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Journal articles on the topic 'Cascade synthesis'

Author: Grafiati

Published: 4 June 2021

Last updated: 18 February 2022

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1

Fateev, Ilja V., Maria A. Kostromina, Yuliya A. Abramchik, Barbara Z. Eletskaya, Olga O. Mikheeva, Dmitry D. Lukoshin, Evgeniy A. Zayats, et al. "Multi-Enzymatic Cascades in the Synthesis of Modified Nucleosides: Comparison of the Thermophilic and Mesophilic Pathways." Biomolecules 11, no. 4 (April 16, 2021): 586. http://dx.doi.org/10.3390/biom11040586.

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A comparative study of the possibilities of using ribokinase → phosphopentomutase → nucleoside phosphorylase cascades in the synthesis of modified nucleosides was carried out. Recombinant phosphopentomutase from Thermus thermophilus HB27 was obtained for the first time: a strain producing a soluble form of the enzyme was created, and a method for its isolation and chromatographic purification was developed. It was shown that cascade syntheses of modified nucleosides can be carried out both by the mesophilic and thermophilic routes from D-pentoses: ribose, 2-deoxyribose, arabinose, xylose, and 2-deoxy-2-fluoroarabinose. The efficiency of 2-chloradenine nucleoside synthesis decreases in the following order: Rib (92), dRib (74), Ara (66), F-Ara (8), and Xyl (2%) in 30 min for mesophilic enzymes. For thermophilic enzymes: Rib (76), dRib (62), Ara (32), F-Ara (<1), and Xyl (2%) in 30 min. Upon incubation of the reaction mixtures for a day, the amounts of 2-chloroadenine riboside (thermophilic cascade), 2-deoxyribosides (both cascades), and arabinoside (mesophilic cascade) decreased roughly by half. The conversion of the base to 2-fluoroarabinosides and xylosides continued to increase in both cases and reached 20-40%. Four nucleosides were quantitatively produced by a cascade of enzymes from D-ribose and D-arabinose. The ribosides of 8-azaguanine (thermophilic cascade) and allopurinol (mesophilic cascade) were synthesized. For the first time, D-arabinosides of 2-chloro-6-methoxypurine and 2-fluoro-6-methoxypurine were synthesized using the mesophilic cascade. Despite the relatively small difference in temperatures when performing the cascade reactions (50 and 80 °C), the rate of product formation in the reactions with Escherichia coli enzymes was significantly higher. E. coli enzymes also provided a higher content of the target products in the reaction mixture. Therefore, they are more appropriate for use in the polyenzymatic synthesis of modified nucleosides.

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2

Satpathy, Sanket, and Paul Cuff. "Secure Cascade Channel Synthesis." IEEE Transactions on Information Theory 62, no. 11 (November 2016): 6081–94. http://dx.doi.org/10.1109/tit.2016.2588499.

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3

Huffman, Mark A., Anna Fryszkowska, Oscar Alvizo, Margie Borra-Garske, Kevin R. Campos, Keith A. Canada, Paul N. Devine, et al. "Design of an in vitro biocatalytic cascade for the manufacture of islatravir." Science 366, no. 6470 (December 5, 2019): 1255–59. http://dx.doi.org/10.1126/science.aay8484.

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Enzyme-catalyzed reactions have begun to transform pharmaceutical manufacturing, offering levels of selectivity and tunability that can dramatically improve chemical synthesis. Combining enzymatic reactions into multistep biocatalytic cascades brings additional benefits. Cascades avoid the waste generated by purification of intermediates. They also allow reactions to be linked together to overcome an unfavorable equilibrium or avoid the accumulation of unstable or inhibitory intermediates. We report an in vitro biocatalytic cascade synthesis of the investigational HIV treatment islatravir. Five enzymes were engineered through directed evolution to act on non-natural substrates. These were combined with four auxiliary enzymes to construct islatravir from simple building blocks in a three-step biocatalytic cascade. The overall synthesis requires fewer than half the number of steps of the previously reported routes.

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4

Becker, Martin, Patrick Nikel, Jennifer N. Andexer, Stephan Lütz, and Katrin Rosenthal. "A Multi-Enzyme Cascade Reaction for the Production of 2′3′-cGAMP." Biomolecules 11, no. 4 (April 16, 2021): 590. http://dx.doi.org/10.3390/biom11040590.

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Multi-enzyme cascade reactions for the synthesis of complex products have gained importance in recent decades. Their advantages compared to single biotransformations include the possibility to synthesize complex molecules without purification of reaction intermediates, easier handling of unstable intermediates, and dealing with unfavorable thermodynamics by coupled equilibria. In this study, a four-enzyme cascade consisting of ScADK, AjPPK2, and SmPPK2 for ATP synthesis from adenosine coupled to the cyclic GMP-AMP synthase (cGAS) catalyzing cyclic GMP-AMP (2′3′-cGAMP) formation was successfully developed. The 2′3′-cGAMP synthesis rates were comparable to the maximal reaction rate achieved in single-step reactions. An iterative optimization of substrate, cofactor, and enzyme concentrations led to an overall yield of 0.08 mole 2′3′-cGAMP per mole adenosine, which is comparable to chemical synthesis. The established enzyme cascade enabled the synthesis of 2′3′-cGAMP from GTP and inexpensive adenosine as well as polyphosphate in a biocatalytic one-pot reaction, demonstrating the performance capabilities of multi-enzyme cascades for the synthesis of pharmaceutically relevant products.

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5

Padwa, A. "Application of cascade processes toward heterocyclic synthesis." Pure and Applied Chemistry 75, no. 1 (January 1, 2003): 47–62. http://dx.doi.org/10.1351/pac200375010047.

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The reactions of N-acyliminium ions with tethered π-bonds are among the most important methods for preparing complex nitrogen-containing heterocycles. Pummerer-based cyclizations are also finding widespread application in both carbo- and heterocyclic syntheses. As part of a program concerned with new methods for alkaloid synthesis, we became interested in using a linked Pummerer/N-acyliminium ion cyclization sequence since we felt that this combination offers unique opportunities for the assemblage of complex target molecules. A synthetic method that combines transformations of different reaction types significantly broadens the scope of such procedures in synthetic chemistry. α-Thiocarbocations generated from the Pummerer reaction of β-phenylsulfinylmethyl-α,β-unsaturated amides can be intercepted by the adjacent amido group to produce transient amino- substituted furans, which undergo subsequent Diels-Alder cycloadditions. Using this domino amido-Pummerer/Diels-Alder cascade, we were able to assemble novel polycyclic systems in a single operation. The key step in the process involves the generation of a reactive N-acyliminium ion by fragmentation of an amino-substituted [4+2] cycloadduct. The successful synthesis of a number of alkaloids by this sequence of reactions reveals the usefulness and importance of this unique domino cascade.

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6

Holman, K. R., A. M. Stanko, and S. E. Reisman. "Palladium-catalyzed cascade cyclizations involving C–C and C–X bond formation: strategic applications in natural product synthesis." Chemical Society Reviews 50, no. 14 (2021): 7891–908. http://dx.doi.org/10.1039/d0cs01385d.

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This tutorial review highlights the use of palladium-catalyzed cascade cyclizations in natural product synthesis, focusing on cascades that construct multiple rings and form both C–C and C–X (X = O, N) bonds in a single synthetic operation.

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7

Taber, Douglass F., Rama S. Bhamidipati, and Mitchell L. Thomas. "Cascade Cyclization: Synthesis of (+)-Tuberine." Journal of Organic Chemistry 59, no. 12 (June 1994): 3442–44. http://dx.doi.org/10.1021/jo00091a038.

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8

Nicolaou, K. C., David J. Edmonds, and Paul G. Bulger. "Cascade Reactions in Total Synthesis." Angewandte Chemie International Edition 45, no. 43 (November 6, 2006): 7134–86. http://dx.doi.org/10.1002/anie.200601872.

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9

Gong, Jianxian, Zhen Yang, Yueqing Gu, and Ceheng Tan. "Diversity-Oriented Synthesis of Natural Products via Gold-Catalyzed Cascade Reactions." Synlett 29, no. 12 (May 16, 2018): 1552–71. http://dx.doi.org/10.1055/s-0037-1610126.

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This account describes our group’s latest research in the field of diversity-oriented synthesis of natural products via gold-catalyzed cascade reactions. We present two general strategies based on gold-catalyzed cycloisomerization: a gold-catalyzed cascade reaction of 1,7-diynes and a pinacol-terminated gold-catalyzed cascade reaction. We highlight our development of synthetic methods for the construction of biologically active natural products by using these two strategies.1 Introduction2 Gold-Catalyzed Cascade Reactions of 1,7-Diynes2.1 Collective Synthesis of C15 Oxygenated Drimane-Type Sesquiterpenoids2.2 Synthesis of Left-Wing Fragment of Azadirachtin I2.3 Collective Synthesis of Cladiellins3 Pinacol-Terminated Gold-Catalyzed Cascade Reaction3.1 Asymmetric Formal Total Synthesis of (+)-Cortistatins3.2 Total Synthesis of Orientalol F3.3 Asymmetric Total Synthesis of (–)-Farnesiferol C4 Summary and Outlook

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10

Qian, Jin Gui, Si Jia Zhou, Hai Yang Liu, and Yan Jun Wang. "The Topological Structure Analysis of Novel Cascaded Wind Power Generation System." Advanced Materials Research 1008-1009 (August 2014): 151–54. http://dx.doi.org/10.4028/www.scientific.net/amr.1008-1009.151.

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This article focuses on the topics of cascaded wind power generation system with Variable Speed Constant Frequency (VSCF). It consists of four key components, including the wind turbine, dual-rotor motors, low-speed synchronous motor and inverter. This paper summarizes and compares multiple topology form of cascade wind power system, and through the study of the relevant working mechanism, structure and layout of the form, the applicable conditions and scope of the new system are expounded in detail. In particular, as the superiority of cascade system, it makes a synthesis of variable speed and constant speed power generation into reality, thereby the cascaded systems comprehensive operational efficiency are improved.

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11

Lynch, Dylan M., and Eoin M. Scanlan. "Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates." Molecules 25, no. 13 (July 7, 2020): 3094. http://dx.doi.org/10.3390/molecules25133094.

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Sulfur centered radicals are widely employed in chemical synthesis, in particular for alkene and alkyne hydrothiolation towards thioether bioconjugates. The steadfast radical chain process that enables efficient hydrothiolation has been explored in the context of cascade reactions to furnish complex molecular architectures. The use of thiyl radicals offers a much cheaper and less toxic alternative to the archetypal organotin-based radical methods. This review outlines the development of thiyl radicals as reactive intermediates for initiating carbocyclization cascades. Key developments in cascade cyclization methodology are presented and applications for natural product synthesis are discussed. The review provides a chronological account of the field, beginning in the early seventies up to very recent examples; a span of almost 50 years.

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12

Calderini, Elia, Philipp Süss, Frank Hollmann, Rainer Wardenga, and Anett Schallmey. "Two (Chemo)-Enzymatic Cascades for the Production of Opposite Enantiomers of Chiral Azidoalcohols." Catalysts 11, no. 8 (August 17, 2021): 982. http://dx.doi.org/10.3390/catal11080982.

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Multi-step cascade reactions have gained increasing attention in the biocatalysis field in recent years. In particular, multi-enzymatic cascades can achieve high molecular complexity without workup of reaction intermediates thanks to the enzymes’ intrinsic selectivity; and where enzymes fall short, organo- or metal catalysts can further expand the range of possible synthetic routes. Here, we present two enantiocomplementary (chemo)-enzymatic cascades composed of either a styrene monooxygenase (StyAB) or the Shi epoxidation catalyst for enantioselective alkene epoxidation in the first step, coupled with a halohydrin dehalogenase (HHDH)-catalysed regioselective epoxide ring opening in the second step for the synthesis of chiral aliphatic non-terminal azidoalcohols. Through the controlled formation of two new stereocenters, corresponding azidoalcohol products could be obtained with high regioselectivity and excellent enantioselectivity (99% ee) in the StyAB-HHDH cascade, while product enantiomeric excesses in the Shi-HHDH cascade ranged between 56 and 61%.

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13

Castagnolo, Daniele, and Kate Lauder. "Photo-Biocatalytic Cascades for the Synthesis of Volatile Sulfur Compounds and Chemical Building Blocks." Synlett 31, no. 08 (January 10, 2020): 737–44. http://dx.doi.org/10.1055/s-0039-1690784.

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Biocatalysis is a branch of catalysis that exploits enzymes to perform highly stereoselective chemical transformations under mild and sustainable conditions. This Synpact highlights how biocatalysis can be used in the synthesis of chiral 1,3-mercaptoalkanols, an important class of compounds responsible for the flavours and aromas of many foods and beverages. The identification of two ketoreductase (KRED) enzymes able to reduce prochiral ketone precursors enantioselectively to 1,3-mercaptoalkanols bearing a C–O stereocentre is presented. In addition, the combination of a photocatalytic thia-Michael reaction to access prochiral ketones with subsequent KRED-biocatalysed reduction in a one-pot cascade is presented. Photo-biocatalysed cascades represent one of the new and most intriguing challenges in synthetic chemistry, because the combination of different catalytic methodologies in domino processes offers unique opportunities to outperform sequential reactions with a high degree of selectivity and the avoidance of the need to isolate reaction intermediates.1 Introduction2 Biocatalytic Synthesis of 1,3-Mercaptoalkanols3 Photo-Biocatalytic Synthesis of 1,3-Mercaptoalkanols4 Photo-Biocatalysed Cascade Reactions5 Conclusions

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14

Wu, Jing-Jing, Yong Shi, and Wei-Sheng Tian. "Synthesis of the aglycon of aspafiliosides E and F based on cascade reactions." Chemical Communications 52, no. 9 (2016): 1942–44. http://dx.doi.org/10.1039/c5cc08856a.

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Herein, we describe an efficient synthesis of C17α-OH-tigogenin, which is the aglycon of aspafiliosides E and F. The synthesis features three cascade processes, which involve the iodo-lactonization of furostan-26-acid, a cascade hydrolysis/intramolecular S_N2 process, and a cascade intramolecular redox-ketalization process.

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15

Klaus, Tobias, Alexander Seifert, Tim Häbe, Bettina Nestl, and Bernhard Hauer. "An Enzyme Cascade Synthesis of Vanillin." Catalysts 9, no. 3 (March 12, 2019): 252. http://dx.doi.org/10.3390/catal9030252.

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A novel approach for the synthesis of vanillin employing a three-step two-enzymatic cascade sequence is reported. Cytochrome P450 monooxygenases are known to catalyse the selective hydroxylation of aromatic compounds, which is one of the most challenging chemical reactions. A set of rationally designed variants of CYP102A1 (P450 BM3) from Bacillus megaterium at the amino acid positions 47, 51, 87, 328 and 437 was screened for conversion of the substrate 3-methylanisole to vanillyl alcohol via the intermediate product 4-methylguaiacol. Furthermore, a vanillyl alcohol oxidase (VAO) variant (F454Y) was selected as an alternative enzyme for the transformation of one of the intermediate compounds via vanillyl alcohol to vanillin. As a proof of concept, the bi-enzymatic three-step cascade conversion of 3-methylanisole to vanillin was successfully evaluated both in vitro and in vivo.

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16

Anderson, Edward A. "Cascade polycyclisations in natural product synthesis." Organic & Biomolecular Chemistry 9, no. 11 (2011): 3997. http://dx.doi.org/10.1039/c1ob05212h.

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17

Zea, Alex, Andrea-Nekane R. Alba, Andrea Mazzanti, Albert Moyano, and Ramon Rios. "Highly enantioselective cascade synthesis of spiropyrazolones." Organic & Biomolecular Chemistry 9, no. 19 (2011): 6519. http://dx.doi.org/10.1039/c1ob05753g.

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18

Vaidyaraman, Shankar, and Costas D. Maranas. "Synthesis of Mixed Refrigerant Cascade Cycles." Chemical Engineering Communications 189, no. 8 (August 2002): 1057–78. http://dx.doi.org/10.1080/00986440213475.

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19

Knežević, Anamarija, Vladimir Vinković, Nikola Maraković, and Goran Šinko. "Enzyme-catalyzed cascade synthesis of hydroxyiminoacetamides." Tetrahedron Letters 55, no. 31 (July 2014): 4338–41. http://dx.doi.org/10.1016/j.tetlet.2014.06.027.

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20

Rengan, Kasthuri, and Robert Engel. "The synthesis of phosphonium cascade molecules." Journal of the Chemical Society, Perkin Transactions 1, no. 5 (1991): 987. http://dx.doi.org/10.1039/p19910000987.

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21

Li, Zhi, Shuke Wu, and Ji Liu. "Organic Synthesis via Oxidative Cascade Biocatalysis." Synlett 27, no. 19 (October 17, 2016): 2644–58. http://dx.doi.org/10.1055/s-0036-1588627.

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22

Falck, J. R., Anish Bandyopadhyay, Narender Puli, Abhijit Kundu, L. Manmohan Reddy, Deb K. Barma, Anyu He, Hongming Zhang, Dhurke Kashinath, and Rachid Baati. "Cascade Synthesis of (E)-2-Alkylidenecyclobutanols." Organic Letters 11, no. 20 (October 15, 2009): 4764–66. http://dx.doi.org/10.1021/ol901985c.

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23

Ardkhean, R., D. F. J. Caputo, S. M. Morrow, H. Shi, Y. Xiong, and E. A. Anderson. "Cascade polycyclizations in natural product synthesis." Chemical Society Reviews 45, no. 6 (2016): 1557–69. http://dx.doi.org/10.1039/c5cs00105f.

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Cascade (domino) reactions have an unparalleled ability to generate molecular complexity from relatively simple starting materials; these transformations are particularly appealing when multiple rings are forged during this process.

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24

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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25

Wang, Yun, Guanxin Huang, Yong Shi, Wei-sheng Tian, Chunlin Zhuang, and Fen-Er Chen. "Asymmetric synthesis of (−)-solanidine and (−)-tomatidenol." Organic & Biomolecular Chemistry 18, no. 16 (2020): 3169–76. http://dx.doi.org/10.1039/d0ob00457j.

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The asymmetric synthesis of (−)-solanidine (1) and (−)-tomatidenol (2) has been achieved by employing a cascade ringswitching reaction and a cascade azide reduction/intramolecular reductive amination with 32% and 18.7% overall yields respectively.

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26

Zhang, Ye, Lei Zhang, and Xiangbing Qi. "Total Synthesis of (–)-Alstofolinine A: Selected Furan Oxidation/ Cyclization Cascade." Synlett 31, no. 01 (November 5, 2019): 7–12. http://dx.doi.org/10.1055/s-0039-1690247.

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Indole-fused tetracyclic ring systems containing nitrogen atoms are common core skeletons of many indole alkaloids such as sarpagine, macroline, and ajmaline. Efficient and stereoselective construction of these ring systems can promote the development of the corresponding alkaloid syntheses. In this article, we briefly summarize our current progress toward the application of the aza-Achmatowicz reaction and indole nucleophilic addition reaction cascade for the first asymmetric total synthesis of the macroline-type indole alkaloid (–)-Alstofolinine A. Our synthetic strategy is based on furan oxidation/rearrangement and proceeds from easily accessible materials such as indole and furan derivatives.

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27

Ju, Xiaolin, Xiaojun Hu, Hongliang Shi, Shiqiang Ma, Feifei He, Xiaolei Wang, Xingang Xie, and Xuegong She. "Brønsted acid and Lewis acid co-promoted cascade cyclization reaction and application to the total synthesis of Erysotramidine." Organic Chemistry Frontiers 8, no. 17 (2021): 4839–44. http://dx.doi.org/10.1039/d1qo00668a.

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A strategy for the syntheses of pyrrolo [2,1-a] isoquinolines and indolizinoindolones via a Brønsted acid and Lewis acid co-promoted cascade reaction has been developed. The strategy was exemplified in the total synthesis of Erysotramidine.

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28

Shen, Yangyong, Chaorong Wang, Wei Chen, and Sunliang Cui. "Cascade reaction involving Diels–Alder cascade: modular synthesis of amino α-pyrones, indolines and anilines." Organic Chemistry Frontiers 5, no. 24 (2018): 3574–78. http://dx.doi.org/10.1039/c8qo00939b.

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29

Nicolaou, K. C., and Jason S. Chen. "Total synthesis of complex heterocyclic natural products." Pure and Applied Chemistry 80, no. 4 (January 1, 2008): 727–42. http://dx.doi.org/10.1351/pac200880040727.

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Total synthesis campaigns toward complex heterocyclic natural products are a prime source of inspiration for the design and execution of complex cascade sequences, powerful reactions, and efficient synthetic strategies. We highlight selected examples of such innovations in the course of our total syntheses of diazonamide A, azaspiracid-1, thiostrepton, 2,2'-epi-cytoskyrin A and rugulosin, abyssomycin C, platensimycin, and uncialamycin.

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30

Doherty, Oksana. "Informational cascades in financial markets: review and synthesis." Review of Behavioral Finance 10, no. 1 (March 12, 2018): 53–69. http://dx.doi.org/10.1108/rbf-05-2016-0030.

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Purpose The purpose of this paper is to review recent contributions to the theoretical and empirical literature on informational cascades. Design/methodology/approach This paper reviews and synthesises the existing literature, methodologies and evidence on informational cascades. Findings Many financial settings foster situations where informational cascades and herding are likely. Cascades remain mainly an area of experimental research, leaving the empirical evidence inconclusive. Existing measures have limitations that do not allow for a direct test of cascading behaviour. More accurate models and methods for empirical testing of informational cascades could provide more conclusive evidence on the matter. Practical implications Outlined findings have implications for designing policies and regulatory requirements, as well as for the design of collective decisions processes. Originality/value The paper reviews and critiques existing theory; it summarises the recent laboratory and empirical evidence and identifies issues for future research. Most of other theoretical work reviews informational cascades as a subsection of herding. This paper focusses on informational cascades specifically. It distinguishes between informational cascade and herding. The paper also reviews most recent empirical evidence on cascades, presents review and synthesis of the theoretical and empirical development on information cascades up to date, and reviews the model of informational cascades with model criticism.

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31

Kanger, Tõnis, Dmitri Trubitsõn, Sergei Žari, Sandra Kaabel, Marina Kudrjashova, Kadri Kriis, Ivar Järving, and Tõnis Pehk. "Asymmetric Organocatalytic Cascade Synthesis of Tetrahydrofuranyl Spirooxindoles." Synthesis 50, no. 02 (September 18, 2017): 314–22. http://dx.doi.org/10.1055/s-0036-1590918.

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An enantio- and regioselective organocatalytic cascade starting from isatin has been disclosed to construct tetrahydrofuranyl spirooxindoles in high yields and stereoselectivities. Also, a triple cascade leading to the pentacyclic compound with two quaternary and a tertiary stereocenter is described. The reactions were catalyzed by cinchonine-based thiourea.

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32

Sellebjerg, Finn, Michael Christiansen, and Peter Garred. "MBP, anti-MBP and anti-PLP antibodies, and intrathecal complement activation in multiple sclerosis." Multiple Sclerosis Journal 4, no. 3 (June 1998): 127–31. http://dx.doi.org/10.1177/135245859800400307.

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Intrathecal immunoglobulin synthesis and activation of the complement cascade occurs in patients with multiple sclerosis (MS). The present study aimed at further studying the relation between intrathecal immunoglobulin synthesis and complement activation. We compared total intrathecal synthesis of lgA, IgG, and IgM, the number of cells secreting anti-myelin basic protein (MBP) and anti-proteolipid protein (PLP) antibodies of the IgG isotype and intrathecal activation of the complement cascade in patients with possible onset symptoms of MS (n=18) or clinically definite MS (n=30). Early activation of the complement cascade correlated with intrathecal synthesis of IgM. Intrathecal IgG, lgA and IgM synthesis also correlated weakly with the presence of cells secreting anti-MBP or anti-PLP autoantibodies. Full activation of the complement cascade did not correlate with any measures of intrathecal antibody synthesis. These findings suggest a complex relation between different immunoglobulin isotypes and complement activation which may have similarly complex roles in the pathogenesis of MS.

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33

Newkome, George R., Xiaofeng Lin, Chen Yaxiong, and Gregory H. Escamilla. "Cascade polymer series. 27. Two-directional cascade polymer synthesis: effects of core variation." Journal of Organic Chemistry 58, no. 11 (May 1993): 3123–29. http://dx.doi.org/10.1021/jo00063a036.

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34

Frontier, Alison J., Shukree Abdul-Rashed, and Connor Holt. "Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications." Synthesis 52, no. 14 (April 9, 2020): 1991–2007. http://dx.doi.org/10.1055/s-0039-1690869.

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This review focuses on alkynyl Prins and alkynyl aza-Prins cyclization processes, which involve intramolecular coupling of an alkyne with either an oxocarbenium or iminium electrophile. The oxocarbenium or iminium species can be generated through condensation- or elimination-type processes, to achieve an overall bimolecular annulation that enables the synthesis of both oxygen- and nitrogen-containing saturated heterocycles with different ring sizes and substitution patterns. Also discussed are cascade processes in which alkynyl Prins heterocyclic adducts react to trigger subsequent pericyclic reactions, including [4+2] cycloadditions and Nazarov electrocyclizations, to rapidly construct complex small molecules. Finally, examples of the use of alkynyl Prins and alkynyl aza-Prins reactions in the synthesis of natural products are described. The review covers the literature through the end of 2019.1 Introduction1.1 Alkyne-Carbonyl Coupling Pathways1.2 Coupling/Cyclization Cascades Using the Alkynyl Prins Reaction2 Alkynyl Prins Annulation (Oxocarbenium Electrophiles)2.1 Early Work2.2 Halide as Terminal Nucleophile2.3 Oxygen as Terminal Nucleophile2.4 Arene as Terminal Nucleophile (Intermolecular)2.5 Arene Terminal Nucleophile (Intramolecular)2.6 Cyclizations Terminated by Elimination3 Synthetic Utility of Alkynyl Prins Annulation3.1 Alkynyl Prins-Mediated Synthesis of Dienes for a [4+2] Cyclo- addition-Oxidation Sequence3.2 Alkynyl Prins Cyclization Adducts as Nazarov Cyclization Precursors3.3 Alkynyl Prins Cyclization in Natural Product Synthesis4 Alkynyl Aza-Prins Annulation4.1 Iminium Electrophiles4.2 Activated Iminium Electrophiles5 Alkynyl Aza-Prins Cyclizations in Natural Product Synthesis6 Summary and Outlook

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35

Abe, Takumi. "Synthesis of Indoloquinazoline Alkaloids Using Cascade Reactions." Journal of Synthetic Organic Chemistry, Japan 76, no. 8 (August 1, 2018): 802–9. http://dx.doi.org/10.5059/yukigoseikyokaishi.76.802.

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36

Landais, Yannick, and Edouard Godineau. "Synthesis of Piperidinones through a Radical Cascade." Synthesis 2009, no. 15 (May 29, 2009): 2646–49. http://dx.doi.org/10.1055/s-0029-1216860.

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Ceban, Victor, Kane Hands, Marta Meazza, Mark E. Light, and Ramon Rios. "Three-component diastereoselective cascade synthesis of thiohydantoins." Tetrahedron Letters 54, no. 52 (December 2013): 7183–87. http://dx.doi.org/10.1016/j.tetlet.2013.10.110.

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Liu, Wentao, Wenfang Qin, Xiaobei Wang, Fei Xue, Xiao-Yu Liu, and Yong Qin. "Bioinspired Synthesis of (+)-Cinchonidine Using Cascade Reactions." Angewandte Chemie 130, no. 38 (August 28, 2018): 12479–82. http://dx.doi.org/10.1002/ange.201804848.

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Faber, Kurt, Wolf-Dieter Fessner, and Nicholas J. Turner. "Engineering Biocatalysts for Synthesis Including Cascade Processes." Advanced Synthesis & Catalysis 357, no. 8 (May 15, 2015): 1565–66. http://dx.doi.org/10.1002/adsc.201500450.

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Liu, Wentao, Wenfang Qin, Xiaobei Wang, Fei Xue, Xiao-Yu Liu, and Yong Qin. "Bioinspired Synthesis of (+)-Cinchonidine Using Cascade Reactions." Angewandte Chemie International Edition 57, no. 38 (August 28, 2018): 12299–302. http://dx.doi.org/10.1002/anie.201804848.

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RENGAN, K., and R. ENGEL. "ChemInform Abstract: Synthesis of Phosphonium Cascade Molecules." ChemInform 22, no. 32 (August 22, 2010): no. http://dx.doi.org/10.1002/chin.199132199.

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TABER, D. F., R. S. BHAMIDIPATI, and M. L. THOMAS. "ChemInform Abstract: Cascade Cyclization: Synthesis of (+)-Tuberine." ChemInform 25, no. 51 (August 18, 2010): no. http://dx.doi.org/10.1002/chin.199451291.

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Peña, D., E. Guitián, A. Criado, and A. Cobas. "Cascade Cycloadditions for the Synthesis of Perylenes." Synfacts 2010, no. 11 (October 21, 2010): 1237. http://dx.doi.org/10.1055/s-0030-1258730.

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Lou, Zhenbang, Ningning Man, Haijun Yang, Changjin Zhu, and Hua Fu. "Copper-Catalyzed Cascade Synthesis of [1,2,4]-Triazoloquinazolinones." Synlett 29, no. 10 (April 20, 2018): 1395–99. http://dx.doi.org/10.1055/s-0036-1591565.

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An efficient and practical method for the synthesis of 1,2,4-triazolo[5,1-b]quinazolin-9(3H)-ones has been developed via the copper-catalyzed domino reactions of readily available substituted N′-acetyl-2-bromobenzohydrazides with cyanamide. The protocol uses inexpensive CuI as the catalyst, and no other ligand or additive was required. The target products were prepared in good to excellent yields with tolerance of various functional groups.

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Wang, Xiaobei. "Indole Alkaloid Synthesis via Radical Cascade Reactions." Chem 2, no. 6 (June 2017): 749–50. http://dx.doi.org/10.1016/j.chempr.2017.05.012.

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Liu, Bo, and Juan Chen. "Total Synthesis of Natural Terpenoids: Inspired but Not Limited by Biohypothesis." Synlett 29, no. 07 (March 21, 2018): 863–73. http://dx.doi.org/10.1055/s-0036-1591935.

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This account describes our studies on the total synthesis of several natural terpenoids based on our modified biosynthetic hypothesis. Compared to the originally proposed biosynthetic hypothesis, the modified ones proved to be more practicable for the formation of hispidanin A, a dimeric diterpenoid, and sarcandrolide J and shizukaol D, two dimeric sesquiterpenoids, from a viewpoint of chemical reactivity. Moreover, a cascade reaction involving intermolecular and intramolecular cycloaddition was facilitated to expeditiously accumulate molecular complexity in the total synthesis of bolivianine, a sesterterpenoid, on the basis of a modified biohypothesis.1 Introduction2 Total Synthesis of Hispidanin A3 Total Syntheses of Bolivianine and Isobolivianine4 Total Syntheses of Sarcandrolide J and Shizukaol D5 Conclusion

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Konarev, D. I., and A. A. Gulamov. "Synthesis of Neural Network Architecture for Recognition of Sea-Going Ship Images." Proceedings of the Southwest State University 24, no. 1 (June 23, 2020): 130–43. http://dx.doi.org/10.21869/2223-1560-2020-24-1-130-143.

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Purpose of research. The current task is to monitor ships using video surveillance cameras installed along the canal. It is important for information communication support for navigation of the Moscow Canal. The main subtask is direct recognition of ships in an image or video. Implementation of a neural network is perspectively.Methods. Various neural network are described. images of ships are an input data for the network. The learning sample uses CIFAR-10 dataset. The network is built and trained by using Keras and TensorFlow machine learning libraries.Results. Implementation of curving artificial neural networks for problems of image recognition is described. Advantages of such architecture when working with images are also described. The selection of Python language for neural network implementation is justified. The main used libraries of machine learning, such as TensorFlow and Keras are described. An experiment has been conducted to train swirl neural networks with different architectures based on Google collaboratoty service. The effectiveness of different architectures was evaluated as a percentage of correct pattern recognition in the test sample. Conclusions have been drawn about parameters influence of screwing neural network on showing its effectiveness.Conclusion. The network with a single curl layer in each cascade showed insufficient results, so three-stage curls with two and three curl layers in each cascade were used. Feature map extension has the greatest impact on the accuracy of image recognition. The increase in cascades' number has less noticeable effect and the increase in the number of screwdriver layers in each cascade does not always have an increase in the accuracy of the neural network. During the study, a three-frame network with two buckling layers in each cascade and 128 feature maps is defined as an optimal architecture of neural network under described conditions. operability checking of architecture's part under consideration on random images of ships confirmed the correctness of optimal architecture choosing.

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Dahiya, Anjali, Wajid Ali, Tipu Alam, and Bhisma K. Patel. "A cascade synthesis ofS-allyl benzoylcarbamothioatesviaMumm-type rearrangement." Organic & Biomolecular Chemistry 16, no. 42 (2018): 7787–91. http://dx.doi.org/10.1039/c8ob02293c.

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Morris, J. C., and C. S. P. McErlean. "Synthesis of highly enantio-enriched stereoisomers of hydroxy-GR24." Organic & Biomolecular Chemistry 14, no. 4 (2016): 1236–38. http://dx.doi.org/10.1039/c5ob02349a.

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Wall, Erin, Nadim Majdalani, and Susan Gottesman. "The Complex Rcs Regulatory Cascade." Annual Review of Microbiology 72, no. 1 (September 8, 2018): 111–39. http://dx.doi.org/10.1146/annurev-micro-090817-062640.

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RcsB, a response regulator of the FixJ/NarL family, is at the center of a complex network of regulatory inputs and outputs. Cell surface stress is sensed by an outer membrane lipoprotein, RcsF, which regulates interactions of the inner membrane protein IgaA, lifting negative regulation of a phosphorelay. In vivo evidence supports a pathway in which histidine kinase RcsC transfers phosphate to phosphotransfer protein RcsD, resulting in phosphorylation of RcsB. RcsB acts either alone or in combination with RcsA to positively regulate capsule synthesis and synthesis of small RNA (sRNA) RprA as well as other genes, and to negatively regulate motility. RcsB in combination with other FixJ/NarL auxiliary proteins regulates yet other functions, independent of RcsB phosphorylation. Proper expression of Rcs and its targets is critical for success of Escherichia coli commensal strains, for proper development of biofilm, and for virulence in some pathogens. New understanding of how the Rcs phosphorelay works provides insight into the flexibility of the two-component system paradigm.

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