Synthesis and Reactivity of Benzo[1,3,2]dithiazole 1,1-dioxides: Implications in Acylative Redox Dehydration Open Access

Abstract

Benzo-1,3,2-dithiazole-1,1-dioxides (BDTs) are novel 5-membered heterocycles bearing an internal sulfur-nitrogen bond and are structurally similar to benzoisothiazolones (BiTs). A new method for the synthesis of these molecules was developed and a series of BDTs were made and studied as potential BiT alternatives in organocatalytic redox-coupled, metal catalyzed dehydrative bond constructions. The BDTs could be synthesized via generation of a sulfenyl chloride from o-benzylthiobenzene sulfonamide followed by condensation with the adjacent nitrogen. The BDTs could react with carboxylic acids in a redox dehydration with triphenylphosphine or triethyl phosphite to generate BDT-derived thioesters. This reaction worked well with aliphatic acids and to a lesser extent with aromatic acids. These thioesters could then undergo coupling with boronic acids to give S-arylated products, but the reaction between BDT-derived thioester and amine gave only hydrolysis of the thioester with no desired amide formation. Finally, the reduced form of BDT, the o-mercaptobenzene sulfonamide, could be oxidized back to the BDT at temperatures above 100 ^oC in the presence of a variety of oxidants. Future work will be de done to assess the utility of BDTs as organocatalysts in redox dehydration reactions as well as explore other alternative applications.

Table of Contents

Introduction 1

Results / Discussion 8

Benzo-1.3,2-dithiazole-1,1-dioxide Synthesis 8

Phosphine Mediated Thioesterification of BDT 13

Phosphite Mediated Thioesterification of BDT 16

Reactions of BDT-Derived Thioesters 21

Oxidative Recycle of Thiol to BDT 24

Amidation Using Stoichiometric or Catalytic BDT 26

Conclusion 27

Experimental 30

References 50

NMR Spectra 52

About this Master's Thesis

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School	Laney Graduate School
Department	Chemistry
Degree	MS
Submission	Master's Thesis
Language	English
Research Field	Chemistry, Organic
Keyword	Benzo[1,3,2]dithiazole 1,1-dioxide
Committee Chair / Thesis Advisor	Liebeskind, Lanny S, Emory University
Committee Members	Davies, Huw, Emory University Scarborough, Christopher C, Emory University

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