Alkaloid Synthesis: Mearsine (Taylor), Cephalotaxine (Li), Cocaine (Shing), Quinine (Hatakeyama), Cleavamine (Bennasar), Strychnine(Vanderwal)

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Hong Kong ◽  
Malonic Acid ◽  
Selective Hydrogenation ◽  
Aqueous Ammonia ◽  
Conjugate Addition ◽  
University Of California ◽  
The Past ◽  
Chinese University ◽  
Alkaloid Synthesis ◽  
The University

Richard J. K. Taylor of the University of York employed (Tetrahedron Lett. 2011, 52, 2024) the Jørgensen protocol to add 2 to 1, to give the enantiomerically enriched cyclohexenone 3. Condensation of 3 with aqueous ammonia led directly to (-)-mearsine 4. Wei-Dong Z. Li of Nankai University found (Org. Lett. 2011, 13, 3538) that the intermediate from Dibal reduction of the lactone 5 underwent Nazarov cyclization, giving the α-hydroxy cyclopentenone 6. After acetylation, deprotection gave an amine that cyclized with high diastereocontrol, leading to (±)-cephalotaxine 7. Tony K. M. Shing of the Chinese University of Hong Kong cyclized (Org. Lett. 2011, 13, 2916) the aldehyde 8 by exposure to 9. The product 10 was carried on to (-)-cocaine 11, as well as several hydroxylated cocaine derivatives. Susumi Hatakeyama of Nagasaki University found (Tetrahedron Lett. 2011, 52, 923) that exposure of the simple prochiral aldehyde 12 to catalytic proline transformed it, after reduction, into the cyclized diol 13 in high ee. The diol 13 was readily carried on to quinine 14. M.-Lluïsa Bennasar of the University of Barcelona devised (Org. Lett. 2011, 13, 2042) Pd-catalyzed conditions for the cyclization of 15 that selectively delivered the unstable kinetic product 18. Selective hydrogenation of the more reactive bridgehead alkene then led to cleavamine 17. The alkene 16 is also prochiral, so it is possible that a catalyst could be found that would deliver 17 in high ee. The synthesis of the heptacyclic alkaloid strychnine 23 would, in the past, have been a major undertaking. Christopher D. Vanderwal of the University of California, Irvine, prepared (Chem. Sci. 2011, 2, 649) 23 in just six linear steps. The dienyl aldehyde 18 was available in two steps from tryptophyl bromide. Exposure to t -BuOK cyclized 18 to 19. N-deallylation followed by alkylation with 20 provided 21, setting the stage for a truly spectacular Brook rearrangement/conjugate addition, to give the Wieland-Gumlich aldehyde 22. The known condensation with malonic acid completed the preparation of 23.

The Toste Synthesis of ( + )-Fawcettimine

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Current Method ◽  
Conjugate Addition ◽  
Enantioselective Synthesis ◽  
University Of California ◽  
Lycopodium Alkaloid ◽  
Silyl Enol Ether ◽  
Terminal Alkene ◽  
Robinson Annulation ◽  
The University ◽  
Stereogenic Center

The tetracyclic Lycopodium alkaloid fawcettimine 3 and its derivatives are of interest as inhibitors of acetylcholine esterase. F. Dean Toste of the University of California, Berkeley recently reported (Angew. Chem. Int. Ed. 2007, 46, 7671) the first enantioselective synthesis of 3. The key to the synthesis was the rapid assembly of the enantiomerically-enriched hydrindane 2. The preparation of 2 began with the enantioselective Robinson annulation of the β-keto ester 4 with crotonaldehyde 5, mediated by the organocatalyst 6. In this protocol, originally developed by Karl Anker Jørgensen, the single stereogenic center was established by conjugate addition, presumably to the chiral iminium salt generated by the condensation of 5 with 6. Subsequent aldol (or more likely Mannich) cyclization followed by elimination gave 7. Hydrolysis and decarboxylation by heating with p-TsOH converted 7 to 1. This procedure was robust enough to allow preparation of a ten gram batch of 1. This Jørgensen annulation is the current method of choice for the enantioselective preparation of 2,5-dialkyl cyclohexenones. Conjugate addition of the propargyl anion equivalent 8 to 1 proceeded with the expected > 95:5 axial diastereoselectivity, to give the silyl enol ether 9. Exposure of the derived iodide 10 to catalytic [Ph3 PAu]Cl and AgBF4 induced smooth cyclization to the cis hydrindane 2. Before constructing the nine-membered ring amine of fawcettimine 3, it was first necessary to protect the ketone as the ketal. Pd-mediated coupling of the alkenyl iodide with the organoborane derived from 11 then proceeded smoothly, as did the subsequent hydroboration of the terminal alkene. Neither the mesylate nor the tosylate derived from 12 could be induced to cyclize. In contrast, intramolecular displacement of the iodide proceeded well, to give 13. Hydroboration followed by oxidation then gave 15, which on deprotection cyclized to (+)-fawcettimine 3. Several aspects of this synthesis are attractive. While the stereochemical outcome of the hydroboration of 14 could not necessarily be predicted with confidence, in fact it did not matter, as the stereogenic center adjacent to the ketone could be epimerized under the trifluoroacetic acid deprotection conditions, and only the desired diastereomer would be able to add in an intramolecular fashion to the cyclohexanone.

Ibsen Our Contemporary

2014 ◽  
Vol 30 (3) ◽  
pp. 243-248
Author(s):  
Richard Hornby
Keyword(s):  
Social Problem ◽  
University Of California ◽  
Keynote Address ◽  
Emeritus Professor ◽  
Avant Garde ◽  
The Past ◽  
Theatre Company ◽  
The University ◽  
The Grotesque

In this article Richard Hornby argues that Ibsen's plays are badly performed today, or not performed at all, because of directors' refusal to take them with appropriate seriousness. The tendency is to stage the plays' reputation as simplistic social problem plays rather than as the complex, challenging, bizarre dramas that Ibsen actually wrote. In particular, directors avoid the grotesque elements that are the true ‘quintessence of Ibsenism’, and that are often remarkably similar in style to that of avant-garde playwrights today. Richard Hornby is Emeritus Professor of Theatre at the University of California, Riverside. For the past twenty-eight years he has been theatre critic for The Hudson Review, and is author of six books and over two hundred published articles on various aspects of theatre. This essay was delivered as the keynote address at the fourteenth annual Ibsen Festival of the Commonweal Theatre Company, Lanesboro, Minnesota, in April 2011.

scholarly journals Very Complex Matter: Collaborations in Art and Geobiology

Artnodes ◽  
2017 ◽  
pp. 67-75
Author(s):  
Meredith Tromble
Keyword(s):  
Early Life ◽  
Scientific Practice ◽  
University Of California ◽  
The Past ◽  
Physical Theater ◽  
The University ◽  
Complex Matter

Geobiologist Dawn Sumner, known for her research on early life in Antarctica, her contributions to the Mars Curiosity science team, and for co-founding KeckCAVES at the University of California Davis, has also spent the past decade working in collaboration with artists. This paper addresses the relevance of these art/science collaborations to her scientific practice through an analysis of four of her projects: Collapse (suddenly falling down) with Sideshow Physical Theater; Dream Vortex with Meredith Tromble; Life Extreme with Philip Alden Benn; and The Vortex with Donna Sternberg and Meredith Tromble. The experiences gained by Sumner and her collaborators show that there are many different ways in which artists and scientists can learn from each other. Echoing throughout the collaborations is the realisation that turning ideas into form yields a result that can stimulate the next cycle of creativity.

scholarly journals ISAHP2018 Conference in Hong Kong, July 12-15

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
Rozann W. Saaty
Keyword(s):  
Hong Kong ◽  
Analytic Hierarchy Process ◽  
International Symposium ◽  
Graduate School ◽  
Analytic Hierarchy ◽  
The Past ◽  
University Professor ◽  
The Analytic Hierarchy Process ◽  
The University ◽  
Hierarchy Process

This year the International Symposium on the Analytic Hierarchy Process (ISAHP2018) was dedicated to the memory of Thomas Saaty, the father of the Analytic Hierarchy Process, and my husband of 52 years, who passed away on August 17, 2017, at the age of 91 The conference chair was Luis Vargas, Tom’s longtime colleague at the University of Pittsburgh's Joseph M. Katz Graduate School of Business where he held the chair of Distinguished University Professor. Their names are linked on many AHP articles and books that they co-authored during the past 40 years.

Conspiracy Rises Again

Qui Parle ◽  
2019 ◽  
Vol 28 (2) ◽  
pp. 307-333
Author(s):  
Poulomi Saha
Keyword(s):  
San Francisco ◽  
Central Valley ◽  
The United States ◽  
University Of California ◽  
British India ◽  
Philosophical Concept ◽  
The Past ◽  
Revolutionary Violence ◽  
The University ◽  
Indian Students

Abstract This essay takes up conspiracy as a discursive, political, and philosophical concept. By tracing the ideological and textual kinship between anticolonialism in India and Ireland and radicalism in the United States, it illuminates transcolonial circuits of a curiously shared revolutionary project. Rather than simply offer a historical account of those interconnections, it theorizes a practice of reading revolutionary violence as perpetual, repetitive haunting, a politics of the undead. It argues for a historiographical live burial by which violences of the past reappear to disrupt the imperial promise of futurity and continuity. From the 1916 “Hindu-German Conspiracy Trial” in San Francisco, during which members of the Ghadr Party—consisting of diasporic Indian students at the University of California, Berkeley, and Punjabi farmers in the Central Valley—were accused of conspiring with German diplomats to arm anticolonial revolt in British India, this essay tracks forms of radical sympathy that emerge, flourish, and stutter in an era of ethnonationalist constriction.

scholarly journals He’s ready for his closeup: Peter the Anteater’s guide to the library

2020 ◽  
Vol 81 (3) ◽  
pp. 125
Author(s):  
Nicole Arnold ◽  
Stacy Brinkman ◽  
Lily Correa ◽  
Carolyn Downey
Keyword(s):  
University Of California ◽  
Library Services ◽  
The Past ◽  
The University

The scene opens with a laptop kiosk. In the foreground, a furry head comes into focus with the text: “With an essay to write, a laptop would come in handy!” Meet Peter, the anteater puppet who discovers a laptop kiosk in the library and learns to check one out and return it. In the past year, the libraries at the University of California-Irvine have created several videos with Peter to raise awareness of library services and resources.

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