Model Studies Towards the Total Synthesis of Lyconadin A Via an Acyl Radical Cascade Reaction PDF Download
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Author: Koudi Zhu
Publisher:
ISBN:
Category : Alkaloids
Languages : en
Pages : 74
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Book Description
Lyconadin A is an alkaloid possessing a unique structure and antitumor activity. The total synthesis of Lyconadin A was proposed via an acyl radical cascade reaction. To investigate the possibility and stereoselectivity of the cascade cyclization, phenyl selenoester 16 was chosen as a model substrate to study the 7-exo-5-exo radical cyclization. A synthetic route to phenyl selenoester 16 was developed. The 7-exo-5-exo radical cyclization was found to occur with a high yield and excellent stereoselectivty. Attempts were also tried to synthesize another radical precursor 14 albeit with less success. A synthetic pathway to the synthesis of 14 as well as its potential use in the context of the synthesis of Lyconadin A was proposed.
Author: Koudi Zhu
Publisher:
ISBN:
Category : Alkaloids
Languages : en
Pages : 74
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Book Description
Lyconadin A is an alkaloid possessing a unique structure and antitumor activity. The total synthesis of Lyconadin A was proposed via an acyl radical cascade reaction. To investigate the possibility and stereoselectivity of the cascade cyclization, phenyl selenoester 16 was chosen as a model substrate to study the 7-exo-5-exo radical cyclization. A synthetic route to phenyl selenoester 16 was developed. The 7-exo-5-exo radical cyclization was found to occur with a high yield and excellent stereoselectivty. Attempts were also tried to synthesize another radical precursor 14 albeit with less success. A synthetic pathway to the synthesis of 14 as well as its potential use in the context of the synthesis of Lyconadin A was proposed.
Author: Seth Wilson Grant
Publisher:
ISBN:
Category : Lycopodium powder
Languages : en
Pages : 111
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Book Description
Lyconadin A (1) is a structurally unique Lycopodium alkaloid with antitumor properties, isolated from the club moss Lycopodium complanatum. We are developing a synthetic route to 1 based on a novel 7-exo-trig/6-exo-trig acyl radical cascade cyclization. The synthesis of model acyl radical cascade precursor 23 will be presented. Key features of this synthesis include the suppression of competing elimination during the alkylation of a hindered phenethyl bromide and the use of a lactone as a precursor to a compound bearing two differentially protected primary alcohols. An account of our studies on the model acyl radical cascade cyclization (23 to 24 above) will also be given, including a stereochemical analysis of the product. Our findings have been applied to develop a more detailed stereoselective synthetic plan for Lyconadin A (1).
Author: Yu Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 173
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Book Description
Lyconadin A is a pentacyclic Lycopodium alkaloid isolated from the club moss Lycopodium complanatum with antitumor properties. We have developed a novel 7-exo/6-exo acyl radical cascade cyclization as a method of making the bicyclo[5.4.0]undecane ring system of lyconadin A. The model products are trans-fused ring systems, while a cis-fused ring system is needed in lyconadin A. We have discovered a method to convert the trans-fused model cascade cyclization product into the desired cis isomer. Based on Donohoe's pyridone synthesis, we developed a method for the construction of 5-alkyl and 3,5-dialkyl-6-carbomethoxy-2-pyridones, the former of which is a subunit of lyconadin A. An intramolecular Reformatsky reaction is a key step in this process. We have proceeded with our total synthesis, in which we generated an epoxide by Shi asymmetric epoxidation and regioselectively opened epoxide rings. We have prepared carboxylic acid 197.
Author: Miguel A. Sierra
Publisher: John Wiley & Sons
ISBN: 352765464X
Category : Science
Languages : en
Pages : 297
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Book Description
Success comes in many forms and in synthesis it can be a failure that results in their ultimate successful solutions. This long-awaited sequel to "Dead Ends and Detours" retains the proven concept while featuring over 20 new case studies of failed strategies and their (successful) solutions in natural product total synthesis. Additionally, computational models are used to discuss the problem in much more detail and to provide readers with additional information not found in the primary literature. The topics range from classic synthetic reactions (e.g. Diels Alder reaction), metal-mediated coupling reactions, metathesis, and asymmetric catalysis to the importance of protecting and activating groups. This book will benefit not only graduate students in organic chemistry but also advanced researchers as they gain knowledge derived from the step-by-step analysis of mistakes made in the past and, thus be able to improve their own chemical reaction planning. With its coverage of the most commonly applied reaction types, the book perfectly complements its predecessor, which focuses on general aspects, such as reactivity and selectivity.
Author: Brad M. Loertscher
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 191
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Book Description
Lyconadin A is a pentacyclic Lycopodium alkaloid isolated from the club moss Lycopodium companatum with anticancer activity. Our approach sought to incorporate a 7-exo-6-exo acyl radical cyclization cascade to access the bicyclo[5.4.0]undecane framework of lycoadin A. Our studies created methodology for the synthesis of 5-alkyl and 3,5-dialkyl-6-carbomethoxy-2-pyridones and sterically demanding epoxide substrates. These epoxide substrates underwent an unanticipated Payne rearrangement.
Author: Nathan Edward Genung
Publisher:
ISBN:
Category :
Languages : en
Pages : 1020
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Book Description
"I. Studies Towards the Total Synthesis of (±)-Lycoramine. The tricyclic core of the amaryllidaceae alkaloids was prepared in a convergent synthesis via an intramolecular Heck/phenol capture sequence. The versatile cascade reaction allows for a rapid assembly of numerous key intermediates that can be elaborated to give the necessary framework for the completion of the total synthesis of lycoramine"--Leaf v.
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 312
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Book Description
"Education, arts and social sciences, natural and technical sciences in the United States and Canada".
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A study directed at the total synthesis of lycolucine was carried out and discussed within. Various synthetic routes were attempted toward this end. The synthetic schemes all revolve around utilization of the well-established N-acylpyridinium salt chemistry as the foundational method of synthesis. One approach employs metathesis chemistry to attempt the construction of a key carbon-carbon bond. The development of a one-pot alkene homologation was discovered. This investigation reveals the ability to homologate terminal alkenes by one carbon utilizing the 2nd generation Grubbs catalyst. Various aromatic and non-aromatic substrates were used to demonstrate the scope of the reaction, with yields ranging from 65% to 86%. This work reveals the first example of a one-pot one carbon alkene homologation from an existing terminal alkene. A few synthetic methods, such as the formation of indolizidine scaffolds and amino alcohols, are also discussed. Various compounds were realized that could potentially lead to the development of more complex structures.
Author: Anthony John Roecker
Publisher:
ISBN: 9780496044160
Category : Combinatorial chemistry
Languages : en
Pages : 628
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Book Description
Two areas that continue to fascinate the chemistry community are the total synthesis of complex natural products and the application of combinatorial chemistry to natural products and natural product-like molecules. This thesis outlines recent studies in both of these frontiers in chemistry. First, the daunting chemical architecture of azadirachtin has flummoxed synthetic chemists for over two decades. A recent effort was undertaken by our laboratory to create novel solutions to the overarching problem in the synthesis of azadirachtin, namely the formation of the C 8 -C14 bond. Chapter two describes our initial explorations toward C8 -C14 bond formation via organometallic chemistry. Chapter three details an enantioselective entry into the azadirachtin framework through radical chemistry and cascade reactions. This route remains our central focus in the drive toward the total synthesis of azadirachtin. Second, chapter four details a study in the application of natural product-like libraries to chemical biology. Specifically, we utilized a novel library based on a 2,2-dimethylbenzopyran scaffold to discover potent and selective agonists for the farnesoid X receptor (FXR). Finally, chapter five outlines an exploration in the technology development of privileged templates on solid support, namely indolines and indoles. Using a novel phenylselenenyl bromide resin, we were able to develop several novel solid phase syntheses of 2-methyl indolines, polycyclic indolines, 2-methyl indoles, and 2-propenyl indolines.
Author: Douglas C. Beshore
Publisher:
ISBN:
Category :
Languages : en
Pages :
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