Author: Tao Qu
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Marine sponges produce a series of complex polycyclic diamine alkaloids which appear to have a common biogenesis from simple bis-pyridine macrocycles. These structurally novel secondary metabolites are presumably biosynthetically produced by the controlled ionic coupling of macrocyclic 3-alkyl piperidines leading to 3,4'-linked bis-piperidines (ii). Included among these diamine marine alkaloids is haliclonacyclamine C (i) which serves as our synthetic target. Chapter I in this thesis provides background information describing biological activity and proposed biosynthetic pathways to these important diamine marine alkaloids. Chapter II details progress towards the total synthesis of haliclonacyclamine C. The focus of Chapter II will be on our successful construction of the 3,4'-linked bispiperidine central core (ii) highlighted by the use of palladium-mediated C-C bond forming processes. The stereoselective hydrogenation of a coupled product will also be discussed.
Author: Brian Joseph Smith
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 238
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Author: Xiangyu Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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As a classic and powerful tool for carbon-carbon bond formation, the nitro-Mannich reaction has shown its versatility in drugs and natural products syntheses. The 1,2-diamine structure, a reduced moiety from nitro-Mannich adduct, is widely present in naturally occurring alkaloids and this feature suggested the potential application of nitro-mannich reaction in such alkaloids synthesis. This thesis showcases the nitro-Mannich reaction as a key strategic reaction through studies towards the total synthesis of 1,2-diamine contained alkaloids, schizozygine, vallesamidine and strempeliopine (Chapter 1 and 2). Initial studies on the schizozygine molecule (Chapter 3) generated a diastereoselective nitro-Mannich reaction on -branched nitroalkanes to synthesise complex -nitroamines with three contigurous chiral centres and syn,anti stereochemistry. This reaction was followed by a reductive cyclisation to achieve the functionalised piperidine ring C. Although the subsequent manipulation towards advanced shcizozygine intermediate was unsuccessful, the nitro-Mannich/reductive cyclisation sequence provided methodology for highly functionalised piperidine ring synthesis. A second generation route using nitro-Mannich reaction was accompanied by other nitro group chemistry, Michael addition, Tsuji-Trost allylation and nitro group reduction/C-N coupling reaction, to realise the quick and concise preparation of an A/B/C ring intermediate. An unusual and novel [1,4]-hydride tansfer/Mannich type cyclisation was carried out to build the ring E. The resulting A/B/C/E ring intermediate was used divergently to complete the total synthesis of (+)-vallesamidine (Chapter 4) and (+)-14,15-dehydrostrempeliopine (Chapter 5) as well as three other unnatural analogues. These natural and unnatural products could be candidates for drug discovery research and the route would be applicale for the synthesis of schizozygine and related molecules.
Author: Hans-Joachim Knoelker
Publisher: Springer Science & Business Media
ISBN: 3642255280
Category : Science
Languages : en
Pages : 268
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Lycopodium Alkaloids: Isolation and Asymmetric Synthesis, by Mariko Kitajima and Hiromitsu Takayama.- Synthesis of Morphine Alkaloids and Derivatives, by Uwe Rinner and Tomas Hudlicky.- Indole Prenylation in Alkaloid Synthesis, by Thomas Lindel, Nils Marsch and Santosh Kumar Adla.- Marine Pyrroloiminoquinone Alkaloids, by Yasuyuki Kita and Hiromichi Fujioka.- Synthetic Studies on Amaryllidaceae and Other Terrestrially Derived Alkaloids, by Martin G. Banwell, Nadia Yuqian Gao, Brett D. Schwartz and Lorenzo V. White.- Synthesis of Pyrrole and Carbazole Alkaloids, by Ingmar Bauer and Hans-Joachim Knölker.-
Author: Benedikt Johannes Maier
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Guillermo Stanley Cortez Veliz
Publisher:
ISBN:
Category :
Languages : en
Pages : 380
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Author: Dominik Hager
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Anastasia Hager
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Category :
Languages : de
Pages :
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Author: Junpei Matsuoka
Publisher: Springer Nature
ISBN: 9811586527
Category : Science
Languages : en
Pages : 91
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This book explores efficient syntheses of indole alkaloids based on gold-catalyzed cascade cyclizations, presenting two strategies for total synthesis of these natural products based on gold-catalyzed reactions of conjugated diyne or ynamide. The book first describes the total and formal synthesis of dictyodendrins A–F based on direct construction of the pyrrolo[2,3-c]carbazole core using the gold-catalyzed annulation of azido-diynes and protected pyrrole. This synthetic strategy features late-stage functionalization of the pyrrolo[2,3-c]carbazole scaffold at several positions and allows diverse access to dictyodendrins and their derivatives. Secondly, the book discusses the formal synthesis of vindorosine based on the pyrrolo[2,3-d]carbazole construction using the gold-catalyzed cascade cyclization of ynamide. Importantly, the reaction using a chiral gold complex provides the optically active pyrrolo[2,3-d]carbazole. This strategy facilitates the rapid construction of the pyrrolocarbazole core structure of aspidosperma and related alkaloids, including vindorosine. These methodologies can accelerate the medicinal application of pyrrolocarbazole-type alkaloids and related compounds.
Author: Christian Leitner
Publisher:
ISBN:
Category :
Languages : en
Pages :
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