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Synthetic Approaches Toward The Total Synthesis Of Jatrophatrione
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Book Synopsis Synthetic Approaches Toward the Total Synthesis of (±) Jatrophatrione by : Richard Harrison
Download or read book Synthetic Approaches Toward the Total Synthesis of (±) Jatrophatrione written by Richard Harrison and published by . This book was released on 1984 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthetic Approaches Toward Total Synthesis of Alkoxydioxine Natural Products by : Qiang Han
Download or read book Synthetic Approaches Toward Total Synthesis of Alkoxydioxine Natural Products written by Qiang Han and published by . This book was released on 2000 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Progress Towards the Total Synthesis of Ingenol and Jatrophatrione by : Scott Douglas Edmondson
Download or read book Progress Towards the Total Synthesis of Ingenol and Jatrophatrione written by Scott Douglas Edmondson and published by . This book was released on 1996 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Model Studies Toward the Total Synthesis of Jatrophatrione by : Candice Joy McCloskey
Download or read book Model Studies Toward the Total Synthesis of Jatrophatrione written by Candice Joy McCloskey and published by . This book was released on 1985 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Total Syntheses of Jatrophatrione, Citlalitrione, and Sclerophytin A by : Jiong Yang
Download or read book The Total Syntheses of Jatrophatrione, Citlalitrione, and Sclerophytin A written by Jiong Yang and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The highly functionalized [5.9.5] tricyclic diterpenoids (")-jatrophatrione and (")-citlalitrione have been synthesized. The route begins with the tandem anionic oxy-Cope rearrangement/methylation/transannular ene cyclization to set in place a tetracyclic structural framework capable of ready chemical modification. Introduction of a conjugated enone double bond is followed by hydroxyl-directed 1,4-reduction to set the stage for the implementation of a Grob fragmentation. Stereocontrolled intramolecular hydrosilylation allows for subsequent introduction of a cyclic carbonate. Other key transformations include intramolecular hydrosilylation for efficient functionalization of the C12-position, Treibs oxidation for installation of the enone functionality on the southern edge, and syn-elimination with thiocarbonyldiimidazole to generate the dienone functionality. The length of the linear sequence from the point of convergence is 20 steps. Starting from an advanced intermediate, ( - )-sclerophytin A and its three diastereomers have been synthesized. The total synthesis unequivocally confirmed the detailed structure of the natural product to be consistent with the recently revised assignment. The absolute stereochemistry of ( - )-sclerophytin A was also confirmed by our total synthesis. Attempts have been made toward an enantioselective total synthesis of fomannosin. It was demonstrated that zirconocene-mediated ring-contraction delivered cyclobutanol with the desired stereochemistry, ring-closing metathesis has been shown to be a powerful reaction for synthesis of the strained cyclopentene, and samarium(II) iodide-mediated dehydroxylation of hydroxy ketones was found to be a convenient way for functionalization of the sterically demanding cyclopentene. A full scale fomannosin framework has been assembled. It has been demonstrated that the positioning of a 4-vinyl substituted cyclopentenone ring results in adoption of several different reaction pathways of the ini tial photochemically generated diradicals. Based on the specific environment of the 4-methoxy-4-vinyl-2-cyclopentenones, the diradicals undergo rearrangement, proton abstraction, or dimerization.
Book Synopsis Progress Towards Jatrophatrione by : Baohua Huang
Download or read book Progress Towards Jatrophatrione written by Baohua Huang and published by . This book was released on 1994 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthetic Studies Toward the Total Synthesis (±)-ajmaline and the Development Of, Investigation Into, and Application of a Phosphine-catalyzed [4+1] Annulation by : Brian Richard Blank
Download or read book Synthetic Studies Toward the Total Synthesis (±)-ajmaline and the Development Of, Investigation Into, and Application of a Phosphine-catalyzed [4+1] Annulation written by Brian Richard Blank and published by . This book was released on 2014 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Total Synthesis of Plakortide E and Biomimetic Synthesis of Plakortone B by : Xiao-Yu Sun
Download or read book Total Synthesis of Plakortide E and Biomimetic Synthesis of Plakortone B written by Xiao-Yu Sun and published by Springer. This book was released on 2014-02-22 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In his thesis, Xiaoyu Sun conducts the first total synthesis of all possible stereoisomers of plakortide E and also confirms the absolute configuration of natural plakortide E. Xiaoyu Sun subsequently converts Plakortide E methyl ester to plakortone B in a biomimetic conversion. Construction and functionalization of cyclic peroxides are notoriously difficult due to the very low O-O bond dissociation energy. Plaktoride E is isolated from the Jamaican marine sponge platorits halichondrioides and contains a five-membered peroxide ring, with oxygen atoms linked to tertiary C4 and C6 centers. The methodology used for synthesizing highly substituted cyclic peroxides is novel and useful, and not only extends the field of Pd-catalyzed reactions, but also provides a convenient synthetic approach for the preparation of the 1,2-dioxolanes series. Plakortide E and plakortone B are bioactive, which means that the synthetic studies on them and their analogs are pivotal in drug discovery.
Book Synopsis Total Syntheses of (3S, 18S, 4E, 16E)-eicosa-1,19-diyne-3,18-diol, (+)-Duryne, (+)-Dideoxypetrosynol A, Cicutoxin and Attempts Toward the Total Synthesis of Petrosynol by : Ann Ondera Omollo
Download or read book Total Syntheses of (3S, 18S, 4E, 16E)-eicosa-1,19-diyne-3,18-diol, (+)-Duryne, (+)-Dideoxypetrosynol A, Cicutoxin and Attempts Toward the Total Synthesis of Petrosynol written by Ann Ondera Omollo and published by . This book was released on 2008 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: (3S, 18S, 4E, 16E)-eicosa-1,19-diyne-3,18-diol, (+)-Duryne, Dideoxypetrosynol A, and Petrosynol are potent anticancer polyacetylenic alcohols with a variety of other interesting biological activities. The total syntheses of (3S, 18S, 4E, 16E)-eicosa-1,19-diyne-3,18-diol, (+)-Duryne, and Dideoxypetrosynol A, were accomplished utilizing double convergent synthetic approach. An auto-Wittig oxidation reaction was used as the key step in the institution of the central cis- double bond in the syntheses of (+)-Duryne and (+)-Dideoxypetrosynol A. The first enantioselective total synthesis of cicutoxin is reported. An endeavor toward the total synthesis of Petrosynol is also discussed.
Book Synopsis Synthetic Methods Development Towards the Total Synthesis of Chlorosulfolipids by : Andres Villalpando
Download or read book Synthetic Methods Development Towards the Total Synthesis of Chlorosulfolipids written by Andres Villalpando and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Protecting Group Free Total Synthesis of (-)-palmyrolide A and Synthetic Studies Towards the Syntheses of Taumycin A by : Tara Devi Newar
Download or read book Protecting Group Free Total Synthesis of (-)-palmyrolide A and Synthetic Studies Towards the Syntheses of Taumycin A written by Tara Devi Newar and published by . This book was released on 2016 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: A full account of our synthetic work toward the first total synthesis of the neuroactive marine macrolide (-)-palmyrolide A is highlighted. Our first-generation approach aimed to unlock the unknown C(5)- C(7) stereochemical relationship via the synthesis of four diastereomers of palmyrolide A aldehyde, a known degradation product. When these efforts provided inconclusive results, recourse to synthesizing all possible stereocombinations of the 15-membered macrolide was undertaken. These studies were critical in confirming the absolute stereochemistry, yielding the first total synthesis of (+)-ent palmyrolide A. Subsequent to this work, the first protecting group-free total synthesis of natural (-)-palmyrolide A is also described. After the successful total synthesis, a small library of synthetic (-)-palmyrolide A diastereomers, analogues, and acyclic precursors have been synthesized and examined with respect to their interaction with voltage-gated sodium channels (VGSCs). A detailed NMR and computational analysis of four diastereomers revealed that none had the same combination of shape and electrostatic potential as exhibited by natural (-)-palmyrolide A. These data indicated that the relative configuration about the tert-butyl and methyl substituents and an intact macrolide is required a prerequisite for biological function. Synthetic work towards the total synthesis of the lipodesipeptides Taumycins A and B was investigated. Enantiomeric isoleucine residues and the unique side chain consisting of a methyl stereocenter imbedded between two trisubstituted E-olefins are key features of this structurally intriguing natural product. By first targeting the taumycin aldehyde, the relative configuration of the macrocycle was identified in 2014 by the Maio laboratory. With the known relative configuration in hand, A total synthesis campaign was initiated, making use of a stereoselective aldol union between a pseudo-symmetrical side chain with orthogonal protecting groups, as a means to access the two possible diastereomeric combinations of the desired natural product. Synthetic studies to synthesize the pseudosymmetric side chain exploring a variety of methods, including an sp3-sp2 Negishi cross coupling reaction, are described.
Book Synopsis Applications of Aziridinium Ylides for the Formation of N-heterocycles and Progress Toward the Total Synthesis of Jogyamycin by : Kate Anne Nicastri
Download or read book Applications of Aziridinium Ylides for the Formation of N-heterocycles and Progress Toward the Total Synthesis of Jogyamycin written by Kate Anne Nicastri and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amines are a prominent motif in natural products, agrochemicals, and pharmaceuticals. In the pharmaceutical sector alone 84% of approved, structurally unique drugs contain at least one nitrogen atom. Given the utility of amines, methods and synthetic routes that generate complex amines are highly sought after. The first section of this work will entail the development of methods for the preparation of densely functionalized and stereochemically complex dehydropiperidines (Chapter 2) and dehydromorpholines (Chapter 3) through the intermediacy of aziridinium ylides. The development of these methods has enabled the application of aziridinium ylides for the formation of C-C, C-N, and C-O bonds and has led to several mechanistic discoveries that will prove insightful for the expansion of this chemistry. The second part of this work will be focused on progress toward the total synthesis of jogyamycin (Chapter 5). Jogyamycin is a member of the aminocyclopentitol class of natural products most notably recognized for its high antiprotozoal activity against the parasites responsible for malaria and African trypanosomiasis (sleeping sickness). This complex aminated natural product possesses a heteroatom-bearing stereocenter at each cyclic carbon, three contiguous amine stereocenters, and three quaternary stereocenters. Given its dense functionality and high level of complexity, a total synthesis of jogyamycin has so far eluded synthetic chemists. In this section, a new approach toward the total synthesis of jogyamycin will be discussed which includes a key tandem Ichikawa/Winstein rearrangement that sets adjacent amine stereocenters in a single step.
Book Synopsis I. Synthetic Approaches to 1, 1-dilithiocyclopropanes. II. A Method for the Synthesis of Functionalized 2, 4-dimethyl-1, 3-pentadienes. III. Electrophilic Additions to [4.3.1] Propellenes by : Diem Duy Le
Download or read book I. Synthetic Approaches to 1, 1-dilithiocyclopropanes. II. A Method for the Synthesis of Functionalized 2, 4-dimethyl-1, 3-pentadienes. III. Electrophilic Additions to [4.3.1] Propellenes written by Diem Duy Le and published by . This book was released on 1982 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Approaches to the Total Synthesis of Carbomethoxyvelbanamine by : Keith Raynor Osterhout
Download or read book Approaches to the Total Synthesis of Carbomethoxyvelbanamine written by Keith Raynor Osterhout and published by . This book was released on 1974 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthetic Studies Towards the Total Synthesis of Norzoanthamine by : Fatima R. Rivas
Download or read book Synthetic Studies Towards the Total Synthesis of Norzoanthamine written by Fatima R. Rivas and published by . This book was released on 2006 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented herein is the conclusion of synthetic studies toward the total synthesis of norzoanthamine. This dissertation on the norzoanthamine synthetic studies will be divided into 3 sections: (1) an introduction describing the norzoanthamine family along with their biological significance and previous studies; (2) a stereoselective synthesis of the ABC ring system, and the crucial development of the fully functionalized C ring; (3) a biomimetic approach towards norzoanthamine; which will discuss studies to create the C ring from a polyene system through a Diels-Alder reaction, studies to synthesize the A ring through a sigmatropic rearrangement, studies to generate the BC ring through an intramolecular Diels-Alder reaction from carvone as a chiral pool, development of isocarvone, and studies of 2-acylamino 1,3 dienes as a viable synthon to form the BC ring through a [4+2] cycloaddition reaction.
Book Synopsis Two Approaches to the Total Synthesis of Coriolin by : Paul D. Michna
Download or read book Two Approaches to the Total Synthesis of Coriolin written by Paul D. Michna and published by . This book was released on 1979 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthetic Studies Toward a Total Synthesis of Paeoniflorigenin by : Zhenqiu Hong
Download or read book Synthetic Studies Toward a Total Synthesis of Paeoniflorigenin written by Zhenqiu Hong and published by . This book was released on 1998 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: