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Journal articles on the topic 'Chiral Lewis acid'

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Published: 4 June 2021

Last updated: 19 February 2022

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1

Kim, Yong Hae, Doo Young Jung, So Won Youn, Sam Min Kim, and Doo Han Park. "Dual enantioselective control by heterocycles of (S)-indoline derivatives." Pure and Applied Chemistry 77, no. 12 (January 1, 2005): 2053–59. http://dx.doi.org/10.1351/pac200577122053.

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Diastereo-and enantioselective pinacol coupling reactions of chiral α-ketoamides mediated by samarium diiodide afforded extremely high diastereoselectivities. Enantiopure (S,S)- or (R,R)-2,3-dialkyltartaric acid and derivatives can be synthesized. Diels-Alder cycloadditions of S-indoline chiral acrylamides with cyclopentadiene in the presence of Lewis acids proceed with high diastereofacial selectivity, giving either endo-R or endo-S products depending on Lewis acid and the structures of chiral dienophiles.

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2

Kim, Yong Hae, Sam Min Kim, and So Won Youn. "Asymmetric synthesis by stereocontrol." Pure and Applied Chemistry 73, no. 2 (January 1, 2001): 283–86. http://dx.doi.org/10.1351/pac200173020283.

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Diels-Alder cycloadditions of S-indoline chiral acrylamides with cyclopentadiene in the presence of Lewis acids proceed with high diastereofacial selectivity, giving either endo-R or endo-S products depending on Lewis acid and the structures of chiral dienophiles. Diastereo- and enantioselective pinacol coupling reactions of chiral α-ketoamides mediated by samarium diiodide afforded extremely high diastereoselectivities. Enantiopure (S,S) - or (R,R) -2,3-dialkyltartaric acid and derivatives can be synthesized. Furthermore, it was demonstrated that α,β-unsaturated amides coupled with SmI2 to dimerized products containing two chiral carbons which were first obtained as the adjacent chiral carbons.

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3

Cantú-Reyes, Margarita, Isabel Alvarado-Beltrán, Ricardo Ballinas-Indilí, Cecilio Álvarez-Toledano, and Marcos Hernández-Rodríguez. "Stereodivergent Mannich reaction of bis(trimethylsilyl)ketene acetals with N-tert-butanesulfinyl imines by Lewis acid or Lewis base activation, a one-pot protocol to obtain chiral β-amino acids." Organic & Biomolecular Chemistry 15, no. 36 (2017): 7705–9. http://dx.doi.org/10.1039/c7ob01853c.

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4

Carlos Dias, Luiz. "Chiral Lewis Acid Catalyzed Ene-Reactions." Current Organic Chemistry 4, no. 3 (March 1, 2000): 305–42. http://dx.doi.org/10.2174/1385272003376274.

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5

Ogawa, Chikako, and Shu Kobayashi. "Chiral Lewis Acid Catalysis in Water." Current Organic Synthesis 8, no. 3 (June 1, 2011): 345–55. http://dx.doi.org/10.2174/157017911795529119.

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6

ISHIHARA, K., and H. YAMAMOTO. "ChemInform Abstract: Chiral Lewis Acid Catalysts." ChemInform 27, no. 36 (August 5, 2010): no. http://dx.doi.org/10.1002/chin.199636262.

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7

Rossi, Sergio, Tiziana Benincori, Laura Maria Raimondi, and Maurizio Benaglia. "3,3′-Bithiophene-Based Chiral Bisphosphine Oxides as Organocatalysts in Silicon-Derived Lewis Acid Mediated Reactions." Synlett 31, no. 06 (January 7, 2020): 535–46. http://dx.doi.org/10.1055/s-0039-1690777.

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This account summarizes the development of new biheteroaromatic chiral bisphosphine oxides. 3,3′-Bithiophene-based phosphine oxides (BITIOPOs) have been successfully used as organocatalysts to promote Lewis base catalyzed, Lewis acid mediated stereoselective transformations. These highly electron-rich compounds, in combination with trichorosilyl derivatives (allyltrichlorosilane and silicon tetrachloride), generate hypervalent silicon species that act as chiral Lewis acids in highly diastereo- and enantioselective organic reactions. Several relevant examples related to these applications are discussed in detail.1 Introduction2 The BITIOPO Family3 Enantioselective Opening of Epoxides4 Enantioselective Allylation of Aldehydes5 Stereoselective Direct (Double) Aldol-Type Reaction with Ketones6 Stereoselective Direct Aldol-Type Reaction with Ester Derivatives7 Conclusions

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8

Kobayashi, Shū. "Asymmetric catalysis in aqueous media." Pure and Applied Chemistry 79, no. 2 (January 1, 2007): 235–45. http://dx.doi.org/10.1351/pac200779020235.

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Lewis acid catalysis has attracted much attention in organic synthesis because of unique reactivity and selectivity attained under mild conditions. Although various kinds of Lewis acids have been developed and applied in industry, these Lewis acids must be generally used under strictly anhydrous conditions. The presence of even a small amount of water handles the reactions owing to preferential reactions of the Lewis acids with water rather than the substrates. In contrast, rare earth and other metal complexes have been found to be water-compatible. Several catalytic asymmetric reactions in aqueous media, including hydroxymethylation of silicon enolates with an aqueous solution of formaldehyde in the presence of Sc(OTf)3-chiral bipyridine ligand or Bi(OTf)3-chiral bipyridine ligand, Sc- or Bi-catalyzed asymmetric meso-epoxide ring-opening reactions with amines, and asymmetric Mannich-type reactions of silicon enolates with N-acylhydrazones in the presence of a chiral Zn catalyst have been developed. Water plays key roles in these asymmetric reactions.

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9

HAYASHI, Yujiro, and Koichi NARASAKA. "Chiral lewis acid in catalytic asymmetric reactions." Journal of Synthetic Organic Chemistry, Japan 48, no. 4 (1990): 280–91. http://dx.doi.org/10.5059/yukigoseikyokaishi.48.280.

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10

McKay, M. Kevin, and James R. Green. "Asymmetric synthesis based on chiral (arene)tricarbonylchromium acetal complexes. Addition reactions to the ortho-formyl complex." Canadian Journal of Chemistry 78, no. 12 (December 1, 2000): 1629–36. http://dx.doi.org/10.1139/v00-150.

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The addition reactions of organolithium and Grignard reagents to chiral, enantiomerically pure ortho-formyl (arene)tricarbonylchromium acetal complex (2) have been studied. The diastereoselectivity of the addition process is fair in the absence of an additional Lewis acid, and good in the presence of Ti(OiPr)4. The nature of the newly formed chiral centre, and studies on the possible nature of the nucleophilic species suggest that the Lewis acid acts through monodentate coordination to the aldehyde carbonyl, and thereby alters the carbonyl rotamer population more heavily in favour of the s-trans conformation. Nucleophilic attack then occurs on the face anti- to that bearing the Cr(CO)3 unit.Key words: (arene)tricarbonylchromium complexes, asymmetric synthesis, carbonyl additions, Lewis acids.

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11

Maruoka, Keiji. "Bidentate Lewis acid catalysts in asymmetric synthesis." Pure and Applied Chemistry 74, no. 1 (January 1, 2002): 123–28. http://dx.doi.org/10.1351/pac200274010123.

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The chemistry of bidentate Lewis acids belongs to an unexplored field of science, and so far has been only poorly studied. This paper illustrates the design of several bidentate Al and Ti Lewis acids, and their successful application to selective organic synthesis, particularly to asymmetric synthesis. For example, a new, chiral bidentate Ti(IV) complex is successfully designed by adding commercially available Ti(OPri)4 and (S)-binaphthol sequentially to 2,2'-bis(tritylamino)-4,4'-dichlorobenzophenone in CH2Cl2, and can be utilized for simultaneous coordination to aldehyde carbonyls, thereby allowing the precise enantioface discrimination of such carbonyls for a new catalytic, practical enantioselective allylation of aldehydes with allyltributyltin. This chiral bidentate Ti(IV) catalyst exhibits uniformly high asymmetric induction as well as high chemical yields for various aldehydes. The present enantioselective allylation is highly chemoselective in the presence of other carbonyl moieties.

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12

Vargová, Denisa, Juana M. Pérez, Syuzanna R. Harutyunyan, and Radovan Šebesta. "Trapping of chiral enolates generated by Lewis acid promoted conjugate addition of Grignard reagents to unreactive Michael acceptors by various electrophiles." Chemical Communications 55, no. 78 (2019): 11766–69. http://dx.doi.org/10.1039/c9cc05041h.

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Chiral enolates generated by asymmetric Cu-catalyzed and Lewis acid promoted conjugate addition of Grignard reagents to unsaturated amides, alkenylheterocycles, and carboxylic acids are trapped with cations, activated alkenes, or bromine.

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13

Ma, Jiajia, Xiaodong Shen, Klaus Harms, and Eric Meggers. "Expanding the family of bis-cyclometalated chiral-at-metal rhodium(iii) catalysts with a benzothiazole derivative." Dalton Transactions 45, no. 20 (2016): 8320–23. http://dx.doi.org/10.1039/c6dt01063f.

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14

Larionov, Vladimir A., Thomas Cruchter, Thomas Mietke, and Eric Meggers. "Polymer-Supported Chiral-at-Metal Lewis Acid Catalysts." Organometallics 36, no. 8 (February 16, 2017): 1457–60. http://dx.doi.org/10.1021/acs.organomet.7b00016.

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15

Brinkmann, Yasmin, Reniguntala J. Madhushaw, Rodolphe Jazzar, Gerald Bernardinelli, and E. Peter Kündig. "Chiral ruthenium Lewis acid-catalyzed nitrile oxide cycloadditions." Tetrahedron 63, no. 35 (August 2007): 8413–19. http://dx.doi.org/10.1016/j.tet.2007.06.033.

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16

Lanza, Francesco, Juana Pérez, Ravindra Jumde, and Syuzanna Harutyunyan. "Lewis Acid Promoted Trapping of Chiral Aza-enolates." Synthesis 51, no. 05 (January 29, 2019): 1253–62. http://dx.doi.org/10.1055/s-0037-1611657.

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We present a study on sequential conjugate addition of Grignard reagents to alkenyl-heteroarenes followed by trapping of the resulting enolates, yielding moderate to good diastereoselectivities. Contrary to conventional wisdom, one-pot conjugate addition/trapping using two reactive Michael acceptors in combination with Grignard reagents can proceed via conjugate addition to the least reactive Michael acceptor. This unusual chemoselectivity is triggered by the presence of a Lewis acid, reverting the usual reactivity order of Michael acceptors.

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17

Sibi, Mukund P., Kennosuke Itoh, and Craig P. Jasperse. "Chiral Lewis Acid Catalysis in Nitrile Oxide Cycloadditions." Journal of the American Chemical Society 126, no. 17 (May 2004): 5366–67. http://dx.doi.org/10.1021/ja0318636.

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18

Dias, Luiz Carlos. "ChemInform Abstract: Chiral Lewis Acid Catalyzed Ene Reactions." ChemInform 31, no. 41 (October 10, 2000): no. http://dx.doi.org/10.1002/chin.200041244.

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19

Yang, Kung-Shuo, Wei-Der Lee, Jia-Fu Pan, and Kwunmin Chen. "Chiral Lewis Acid-Catalyzed Asymmetric Baylis−Hillman Reactions." Journal of Organic Chemistry 68, no. 3 (February 2003): 915–19. http://dx.doi.org/10.1021/jo026318m.

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20

Guo, Chang. "(Invited) Chiral Lewis Acid-Catalyzed Asymmetric Electrochemical Reactions." ECS Meeting Abstracts MA2021-01, no. 42 (May 30, 2021): 1736. http://dx.doi.org/10.1149/ma2021-01421736mtgabs.

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21

Bădoiu, Andrei, Yasmin Brinkmann, Florian Viton, and E. Peter Kündig. "Asymmetric Lewis acid-catalyzed 1,3-dipolar cycloadditions." Pure and Applied Chemistry 80, no. 5 (January 1, 2008): 1013–18. http://dx.doi.org/10.1351/pac200880051013.

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Highly tuned, one-point binding chiral iron and ruthenium complexes selectively coordinate and activate α,β-unsaturated aldehydes and ketones toward asymmetric catalytic Diels-Alder cycloaddition reactions. Here we focus on the application of these transition-metal Lewis acids to asymmetric catalytic 1,3-dipolar cycloaddition reaction between enals and cyclic and acyclic nitrones as well as aryl nitrile oxides to give isoxazolidines and isoxazolines, respectively.

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22

Hashimoto, Takuya, Kumiko Yamamoto, and Keiji Maruoka. "Catalytic enantioselective intramolecular cyclization of N-aryl diazoamides using a titanium–BINOLate complex." Chem. Commun. 50, no. 24 (2014): 3220–23. http://dx.doi.org/10.1039/c3cc49837a.

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23

Wang, Chuanyong, Liang-An Chen, Haohua Huo, Xiaodong Shen, Klaus Harms, Lei Gong, and Eric Meggers. "Asymmetric Lewis acid catalysis directed by octahedral rhodium centrochirality." Chemical Science 6, no. 2 (2015): 1094–100. http://dx.doi.org/10.1039/c4sc03101f.

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24

Xu, Chaoran, Haifeng Zheng, Bowen Hu, Xiaohua Liu, Lili Lin, and Xiaoming Feng. "Chiral cobalt(ii) complex catalyzed Friedel–Crafts aromatization for the synthesis of axially chiral biaryldiols." Chemical Communications 53, no. 70 (2017): 9741–44. http://dx.doi.org/10.1039/c7cc05266a.

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25

Miyabe, Hideto, Ryuta Asada, and Yoshiji Takemoto. "Cascade radical reaction of substrates with a carbon–carbon triple bond as a radical acceptor." Beilstein Journal of Organic Chemistry 9 (June 13, 2013): 1148–55. http://dx.doi.org/10.3762/bjoc.9.128.

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The limitation of hydroxamate ester as a chiral Lewis acid coordination moiety was first shown in an intermolecular reaction involving a radical addition and sequential allylation processes. Next, the effect of hydroxamate ester was studied in the cascade addition–cyclization–trapping reaction of substrates with a carbon–carbon triple bond as a radical acceptor. When substrates with a methacryloyl moiety and a carbon–carbon triple bond as two polarity-different radical acceptors were employed, the cascade reaction proceeded effectively. A high level of enantioselectivity was also obtained by a proper combination of chiral Lewis acid and these substrates.

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26

Jia, Qianfa, Yaqiong Li, Yinhe Lin, and Qiao Ren. "The Combination of Lewis Acid with N-Heterocyclic Carbene (NHC) Catalysis." Catalysts 9, no. 10 (October 16, 2019): 863. http://dx.doi.org/10.3390/catal9100863.

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In the last ten years, the combination of Lewis acid with N-heterocyclic carbene (NHC) catalysis has emerged as a powerful strategy in a variety of important asymmetric synthesis, due to the ready availability of starting materials, operational simplicity and mild reaction conditions. Recent findings illustrate that Lewis acid could largely enhance the efficiency and enantioselectivity, reverse the diastereoselectivity, and even influence the pathway of the same reaction partners. Herein, this review aims to reveal the recent advances in NHC-Lewis acid synergistically promoted enantioselective reactions for the expeditious assembly of versatile biologically important chiral pharmaceuticals and natural products.

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27

Mirco, Abbinante Vincenzo, Benaglia Maurizio, Rossi Sergio, Benincori Tiziana, Cirilli Roberto, and Pierini Marco. "TetraPh-Tol-BITIOPO: a new atropisomeric 3,3′-bithiophene based phosphine oxide as an organocatalyst in Lewis base-catalyzed Lewis acid mediated reactions." Organic & Biomolecular Chemistry 17, no. 32 (2019): 7474–81. http://dx.doi.org/10.1039/c9ob01297d.

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28

Yamamoto, Hidetoshi, Sadaka Watanabe, Masayuki Hasegawa, Michihiko Noguchi, and Shuji Kanemasa. "Synthesis of Chiral Isoxazoline Derivatives by Highly Diastereoface-Selective 1,3-Dipolar Cycloaddition of Nitrile Oxides Mediated by Magnesium Bromide and Ytterbium Trifluoromethanesulfonate." Journal of Chemical Research 2003, no. 5 (May 2003): 284–86. http://dx.doi.org/10.3184/030823403103173813.

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In the presence of an equimolar amount of Lewis acid such as magnesium bromide and ytterbium trifluoromethanesulfonate, 1,3-dipolar cycloaddition reactions of aromatic nitrile oxides to a chiral 3-acryloyl-2-oxazolidinone gave the corresponding chiral 2-isoxazolines in a diastereoselective manner.

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29

Yu, Jin-Sheng, Hidetoshi Noda, Naoya Kumagai, and Masakatsu Shibasaki. "Direct Catalytic Asymmetric Mannich-Type Reaction of an α-CF3 Amide to Isatin Imines." Synlett 30, no. 04 (December 18, 2018): 488–92. http://dx.doi.org/10.1055/s-0037-1611642.

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An α-CF3 amide underwent direct asymmetric Mannich-type reaction to isatin imines in the presence of a chiral catalyst comprising a soft Lewis acid Cu(I), a chiral bisphosphine ligand, and Barton’s base. The Mannich adduct was converted in one step into a unique tricycle bearing a trifluoromethylated chiral center and an α-tertiary amine moiety.

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30

Baldauf, Christoph, Nina Dickerhof, Stefan H. Hüttenhain, Stefanie Kern, Nancy Krummrich, Friedrich Kruse, Janine May, et al. "Solvent-Induced Chirality in the Hydroboration of Ketones." Australian Journal of Chemistry 61, no. 6 (2008): 414. http://dx.doi.org/10.1071/ch08093.

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The influence of the systematic variation of chiral solvents and of diverse Lewis acids on the asymmetric induction of the hydroboration of acetophenone has been studied. None of the solvents used could surpass lactic acid methyl ester, and for the Lewis acids, ZnCl2 and ZnI2 showed positive effects on the enantiomeric excess (ee) and the conversion. Also, the effect of the substrate structure was investigated by comparing the conversion and ee of eight different ketones. Apparently, the achievable asymmetric induction was higher with aromatic ketones.

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31

Kobayashi, Shū, Kentaro Kakumoto, Yuichiro Mori, and Kei Manabe. "Chiral lewis acid-catalyzed enantioselective michael reactions in water." Israel Journal of Chemistry 41, no. 4 (December 2001): 247–50. http://dx.doi.org/10.1560/6grq-yrvv-6ku3-rhgx.

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32

Howarth, Joshua, and Paul Glynn. "2-Substituted-1,3,2-dithioborolans as Chiral Lewis Acid Catalysts." Molecules 5, no. 12 (August 15, 2000): 1011–13. http://dx.doi.org/10.3390/50801011.

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33

MARUOKA, Keiji, and Hisashi YAMAMOTO. "Asymmetric Diels-Alder Reactions Using Chiral Lewis Acid Catalysts." Journal of Japan Oil Chemists' Society 39, no. 10 (1990): 852–57. http://dx.doi.org/10.5650/jos1956.39.10_852.

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34

Yoon, Tehshik P. "Photochemical Stereocontrol Using Tandem Photoredox–Chiral Lewis Acid Catalysis." Accounts of Chemical Research 49, no. 10 (August 9, 2016): 2307–15. http://dx.doi.org/10.1021/acs.accounts.6b00280.

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35

Masse, Craig E., Les A. Dakin, Bradford S. Knight, and James S. Panek. "Lewis Acid-Mediated Carbocyclization Reactions of Chiral (E)-Crotylsilanes." Journal of Organic Chemistry 62, no. 26 (December 1997): 9335–38. http://dx.doi.org/10.1021/jo970832o.

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36

Thamapipol, Sirinporn, Gérald Bernardinelli, Céline Besnard, and E. Peter Kündig. "Chiral Ruthenium Lewis Acid Catalyzed Intramolecular Diels−Alder Reactions." Organic Letters 12, no. 24 (December 17, 2010): 5604–7. http://dx.doi.org/10.1021/ol1019103.

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37

MARUOKA, K., and H. YAMAMOTO. "ChemInform Abstract: Asymmetric Reactions with Chiral Lewis Acid Catalysts." ChemInform 25, no. 17 (August 19, 2010): no. http://dx.doi.org/10.1002/chin.199417303.

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38

ISHIHARA, K., and H. YAMAMOTO. "ChemInform Abstract: Asymmetric Synthesis with Chiral Lewis Acid Catalysts." ChemInform 29, no. 47 (June 18, 2010): no. http://dx.doi.org/10.1002/chin.199847330.

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39

Li, Hui Jing, Hong Yu Tian, Yong Jun Chen, Dong Wang, and Chao Jun Li. "Chiral Anionic Surfactants for Asymmetric Mukaiyama Aldol-Type Reaction in Water." Journal of Chemical Research 2003, no. 3 (March 2003): 153–56. http://dx.doi.org/10.3184/030823403103173318.

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Sulfonate derivatives of chiral 1,1′-binaphthol were used as chiral anionic surfactants in asymmetric aldol-type reaction in water to give aldol adducts with moderate to good diastereo- and enantioselectivities; Ga(OTf)3 and Cu(OTf)2 were better than Sc(OTf)3 as Lewis acid catalysts.

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40

Wang, Zhan-Yong, Ya-Li Ding, Gang Wang, and Ying Cheng. "Chiral N-heterocyclic carbene/Lewis acid cooperative catalysis of the reaction of 2-aroylvinylcinnamaldehydes: a switch of the reaction pathway by Lewis acid activation." Chemical Communications 52, no. 4 (2016): 788–91. http://dx.doi.org/10.1039/c5cc08866f.

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Chiral N-heterocyclic carbene/Lewis acid co-catalyzed reaction of 2-aroylvinylcinnamaldehydes produced good yields of indeno[1,2-c]furan-1-ones with excellent enantioselectivity. A switch of intramolecular to intermolecular reaction was achieved by the cooperative catalysis of NHC/Ti(OPr-i)₄ catalysts.

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41

Banik, Steven M., Anna Levina, Alan M. Hyde, and Eric N. Jacobsen. "Lewis acid enhancement by hydrogen-bond donors for asymmetric catalysis." Science 358, no. 6364 (November 9, 2017): 761–64. http://dx.doi.org/10.1126/science.aao5894.

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Small-molecule dual hydrogen-bond (H-bond) donors such as ureas, thioureas, squaramides, and guanidinium ions enjoy widespread use as effective catalysts for promoting a variety of enantioselective reactions. However, these catalysts are only weakly acidic and therefore require highly reactive electrophilic substrates to be effective. We introduce here a mode of catalytic activity with chiral H-bond donors that enables enantioselective reactions of relatively unreactive electrophiles. Squaramides are shown to interact with silyl triflates by binding the triflate counterion to form a stable, yet highly Lewis acidic, complex. The silyl triflate-chiral squaramide combination promotes the generation of oxocarbenium intermediates from acetal substrates at low temperatures. Enantioselectivity in nucleophile additions to the cationic intermediates is then controlled through a network of noncovalent interactions between the squaramide catalyst and the oxocarbenium triflate.

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42

Guo, Jing, Yangbin Liu, Xiangqiang Li, Xiaohua Liu, Lili Lin, and Xiaoming Feng. "Nickel(ii)-catalyzed enantioselective cyclopropanation of 3-alkenyl-oxindoles with phenyliodonium ylide via free carbene." Chemical Science 7, no. 4 (2016): 2717–21. http://dx.doi.org/10.1039/c5sc03658e.

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43

Ma, Jiajia, Klaus Harms, and Eric Meggers. "Enantioselective rhodium/ruthenium photoredox catalysis en route to chiral 1,2-aminoalcohols." Chemical Communications 52, no. 66 (2016): 10183–86. http://dx.doi.org/10.1039/c6cc04397f.

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44

Wang, Guo-Peng, Meng-Qing Chen, Shou-Fei Zhu, and Qi-Lin Zhou. "Enantioselective Nazarov cyclization of indole enones cooperatively catalyzed by Lewis acids and chiral Brønsted acids." Chemical Science 8, no. 10 (2017): 7197–202. http://dx.doi.org/10.1039/c7sc03183a.

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The first enantioselective Nazarov cyclization of substrates with only one coordinating site and with proton-transfer as an enantioselective-determining step was realized by means of cooperative catalysis with a Lewis acid and a chiral Brønsted acid.

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45

Zhong, Xia, Ziwei Zhong, Zhikun Wu, Zhen Ye, Yuxiang Feng, Shunxi Dong, Xiaohua Liu, Qian Peng, and Xiaoming Feng. "Chiral Lewis acid-bonded picolinaldehyde enables enantiodivergent carbonyl catalysis in the Mannich/condensation reaction of glycine ester." Chemical Science 12, no. 12 (2021): 4353–60. http://dx.doi.org/10.1039/d0sc07052a.

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The catalytic asymmetric Mannich/condensation of glycine ester with aldimines was achieved by merging chiral N,N′-dioxide/Yb^III complex Lewis acid catalysis/carbonyl catalysis under mild condition.

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46

Nasir, Shah Bakhtiar, Noorsaadah Abd Rahman, and Chin Fei Chee. "Enantioselective Syntheses of Flavonoid Diels-Alder Natural Products: A Review." Current Organic Synthesis 15, no. 2 (April 24, 2018): 221–29. http://dx.doi.org/10.2174/1570179414666170821120234.

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Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples. Conclusion: It is clear from the review that a significant amount of research has been done investigating various types of catalysts and chiral ligand-Lewis acid complexes for the enantioselective synthesis of flavonoid Diels-Alder natural products. The results have demonstrated improved yield and enantioselectivity. Much emphasis has been placed on the synthesis but important mechanistic work aimed at understanding the enantioselectivity has also been discussed.

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47

Zhang, Qichao, Jian Lv, and Sanzhong Luo. "Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis." Beilstein Journal of Organic Chemistry 15 (June 14, 2019): 1304–12. http://dx.doi.org/10.3762/bjoc.15.129.

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The combination of the trityl cation and a chiral weakly coordinating Fe(III)-based bisphosphate anion was used to develop a new type of a highly active carbocation Lewis acid catalyst. The stereocontrol potential of the chiral tritylium ion pair was demonstrated by its application in an enantioselective Diels–Alder reaction of anthracene.

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48

Kim, Yong Hae, Sam Min Kim, Doo Han Park, and So Won Youn. "Stereocontrolled asymmetric synthesis." Pure and Applied Chemistry 72, no. 9 (January 1, 2000): 1691–97. http://dx.doi.org/10.1351/pac200072091691.

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Abstract:

Stereo differentiated asymmetric syntheses have been achieved by S-indoline derivations. Diels-Alder cycloadditions of S-indoline chiral acrylamides with cyclopentadiene proceed with high diastereofacial selectivity, giving either endo-R or endo-S products depending on Lewis acid and the structures of chiral dienophiles. Diastereo- and enantio-selective pinacol coupling reactions of chiral α-ketoamides mediated by samarium diiodide afforded extremely high diastereoselectivities. Enantiopure (S,S)- or (R,R)-2,3-dialkyltar-taric acid and derivatives can be synthesized for the first time depending on the structure of α-ketoamides.

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49

Morrison, D. J., J. M. Blackwell, and W. E. Piers. "Mechanistic insights into perfluoroaryl borane-catalyzed allylstannations: Toward asymmetric induction with chiral boranes." Pure and Applied Chemistry 76, no. 3 (January 1, 2004): 615–23. http://dx.doi.org/10.1351/pac200476030615.

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Abstract:

The perfluoroaryl borane B(C6F5)3 is an effective catalyst for a variety of organic transformations. In the hydrosilation of carbonyl functions, it activates the silane rather than the carbonyl substrate. In allylstannation reactions, two competing reaction pathways are observed, one involving tin cation catalysis, the other "true" borane catalysis. For B(C6F5)3, the former mechanism dominates, while for the weaker Lewis acid PhB(C6F5)2, the latter pathway is more prominent. Thus, chiral boranes of similar Lewis acid strength to PhB(C6F5)2 have the potential to mediate asymmetric allylstannation of aldehyde substrates.

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50

MARUOKA, Keiji, and Hisashi YAMAMOTO. "New reagents. II. Reagents for asymmetric synthesis. Chiral Lewis acid." Journal of Synthetic Organic Chemistry, Japan 48, no. 11 (1990): 990–91. http://dx.doi.org/10.5059/yukigoseikyokaishi.48.990.

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