Download or read book Total Synthesis of Kealiinines A C Kealiiquinone 2 deoxy 2 aminokealiquinone and Study Towards Total Synthesis of Spirocalcaridines A B written by Jayanta Kumar Das and published by . This book was released on 2019 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our group is mainly interested in the total synthesis of imidazole-containing alkaloids along with other kinds of alkaloids. A new family of imidazole alkaloids, the Leucetta alkaloids, is a group of 60 or so 2-aminoimidazole natural products found in marine sponges, which have received substantial attention recently because of their challenging structures and strong biological activities. Over the past few years, our laboratory has developed several synthetic methods for the total synthesis of 2-aminoimidazole alkaloids using site-selective functionalization of polyhaloimidazoles. By using this basic synthetic strategy, the development of high yielding and protecting group-free total syntheses of the reported structures of the Leucetta alkaloids kealiinine A-C has been accomplished. In addition to the challenging syntheses of these molecules, the spectroscopic data for the natural occurring and synthetic materials did not match. Extensive spectroscopic analysis (HMQC, ROESY) unequivocally supported the structures of the synthetic materials which were further corroborated by X-ray crystallography. On the other hand the chromatographic properties of the synthetic and natural materials were consistant, suggesting that impurities in the natural materials caused the mismatch of the spectroscopic data. A second set of targets was accessed using a biosynthetic guided strategy according to which, kealiinine C would serve as a precursor to kealiiquinone and 2-deoxy-2-aminokealiiquinone. The synthesis of both alkaloids was completed from a late stage intermediate in the kealiinine C synthesis by oxidation of the C-ring. Although the first total synthesis of kealiiquinone was accomplished by Ohta et al. in 1995, the current method was protecting group-free and required only 6 steps in comparison to 12 steps by the Japanese group. The first total synthesis of the 2-amino congener 2-deoxy-2-aminokealiiquinone was also accomplished. After successful syntheses of these naphthimidazole natural products, the cytotoxicity of these alkaloids along with several precursors and intermediates was examined. Several of these natural products and their intermediate compounds showed potential anti-cancer activity when subjected to in vitro testing against a breast cancer cell line (MCF7) using a MTT growth assay. Currently, in the study toward the total synthesis of spirocalcaridine A and B, an yneguanidine intermediate has been synthesized by using a three-component coupling as a key reaction en route to the desired products. The core structure of spirocalcaridines was furnished through a diacetoxyiodobenzene assisted concerted spirocyclization of the yne-guanidine molecule. Further studies are on going to improve the poor yield and selectivity of the above transformation and consequently allowing the completion of the total synthesis of spirocalcaridines A-B.
Download or read book The Total Synthesis of Natural Products written by James Martin Frincke and published by . This book was released on 1979 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies Towards the Total Synthesis of Spiroquinazoline written by Siyuan Chen (Ph.D.) and published by . This book was released on 2007 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Part I Total Synthesis of ratjadone Part II Studies Toward the Total Synthesis of Zoanthenol written by David C. Ihle and published by . This book was released on 2003 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies Toward the Total Synthesis of Bryostatin 1 written by David Curtis Whritenour and published by . This book was released on 1988 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies Toward the Total Synthesis of Aplysistatin and the Total Synthesis of Ancistrofuran written by Andrew James Caruso and published by . This book was released on 1980 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Directed Study Toward the Total Synthesis of tecomanine Synthesis of Cyclic Ethers Utilizing a Cyclization Fragmentation Strategy written by Denise Ann Ockey and published by . This book was released on 1999 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Total Synthesis of Dihydrocallitrisin and Studies Related to the Synthesis of Other Eudesmane and Elemane Sesquiterpenes written by Jollie Duaine Godfrey and published by . This book was released on 1978 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Asymmetric Synthesis of Bioactive Lactones and the Development of a Catalytic Asymmetric Synthesis of Aryl Ketones written by Robert Doran and published by Springer. This book was released on 2015-07-09 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis addresses two fundamental areas in contemporary organic chemistry: synthesis of natural products and catalytic asymmetric synthesis. Firstly, a new methodology, developed by our research group, which allows the asymmetric synthesis of lactones, a structural unit ubiquitous in natural products, was utilised in the synthesis of a number of natural product analogues that showed significant biological activity. Secondly, the development of a catalytic asymmetric synthesis of a key structural motif present in a number of natural products and pharmaceuticals was accomplished. During the course of this work we discovered dual stereo control, which is significant because it allows the configuration of a new stereo centre to be controlled by a simple change of proton source.
Download or read book Total Synthesis of Welwitindolinones and Nickel Catalyzed Reactions of Amide Derivatives written by Nicholas Anthony Weires and published by . This book was released on 2017 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes our efforts toward the total synthesis of welwitindolinone natural products, as well as the development of reactions involving the nickel-catalyzed activation of amide C-N bonds. The welwitindolinones have been long-standing targets in total synthesis for over two decades, and this dissertation describes two completed total syntheses of these alkaloids. In addition, several nickel-catalyzed transformations of amides are outlined, each of which demonstrate the powerful reactivity of nickel and highlight the utility of amides as synthetic building blocks. Chapters one and two present our enantiospecific total syntheses of the welwitindolinone alkaloids N-methylwelwitindolinone D isonitrile and N-methylwelwitindolinone B isothiocyanate. Our approach to these natural products features an aryne cyclization to construct the bicyclo[4.3.1]decane core of the molecules, as well as a C-H nitrene insertion reaction to introduce the bridgehead nitrogen substituent. In chapter one, a dual C-H functionalization event installs the challenging ether linkage and allows for completion of (-)-N-methylwelwitindolinone D isonitrile. In chapter two, a regio- and diastereoselective chlorinative oxabicyclic opening is detailed, which enables the first total synthesis of N-methylwelwitindolinone B isothiocyanate. Chapters three, four, and five describe the development of nickel-catalyzed carbon-carbon bond-forming reactions of amides. More specifically, chapters three and four outline the Suzuki-Miyaura couplings of aromatic and aliphatic amides, respectively, whereas chapter five details the alkylation of amide derivatives. These methodologies represent mild and complementary tools to the Weinreb ketone synthesis, proceeding through the nickel-catalyzed activation of the amide C-N bond. It is shown that amides, which were traditionally thought of as inert functionalities, can be utilized as synthons in C-C bond-forming reactions. Chapter six describes a method for the benchtop delivery of Ni(cod)2 involving the encapsulation of Ni(cod)2 in paraffin wax. Due to air- and moisture-sensitivity, Ni(cod)2 is normally handled under an inert atmosphere. Using our method of wax encapsulation, several nickel-catalyzed transformations are performed without the use of a glove box, including various amide C-N bond cleavage reactions. These studies are aimed at promoting the widespread use of nickel in transition metal catalysis. Chapter seven illustrates the kinetic modeling of the nickel-catalyzed esterification of amides. By developing a kinetic model, an optimization is undertaken that allows for the employment of catalyst loadings as low as 0.4 mol% nickel. This demonstration is intended to foster the advancement of kinetic modeling as a powerful tool in methodology development.
Download or read book I Cationic Cascade Reactions of Alkylidene beta ketoesters written by Dylan E. Parsons and published by . This book was released on 2019 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Cation-[pi] cyclization cascades of alkylidene [beta]-ketoesters bearing a pendent alkene with various substitution patterns are described. Depending upon the alkene substitution pattern and the reaction conditions employed, it is possible to achieve selective synthesis of the five different types of products, including 1-halo-3-carbomethoxycyclohexanes, spiro-fused tricyclic systems, [4.3.1] bridged bicyclic ring systems, bridged dihydropyrans, and [4.2.2] bridged pyrans and piperidines. All pathways begin with addition of an olefin to the alkylidene [beta]-ketoester electrophile, followed by one of five different cation capture events, to afford each of the unusual polycyclic systems with a high degree of stereocontrol. Herein, work accomplished towards the total synthesis of arnicenone is also reported. Synthesis of a test substrate is described, which was cyclized to examine the proposed key step. After analysis of the key step, the synthetic route was modified to accommodate the results. A racemic synthesis was then attempted which provided small quantities of the key intermediate to be cyclized"--Page viii.
Download or read book Total Synthesis of Lycoramine and Studies Related to the Synthesis of Eudesmane and Elemane Sesquiterpenes written by Ying-Kwong Yee and published by . This book was released on 1978 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies Towards the Total Synthesis of Limnophilaspiroketone and the Synthesis of Alpha modified Enones of Natural Product Derived Model Compound Limno CP written by Simon Lindner and published by . This book was released on 2011 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Part 1 Metal catalyzed Stereospecific Michael Reaction written by Edwin Bernard Villhauer and published by . This book was released on 1986 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies Toward the Total Synthesis of Calyculin A written by Samuel William Gerritz and published by . This book was released on 1993 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies Towards the Total Synthesis of Limnophilaspiroketone and the Synthesis of modified alpha modified Enones of Natural Product Derived Model Compound Limno CP written by Simon Lindner and published by . This book was released on 2011 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
