THE DEVELOPMENT OF AN ENANTIOSELECTIVE CATION RADICAL DIELS-ALDER REACTION AND OTHER COMPLEXITY GENERATING TRANSFORMATIONS

Morse, Peter

THE DEVELOPMENT OF AN ENANTIOSELECTIVE CATION RADICAL DIELS-ALDER REACTION AND OTHER COMPLEXITY GENERATING TRANSFORMATIONS Public Deposited

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March 19, 2019

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Morse, Peter
- Affiliation: College of Arts and Sciences, Department of Chemistry

Abstract

Herein is described the development of three synthetic transformations that are united in their being initiated by the single electron oxidation of olefins to cation radical intermediates. The development of an enantioselective cation radical Diels-Alder reaction is first described. The control of the absolute stereochemistry of cation radical reactions is a major challenge to the field. This methodology centers on the use of chiral anions as a means of inducing asymmetry, and sets important precedent that ion pairing is a viable means of enantioinduction in cation radical reactions. An anti-Markovnikov intramolecular hydrofunctionalization reaction using amide and thioamide nucleophiles is also described. This transformation is a mild route to construct oxazoline and thiazoline motifs bearing substitution patterns that are challenging to synthesize by alternative methods. Additionally, evidence for disparate mechanisms for amide and thioamide substrate cyclization is presented. Finally, progress towards the total synthesis of the natural product rubriflordilactone B is presented. The development of a route to this molecule has so far focused on the development of two key steps: a Mukuiyama vinylogous aldol reaction and subsequent polar radical crossover cycloaddition. The successful implementation of this strategy would allow the absolute stereochemistry of the molecule to be set and five contiguous stereocenters to be formed over two steps, and would highlight the utility of photoredox catalysis in complex molecule synthesis.

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