Synthetic Studies Toward the Total Synthesis of Lomaiviticin A and B PDF Download
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Author: Virginia Heather Sharron Grant
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ISBN:
Category : Antineoplastic antibiotics
Languages : en
Pages : 192
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Author: Virginia Heather Sharron Grant
Publisher:
ISBN:
Category : Antineoplastic antibiotics
Languages : en
Pages : 192
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Author: Yang Su Tran
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ISBN:
Category :
Languages : en
Pages : 192
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Author: Andrea Lindsay Nold
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ISBN:
Category : Antibiotics
Languages : en
Pages : 572
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This thesis is separated into two parts: the synthesis of the marinomycins and their monomeric counterparts, and the studies toward the total synthesis of the lomaiviticins. Background on antibiotic resistance, the isolation of the marinomycins by the Fenical lab, and our retrosynthetic analysis of the marinomycins is included in Chapter 1. In Chapter 2, our synthesis of the marinomycin monomeric counterparts, our attempted dimerizations to form the marinomycins, and our step-wise synthesis of the marinomycins is included. Chapter 3 focuses on the background of the lomaiviticins, including the isolation and structure determination of the kinamycins (a related family of natural products) and the lomaiviticins, approaches by other groups to the diazoparaquinone natural products, our original approach to the lomaiviticins (early-stage dimerization), and our modified approach to the lomaiviticins (late-stage dimerization). We then go on to synthesize the kinamycins (Chapter 4) as an elaborate model system of the lomaiviticin monomer, and use our acquired knowledge this approach to synthesize the lomaiviticin aglycon monomer, and explore a late-stage dimerization of this monomer (Chapter 5).
Author: Aleksandra Baranczak
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ISBN:
Category : Antineoplastic antibiotics
Languages : en
Pages : 232
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Author: Zhang Wang
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Category :
Languages : en
Pages :
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The first part describes the total synthesis and structural revision of (±)-tricholomalides A and B. The synthetic strategy started from a homo-Robinson annulation, followed by a ketene-olefin [2+2] cycloaddition to introduce the lactone ring. Then a Grignard-type reaction appended the isopropenyl moiety, and the synthesis of tricholomalides A and B was achieved. During the course of synthesis, the structures of tricholomalides A and B were revised. The second part describes the synthetic studies towards (+)-cortistatin A, especially the A ring functionalization. The C3 nitrogen was introduced by azide displacement, and C2 hydroxyl was built up by Luche reduction. The challenging C1 functionalization was achieved with bromine-induced methoxymethyl deprotection, and some interesting chemistry was found in this system. The synthetic endeavor set a promising stage for the total synthesis of cortistatin A.
Author: Aubert Ribaucourt
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ISBN:
Category :
Languages : en
Pages : 0
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Author: Srinivas Achanta
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 242
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Part II: Studies toward the total synthesis of englerin A. Englerin A is a new guaiane sesquiterpene isolated recently in 2008. It has been shown to be a selective renal cancer inhibitor. We envisioned the synthesis of englerin A via a novel strategy featuring Wagner-Meerwein rearrangement followed by intramolecular cation trapping. This chapter describes the stereoselective synthesis of the key cis-decalin intermediate from ( - )-carvone and the unsuccessful attempts to realize the skeletal rearrangement.
Author: Stuart Edward Bradley
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Category :
Languages : en
Pages :
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Author: Wei Zhang
Publisher:
ISBN:
Category : Antineoplastic agents
Languages : en
Pages : 660
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![Synthetic Studies Toward the Total Synthesis (±)-ajmaline and the Development Of, Investigation Into, and Application of a Phosphine-catalyzed [4+1] Annulation PDF](https://books.google.com/books/content/images/frontcover/ULSjAQAACAAJ?fife=w80-h100)
Author: Brian Richard Blank
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ISBN:
Category :
Languages : en
Pages : 325
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Several synthetic routes toward the synthesis of the indole alkaloid (±)-ajmaline have been explored. The retrosynthetic plan was devised around two key transformations, one being a tandem aza-Michael-Michael reaction, and the other a phosphine-catalyzed [4+2] annulation. While these approaches have not allowed for the completion of ajmaline, they have provided a great deal of insight into the chemistry of many intermediates. For example, it was discovered that following installation of the D-ring, functionalization of the tricyclic scaffold to deliver a precursor for the aza-Michael-Michael sequence was a futile undertaking. As such, the necessary functionality had to be installed prior to the [4+2] annulation. For this purpose, ethyl 3-allyl-1H-indole-2-carboxylate was prepared by way of a stepwise Japp-Klingemann reaction, and a subsequent Fischer indolization. Successful conversion of this compound into the N-sulfonyl imine required the employment of 2,6-lutidine to impede isomerization of the allyl moiety. This imine was converted into the tetrahydropyridine through a phosphine-catalyzed [4+2] annulation with ethyl 2-methyl-2,3-butadienoate. Cross-metathesis with methyl acrylate provided the first precursor to the desired aza-Michael-Michael reaction sequence. Unfortunately, only mono-Michael addition was observed when this substrate was employed in the reaction, providing a tetracyclic structure instead of the desired pentacyclic scaffold. As a result, we are currently pursuing tricyclic derivatives that feature either alternative Michael donors or an increased strength of the second Michael acceptor. A phosphine-catalyzed [4+1] annulative rearrangement has been developed to prepare 3-pyrrolines from allenylic carbamates through phosphonium diene intermediates. This methodology was employed to synthesize an array of 1,3-disubstituted- and 1,2,3-trisubstituted-3-pyrrolines, including the often difficult to prepare 2-alkyl variants. A mechanistic investigation employing allenylic acetates and mononucleophiles unexpectedly unveiled that a phosphine-catalyzed [4+1] reaction previously reported by Tong might not occur through a phosphonium diene as was proposed, but rather involves multiple mechanisms working in concert to construct cyclopentene products. Consequentially, our phosphine-catalyzed rearrangement is most likely the first reaction that unequivocally forms a phosphonium diene intermediate along the reaction pathway. Concise formal syntheses of pyrrolizidine alkaloids (±)-trachelanthamidine and (±)-supinidine were completed, demonstrating the synthetic utility of this newly developed reaction.
