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Journal articles on the topic 'Chiral organocatalyst'

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Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Félix, Ana Rita G., Pedro R. D. Simões, Francisco J. P. M. Sousa, M. Elisa Silva Serra, and Dina Murtinho. "Chiral Thiazolidine based Organocatalysts: Synthesis and Application in Asymmetric Aldol Reactions." Letters in Organic Chemistry 17, no. 5 (April 28, 2020): 372–80. http://dx.doi.org/10.2174/2210681209666190807155816.

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Several novel chiral organocatalysts derived from thiazolidines containing amide and thioureia functionalities were synthesized in good yields. These organocatalysts were tested in the asymmetric aldol reaction of acetone with p-nitrobenzaldehyde. Reaction parameters such as reaction time, catalyst loading and solvent were optimized. Products with conversions up to 84% and enantiomeric ratios (er) up to 84.5:15.5 (R:S) were obtained. The effect of several chiral and non-chiral additives on the reactivity and selectivity of the reaction was also evaluated. The reaction was extended to other aromatic aldehydes with the best organocatalyst and when p-bromobenzaldehyde was used, an er of 94.5:5.5 (R:S) was obtained.

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2

Çetin, Adnan, Ishak Bildirici, and Selçuk Gümüş. "Novel Pyrazole Derivatives Having Mono/Di Chiral Centered Group as Organocatalyst for Henry Reaction." Macedonian Journal of Chemistry and Chemical Engineering 39, no. 1 (June 9, 2020): 17. http://dx.doi.org/10.20450/mjcce.2020.1954.

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The chiral substituted pyrazole-3-carboxamides (4a-c), pyrazole-3-carboxylates (5a-c), pyrazole-3-thioureides (7a-c) and pyrazole-3,4-dicarboxamides (10a-c) were prepared via the pyrazolo-3-chlorocarbonyl 2, pyrazolo-3,4-dicarboxy methyl ester 3 with pyrazole-3-isothiocyanate 6 with different (R)-chiral amino alcohols. All of the synthesized chiral compounds binding a pyrazole skeleton were investigated as organocatalysts for asymmetric aldol reactions between nitromethane and p-nitrobenzaldehyde in the presence of CuCl. Enantiomeric excesses and the reaction yields were found to be appropriate values. Furthermore, the best organocatalyst applied in this study was identified after careful optimization of conditions. Lastly, all of the novel compounds were subjected to computational analysis at the B3LYP/6-31++G(d,p) level of theory to obtain information about their structural and electronic properties.

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3

Porcar, Raúl, Eduardo García-Verdugo, Belén Altava, Maria Isabel Burguete, and Santiago V. Luis. "Chiral Imidazolium Prolinate Salts as Efficient Synzymatic Organocatalysts for the Asymmetric Aldol Reaction." Molecules 26, no. 14 (July 9, 2021): 4190. http://dx.doi.org/10.3390/molecules26144190.

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Chiral imidazolium l-prolinate salts, providing a complex network of supramolecular interaction in a chiral environment, have been studied as synzymatic catalytic systems. They are demonstrated to be green and efficient chiral organocatalysts for direct asymmetric aldol reactions at room temperature. The corresponding aldol products were obtained with moderate to good enantioselectivities. The influence of the presence of chirality in both the imidazolium cation and the prolinate anion on the transfer of chirality from the organocatalyst to the aldol product has been studied. Moreover, interesting match/mismatch situations have been observed regarding configuration of chirality of the two components through the analysis of results for organocatalysts derived from both enantiomers of prolinate (R/S) and the trans/cis isomers for the chiral fragment of the cation. This is associated with differences in the corresponding reaction rates but also to the different tendencies for the formation of aggregates, as evidenced by nonlinear effects studies (NLE). Excellent activities, selectivities, and enantioselectivities could be achieved by an appropriate selection of the structural elements at the cation and anion.

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4

Nájera, Carmen, José Miguel Sansano, and Enrique Gómez-Bengoa. "Heterocycle-based bifunctional organocatalysts in asymmetric synthesis." Pure and Applied Chemistry 88, no. 6 (June 1, 2016): 561–78. http://dx.doi.org/10.1515/pac-2016-0403.

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AbstractDifferent chiral bifunctional organocatalysts derived from trans-cyclohexane-1,2-diamine bearing different types of guanidine units able to form-hydrogen bonding activation have been designed. Conformational rigid 2-aminobenzimidazoles bearing a tertiary amino group have been used in enantioselective Michael type reactions of activated methylene compounds to nitroalkenes. The C2 symmetric bis(2-aminobenzimidazole) derivatives the appropriate organocatalyst for the conjugate addition of 1,3-dicarbonyl compounds to maleimides as well as for the SN1 reaction of benzylic alcohols with carbon nucleophiles. 2-Aminobenzimidazoles bearing a primary amino group have shown excellent catalytic activity in the Michael reaction of aldehydes to maleimides and nitroalkenes. Diastereomeric 2-aminopyrimidines bearing a prolinamide unit have been incorporated in the trans-cyclohexane-1,2-diamine scaffold and have been used for the inter- and intra-molecular direct aldol reaction under solvent-free conditions. For the Michael reaction of aldehydes with maleimides the primary amine 2-aminopyrimidine has shown excellent efficiency as organocatalyst. The bifunctional character of these organocatalysts has been demonstrated by means of DFT calculations.

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5

Mangawa, Shrawan K., Ashawani K. Singh, and Satish K. Awasthi. "Design and synthesis of a s-triazene based asymmetric organocatalyst and its application in enantioselective alkylation." RSC Advances 5, no. 75 (2015): 61144–47. http://dx.doi.org/10.1039/c5ra11209e.

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6

Vural, Ummu, Mustafa Durmaz, and Abdulkadir Sirit. "A novel calix[4]arene-based bifunctional squaramide organocatalyst for enantioselective Michael addition of acetylacetone to nitroolefins." Organic Chemistry Frontiers 3, no. 6 (2016): 730–36. http://dx.doi.org/10.1039/c6qo00135a.

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A new chiral calix[4]arene-based organocatalyst 3 bearing bis-squaramide moieties was designed and synthesized from p-tert-butylcalix[4]arene. This bifunctional organocatalyst was used in the enantioselective conjugate addition of acetyl acetone to β-nitrostyrenes. The corresponding adducts were obtained in good to excellent yields with high enantioselectivities.

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7

Wagner, Christian, Andreas F. Kotthaus, and Stefan F. Kirsch. "The asymmetric reduction of imidazolinones with trichlorosilane." Chemical Communications 53, no. 32 (2017): 4513–16. http://dx.doi.org/10.1039/c7cc01561e.

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8

Geng, Zhi-Cong, Jian Chen, Ning Li, Xiao-Fei Huang, Yong Zhang, Ya-Wen Zhang, and Xing-Wang Wang. "Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives." Beilstein Journal of Organic Chemistry 8 (October 9, 2012): 1710–20. http://dx.doi.org/10.3762/bjoc.8.195.

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The catalytic synthesis of nitrogen-containing heterocycles is of great importance to medicinal and synthetic chemists, and also a challenge for modern chemical methodology. In this paper, we report the synthesis of pyrazolidine derivatives through a domino aza-Michael/hemiacetal sequence with chiral or achiral secondary amines as organocatalysts. Thus, a series of achiral pyrazolidine derivatives were obtained with good yields (up to 90%) and high diastereoselectivities (>20:1) with pyrrolidine as an organocatalyst, and enantioenriched pyrazolidines are also achieved with good results (up to 86% yield, >10/1 regioselectivity, >20:1 dr, 99% ee) in the presence of (S)-diphenylprolinol trimethylsilyl ether catalyst.

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9

Zhou, Muxing, Ende He, Lu Zhang, Jianzhong Chen, Zhenfeng Zhang, Yangang Liu, and Wanbin Zhang. "Development of a new bicyclic imidazole nucleophilic organocatalyst for direct enantioselective C-acylation." Organic Chemistry Frontiers 6, no. 24 (2019): 3969–72. http://dx.doi.org/10.1039/c9qo01025d.

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10

Haraguchi, Naoki, and Shinichi Itsuno. "ChemInform Abstract: Polymer-Immobilized Chiral Organocatalyst." ChemInform 43, no. 17 (March 29, 2012): no. http://dx.doi.org/10.1002/chin.201217232.

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11

Kishi, Kenta, Fernando Arteaga Arteaga, Shinobu Takizawa, and Hiroaki Sasai. "Multifunctional catalysis: stereoselective construction of α-methylidene-γ-lactams via an amidation/Rauhut–Currier sequence." Chemical Communications 53, no. 55 (2017): 7724–27. http://dx.doi.org/10.1039/c7cc02839c.

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Novel chiral organocatalyst 5a, which can simultaneously act as Brønsted and Lewis base catalysts, leads to a one-pot amidation/Rauhut–Currier sequence that affords highly functionalized α-methylidene-γ-lactams with chiral tetrasubstituted carbon stereogenic centers.

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12

Tian, Jin-Miao, Yong-Hai Yuan, Yong-Qiang Tu, Fu-Min Zhang, Xiao-Bo Zhang, Shi-Heng Zhang, Shao-Hua Wang, and Xiao-Ming Zhang. "The design of a spiro-pyrrolidine organocatalyst and its application to catalytic asymmetric Michael addition for the construction of all-carbon quaternary centers." Chemical Communications 51, no. 49 (2015): 9979–82. http://dx.doi.org/10.1039/c5cc02765a.

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13

Tözendemir, Deniz, and Cihangir Tanyeli. "The synthesis of chiral β-naphthyl-β-sulfanyl ketones via enantioselective sulfa-Michael reaction in the presence of a bifunctional cinchona/sulfonamide organocatalyst." Beilstein Journal of Organic Chemistry 17 (February 18, 2021): 494–503. http://dx.doi.org/10.3762/bjoc.17.43.

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Cinchona alkaloid-derived organocatalysts are widely employed in various asymmetric transformations, yielding products with high enantiopurity. In this respect, a bifunctional quinine-derived sulfonamide organocatalyst was developed to catalyze the asymmetric sulfa-Michael reaction of naphthalene-1-thiol with trans-chalcone derivatives. The target sulfa-Michael adducts were obtained with up to 96% ee under mild conditions and with a low (1 mol %) catalyst loading. Selected enantiomerically enriched sulfa-Michael addition products were subjected to oxidation to obtain the corresponding sulfones.

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14

Xu, Di, Li Dai, Marta Catellani, Elena Motti, Nicola Della Ca’, and Zhiming Zhou. "A novel enantioselective synthesis of 6H-dibenzopyran derivatives by combined palladium/norbornene and cinchona alkaloid catalysis." Organic & Biomolecular Chemistry 13, no. 8 (2015): 2260–63. http://dx.doi.org/10.1039/c4ob02551b.

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15

Xu, En-Jie, Yan Song, Zhong-Lin Wei, Rui Wang, Hai-Feng Duan, Ying-Jie Lin, Qing-Biao Yang, and Yao-Xian Li. "Novel chiral proline-based organocatalysts with amide and thiourea–amine units for highly efficient asymmetric aldol reaction in saturated brine without additives." Canadian Journal of Chemistry 97, no. 5 (May 2019): 352–59. http://dx.doi.org/10.1139/cjc-2018-0352.

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A series of novel proline-based organocatalysts with amide and thiourea-amine units (7a–7f) were developed and evaluated in the asymmetric aldol reaction of 4-nitrobenzaldehyde with cyclohexanone. The organocatalyst (7c or 7d, 5 mol%) exhibited efficient catalytic activity to afford aldol products in high diastereoselectivity (up to >99:1), enantioselectivity (up to >99%), and yield (up to >96%) at 0 °C in saturated brine without adding an acid. Aldol products of benzaldehyde derivatives almost universally provide high diastereoselectivity and enantioselectivity.

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16

Yang, Zhongbo, Han Li, Sujia Li, Ming-Tian Zhang, and Sanzhong Luo. "A chiral ion-pair photoredox organocatalyst: enantioselective anti-Markovnikov hydroetherification of alkenols." Organic Chemistry Frontiers 4, no. 6 (2017): 1037–41. http://dx.doi.org/10.1039/c6qo00806b.

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A chiral ion-pair photoredox organocatalyst was reported to facilitate visible-light-meditated asymmetric anti-Markovnikov hydroetherification of alkenols with high reactivity and moderate enantioselectivity.

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17

Lee, Sang Gyu, and Sung-Gon Kim. "An asymmetric Brønsted acid-catalyzed Friedel–Crafts reaction of indoles with cyclic N-sulfimines." RSC Advances 7, no. 54 (2017): 34283–86. http://dx.doi.org/10.1039/c7ra06244c.

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18

Ayyanar, Siva, Ponmuthu Kottala Vijaya, Madhappan Mariyappan, Veeramanoharan Ashokkumar, Velu Sadhasivam, Sankar Balakrishnan, Chithiraikumar Chinnadurai, and Sepperumal Murugesan. "Enantioselective synthesis of dihydroquinazolinone derivatives catalyzed by a chiral organocatalyst." New Journal of Chemistry 41, no. 16 (2017): 7980–86. http://dx.doi.org/10.1039/c7nj00538e.

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The asymmetric condensation/amine addition cascade reaction catalysed by a effective chiral organocatalyst for the formation of 2,3-dihydroquinazolinones with high yields (up to 99%) and ee's (up to 97%).

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19

Kracht, Daniel, Susumu Saito, Roland Fröhlich, and Bernhard Wünsch. "Synthesis of a Silanol-substituted Proline Analog as Organocatalyst." Zeitschrift für Naturforschung B 64, no. 10 (October 1, 2009): 1169–75. http://dx.doi.org/10.1515/znb-2009-1009.

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A proline-derived silanol, was designed as a novel potential organocatalyst, and synthesized starting from the tetrazole 3. The central idea was the combination of an acidic (tetrazole) and a basic functionality (pyrrolidine) with a silanol moiety in the same molecule. The synthesis of 7 was performed in four reaction steps starting with the tetrazole 3. In the solid state (X-ray crystal structure analysis) the crucial functional groups show a favorable orientation. A chiral HPLC method and a chiral capillary electrophoresis method have been established for the investigation of the kinetic resolution of the racemic alcohols 9 and 11. Acetylation reactions of alcohols were not accelerated by the organocatalyst 7, and the produced ee values were rather low.

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20

Thorat, Prashant B., Santosh V. Goswami, Wamanrao N. Jadhav, and Sudhakar R. Bhusare. "Water-Assisted Organocatalysis: An Enantioselective Green Protocol for the Henry Reaction." Australian Journal of Chemistry 66, no. 6 (2013): 661. http://dx.doi.org/10.1071/ch12428.

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We report an enantioselective Henry (nitroaldol) reaction catalysed by an organocatalyst using water as solvent. The enantioselective synthesis of β-nitroalcohols was achieved by using a neutral chiral organocatalyst, through strong hydrogen bonding, which results in the formation of corresponding products in excellent yield and enantioselectivity at room temperature. Other attractive features of the method are the eco-friendly, non-hazardous, and mild reaction conditions, inexpensive catalyst, and simple work up conditions.

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21

Fu, Zu-Kang, Jin-Yun Pan, Dong-Cheng Xu, and Jian-Wu Xie. "Organocatalytic domino Michael/cyclization reaction: efficient synthesis of multi-functionalized tetracyclic spirooxindoles with multiple stereocenters." RSC Adv. 4, no. 93 (2014): 51548–57. http://dx.doi.org/10.1039/c4ra07860h.

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A series of chiral multi-functionalized tetracyclic spiro[chromeno[3,4-c]pyrrole-1,3′-indoline] derivatives with four vicinal chiral carbon centers including two quaternary stereocenters were successfully preparedviadomino reaction of various 3-nitro-2H-chromene derivatives to 3-isothiocyanato oxindole with moderate to good enantioselectivities, employing readily available bifunctional thiourea1das the organocatalyst.

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22

Weiss, Robin, Emmanuel Aubert, Paola Peluso, Sergio Cossu, Patrick Pale, and Victor Mamane. "Chiral Chalcogen Bond Donors Based on the 4,4′-Bipyridine Scaffold." Molecules 24, no. 24 (December 6, 2019): 4484. http://dx.doi.org/10.3390/molecules24244484.

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Organocatalysis through chalcogen bonding (ChB) is in its infancy, as its proof-of-principle was only reported in 2016. Herein, we report the design and synthesis of new chiral ChB donors, as well as the catalytic activity evaluation of the 5,5′-dibromo-2,2′-dichloro-3-((perfluorophenyl)selanyl)-4,4′-bipyridine as organocatalyst. The latter is based on the use of two electron-withdrawing groups, a pentafluorophenyl ring and a tetrahalo-4,4′-bipyridine skeleton, as substituents at the selenium center. Atropisomery of the tetrahalo-4,4′-bipyridine motif provides a chiral environment to these new ChB donors. Their synthesis was achieved through either selective lithium exchange and trapping or a site-selective copper-mediated reaction. Pure enantiomers of the 3-selanyl-4,4′-bipyridine were obtained by high performance liquid chromatography enantioseparation on specific chiral stationary phase, and their absolute configuration was assigned by comparison of the measured and calculated electronic circular dichroism spectra. The capability of the selenium compound to participate in σ-hole-based interactions in solution was studied by 19F NMR. Even if no asymmetric induction has been observed so far, the new selenium motif proved to be catalytically active in the reduction of 2-phenylquinoline by Hantzsch ester.

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23

Sohtome, S., K. Nagasawa, S. Tanaka, K. Takada, and T. Yamaguchi. "Enantioswitching Catalysis with a Single Chiral Organocatalyst." Synfacts 2011, no. 01 (December 21, 2010): 0100. http://dx.doi.org/10.1055/s-0030-1259184.

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24

Fan, Lulu, Shinobu Takizawa, Yoshiki Takeuchi, Kazuhiro Takenaka, and Hiroaki Sasai. "Pd-catalyzed enantioselective intramolecular α-arylation of α-substituted cyclic ketones: facile synthesis of functionalized chiral spirobicycles." Organic & Biomolecular Chemistry 13, no. 17 (2015): 4837–40. http://dx.doi.org/10.1039/c5ob00382b.

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Synthesis of chiral spirocyclic ketones was accomplishedviathe Pd-catalyzed intramolecular α-arylation of α-substituted cyclic ketones. The obtained spirocyclic ketone could be converted into an acid–base organocatalyst.

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25

Yuan, Yu-Chao, Mariam Abd El Sater, Mohamed Mellah, Nada Jaber, Olivier R. P. David, and Emmanuelle Schulz. "Enantiopure isothiourea@carbon-based support: stacking interactions for recycling a lewis base in asymmetric catalysis." Organic Chemistry Frontiers 8, no. 17 (2021): 4693–99. http://dx.doi.org/10.1039/d1qo00646k.

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An enantiopure isothiourea (hyperBTM) was functionalized by a pyrene moiety via click chemistry; immobilized on reduced Graphene Oxide, this recyclable chiral organocatalyst promotes formal [3+2] cycloaddition of ammonium enolates with oxaziridines.

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26

Matsunaga, Hirofumi, Daisuke Tajima, Tetsuro Kawauchi, Takuro Yasuyama, Shin Ando, and Tadao Ishizuka. "A dramatic synergistic effect of a flexible achiral linker on a rigid chiral cis-1,2-diamine bifunctional organocatalyst." Organic & Biomolecular Chemistry 15, no. 14 (2017): 2892–96. http://dx.doi.org/10.1039/c6ob02743a.

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The combination of a “rigid” chiral bicyclic cis-1,2-diamine skeleton and a “flexible” achiral linker was newly designed as a bifunctional organocatalyst framework and showed excellent catalytic activity, accompanied by the reversal of enantioselection.

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27

Han, Jianwei, Yanxia Zhang, Xin-Yan Wu, and Henry N. C. Wong. "Chiral iminophosphorane catalyzed asymmetric sulfenylation of 4-substituted pyrazolones." Chemical Communications 55, no. 3 (2019): 397–400. http://dx.doi.org/10.1039/c8cc09049a.

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An excellent level of enantioselectivity in asymmetric sulfenylation of 4-substituted pyrazolones was achieved with chiral iminophosphorane as organocatalyst under the continuum solvation conditions. The use of hydrocarbon solvents enabled to enhance the enantiomeric excesses of the desired 4-phenylthio-pyrazol-5-ones (up to 99% ee).

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28

Šámal, Michal, Jiří Míšek, Irena G. Stará, and Ivo Starý. "Organocatalysis with azahelicenes: the first use of helically chiral pyridine-based catalysts in the asymmetric acyl transfer reaction." Collection of Czechoslovak Chemical Communications 74, no. 7-8 (2009): 1151–59. http://dx.doi.org/10.1135/cccc2009067.

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The successful utilisation of a helicene-based organocatalyst in acylative kinetic resolution of racemic secondary alcohol was described. Employing rac-1-phenylethanol, optically pure (–)-(M)-2-aza[6]helicene (5–20 mole %), isobutyric anhydride and N-ethyldiisopropylamine in chloroform at 22–40 °C, an asymmetric acyl transfer reaction took place overwhelming the uncatalysed background process. Moderate reactivity as well as selectivity factor (s = 9, 10) were observed. An effective control of the enantiodiscriminating step in acylative kinetic resolution by the helically chiral organocatalyst was proven for the first time.

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29

Shen, Zhigao, Xixian Pan, Yisheng Lai, Jiadong Hu, Xiaolong Wan, Xiaoge Li, Hui Zhang, and Weiqing Xie. "Chiral ion-pair organocatalyst promotes highly enantioselective 3-exo iodo-cycloetherification of allyl alcohols." Chemical Science 6, no. 12 (2015): 6986–90. http://dx.doi.org/10.1039/c5sc02485d.

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30

Asano, Keisuke, and Seijiro Matsubara. "Asymmetric Cycloetherification by Bifunctional Organocatalyst." Synthesis 50, no. 21 (June 26, 2018): 4243–53. http://dx.doi.org/10.1055/s-0036-1591592.

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Attempts to obtain enantiomerically enriched tetrahydrofuran derivatives via an intramolecular oxy-Michael addition reaction of ε-hydroxyenone is discussed. Despite previous difficulties associated with the asymmetric induction of this reaction, which can proceed even without a catalyst, a highly efficient asymmetric induction was realized using a bifunctional organocatalyst derived from a cinchona alkaloid. The reaction could be extended to ζ-hydroxyenone to yield an optically active tetrahydropyran derivative with a high ee. In these reactions, it is important for the gentle acidic and basic sites in the bifunctional organocatalyst to be arranged properly within the molecular skeleton of the catalyst. The high performance asymmetric induction relied on the affinity of the catalyst for the substrate, which played an important role. A disubstituted tetrahydropyran synthesis could be effectively performed via kinetic resolution using ζ-hydroxyenone containing a secondary alcohol moiety using a chiral phosphoric acid catalyst.

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31

Lacoste, Eric. "Proline: An Essential Amino Acid as Effective Chiral Organocatalyst." Synlett 2006, no. 12 (August 2006): 1973–74. http://dx.doi.org/10.1055/s-2006-947332.

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32

Liu, Yi, Junfeng Wang, Qi Sun, and Runtao Li. "Chiral 1,2-diaminocyclohexane as organocatalyst for enantioselective aldol reaction." Tetrahedron Letters 52, no. 28 (July 2011): 3584–87. http://dx.doi.org/10.1016/j.tetlet.2011.04.116.

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33

Murai, Kenichi, Shunsuke Fukushima, Shoko Hayashi, Yusuke Takahara, and Hiromichi Fujioka. "C3-Symmetric Chiral Trisimidazoline: Design and Application to Organocatalyst." Organic Letters 12, no. 5 (March 5, 2010): 964–66. http://dx.doi.org/10.1021/ol902958m.

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34

Bleschke, Christian, Johannes Schmidt, Dipti S. Kundu, Siegfried Blechert, and Arne Thomas. "A Chiral Microporous Polymer Network as Asymmetric Heterogeneous Organocatalyst." Advanced Synthesis & Catalysis 353, no. 17 (November 2011): 3101–6. http://dx.doi.org/10.1002/adsc.201100674.

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35

Parasuraman, Perumalsamy, Zubeda Begum, Madhu Chennapuram, Chigusa Seki, Yuko Okuyama, Eunsang Kwon, Koji Uwai, et al. "Simple organocatalyst component system for asymmetric hetero Diels–Alder reaction of isatins with enones." RSC Advances 10, no. 30 (2020): 17486–91. http://dx.doi.org/10.1039/d0ra03006f.

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A simple two catalysts component system of β-amino alcohols (catalyst) and amino acids (co-catalyst) works as an efficient organocatalysts in hetero Diels–Alder reaction of isatins with enones to afford chiral spirooxindole-tetrahydropyranones.

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36

Shim, Jae Ho, Si Hun Nam, Byeong-Seon Kim, and Deok-Chan Ha. "Organocatalytic Asymmetric Michael Addition of Ketones to α, β-Unsaturated Nitro Compounds." Catalysts 10, no. 6 (June 2, 2020): 618. http://dx.doi.org/10.3390/catal10060618.

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An organic catalyst “(R, R)-1,2-diphenylethylenediamine(DPEN) derivative’’ was devel-oped as a chiral bifunctional organocatalyst and applied for asymmetric Michael additions of aromatic ketones to trans-β-nitroalkene compounds under neutral conditions. The isopropyl-subs-tituted thiourea catalyst in neutral condition provides high chemical yield and enantioselectivities (ee) (up to 96% yield, 98% ee).

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37

Kalek, Marcin, Manoj Ghosh, and Adam Rajkiewicz. "Organocatalytic Group Transfer Reactions with Hypervalent Iodine Reagents." Synthesis 51, no. 02 (November 8, 2018): 359–70. http://dx.doi.org/10.1055/s-0037-1609639.

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In recent years, a plethora of synthetic methods that employ hypervalent iodine compounds donating an atom or a group of atoms to an acceptor molecule have been developed. Several of these transformations utilize organocatalysis, which complements well the economic and environmental advantages offered by iodine reagents. This short review provides a systematic survey of the organocatalytic approaches that have been used to promote group transfer from hypervalent iodine species. It covers both the reactions in which an organocatalyst is applied to activate the acceptor, as well as those that exploit the organocatalytic activation of the hypervalent iodine reagent itself.1 Introduction2 Organocatalytic Activation of Acceptor2.1 Amine Catalysis via Enamine and Unsaturated Iminium Formation2.2 NHC Catalysis via Acyl Anion Equivalent and Enolate Formation2.3 Chiral Cation Directed Catalysis and Brønsted Base Catalysis via Pairing with Stabilized Enolates3 Organocatalytic Activation of Hypervalent Iodine Reagent3.1 Brønsted and Lewis Acid Catalysis3.2 Lewis Base Catalysis3.3 Radical Reactions with Organic Promoters and Catalysts4 Summary and Outlook

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38

Torregrosa-Chinillach, Alejandro, Adrien Moragues, Haritz Pérez-Furundarena, Rafael Chinchilla, Enrique Gómez-Bengoa, and Gabriela Guillena. "Enantioselective Michael Addition of Aldehydes to Maleimides Organocatalyzed by a Chiral Primary Amine-Salicylamide." Molecules 23, no. 12 (December 12, 2018): 3299. http://dx.doi.org/10.3390/molecules23123299.

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A primary amine-salicylamide derived from chiral trans-cyclohexane-1,2-diamine was used as an organocatalyst for the enantioselective conjugate addition of aldehydes, mainly α,α-disubstituted to N-substituted maleimides. The reaction was performed in toluene as a solvent at room temperature. The corresponding enantioenriched adducts were obtained with high yields and enantioselectivities up to 94%. Theoretical calculations were used to justify the stereoinduction.

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39

Muñiz, Kilian, and Laura Fra. "Enantioselective 4-Hydroxylation of Phenols under Chiral Organoiodine(I/III) Catalysis." Synthesis 49, no. 13 (May 4, 2017): 2901–6. http://dx.doi.org/10.1055/s-0036-1588808.

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A procedure for the intermolecular enantioselective dearomatization of phenols under chiral (I/III) catalysis is reported. This protocol employs 3-chloroperoxybenzoic acid (m-CPBA) as the terminal oxidant together with a defined C 2-symmetric aryl iodide as the effective organocatalyst. This enantioselective reaction proceeds with complete selectivity under mild conditions and enables the hydroxylative dearomatization of a number of phenols to give the corresponding p-quinol products with up to 50% ee.

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40

Torregrosa-Chinillach, Alejandro, Alba Sánchez-Laó, Elisa Santagostino, and Rafael Chinchilla. "Organocatalytic Asymmetric Conjugate Addition of Aldehydes to Maleimides and Nitroalkenes in Deep Eutectic Solvents." Molecules 24, no. 22 (November 9, 2019): 4058. http://dx.doi.org/10.3390/molecules24224058.

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A chiral primary amine-salicylamide is used as an organocatalyst for the enantioselective conjugate addition of α,α-disubstituted aldehydes to maleimides and nitroalkenes. The reactions are performed in deep eutectic solvents as reaction media at room temperature, leading to the corresponding adducts with enantioselectivities up to 88% (for maleimides) and 80% (for nitroalkenes). Catalyst and solvent can be recovered and reused.

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41

Wang, Lei, Zhen Chen, Manyuan Ma, Wenzeng Duan, Chun Song, and Yudao Ma. "Synthesis and application of a dual chiral [2.2]paracyclophane-based N-heterocyclic carbene in enantioselective β-boration of acyclic enones." Organic & Biomolecular Chemistry 13, no. 43 (2015): 10691–98. http://dx.doi.org/10.1039/c5ob01609f.

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42

Kumar, Togapur Pavan, Rapelli Chandra Shekhar, Kondepudi Sugnana Sunder, and Rajesh Vadaparthi. "Myrtanyl-prolinamide: a new chiral organocatalyst for stereoselective aldol reactions." Tetrahedron: Asymmetry 26, no. 10-11 (May 2015): 543–47. http://dx.doi.org/10.1016/j.tetasy.2015.03.009.

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43

Kucherenko, Alexander S., Alexey A. Kostenko, Andrey N. Komogortsev, Boris V. Lichitsky, Michael Yu Fedotov, and Sergei G. Zlotin. "C2-Symmetric Chiral Squaramide, Recyclable Organocatalyst for Asymmetric Michael Reactions." Journal of Organic Chemistry 84, no. 7 (March 5, 2019): 4304–11. http://dx.doi.org/10.1021/acs.joc.9b00252.

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44

Saravanan, S., Noor-ul H. Khan, Rukhsana I. Kureshy, Sayed H. R. Abdi, and Hari C. Bajaj. "Small Molecule as a Chiral Organocatalyst for Asymmetric Strecker Reaction." ACS Catalysis 3, no. 12 (November 8, 2013): 2873–80. http://dx.doi.org/10.1021/cs400742d.

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45

Judeh, Zaher, and Duc Khong. "Short Synthesis of Phenylpropanoid Glycosides Calceolarioside A and Syringalide B." Synlett 29, no. 08 (January 31, 2018): 1079–83. http://dx.doi.org/10.1055/s-0036-1591753.

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An efficient and practical three-step synthesis of phenylpropanoid glycosides calceolarioside A and syringalide B in >62% overall yield is disclosed. The key step involves the chemoselective and regioselective direct O-4 cinnamoylation of unprotected 2-phenylethyl-β-d-glucosides with cinnamic anhydrides using a chiral 4-pyrrolidinopyridine organocatalyst. This approach serves as a model for the short synthesis of phenylpropanoid glycosides acylated at O-4 without protection/deprotection steps.

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46

Alves, Cláudia, Carla Grosso, Pedro Barrulas, José A. Paixão, Ana L. Cardoso, Anthony J. Burke, Américo Lemos, and Teresa M. V. D. Pinho e Melo. "Asymmetric Neber Reaction in the Synthesis of Chiral 2-(Tetrazol-5-yl)-2H-Azirines." Synlett 31, no. 06 (December 17, 2019): 553–58. http://dx.doi.org/10.1055/s-0039-1691533.

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A successful one-pot methodology for the synthesis of chiral 2-tetrazolyl-2H-azirines has been established, resorting to organocatalysis. The protocol involves the in situ tosylation of β-ketoxime-1H-tetrazoles followed by the Neber reaction, in the presence of chiral organocatalysts. Among the organocatalysts studied a novel thiourea catalyst derived from 6β-aminopenicillanic acid afforded excellent enantioselectivities.

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47

Yu, Ji-cong, Le-mao Yu, Xiao-yun Zhao, Lu Gan, Wei-wei Zhu, Ze-chen Wang, Rui Wang, and Xianxing Jiang. "Organocatalytic asymmetric [3 + 2] annulation of 1,4-dithiane-2,5-diol with azlactones: access to chiral dihydrothiophen-2(3H)-one derivatives." Organic Chemistry Frontiers 5, no. 13 (2018): 2040–44. http://dx.doi.org/10.1039/c8qo00305j.

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Herein, the first organocatalyst-mediated enantioselective [3 + 2] annulations of 1,4-dithiane-2,5-diol with various azlactones utilizing C4 and C5 reactivity using squaramide as the catalyst in a ring-opening manner have been reported.

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48

Mino, Takashi, Ayaka Omura, Yukari Uda, Kazuya Wakui, Yuri Haga, Masami Sakamoto, and Tsutomu Fujita. "Chiral phosphine-prolineamide as an organocatalyst in direct asymmetric aldol reactions." Tetrahedron: Asymmetry 22, no. 23 (December 2011): 2024–28. http://dx.doi.org/10.1016/j.tetasy.2011.11.021.

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49

Lacoste, Eric, Yannick Landais, Kurt Schenk, Jean-Baptiste Verlhac, and Jean-Marc Vincent. "Benzoimidazole–pyrrolidine (BIP), a highly reactive chiral organocatalyst for aldol process." Tetrahedron Letters 45, no. 43 (October 2004): 8035–38. http://dx.doi.org/10.1016/j.tetlet.2004.08.171.

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50

Liu, Yan, Xiaobing Xi, Chengcheng Ye, Tengfei Gong, Zhiwei Yang, and Yong Cui. "Chiral Metal-Organic Frameworks Bearing Free Carboxylic Acids for Organocatalyst Encapsulation." Angewandte Chemie 126, no. 50 (November 7, 2014): 14041–45. http://dx.doi.org/10.1002/ange.201408896.

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