Date of Graduation
Eberly College of Arts and Sciences
John H Penn
De novo asymmetric syntheses of daumone I-1 and the fluorescent analog have been described. This route took advantage of the Noyori asymmetric hydrogenation of acetyl furan and alkynyl ketone, the Pd-catalyzed glycosylation and various post-glycosylation transformations to finish the total synthesis of Daumone I-1, which provided materials for mechanism of action studies.;In an effort to mimics natures use of rare sugars in the synthesis of biologically important natural products (e.g., the carbohydrate portion of Daumone I-1), the O'Doherty group has been interested in developing new methods for practical and stereoselective synthesis. As part of these efforts, a concise synthesis of benzyl alpha-6-deoxy-altro-pyranoside and benzyl-ascarylo-pyranoside has been developed. The synthesis relied upon a Pd-catalyzed glycosylation reaction, a highly diastereoselecitve epoxidation and ring opening.;An enantioselective synthesis of cladospolide B, C and (ent)-cladospolide D has been achieved. This synthesis not only provided access to these antimicrobial natural products but also corrected the structural assignment of cladospolide D by means of a de novo synthesis and kinetic/thermodynamic alkene isomerization. The synthesis coupled the Noyori reduction of alkynyl ketone and the alkyl zipper reaction with the conversion to and asymmetric oxidation of dienoates to enable the successful synthesis of cladospolides B-D.;A de novo asymmetric total synthesis of aspergilliges has been investigated. The challenge of our route is using a novel palladium-catalyzed addition of a vinyl group to install the key trans-pyran ring system. To date, an intermediate which is five steps away from a formal synthesis of aspergillide C has been prepared by Pd-catalyzed C-glycosylation and Julia olefination. Noyori reductions of furyl and propargyl ketone, alkyne zipper reaction and Au-catalyzed alkyne hydration have been utilized.
Xing, Yalan, "De Novo Asymmetric Syntheses of Bioactive Natural Products and Carbohydrate Motifs" (2011). Graduate Theses, Dissertations, and Problem Reports. 4819.