Investigating Rings: From Iridium-Catalyzed [4+2] Cycloadditions of Alkynyl Halides to Ring Openings of Cyclopropanated Oxabenzonorbornadiene

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Date
2012-09-06
Authors
Tigchelaar, Andrew
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University of Guelph
Abstract

This thesis describes two unrelated projects. Iridium-catalyzed intramolecular [4+2] cycloadditions of alkynyl halides were investigated, and the catalyst conditions were optimized for ligand, solvent, and temperature. Several substrates successfully underwent cycloaddition under the optimized conditions, with yields ranging from 75- 94%. The halide moiety is compatible with the reaction conditions and no oxidative insertion to the alkynyl halide was observed. These results are the first examples of cycloadditions of alkynyl halides using an iridium catalyst. The second part of this thesis describes acid-catalyzed ring opening reactions of cyclopropanated oxabenzonorbornadiene. First, the reaction was optimized for the acid source and temperature using methanol as a solvent and nucleophile, and then the scope of the reaction was expanded to a variety of other alcohols. Several successful examples with different alcohol nucleophiles are described, with yields of up to 82%.

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Keywords
Iridium-catalyzed imtramolecular cycloadditions, Alkynyl halides, Halide moiety, Iridium catalyst, Cyclopropanated oxabenzonorbornadiene
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