UBC Theses and Dissertations

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UBC Theses and Dissertations

Development of a novel radical cyclization and new synthetic methods utilizing sulfur fluoride reagents Mo, Jia Yi


This thesis describes my contribution to the development of radical reactions for the synthesis of nitrogen heterocycles and new synthetic methods using sulfuryl fluoride and thionyl fluoride. Chapter 2 contains the development of a novel diastereoselective 6-endo-trig radical cyclization for the synthesis of disubstituted tetrahydrophthalazines from hydrazone. Four of the Boc-hydrazones were useful substrates to form trans-1,4-disubstituted tetrahydrophthalazines in 55-80% yield and up to 90% diastereomeric excess. In Chapter 3, I explain how I develop the first efficient method for SO₂F₂-mediated activation and substitution of aliphatic alcohols. This new method is effective for a wide range of primary alcohols using nitrogen, sulfur-, carbon-, oxygen-based nucleophiles (43-89% yield). Secondary alcohols were also successful substrates using aryl thiols in 49-65% yield and 94-100% enantiomeric excess. Chapter 4 sets forth the development of a more general SO₂F₂-mediated one-pot alcohol activation and substitution method that relies on the alkyl halide intermediates. This method expanded the scope include substitution to nucleophiles that were previously incompatible with one-pot SO₂F₂-mediated alcohol activation and substitution in Chapter 3. Lastly, I describe the development of an efficient sulfamate ester synthesis mediated by SOF₂ in Chapter 5. This new method relies on a key intermediate, either an alkyl fluorosulfite or aminosulfinyl fluoride. Subsequent substitution and oxidation of an alkyl fluorosulfite or aminosulfinyl fluoride affords the corresponding sulfamate ester in 38% to 90% isolated yield. I also applied this method to modify the surface of cellulose nanocrystals (CNCs), affording seven modified CNCs. These modified CNCs are currently undergoing detailed characterization.

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