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Journal articles on the topic 'Enantioselective synthesi'

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Author: Grafiati

Published: 9 March 2023

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1

Gualandi, Andrea, Luca Mengozzi, and Pier Cozzi. "Stereoselective SN1-Type Reaction of Enols and Enolates." Synthesis 49, no. 15 (June 13, 2017): 3433–43. http://dx.doi.org/10.1055/s-0036-1588871.

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Stereoselective alkylation of enolates represents a valuable and important procedure for accessing carbon–carbon-bond frameworks in natural and nonnatural product synthesis. Usually, activated electrophilic partners that react through an SN2 mechanism are employed. To overcome the limitations due to reduced reactivity and steric hindrance, SN1-type reactions can be considered a valid and practical alternative. Accessible enolates can be used in stereoselective (diastereo- or enantioselective) reactions with electrophilic carbenium ions, either used as stable reagents or generated in situ from suitable precursors. The results achieved in this active field are summarized in this review.1 Introduction2 Alcohols in SN1-Type Reactions with Enolates2.1 Enantioselective Reactions with Metal Complexes2.2 Organocatalytic Enantioselective Reactions3 Alcohols and Alcohol Derivatives in SN1-Type Reactions with Enolates: Enantioselective Reactions with Metal Enolates4 Isolated Carbenium Ions in SN1-Type Reactions with Enolates: Enantioselective Reactions with Metal Enolates5 Miscellaneous6 Conclusion

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2

Du, Kang, He Yang, Pan Guo, Liang Feng, Guangqing Xu, Qinghai Zhou, Lung Wa Chung, and Wenjun Tang. "Efficient syntheses of (−)-crinine and (−)-aspidospermidine, and the formal synthesis of (−)-minfiensine by enantioselective intramolecular dearomative cyclization." Chemical Science 8, no. 9 (2017): 6247–56. http://dx.doi.org/10.1039/c7sc01859b.

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Palladium-catalyzed enantioselective dearomative cyclization has enabled the concise and enantioselective total syntheses of (−)-crinine and (−)-aspidospermidine, as well as a formal total synthesis of (−)-minfiensine.

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3

Enders, Dieter, and Christoph Thiebes. "Efficient stereoselective syntheses of piperidine, pyrrolidine, and indolizidine alkaloids." Pure and Applied Chemistry 73, no. 3 (January 1, 2001): 573–78. http://dx.doi.org/10.1351/pac200173030573.

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Recent advances in the diastereo- and enantioselective synthesis of piperidine, pyrrolidine, and indolizidine alkaloids, based on the highly stereoselective 1,2-addition to the CN double bond of chiral aldehyde-SAMP/RAMP hydrazones, are described. The enantioselective syntheses of the pyrrolidine alkaloids bgugaine and (2S,12¢R)-2-(12¢-aminotridecyl)-pyrrolidine, a defense alkaloid of the Mexican bean beetle are reported. Furthermore, the SAMP/RAMP-hydrazone method was applied to the syntheses of two 5,8-disubstituted indolizidine alkaloids that have been extracted from neotropical poison-dart frogs. The a-alkylation of aldehyde-SAMP/RAMP hydrazones has been used in the enantioselective synthesis of two epimers of stenusine, a 3-substituted piperidine alkaloid and spreading reagent of the beetle Stenus comma.

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4

Chen, Bo, Xin Liu, Ya-Jian Hu, Dong-Mei Zhang, Lijuan Deng, Jieyu Lu, Long Min, Wen-Cai Ye, and Chuang-Chuang Li. "Enantioselective total synthesis of (−)-colchicine, (+)-demecolcinone and metacolchicine: determination of the absolute configurations of the latter two alkaloids." Chemical Science 8, no. 7 (2017): 4961–66. http://dx.doi.org/10.1039/c7sc01341h.

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5

Sundermann, Tom, Martina Arnsmann, Julian Schwarzkopf, Walburga Hanekamp, and Matthias Lehr. "Convergent and enantioselective syntheses of cytosolic phospholipase A2α inhibiting N-(1-indazol-1-ylpropan-2-yl)carbamates." Org. Biomol. Chem. 12, no. 23 (2014): 4021–30. http://dx.doi.org/10.1039/c4ob00535j.

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6

Sathish, Manda, Fabiane M. Nachtigall, and Leonardo S. Santos. "Bifunctional thiosquaramide catalyzed asymmetric reduction of dihydro-β-carbolines and enantioselective synthesis of (−)-coerulescine and (−)-horsfiline by oxidative rearrangement." RSC Advances 10, no. 63 (2020): 38672–77. http://dx.doi.org/10.1039/d0ra07705d.

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A simple and efficient asymmetric synthesis of THBCs through a chiral thiosquaramide 11b catalyzed imine reduction of dihydro-β-carbolines (17a−f) and syntheses of (−)-coerulescine and (–)-horsfiline via enantioselective oxidative rearrangement.

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7

Liu, Yiyang, Marc Liniger, Ryan M. McFadden, Jenny L. Roizen, Jacquie Malette, Corey M. Reeves, Douglas C. Behenna, et al. "Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation." Beilstein Journal of Organic Chemistry 10 (October 28, 2014): 2501–12. http://dx.doi.org/10.3762/bjoc.10.261.

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Pd-catalyzed enantioselective alkylation in conjunction with further synthetic elaboration enables the formal total syntheses of a number of “classic” natural product target molecules. This publication highlights recent methods for setting quaternary and tetrasubstituted tertiary carbon stereocenters to address the synthetic hurdles encountered over many decades across multiple compound classes spanning carbohydrate derivatives, terpenes, and alkaloids. These enantioselective methods will impact both academic and industrial settings, where the synthesis of stereogenic quaternary carbons is a continuing challenge.

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8

Zhang, Yun, Yibin Xue, Gang Li, Haosen Yuan, and Tuoping Luo. "Enantioselective synthesis of Iboga alkaloids and vinblastine via rearrangements of quaternary ammoniums." Chemical Science 7, no. 8 (2016): 5530–36. http://dx.doi.org/10.1039/c6sc00932h.

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We present an efficient and unified strategy for the enantioselective syntheses of various iboga alkaloids and vinblastine, involving gold-catalyzed oxidation and Stevens rearrangement. New vinblastine analogs were prepared by our 10-step synthesis.

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9

T. Mohd Ali, M., and . "Synthesis of -Hydroxy -Proline: Potential for Organocataly-sis Reactions." International Journal of Engineering & Technology 7, no. 4.14 (December 24, 2019): 237. http://dx.doi.org/10.14419/ijet.v7i4.14.27571.

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A chiral organic molecule, L-proline catalyzed an enantioselective transformation reaction has becoming interesting synthetic protocol especially in the area of organocatalysis. Herein, a synthetic approach towards -hydroxy--proline starting from bicyclic lactone lactam is hereby described. The syntheses utilized dicarboxylation reaction of bicyclic lacton lactam, followed by ether hydrolysis of the bicyclic ether and oxidation reaction of the primary alcohol. The synthetic strategy disclosed here allows further the enantioselective synthesis of a variety of unnatural amino acids based on -proline structure.

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10

Martin, Stephen F. "Ring-closing metathesis: A facile construct for alkaloid synthesis." Pure and Applied Chemistry 77, no. 7 (January 1, 2005): 1207–12. http://dx.doi.org/10.1351/pac200577071207.

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Ring-closing metathesis has been found to be a highly effective reaction for the synthesis of functionalized, bridged nitrogen heterocycles. The utility of the process has been established in several case studies, including a facile synthesis of the tropane ring system and efficient, enantioselective syntheses of the natural products (–)-peduncularine and (+)-anatoxin-a.

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11

Mane, Baliram B., D. D. Kumbhar, and Suresh B. Waghmode. "Enantioselective Total Synthesis of Ligraminol D and Ligraminol E." Synlett 30, no. 20 (October 30, 2019): 2285–89. http://dx.doi.org/10.1055/s-0039-1690249.

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As a part of our ongoing research on the synthesis of bioactive constituents or molecules by using an organocatalytic approach, enantioselective total syntheses of ligraminol D and ligraminol E were achieved starting from a commercially available nonchiral aldehyde. Key steps in this synthesis were an asymmetric α-aminoxylation of an aldehyde and a Mitsunobu reaction.

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12

Yamamoto, Yasunori, Takashi Nishikata, and Norio Miyaura. "1,4-Additions of arylboron, -silicon, and -bismuth compounds to α,β-unsaturated carbonyl compounds catalyzed by dicationic palladium(II) complexes." Pure and Applied Chemistry 80, no. 5 (January 1, 2008): 807–17. http://dx.doi.org/10.1351/pac200880050807.

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An enantioselective synthesis of cyclic and acyclic β-aryl ketone and aldehydes via Pd(II)-catalyzed 1,4-addition of Ar-m [m = B(OH)2, BF3K, Si(OMe)3, SiF3, BiAr2] to α,β-unsaturated ketones or aldehydes is described. The catalytic cycle involves transmetallation between Ar-m and Pd complexes as a key process, the mechanism of which is discussed on the basis of characterization of the transmetallation intermediate and electronic effect of the substituents. The enantioselection mechanism and efficiency of a chiraphos ligand for structurally planar α,β-unsaturated ketones are discussed on the basis of the X-ray structure of the catalyst and results of density functional theory (DFT) computational studies on the model of coordination of the substrates to the phenylpalladium(II)/(S,S)-chiraphos intermediate.

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13

Stoltz, Brian, Christian Defieber, Justin Mohr, and Gennadii Grabovyi. "Short Enantioselective Formal Synthesis of (–)-Platencin." Synthesis 50, no. 22 (July 23, 2018): 4359–68. http://dx.doi.org/10.1055/s-0037-1610437.

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A short enantioselective formal synthesis of the antibiotic natural product platencin is reported. Key steps in the synthesis include enantioselective decarboxylation alkylation, aldehyde/olefin radical cyclization, and regioselective aldol cyclization.

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14

Katoh, Tadashi. "Enantioselective Total Synthesis of Otteliones A and B, Novel and Powerful Antitumor Agents from the Freshwater Plant Ottelia alismoides." Natural Product Communications 8, no. 7 (July 2013): 1934578X1300800. http://dx.doi.org/10.1177/1934578x1300800724.

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Otteliones A and B isolated from the freshwater plant Ottelia alismoides have attracted significant attention because of their potential as novel anticancer agents. In this review four independent enantioselective total syntheses and one formal synthesis of these natural products are presented with particular focus on their methodology and strategy.

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15

Cai, Quan, Xu-Ge Si, and Zhi-Mao Zhang. "Asymmetric Inverse-Electron-Demand Diels–Alder Reactions of 2-Pyrones by Lewis Acid Catalysis." Synlett 32, no. 10 (January 24, 2021): 947–54. http://dx.doi.org/10.1055/a-1371-4391.

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AbstractDiels–Alder reactions of 2-pyrones with alkenes can provide highly functionalized [2,2,2]-bicyclic lactones under mild reaction conditions. Synthetic utilizations of these reactions have been well demonstrated in natural-product synthesis. Although several catalytic asymmetric strategies have been realized, current research in this area is still largely underdeveloped. Recent advances in enantioselective inverse-electron-demand Diels–Alder reactions with Lewis acid catalysis are reviewed.1 Introduction2 State of the Art of Enantioselective Diels–Alder Reactions of 2-Pyrones by Lewis Acid Catalysis3 Enantioselective Synthesis of Arene cis-Dihydrodiols by Diels–Alder/Retro-Diels–Alder Reactions of 2-Pyrones4 Enantioselective Synthesis of cis-Decalin Derivatives by Diels–Alder Reactions of 2-Pyrones5 Conclusions

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16

Liu, Jun, Zhi-Bing Dong, Caizhu Chang, Jialin Geng, Yinxin Liu, and Yuguo Du. "Stereoselective Total Synthesis of Arundinolides A and B." Synthesis 52, no. 10 (February 5, 2020): 1576–84. http://dx.doi.org/10.1055/s-0039-1691699.

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The efficient and enantioselective syntheses of arundinolides A and B have been accomplished for the first time from chiral pool methyl-2,3-O-isopropylidene-β-d-ribofuranoside and d-ethyl lactate. The key features of the total synthesis are intramolecular crotonyl migration and NaBH4-CuCl catalyzed regioselective reduction and cross-metathesis reaction.

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17

Majewski, Marek, D. Mark Gleave, and Pawel Nowak. "1,3-Dioxan-5-ones: synthesis, deprotonation, and reactions of their lithium enolates." Canadian Journal of Chemistry 73, no. 10 (October 1, 1995): 1616–26. http://dx.doi.org/10.1139/v95-201.

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A general synthetic route to 2-alkyl- and 2,2-dialkyl-1,3-dioxan-5-ones, using tris(hydroxymethyl)-nitromethane as the starting material, is described. Deprotonation of these compounds was studied. It was established that these dioxanones could be deprotonated with LDA; however, the reduction of the carbonyl group via a hydride transfer from LDA, giving the corresponding dioxanols, often competed with deprotonation. The reduction could be minimized by using Corey's internal quench procedure to form silyl enol ethers and was less pronounced in 2,2-dialkyldioxanones (ketals) than in 2-alkyldioxanones (acetals). Self-aldol products were observed when dioxanone lithium enolates were quenched with H2O. Addition reactions of lithium enolates of dioxanones to aldehydes were threo-selective as predicted by the Zimmerman–Traxler model. Dioxanones having two different alkyl groups at the 2-position were deprotonated enantioselectively by chiral lithium amide bases with enantiomeric excess (ee) of up to 70%. Keywords: 1,3-dioxan-5-ones, enantioselective deprotonation, chiral lithium amides.

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18

Pedro, José R., Carlos Vila, Laura Carceller-Ferrer, and Gonzalo Blay. "Recent Advances in Catalytic Enantioselective Synthesis of Pyrazolones with a Tetrasubstituted Stereogenic Center at the 4-Position." Synthesis 53, no. 02 (October 8, 2020): 215–37. http://dx.doi.org/10.1055/s-0040-1707298.

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AbstractPyrazolone [2,4-dihydro-3H-pyrazol-4-one] represents one of the most important five-membered nitrogen heterocycles which is present in numerous pharmaceutical drugs and molecules with biological activity. Recently, many catalytic methodologies for the asymmetric synthesis of chiral pyrazolones have been established with great success, specially, for the synthesis of pyrazolones bearing a tetrasubstituted stereocenter at C-4. This review summarizes these excellent research studies since 2018, including representative examples and some mechanistic pathways explaining the observed stereochemistry.1 Introduction2 Catalytic Enantioselective Synthesis of Chiral Pyrazolones with a Full Carbon Tetrasubstituted Stereocenter at C-43 Catalytic Enantioselective Synthesis of Chiral Pyrazolones with a Quaternary Carbon Stereocenter at C-4 bearing a Heteroatom4 Catalytic Enantioselective Synthesis of Chiral Spiropyrazolones5 Conclusion

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19

Reynolds, Rebekah G., Huong Quynh Anh Nguyen, Jordan C. T. Reddel, and Regan J. Thomson. "Recent strategies and tactics for the enantioselective total syntheses of cyclolignan natural products." Natural Product Reports 39, no. 3 (2022): 670–702. http://dx.doi.org/10.1039/d1np00057h.

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This review highlights strategies for the enantioselective total synthesis of cyclolignan natural products from 2000 to 2021. Each subsection focuses on the key strategic disconnections and the enantioselective steps controlling asymmetric induction.

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20

Li, Chengxi, Sherif Shaban Ragab, Guodu Liu, and Wenjun Tang. "Enantioselective formation of quaternary carbon stereocenters in natural product synthesis: a recent update." Natural Product Reports 37, no. 2 (2020): 276–92. http://dx.doi.org/10.1039/c9np00039a.

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The enantioselective formation of quaternary carbon stereocenters in complex natural product synthesis in the latest six years is reviewed, with particular emphasis on the analysis of the stereochemical model of each enantioselective transformation.

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21

Zhang, Yan, Jiang Pan, Zheng-Jiao Luan, Guo-Chao Xu, Sunghoon Park, and Jian-He Xu. "Cloning and Characterization of a Novel Esterase from Rhodococcus sp. for Highly Enantioselective Synthesis of a Chiral Cilastatin Precursor." Applied and Environmental Microbiology 80, no. 23 (September 19, 2014): 7348–55. http://dx.doi.org/10.1128/aem.01597-14.

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ABSTRACTA novel nonheme chloroperoxidase (RhEst1), with promiscuous esterase activity for enantioselective hydrolysis of ethyl (S)-2,2-dimethylcyclopropanecarboxylate, was identified from a shotgun library ofRhodococcussp. strain ECU1013.RhEst1 was overexpressed inEscherichia coliBL21(DE3), purified to homogeneity, and functionally characterized. Fingerprinting analysis revealed thatRhEst1 preferspara-nitrophenyl (pNP) esters of short-chain acyl groups.pNP esters with a cyclic acyl moiety, especially that with a cyclobutanyl group, were also substrates forRhEst1. TheKmvalues for methyl 2,2-dimethylcyclopropanecarboxylate (DmCpCm) and ethyl 2,2-dimethylcyclopropane carboxylate (DmCpCe) were 0.25 and 0.43 mM, respectively.RhEst1 could serve as an efficient hydrolase for the bioproduction of optically pure (S)-2,2-dimethyl cyclopropane carboxylic acid (DmCpCa), which is an important chiral building block for cilastatin. As much as 0.5 M DmCpCe was enantioselectively hydrolyzed into (S)-DmCpCa, with a molar yield of 47.8% and an enantiomeric excess (ee) of 97.5%, indicating an extremely high enantioselectivity (E= 240) of this novel and unique biocatalyst for green manufacturing of highly valuable chiral chemicals.

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22

Gong, Liu-Zhu, Pu-Sheng Wang, and Meng-Lan Shen. "Transition-Metal-Catalyzed Asymmetric Allylation of Carbonyl Compounds with Unsaturated Hydrocarbons." Synthesis 50, no. 05 (December 21, 2017): 956–67. http://dx.doi.org/10.1055/s-0036-1590986.

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The asymmetric allylation of carbonyl compounds is an important process for the formation of carbon–carbon bonds, generating optically active homoallylic alcohols that are versatile building blocks with widespread applications in organic synthesis. The use of readily available unsaturated hydrocarbons as allylating reagents in the transition-metal-catalyzed asymmetric allylation has received increasing interest as either a step- or an atom-economy alternative. This review summarizes transition-metal-catalyzed enantioselective allylations on the basis of the ‘indirect’ and ‘direct’ use of simple unsaturated hydrocarbons (include dienes, allenes, alkynes, and alkenes) as allylating reagents, with emphasis on highlighting conceptually novel reactions.1 Introduction2 ‘Indirect’ Use of Unsaturated Hydrocarbons in Asymmetric Allylation of Carbonyl Compounds2.1 Enantioselective Allylation with 1,3-Dienes2.2 Enantioselective Allylation with Allenes2.3 Enantioselective Allylation with Alkenes3 ‘Direct’ Use of Unsaturated Hydrocarbons in Asymmetric Allylation of Carbonyl Compounds3.1 Enantioselective Allylation with 1,3-Dienes3.2 Enantioselective Allylation with Allenes3.3 Enantioselective Allylation with Alkynes3.4 Enantioselective Allylation with Alkenes4 Conclusions

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23

Jacobi, Peter Alan. "4-Alkynoic Acids in the Synthesis of Biologically Important Porphyrinoids." ECS Meeting Abstracts MA2022-01, no. 14 (July 7, 2022): 947. http://dx.doi.org/10.1149/ma2022-0114947mtgabs.

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In this talk an account is given of the author's use of 4-alkynoic acid derivatives in the synthesis of members of the chlorin, bacteriochlorin and corrin classes of macrocyclic tetrapyrroles. In the case of chlorins, we employed a novel "2+2" condensation to prepare both C,D-symmetric and non-symmetric chlorins, made possible by the ready availability of highly substituted semicorrins derived from 4-alkynoic acids. Alkyne acids also played a prominent role in a new 16p-electrocyclization route to bacteriochlorins, and in iterative syntheses of semicorrins and secocorrins related to vitamin B12. Finally, we describe enantioselective syntheses of ring-C and ring-D alkyne acids for a proposed synthesis of cobyric acid. Figure 1

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24

Menéndez Ramos, José Carlos. "The Origins of Enantioselective Organocatalysis and the 2021 Nobel Prize in Chemistry." Anales de la Real Academia Nacional de Farmacia 87, no. 87(04) (2021): 459–72. http://dx.doi.org/10.53519/analesranf.2021.87.04.09.

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Any advanced society requires new molecules and materials to be used as drugs, agrochemicals, energy production and storage and countless other applications. This, in turn, requires the development of new methods for synthesis. The 2021 Nobel Prize in Chemistry was awarded to Professors Benjamin List and David MacMillan “for the development of asymmetric organocatalysis”. This is a relatively new tool for enantioselective organic synthesis that has undergone an explosive growth since its introduction in 2000 by the awardees and serves as an alternative to the more traditional catalytic procedures based on the use of enzymes and metal-based catalysts.

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25

Kwon, Yongseok, and Ahreum Kim. "Catalytic Atroposelective Dynamic Kinetic Resolution of Substituted Indoles." Synlett 33, no. 03 (November 11, 2021): 201–6. http://dx.doi.org/10.1055/a-1694-4695.

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AbstractAdvances in asymmetric catalysis have led to enormous progress in the atroposelective synthesis of axially chiral biaryls. Because of the biological importance of indoles, stereogenic axes in aryl-substituted indoles have attracted considerable research attention in recent years. Here we present a summary of recent advances in the atroposelective synthesis of aryl-substituted indoles by dynamic kinetic resolution. Although several researchers have developed enantioselective syntheses of 3-arylindoles, N-arylindoles have been much less studied. Accordingly, we have developed a Pictet–Spengler reaction with catalytic and enantioselective control of the axial chirality around the C–N bond of the product. A chiral phosphoric acid induces the cyclization smoothly and with high yields and excellent enantioselectivities. To achieve this high selectivity, an NH group at the ortho-position of the N-substituted aromatic ring that interacts favorably with the catalyst is required. Furthermore, when substituted aldehydes are used instead of paraformaldehyde, both point and axial chiralities can be controlled during the cyclization.1 Introduction2 Atropisomerism in Indoles3 Atroposelective Dynamic Kinetic Resolution of 3-Arylindoles4 Atroposelective Dynamic Kinetic Resolution of N-Arylindoles5 Conclusions

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26

Wencel-Delord, Joanna, and Françoise Colobert. "Challenging Atroposelective C–H Arylation." SynOpen 04, no. 04 (October 2020): 107–15. http://dx.doi.org/10.1055/s-0040-1705981.

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AbstractAtropisomeric molecules are privileged scaffolds, not only as ligands for asymmetric synthesis, but also as biologically active products and advanced materials. Although very attractive from a sustainability viewpoint, the direct construction of the stereogenic axis through asymmetric C–H arylation is very challenging and consequently only a few examples have been reported. This short review summarizes these very recent results on the atropo-enantio or diastereoselective synthesis of atropisomeric (hetero)biaryl molecules; transformations during which the Ar–Ar atropisomeric axis is formed during the C–H activation process.1 Introduction2 Atropo-enantioselective Intermolecular Pd-Catalyzed C–H Arylation of Thiophene Derivatives3 Atropodiastereoselective Intermolecular Pd-Catalyzed C–H Arylation towards Terphenyl Scaffolds Bearing Two Atropisomeric Axes4 Atropo-enantioselective Intramolecular Pd-Catalyzed C–H Arylation towards Atropisomeric Benzodiazepinones5 Atropo-enantioselective Intermolecular Pd-Catalyzed C–H Arylation of Heteroarenes6 Rh-Catalyzed Atropo-enantioselective C–H Arylation of Diazonaphthoquinones7 Conclusion

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27

Chan, T. H., and G. Z. Zheng. "C3 Symmetric oxazolinyl ligand as catalyst in the enantioselective addition of diethylzinc to aldehydes." Canadian Journal of Chemistry 75, no. 6 (June 1, 1997): 629–33. http://dx.doi.org/10.1139/v97-076.

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The C3 symmetric oxazolinyl ligand 1 has been synthesized. Compound 1 catalyzed the addition of diethylzinc to aromatic aldehydes to give secondary alcohols with high enantiomeric excesses (up to 90%). Keywords: diethylzinc, enantioselective synthesis, C3 symmetric ligands, enantioselective addition reactions, oxazolinyl ligands.

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28

Zhang, Jie, Hong-Kui Zhang, and Pei-Qiang Huang. "Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A." Beilstein Journal of Organic Chemistry 9 (November 5, 2013): 2358–66. http://dx.doi.org/10.3762/bjoc.9.271.

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A concise enantioselective synthesis of the advanced intermediate 5 for the synthesis of pumiliotoxins (Gallagher’s intermediate) is described. The synthesis started from the regio- and trans-diastereoselective (dr = 98:2) reductive 3-butenylation of (R)-3-(tert-butyldimethylsilyloxy)glutarimide 14. After O-desilylation and Dess–Martin oxidation, the resulting keto-lactam 10 was subjected to a highly trans-stereoselective addition of the methylmagnesium iodide to give carbinol 11 as sole diastereomer. An efficient ring closure procedure consisting of ozonolysis and reductive dehydroxylation provided the indolizidine derivative 5, which completed the formal enantioselective total synthesis of pumiliotoxins 251D and 237A.

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29

Fukasawa, Sota, Tatsuya Toyoda, Ryohei Kasahara, Chisato Nakamura, Yuuki Kikuchi, Akiko Hori, Gary J. Richards, and Osamu Kitagawa. "Catalytic Enantioselective Synthesis of N-C Axially Chiral N-(2,6-Disubstituted-phenyl)sulfonamides through Chiral Pd-Catalyzed N-Allylation." Molecules 27, no. 22 (November 13, 2022): 7819. http://dx.doi.org/10.3390/molecules27227819.

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Recently, catalytic enantioselective syntheses of N-C axially chiral compounds have been reported by many groups. Most N-C axially chiral compounds prepared through a catalytic asymmetric reaction possess carboxamide or nitrogen-containing aromatic heterocycle skeletons. On the other hand, although N-C axially chiral sulfonamide derivatives are known, their catalytic enantioselective synthesis is relatively underexplored. We found that the reaction (Tsuji–Trost allylation) of allyl acetate with secondary sulfonamides bearing a 2-arylethynyl-6-methylphenyl group on the nitrogen atom proceeds with good enantioselectivity (up to 92% ee) in the presence of (S,S)-Trost ligand-(allyl-PdCl)2 catalyst, affording rotationally stable N-C axially chiral N-allylated sulfonamides. Furthermore, the absolute stereochemistry of the major enantiomer was determined by X-ray single crystal structural analysis and the origin of the enantioselectivity was considered.

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30

Scheidt, Karl A., and Eric R. Miller. "Enantioselective Syntheses of Yohimbine Alkaloids: Proving Grounds for New Catalytic Transformations." Synthesis 54, no. 05 (November 2, 2021): 1217–30. http://dx.doi.org/10.1055/a-1684-2942.

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AbstractThe total synthesis of bioactive alkaloids is an enduring challenge and an indication of the state of the art of chemical synthesis. With the explosion of catalytic asymmetric methods over the past three decades, these compelling targets have been fertile proving grounds for enantioselective bond forming transformations. These activities are summarized herein both to highlight the power and versatility of these methods and to instill future inspiration for new syntheses of these privileged natural products.1 Introduction2 Monoterpenoid Indole Alkaloids2.1 Corynanthe-Type MIAs3 Biosynthesis4 Biological Activity5 Scope6 Strategies in Yohimbine Alkaloid Synthesis6.1 Momose’s Formal Synthesis of (+)-Yohimbine6.2 Jacobsen’s Synthesis of (+)-Yohimbine6.3 Hiemstra’s Synthesis of (+)-Yohimbine6.4 Qin’s Synthesis of (–)-Yohimbine6.5 Tan’s Synthesis of (+)-Rauwolscine6.6 Jacobsen’s Synthesis of (+)-Reserpine6.7 Chen’s Synthesis of (+)-Reserpine6.8 Riva’s Synthesis of (–)-Alloyohimbane6.9 Katsuki’s Synthesis of (–)-Alloyohimbane6.10 Ghosh’s Synthesis of (–)-Yohimbane and (–)-Alloyohimbane6.11 Hong’s Synthesis of (–)-Yohimbane6.12 Gellman’s Synthesis of (–)-Yohimbane6.13 Scheidt’s Synthesis of (–)-Rauwolscine and (–)-Alloyohimbane7 Conclusion

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Rueping, Magnus, Stefan A. Moreth, and Michael Bolte. "Asymmetric Brønsted Acid-catalyzed Intramolecular aza-Michael Reaction – Enantioselective Synthesis of Dihydroquinolinones." Zeitschrift für Naturforschung B 67, no. 10 (October 1, 2012): 1021–29. http://dx.doi.org/10.5560/znb.2012-0183.

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The enantioselective synthesis of 2-aryl-substituted 2,3-dihydroquinolin-4-ones, a class of heterocyclic compounds with interesting biological activities, has been achieved through a Brønsted acidcatalyzed enantioselective intramolecular Michael addition. The products are available in moderate to high yields and with good enantioselectivities.

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Hamashima, Yoshitaka, and Yuji Kawato. "Enantioselective Bromocyclization of Allylic Amides Mediated by Phosphorus Catalysis." Synlett 29, no. 10 (May 14, 2018): 1257–71. http://dx.doi.org/10.1055/s-0036-1591579.

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Halocyclization of alkenes is commonly employed to increase molecular complexity during organic synthesis because it enables double installation of heteroatoms on a carbon–carbon double bond. Moreover, stereodefined halogenated compounds are widely found among naturally occurring compounds and can serve as versatile chiral building blocks. Therefore, the development of asymmetric halocyclization reactions is of great interest and, in recent years, there has been remarkable progress in catalytic asymmetric halogenation reactions. This account summarizes recent progress made by our group on phosphorus-catalyzed enantioselective bromocyclization of allylic amides. Building on a comprehensive study of the reaction mechanism, we discovered an intriguing catalytic reaction in which P+Br species serves as a fine-tuning element for substrate fixation. We also describe the application of this bromocyclization to asymmetric desymmetrization of 1,4-diene substrates and a concise synthesis of the HIV-protease inhibitor nelfinavir using the newly developed desymmetrization reaction as a key step.1 Introduction2 Enantioselective Bromocyclization of Allylic Amides with a BINAP Catalyst2.1 Bromocyclization with a P/P Catalyst2.2 Bromocyclization with a P/P=O Catalyst3 Desymmetrization of Bisallylic Amides through Enantioselective Bromocyclization3.1 Desymmetrization of Bisallylic Amides3.2 Enantioselective Synthesis of Nelfinavir4 Summary

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Wang, Gang, Shutao Sun, Ying Mao, Zhiyu Xie, and Lei Liu. "Chromium(II)-catalyzed enantioselective arylation of ketones." Beilstein Journal of Organic Chemistry 12 (December 19, 2016): 2771–75. http://dx.doi.org/10.3762/bjoc.12.275.

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The chromium-catalyzed enantioselective addition of carbo halides to carbonyl compounds is an important transformation in organic synthesis. However, the corresponding catalytic enantioselective arylation of ketones has not been reported to date. Herein, we report the first Cr-catalyzed enantioselective addition of aryl halides to both arylaliphatic and aliphatic ketones with high enantioselectivity in an intramolecular version, providing facile access to enantiopure tetrahydronaphthalen-1-ols and 2,3-dihydro-1H-inden-1-ols containing a tertiary alcohol.

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Kerr, Daniel J., and Bernard L. Flynn. "Studies Towards a Concise Enantioselective Synthesis of Roseophilins." Australian Journal of Chemistry 68, no. 12 (2015): 1821. http://dx.doi.org/10.1071/ch15407.

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An oxazolidone auxiliary-controlled asymmetric Nazarov reaction has been applied to the synthesis of the cyclopentyl-fused pyrrole core of roseophilins. Additionally, a concise synthetic route to the pyrrole-furan biaryl fragment required in the synthesis of the recently isolated dechlororoseophilin is described. It is anticipated that these two syntheses can be combined in future efforts to provide efficient, convergent access to (+)-dechlororoseophilin.

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Li, Qing Han, Xin Jiang, Kun Wu, Rui Qiang Luo, Meng Liang, Zhi Hao Zhang, and Zhe Yao Huang. "Research Progress on the Catalytic Enantioselective Synthesis of Axially Chiral Allenes by Chiral Organocatalysts." Current Organic Chemistry 24, no. 6 (May 25, 2020): 694–708. http://dx.doi.org/10.2174/1385272824666200306094427.

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Chiral allenes are important structural scaffolds found in many natural products and drugs, and in addition, they also serve as building blocks for many organic transformations. The conventional methods for preparing chiral allenes rely on the resolution of racemic allenes and the chirality transfer between non-racemic propargylic derivatives and nucleophilic reagents. In recent years, the synthesis of chiral allenes by asymmetric catalysis has been achieved fruitful results. Among them, enantioselective synthesis of chiral allenes with chiral organic catalysts is particularly prominent. In this paper, the research progress of enantioselective synthesis of chiral allenes catalyzed by chiral organic catalysts in recent years is reviewed, including various reaction systems and synthesis applications.

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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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Kita, Yasuyuki, and Hiromichi Fujioka. "Enantioselective constructions of quaternary carbons and their application to the asymmetric total syntheses of fredericamycin A and discorhabdin A." Pure and Applied Chemistry 79, no. 4 (January 1, 2007): 701–13. http://dx.doi.org/10.1351/pac200779040701.

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An efficient enantioselective construction of quaternary carbons including spiro carbons is an area of intense interest due to the importance of these units as components of biologically active natural products. Prominent methods are presented for the synthesis of chiral, nonracemic quaternary carbon centers by (i) stereospecific rearrangement of optically active epoxides, (ii) enzyme-catalyzed resolution, and (iii) hypervalent iodine reagent-induced ipso-substitution of para-substituted phenol derivatives. These methods were applied to the total syntheses of fredericamycin A and discorhabdin A.

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Cozzi, Pier Giorgio, Alessandro Mignogna, and Luca Zoli. "Catalytic enantioselective Reformatsky reactions." Pure and Applied Chemistry 80, no. 5 (January 1, 2008): 891–901. http://dx.doi.org/10.1351/pac200880050891.

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The Reformatsky reaction is a venerable named reaction that was introduced more than 120 years ago. Diastereoselective variants based on the use of chiral auxiliary and enantioselective protocols, based on the employment of stoichiometric amount of chiral ligands, have been successfully applied in organic synthesis during the years. However, a facile and general catalytic enantioselective variant was still a difficult task. Recently, we have established a new general and straightforward methodology for catalytic enantioselective Reformatsky reaction based on different concepts. In this paper, we present our general finding in catalytic enantioselective Reformatsky reaction of ketones, imines, and aldehydes. Our simple methodologies could become benchmark reactions for testing new synthesized chiral ligands for asymmetric transformations.

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Pellissier, Hélène. "Asymmetric Organocatalytic Tandem/Domino Reactions to Access Bioactive Products." Current Organic Chemistry 25, no. 13 (September 2, 2021): 1457–71. http://dx.doi.org/10.2174/1385272825666210208142427.

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Tandem and domino reactions constitute economic methodologies to prepare complex molecules starting from simple materials. Especially, combining these powerful procedures to asymmetric catalysis allows direct access to many elaborated chiral products, including important key intermediates in total syntheses of important biologically active compounds. A range of various types of chiral organocatalysts have already been successfully applied to such syntheses. This review presents major developments in the total synthesis of bioactive products based on the use of enantioselective organocatalytic domino/tandem reactions as key steps. It is divided into three parts, dealing successively with syntheses based on organocatalytic asymmetric Michael-initiated domino reactions as key steps; aldol-initiated domino/tandem reactions and other domino reactions.

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Lee, Hyo-Jun, Bora Eun, Eonseon Sung, Gil Tae Hwang, Young Kwan Ko, and Chang-Woo Cho. "Catalytic enantioselective synthesis of carboxy-substituted 2-isoxazolines by cascade oxa-Michael-cyclization." Organic & Biomolecular Chemistry 16, no. 4 (2018): 657–64. http://dx.doi.org/10.1039/c7ob02722b.

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Majewski, Marek, Ryszard Lazny, and Agnieszka Ulaczyk. "Enantioselective ring opening of tropinone. A new entry into tropane alkaloids." Canadian Journal of Chemistry 75, no. 6 (June 1, 1997): 754–61. http://dx.doi.org/10.1139/v97-091.

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The lithium enolate of tropinone reacts with alkyl chloroformates to give 6-N-carboalkoxy-N-methyl-2-cycloheptenones (4). These compounds can be produced enantioselectively, in up to 95% ee, if chiral lithium amides (derived from optically pure amines 5–7) are used for deprotonation of tropinone in the presence of additives. The effect of additives such as LiCl, LiBr, LiF, LiClO4, CeCl3, ZnCl2, LiOH, TMEDA, HMPA, and DMPU on enantioselectivity of this deprotonation–ring opening sequence varies from slight to very large depending on the chiral amide – additive combination. Especially large increases in enantioselectivity are observed when the chiral, C2 symmetrical, lithium bis-α,α′-methylbenzylamide (Li-5a) is used with one equivalent of LiCl. This reagent is best generated in situ from the corresponding amine hydrochloride and n-BuLi (2 equiv.). The ring-opening reaction combined with transposition of the carbonyl group (via Wharton reaction or allylic oxidation) provides a new method of stereoselective synthesis of tropane alkaloids having a protected hydroxyl at C-6 or C-7 (6β- and 7β-acetoxytropanes 14a, b) and physoperuvine (19). Keywords: enantioselective deprotonation, tropane alkaloids.

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Chen, Fen-Er, and Lei Chen. "Total Synthesis of Camptothecins: An Update." Synlett 28, no. 10 (March 15, 2017): 1134–50. http://dx.doi.org/10.1055/s-0036-1588738.

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Over the last few decades, considerable research efforts have been directed toward the development of effective chemical syntheses of camptothecin and its analogs. The last comprehensive review of this area was published in 2003 and many effective new methods have since been reported for the stereoselective synthesis of the camptothecin alkaloids. In this account, we have summarized most of the novel synthetic approaches developed for the synthesis of camptothecins during the last decade. We have focused on strategies for the construction of the pentacyclic ring system and the different methods used to install the chiral quaternary center on the E ring of camptothecin.1 Introduction2 Synthesis of Racemic Camptothecins3 Enantioselective Synthesis of Camptothecins3.1 Sharpless Asymmetric Dihydroxylation3.2 Catalytic Asymmetric Cyanosilylation3.3 Auxiliary-Induced Asymmetric Carbonyl Addition3.4 Catalytic Asymmetric Ethylation3.5 Asymmetric Hydroxylation4 Conclusion

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Lu, Ping, Meng Wang, and Changxu Zhong. "Enantioselective Functionalization of Prochiral Cyclobutanones and Cyclobutenones." Synlett 32, no. 13 (April 28, 2021): 1253–59. http://dx.doi.org/10.1055/a-1493-9489.

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AbstractEnantioselective synthesis of cyclobutane derivatives is still a challenging topic in asymmetric synthesis. [2+2] Cycloaddition and skeleton rearrangement are two primary strategies to this end. Recently, functionalization of cyclobutanones and cyclobutenones, which are readily available via [2+2] cycloadditions as prochiral substrates, has emerged as a powerful tool to access versatile four-membered ring compounds. Herein, we summarize some recent advances in these areas from our and other groups.1 Introduction2 Enantioselective Functionalization of Cyclobutanones2.1 Chiral Lithium Amide Approach2.2 Enamine Approach3 Enantioselective Functionalization of Cyclobutenones4 Conclusion

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Zhao, Yuxiang, Yanren Zhu, Guolan Ma, Qi Wei, Shaoxiong Yang, Xiaoyu Zeng, Hongbin Zhang, and Jingbo Chen. "Short, enantioselective, gram-scale synthesis of (−)-zephyranthine." Chemical Science 12, no. 27 (2021): 9452–57. http://dx.doi.org/10.1039/d1sc03147c.

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A reasonable synthesis design by strategically integrating functional group manipulation into the ring system construction resulted in a short, enantioselective, gram-scale total synthesis of (−)-zephyranthine.

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Bromhead, L. J., A. R. Norman, K. C. Snowden, B. J. Janssen, and C. S. P. McErlean. "Enantioselective total synthesis and biological evaluation of (−)-solanacol." Organic & Biomolecular Chemistry 16, no. 30 (2018): 5500–5507. http://dx.doi.org/10.1039/c8ob01287c.

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Rodríguez-López, Julio, Nuria Ortega, Victor S. Martín, and Tomás Martín. "β-Hydroxy-γ-lactones as nucleophiles in the Nicholas reaction for the synthesis of oxepene rings. Enantioselective formal synthesis of (−)-isolaurepinnacin and (+)-rogioloxepane A." Chem. Commun. 50, no. 28 (2014): 3685–88. http://dx.doi.org/10.1039/c4cc00389f.

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Lafleur-Lambert, Raphaël, and John Boukouvalas. "Asymmetric total synthesis of (+)-O-methylasparvenone, a rare nitrogen-free serotonin 2C receptor antagonist." Organic & Biomolecular Chemistry 14, no. 37 (2016): 8758–63. http://dx.doi.org/10.1039/c6ob01678b.

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Kristensen, Jesper L., Sebastian Clementson, Mikkel Jessing, and Paulo J. Vital. "Development of a Divergent Route to Erythrina Alkaloids." Synlett 31, no. 04 (January 23, 2020): 327–33. http://dx.doi.org/10.1055/s-0039-1690792.

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Erythrina alkaloids were identified at the end of the 19th century and today, more than 100 members of the erythrinane family have been isolated. They are characterized by a unique tetracyclic, α-tertiary spiroamine scaffold. Herein we detail our efforts towards the development of a divergent enantioselective synthesis of (+)-dihydro-β-erythroidine (DHβE) – one of the most prominent members of this intriguing family of natural products.1 Introduction2 Synthetic Strategy2.1 First Generation2.2 Second Generation2.3 Third Generation2.3.1 Radical Endgame2.3.2 Completion of the Total Synthesis3 Conclusion

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Barrios Antúnez, Diego-Javier, Mark D. Greenhalgh, Alexander C. Brueckner, Daniel M. Walden, Pilar Elías-Rodríguez, Patrick Roberts, Benjamin G. Young, et al. "Catalytic enantioselective synthesis of perfluoroalkyl-substituted β-lactones via a concerted asynchronous [2 + 2] cycloaddition: a synthetic and computational study." Chemical Science 10, no. 24 (2019): 6162–73. http://dx.doi.org/10.1039/c9sc00390h.

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Chen, Ching-Nung, and Duen-Ren Hou. "Enantioselective synthesis of (+)-brevipolide H." Organic & Biomolecular Chemistry 14, no. 28 (2016): 6762–68. http://dx.doi.org/10.1039/c6ob01071g.

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