Chapter 1. Part 1: Novel synthesis and biological evaluation of 1,5-linked D-mannoseptanosides. Part 2: Synthesis of D-glucoseptanosides. Chapter 2. Biomimetic total synthesis of the proposed structure of ent-muzitone.

摘要

1,5-Linked D-Mannoseptanosides. Part 2: Synthesis of D-Glucoseptanosides Part 1. Using the tungsten-catalyzed cycloisomerization of an appropriately protected alkynyl alcohol, highly functionalized seven-membered ring (septanose) glycals were synthesized. We used dimethyldioxirane (DMDO) glycal epoxidation/epoxide opening to construct septanose sugars with D-manno absolute configuration, which were glycosylated to give the first known 1,5-linked D-mannoseptanoside mono-, di-, and trisaccharides. These unnatural sugars were found to be innocuous to alpha-mannosidase-catalyzed hydrolysis. Thus, we believe these unique carbohydrate structures have potential application as biomaterials or drug delivery vehicles. Part 2. Using a known strategy of protecting group manipulation of a hexose sugar, we have synthesized a variety of D-glucoseptanose substrates. Our ultimate goal was to construct higher order oligosaccharides composed of D-glucoseptanose monomer units. While that goal remained elusive, we gained much insight into the reactivity patterns of these substrates, which will be of much utility in future studies.;Chapter 2. Biomimetic Total Synthesis of the Proposed Structure of ent-Muzitone Muzitone, a marine sponge-derived polycyclic ether triterpenoid natural product, was synthesized using a bioinspired strategy. Starting from a C30 squalene-like precursor, we successfully implemented tandem biomimetic cyclizations of epoxy-ene substrates to construct ent-muzitone. This synthetic investigation revealed that the structural and/or stereochemical assignment of muzitone was incorrect.