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Total Synthesis of Bioactive Marine Natural Products Inspired by Enolate Chemsitry & Developments of New Haloalkylations via Soft Enolizations

Abstract

Marine natural products have long served as promising compounds and scaffolds for new therapeutic agents; however, their utilization is often extremely limited due to poor availability from natural sources and their molecular complexity. Hence, synthetic investigation of utilizing innovative techniques offers shortcuts in the production of such agents and modification. Studies directed toward the synthesis of marine natural products and their scaffolds inspire the development of new, efficient, and economical methods that are useful for medicinal research and for the synthesis of new pharmaceuticals and organic compounds.

The first part of this dissertation focuses on the synthetic studies directed toward the synthesis of nuphar thiaspirane alkaloids. The main drive of this effort is to allow access to each of the four classes of nuphar thiaspirane alkaloids. During these studies, a new procedure for the generation of tetrasubstituted tetrahydrothiophenes was developed. This method has been further applied for a late-stage Stevens rearrangement to generate each class of nuphar thiaspirane alkaloids from common intermediates.

The second part describes the total synthesis of the marine natural product (+)-brevisamide. The art and science of natural product total synthesis has become increasingly more associated with the various principles of the "economies" of synthesis. Evaluation of protecting group use serves as one metric of synthetic efficiency and can provide a framework for developing a synthesis plan. A new protecting-group-free synthesis of, the marine cyclic ether alkaloid, brevisamide was completed.

The third part describes the development of new and exciting chemical transformations revolving around haloalkylations of N-acyl oxazolidinones via Group IVa metal enolates by both radical and electrophilic methods. These studies include: mechanistic eludication of trichloromethylations, perfluoroalkylation and trifluoromethylation methodology development, and a generic -fluorination method.

The final part describes a new procedure for the generation of syn-1,3-diols, which addresses both stereo- and regiocontrol in the rhenium catalyzed transposition of allylic alcohols.

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