Global ETD Search

1	Direct Carbon-Carbon Bond Formation via Base Mediated and Reductive Soft Enolization of Thioesters, the First Asymmetric Total Synthesis of (+)- and (-)-Clusianone, and Progress Toward the Asymmetric Total Synthesis of Brasilicardin A Garnsey, Michelle Renee January 2012 (has links) <p>Three methodology studies and two total synthesis endeavors are presented. First, a study of Lewis acid and hydrogen bond mediated soft enolization of thioesters and their addition to imines in the Mannich reaction is reported. MgBr2*OEt2 and Hunig's base are used in concert with bulky thioesters and aromatic aldehydes to generate syn-b-aminothioesters with moderate diastereoselectivity and yield. Next, a biomimetic organocatalytic Mannich reaction is presented using a chiral cinchona alkaloid to effect the enantioselective addition of an imines to thioesters with high yield and diastereoselectivity and enantioselectivities up to 88:12.</p><p>The direct addition of enolizable aldehydes to a-iodo thioesters to produce b-hydroxy thioesters enabled by reductive soft enolization is reported. The transformation is operationally simple and efficient and has the unusual feature of giving high syn-selectivity, which is the opposite of that produced in the aldol addition with (thio)esters under conventional conditions. This method is tolerant to aldehydes and imines that contain acidic a-protons, as well as electrophiles containing other acidic protons and base-sensitive functional groups.</p><p>The development of a strategy for the asymmetric synthesis of a large portion of the polycyclic polyprenylated acyl phloroglucinols via N-amino cyclic carbamate hydrazones, and its application to the first asymmetric total synthesis of both (+)- and (-)-clusianone is discussed. The clusianones are synthesized with an er of 99:1 and their anti-HIV activity is found to be 1.53 and 1.13 M, respectively. A library of clusianone-like compounds is synthesized and their biological activity has been probed.</p><p>Finally, efforts towards the total synthesis of brasilicardin A are reported. An appropriate model system was synthesized, and conditions were established using a pinene-based aldol reaction to synthesize the b-methoxy-a-amino ester side chain of the molecule. Next, efforts toward the synthesis of the anti-syn-anti- perhydro-phenanthrene core are discussed.</p> / Dissertation Organic chemistry asymmetric alkylation brasilicardin carbon-carbon bond clusianone Soft Enolization thioester
2	Strukturaufklärung der Phenalinolactone und Beiträge zur Biosynthese der Hexacyclinsäure / structure elucidation of phenalinolactones and contributions to the biosynthesis of hexacyclinic acid Meyer, Sven Wolfgang 21 January 2004 (has links) No description available. Mathematics and Computer Science Phenalinolactone NMR Actinomyceten Sekundärmetaboliten Naturstoffe chemisches Screening OSMAC Brasilicardin Biosynthese Hexacyclinsäure FR182877 Diels-Alderase Strukturaufklärung Terpen 540 Chemie phenalinolactones NMR actinomycetes secondary metabolites natural products chemical screening OSMAC brasilicardin biosynthesis hexacyclinic acid FR182877 diels-alderase structure elucidation terpene 35.50 35.25

Search results

Direct Carbon-Carbon Bond Formation via Base Mediated and Reductive Soft Enolization of Thioesters, the First Asymmetric Total Synthesis of (+)- and (-)-Clusianone, and Progress Toward the Asymmetric Total Synthesis of Brasilicardin A

Strukturaufklärung der Phenalinolactone und Beiträge zur Biosynthese der Hexacyclinsäure / structure elucidation of phenalinolactones and contributions to the biosynthesis of hexacyclinic acid