 2746) the in situ generation of chiral Rh enolates from enones such as 21, and the subsequent aldol condensation with aldehydes such as 22. Shu Kobayashi of the University of Tokyo found (Organic Lett. 2008, 10, 807) that the conjugate addition of 25 to 24 mediated by a chiral Ca catalyst proceeded with high enantiocontrol at both of the newly formed stereogenic centers, to give 26.

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2

Taber, Douglass. "The Carter Synthesis of (-)-Lycopodine." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0099.

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Rich G. Carter of Oregon State University described (J. Am. Chem. Soc. 2008, 130, 9238) the first enantioselective synthesis of the Lycopodium alkaloid (-)-lyopodine 3. A key step in the assembly of 3 was the diastereoselective intramolecular Michael addition of the keto sulfone of 1 to the enone, leading to the cyclohexanone 2. The key cyclization substrate 1 bore a single secondary methyl group. While that could have been derived from a natural product, it was operationally easier to effect chiral auxiliary controlled conjugate addition to the crotonyl amide 4, leading, after methoxide exchange, to the ester 5. The authors reported that double deprotonation with LiTMP gave superior results, vs. LDA or BuLi, in the condensation of 6 with 5 to give 7. Metathesis with pentenone 8 gave the intramolecular Michael substrate 1. The authors thought that they would need a chiral catalyst to drive the desired stereocontrol in the cyclization of 1 to 2. As a control, they tried an achiral base first, and were pleased to observe the desired diastereomer crystallize from the reaction mixture in 89% yield. The structure of 2 was confirmed by X-ray crystallography. To prepare for the intramolecular Mannich condensation, the azide was reduced to give the imine, and the methyl ketone was converted to the silyl enol ether. Under Lewis acid conditions, the sulfonyl group underwent an unanticipated 1,3-migration, to give 11. Cyclization of 12 then delivered the crystalline 14. Reduction converted 14 to the known (in racemic form) ketone 15. To complete the synthesis, the amine 15 was alkylated with 16 to give the alcohol 17. Oppenauer oxidation followed by aldol condensation delivered the cyclized enone, that was reduced with the Stryker reagent to give (-)-Lycopodine 3. Both the cyclization of 1 to 2 and the cyclization of 9 to 14 are striking. It may be that the steric demand of the phenylsulfonyl group destabilizes the competing transition state for the cyclization of 1.

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Taber, Douglass. "Enantioselective Construction of Alkylated Stereogenic Centers." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0040.

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Carsten Bolm of RWTH Aachen developed (Angew. Chem. Int. Ed. 2008, 47, 8920) an Ir catalyst that effected hydrogenation of trisubstituted enones such as 1 with high ee. Benjamin List of the Max-Planck-Institut Mülheim devised (J. Am. Chem. Soc. 2008, 130, 13862) an organocatalyst for the enantioselective reduction of nitro acrylates such as 3 with the Hantzsch ester 4. Gregory C. Fu of MIT optimized (J. Am. Chem. Soc. 2008, 130, 12645) a Ni catalyst for the enantioselective arylation of propargylic halides such as 6. Both enantiomers of 6 were converted to the single enantiomer of 8. Michael C. Willis of the University of Oxford established (J. Am. Chem. Soc. 2008, 130, 17232) that hydroacylation with a Rh catalyst was selective for one enantiomer of the allene 9, delivering 11 in high ee. Similarly, José Luis García Ruano of the Universidad Autónoma de Madrid found (Angew. Chem. Int. Ed. 2008, 47, 6836) that one enantiomer of racemic 13 reacted selectively with the enantiomerically- pure anion 12, to give 14 in high diastereomeric excess. Ei-chi Negishi of Purdue University described (Organic Lett. 2008, 10, 4311) the Zr-catalyzed asymmetric carboalumination (ZACA reaction) of the alkene 15 to give the useful chiron 16. David W. C. MacMillan of Princeton University developed (Science 2008, 322, 77) an intriguing visible light-powered oxidation-reduction approach to enantioselective aldehyde alkylation. The catalytic chiral secondary amine adds to the aldehyde to form an enamine, that then couples with the radical produced by reduction of the haloester. Two other alkylations were based on readily-available chiral auxiliaries. Philippe Karoyan of the Université Pierre et Marie Curie observed (Tetrahedron Lett . 2008, 49, 4704) that the acylated Oppolzer camphor sultam 20 condensed with the Mannich reagent 21 to give 22 as a single diastereomer. Andrew G. Myers of Harvard University developed the pseudoephedrine chiral auxiliary of 23 to direct the construction of ternary alkylated centers. He has now established (J. Am. Chem. Soc. 2008, 130, 13231) that further alkylation gave 24, having a quaternary alkylated center, in high diastereomeric excess.

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Taber, Douglass F. "C–N Ring Construction: The Hattori Synthesis of (+)-Spectaline." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0056.

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Magnus Rueping of RWTH Aachen University found (Chem. Commun. 2015, 51, 2111) that under Fe catalysis, a Grignard reagent would couple with the iodoazetidine 1 to give the substituted azetidine 2. Timothy F. Jamison of MIT established (Chem. Eur. J. 2015, 21, 7379) a protocol for converting 3, readily available from commercial homoserine lactone, to the alkylated azetidine 4. Long-Wu Ye of Xiamen University used (Chem. Commun. 2015, 51, 2126) a gold catalyst to cyclize 5, readily prepared in high ee, to the versatile ene sulfonamide 6. Chang- Hua Ding and Xue-Long Hou of the Shanghai Institute of Organic Chemistry added (Angew. Chem. Int. Ed. 2015, 54, 1604) the racemic aziridine 7 to the enone 8 to give the pyrrolidine 9 in high ee. Arumugam Sudalai of the National Chemical Laboratory employed (J. Org. Chem. 2015, 80, 2024) proline as an organocatalyst to mediate the addition of 11 to 10, leading to the pyrrolidine 12. Aaron D. Sadow of Iowa State University developed (J. Am. Chem. Soc. 2015, 137, 425) a Zr catalyst for the enantioselective cyclization of the prochiral 13 to 14. Masahiro Murakami of Kyoto University devised (Angew. Chem. Int. Ed. 2015, 54, 7418) a Rh catalyst for the enantioselective ring expansion of the photocyclization product of 15 to the enamine 16. Sebastian Stecko and Bartlomiej Furman of the Polish Academy of Sciences reduced (J. Org. Chem. 2015, 80, 3621) the carbohydrate-derived lactam 17 with the Schwartz reagent to give an intermediate that could be coupled with an isonitrile, leading to the amide 18. Lei Liu of Shandong University oxidized (Angew. Chem. Int. Ed. 2015, 54, 6012) the alkene 19 in the presence of 20 to give 21. Tomislav Rovis of Colorado State University optimized (J. Am. Chem. Soc. 2015, 137, 4445) a Zn catalyst for the addition of 22 to the nitro alkene 23, leading, after reduction, to the piperidine 24. Carlos del Pozo and Santos Fustero of the Universidad de Valencia used (Org. Lett. 2015, 17, 960) a chiral auxiliary to direct the cyclization of 25 to the bicyclic amine 26. In another illustration of the use of microwave irradiation to activate amide bond rotation, G. Maayan of Technion showed (Org. Lett. 2015, 17, 2110) that 27 could be cyclized efficiently to the medium ring lactam 28.

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Taber, Douglass F. "Alkaloid Synthesis: (+)-Deoxoprosopinine (Krishna), Alkaloid (–)-205B (Micalizio), FR901483 (Huang), (+)-Ibophyllidine (Kwon), (–)-Lycoposerramine-S (Fukuyama), (±)-Crinine (Lautens)." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0060.

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Palakodety Radha Krishna of the Indian Institute of Chemical Technology observed (Synlett 2012, 2814) high stereocontrol in the addition of allyltrimethylsilane to the cyclic imine derived from 1. The product piperidine 2 was carried onto (+)-deoxoprosopinine 3. Glenn C. Micalizio of Scripps Florida condensed (J. Am. Chem. Soc. 2012, 134, 15237) the amine 4 with 5. The ensuing intramolecular dipolar cycloaddition led to 6, which was carried onto the Dendrobates alkaloid (–)-205B 7. Pei-Qiang Huang of Xiamen University showed (Org. Lett. 2012, 14, 4834) that the quaternary center of 9 could be established with high diastereoselectivity by activation of the lactam 8, then sequential addition of two different Grignard reagents. Subsequent stereoselective intramolecular aldol condensation led to FR901843 10. More recently, Professor Huang, with Hong-Kui Zhang, also of Xiamen University, published (J. Org. Chem. 2013, 78, 455) a full account of this work. In an elegant application of the power of phosphine-catalyzed intermolecular allene cycloaddition, Ohyun Kwon of UCLA added (Chem. Sci. 2012, 3, 2510) 12 to the imine 11 to give 13. The cyclization elegantly set two of the four stereogenic centers of (+)-ibophyllidine 14. Tohru Fukuyama of the University of Tokyo initiated (Angew. Chem. Int. Ed. 2012, 51, 11824) a cascade cyclization between the enone 15 and the chiral auxiliary 16. The product lactam 17 was carried onto (–)-lycoposerramine-S 18. Mark Lautens explored (J. Am. Chem. Soc. 2012, 134, 15572) the utility of the intramolecular aryne ene reaction, as illustrated by the cyclization of 19 to 20. Oxidation cleavage of the vinyl group of 20 followed by an intramolecular carbonyl ene reaction led to (±)-crinine 21.

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Seco, Josi M., Emilio Quiqoa, and Ricardo Riguera. "The Theoretical Basis for Assignment by NMR." In The Assignment of the Absolute Configuration by NMR using Chiral Derivatizing Agents. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780199996803.003.0004.

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The nuclear magnetic resonance (NMR) spectra of two enantiomers are identical. Thus, the first step in using NMR to distinguish between two enantiomers should be to produce different spectra that eventually can be associated with their different stereochemistry (i.e., the assignment of their absolute configuration). Therefore, it is necessary to introduce a chiral reagent in the NMR media. There are two ways to address this problem. One is to use a chiral solvent, or a chiral agent, that combines with each enantiomer of the substrate to produce diastereomeric complexes/associations that lead to different spectra. This is the so-called chiral solvating agent (CSA) approach; it will not be further discussed here [33–34]. The second approach is to use a chiral auxiliary reagent [13–15] (i.e., a chiral derivatizing agent; CDA) that bonds to the substrate by a covalent linkage. Thus, in the most general method, the two enantiomers of the auxiliary CDA react separately with the substrate, giving two diastereomeric derivatives whose spectral differences carry information that can be associated with their stereochemistry. The CDA method that employs arylalcoxyacetic acids as auxiliaries is the most frequently used. It can be applied to a number of monofunctionals [14–15] (secondary alcohols [35–43], primary alcohols [44–46], aldehyde [47] and ketone cyanohydrins [48–49], thiols [50–51], primary amines [52–56], and carboxylic acids [57–58]), difunctional [13] (sec/sec-1,2-diols [59–61], sec/sec-1,2-amino alcohols [62], prim/sec-1,2-diols [63–65], prim/sec-1,2-aminoalcohols, and sec/prim-1,2-aminoalcohols [66–68]), and trifunctional (prim/sec/sec-1,2,3-triols [13, 69–70]) chiral compounds. Its scope and limitations are well established, and its theoretical foundations are well known, making it a reliable tool for configurational assignment. Figure 1.1 shows a summary of the steps to be followed for the assignment of absolute configuration of a chiral compound with just one asymmetric carbon and with substituents that, for simplicity, are assumed to resonate as singlets. Step 1 (Figure 1.1a): A substrate of unknown configuration (?) is separately derivatized with the two enantiomers of a chiral auxiliary reagent, (R)-Aux and (S)-Aux, producing two diastereomeric derivatives.

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Taber, Douglass. "Intermolecular and Intramolecular Diels-Alder Reactions: Platencin (Banwell), Platensimycin (Matsuo), (-)-Halenaquinone (Trauner), ( + )-Cassaine (Deslongchamps)." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0079.

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José Barluenga of the Universidad de Oviedo described (Organic Lett. 2008, 10, 4469) a powerful route from lithiated arenes such as 1 to the benzocyclobutane 3, the immediate precursor to the powerful o-quinone methide Diels-Alder diene. Michael E. Jung of UCLA developed (Organic Lett. 2008, 10, 3647) a triflimide catalyst for the inverse electron demand coupling of the highly substituted diene 4 with the enol ether 5 to give 6 with high diastereocontrol. Joseph M. Fox of the University of Delaware showed (J. Org. Chem. 2008, 73, 4283) that the cyclopropene carboxylate 8 was a powerful and selective dienophile. Richard P. Hsung and Kevin P. Cole of the University of Wisconsin finally (Adv. Synth. Cat. 2008, 350, 2885) reduced to practice the long-sought enantioselective Diels-Alder cycloaddition of a trisubstituted aldehyde, 11. Li Deng of Brandeis University devised (J. Am. Chem. Soc. 2008, 130, 2422) a Cinchona -derived catalyst for Diels-Alder cycloaddition to the diene 13 with high ee. Miguel Á. Sierra of the Universidad Complutense, Madrid, and Alejandra G. Suárez of the Universidad Nacional de Rosario described (Organic Lett. 2008, 10, 3389) a clever switchable chiral auxiliary 16 that favored diastereomer S-18 on thermal addition, but R-18 with EtAlCl2. New approaches to the intramolecular Diels-Alder reaction continue to be introduced. Mathias Christmann, now at the TU Dortmund, showed (Angew. Chem. Int. Ed. 2008, 47, 1450) that a secondary amine organocatalyst converted the prochiral dialdehyde 19 into the bicyclic diene 20 with high de and ee. Martin G. Banwell of the Australian National University prepared (Organic Lett. 2008, 10, 4465) the triene 21 in high ee by microbiological oxidation of iodobenzene. On warming, 21 was converted smoothly into 22, which was carried on in a formal synthesis of platencin. Jun-ichi Matsuo of Kanazawa University was able (Organic Lett. 2008, 10, 4049) to induce (neat, 180 °C) the intermolecular Diels-Alder cycloaddition of 23 with 24, delivering the cycloadduct 25 with 11:1 diastereocontrol.

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8

Lambert, Tristan H. "Asymmetric C–Heteroatom Bond Formation." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0036.

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Tomislav Rovis at Colorado State University developed (Angew. Chem. Int. Ed. 2012, 51, 5904) an enantioselective catalytic cross-aza-benzoin reaction of aldehydes 1 and N-Boc imines 2. The useful α-amido ketone products 4 were configurationally stable under the reaction conditions. In the realm of asymmetric synthesis, few technologies have been as widely employed as the Ellman chiral sulfonamide auxiliary. Francisco Foubelo and Miguel Yus at the Universidad de Alicante in Spain have adapted (Chem. Commun. 2012, 48, 2543) this approach for the indium-mediated asymmetric allylation of ketimines 5, which furnished amines 6 with high diastereoselectivity. There has been vigorous research in recent years into the use of NAD(P)H surrogates, especially Hantzsch esters, for biomimetic asymmetric hydrogenations. Yong-Gui Zhou at the Chinese Academy of Sciences showed (J. Am. Chem. Soc. 2012, 134, 2442) that 9,10-dihydrophenanthridine (10) can also serve as an effective “H2” donor for the asymmetric hydrogenation of imines, including 7. Notably, 10 is used catalytically, with regeneration occurring under mild conditions via Ru(II)-based hydrogenation of the phenanthridine 11. A unique approach for asymmetric catalysis has been developed (Nature Chem. 2012, 4, 473) by Takashi Ooi at Nagoya University, who found that ion-paired complexes 14 could serve as effective chiral ligands in the Pd(II)-catalyzed allylation of α-nitrocarboxylates 12. The resulting products 13 are easily reduced to furnish α-amino acid derivatives. Another novel catalytic platform has been employed (J. Am. Chem. Soc. 2012, 134, 7321) for the chiral resolution of 1,2-diols 15 by Kian L. Tan at Boston College. Using the concept of reversible covalent binding, the catalyst 16 was found to selectively silylate a secondary hydroxyl over a primary one, thus leading to the enantioenriched products 17 and 18. Scott E. Denmark at the University of Illinois has applied (Angew. Chem. Int. Ed. 2012, 51, 3236) his chiral Lewis base strategy to the enantioselective vinylogous aldol reaction of N-silyl vinylketene imines 19 to produce γ-hydroxy-α,β-unsaturated nitriles 22. For the preparation of enantioenriched homopropargylic alcohols 25, the asymmetric addition of allenyl metal nucleophiles (e.g., 24) to aldehydes 23 provides a straightforward approach.

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9

Taber, Douglass F. "The Kan Synthesis of the Streptomyces Alkaloid SB-203207." In Organic Synthesis. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190646165.003.0092.

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The alkaloid SB-203207 3, isolated from a Streptomyces species by a SmithKline Beecham group, was shown to inhibit isoleucyl tRNA synthetase with an IC50 of less than 2 nM. Toshiyuki Kan of the University of Shizuoka envisioned (Org. Lett. 2014, 16, 1646) that the carbocyclic core of 3 could be assembled by the Rh-mediated cyclization of 1 to 2. The authors had already demonstrated (Org. Lett. 2008, 10, 169) the cyclization of 1 to 2. For the assembly of 3, they needed to scale up the preparation of 1. To this end, they required the mandelamide 5 and the aldehyde 8. To prepare 5, they devised a new preparation of diazoacetates, condensation with bromoacetyl bromide followed by exposure to the bis sulfonamide. The aldehyde 8 was prepared from the acid 6 (commercial, or Org. Synth. 2004, Coll. Vol. 10, 228). The preparation of the third component of 3, the acid 9, had been described earlier by Banwell and Easton (Bioorg. Med. Chem. 2003, 11, 2687). The cyclization of 1 proceeded smoothly with 0.1% loading of the Rh catalyst, to give 2 in 72% de (85:15 ratio of enantiomers of the carbocyclic core). The enantiomeric excess could be upgraded by recrystallization of a later intermediate. The ester 2 was exchanged with allyl alcohol to give 10, presumably with recovery of the liberated chiral auxiliary 4. Formaldehyde added to the β-keto ester 10 from the more open face. Hydride addition from that same face then delivered the diol 11. The allyl ester was removed, and the free acid was activated with SOCl2 then condensed with ammonia to give the primary amide. Ozonolysis followed by acidic methanol led to cyclization onto the amide, allowing ready differentiation of the two ends of the alkene. Reduction completed the preparation of the lactam 12. The nitrogen was sulfonylated, then the activated lactam was opened with assistance from the liberated primary alcohol. After acetal hydrolysis, the sulfonamide added to the aldehyde to give, after dehydration, the enamide 13. Inversion of the carboxyl converted the hydroxy acid to the urethane, that was formylated with the modified Vilsmeier reagent. Protection and deprotection followed by methylation then delivered the vinylogous amide 14.

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10

Taber, Douglass F. "Construction of Arrays of Stereogenic Centers: The Zhang Synthesis of (+)-Podophyllotoxin." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0043.

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Varinder K. Aggarwal of the University of Bristol showed (Angew. Chem. Int. Ed. 2009, 48, 1149) that condensation of a boronic ester 2 with a metalated aziridine 1 led, after oxidation, to the defined amino alcohol 3. Hisashi Yamamoto of the University of Chicago developed (Angew. Chem. Int. Ed. 2009, 48, 3333) conditions for the diastereoselective addition of an organometallic to an α-nitrosylated aldehyde, to give, after reduction, the diol 6. Xiaoyu Wu of Shanghai University and Gang Zhao of the Shanghai Institute of Organic Chemistry designed (Adv. Synth. Cat. 2009, 351, 158) an organocatalyst that mediated the enantioselective addition of hydroxyacetone 7 to a range of aldehydes. Andrew G. Myers of Harvard University found (J. Am. Chem. Soc. 2009, 131, 5763) that trialkylaluminum reagents opened epoxides of enol ethers at the more substituted position, delivering protected diols such as 10. Keiji Maruoka of Kyoto University created (Angew. Chem. Int. Ed. 2009, 48, 1838) an organocatalyst for the addition of an aldehyde 11 to an imine 12, to give 13. Markus Kalesse of Leibnitz Universität Hannover showed (Tetrahedron Lett. 2009, 50, 3485) that an organocatalyst could mediate the selective γ-reactivity of 15, leading to 16. Barry M. Trost of Stanford University found (J. Am. Chem. Soc. 2009, 131, 1674) that an organocatalyst directed the addition of diazoacetate 18 to an aldehyde, to give, after further reaction with a trialkylborane, the syn aldol product 19. Professor Trost also demonstrated (J. Am. Chem. Soc. 2009, 131, 4572) that a related complex mediated the conjugate addition of 22 to 21. Enantioselective construction of arrays of alkylated stereogenic centers is a particular challenge. Ji Zhang, then at Pfizer, found (Tetrahedron Lett. 2009, 50, 1167) that the chiral auxiliary of 24 directed both the conjugate addition and the subsequent protonation, and also allowed the product 25 to be brought to > 98% purity by crystallization. Tönis Kanger of Tallinn University of Technology developed (J. Org. Chem. 2009, 74, 3772) an organocatalyst for the conjugate addition of aldehydes to nitrostyrenes such as 26 to give 27.

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Conference papers on the topic "Amine; Chiral auxiliary"

1

Vallribera, Adelina, Marcial Morena-Manas, Elisenda Trepat, and Rosa Sebastian. "Asymmetric Synthesis of Quaternary a-Amino Acids Using D-Ribonolactone Acetonide as a Chiral Auxiliary." In The 3rd International Electronic Conference on Synthetic Organic Chemistry. MDPI, 1999. http://dx.doi.org/10.3390/ecsoc-3-01717.

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