Restriction lift date: 2028-05-31
H-phosphonate-enabled deoxygenative functionalisations of alcohols
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Date
2024
Authors
Cregan, Aidan
Journal Title
Journal ISSN
Volume Title
Publisher
University College Cork
Published Version
Abstract
Recent efforts in organic synthesis have been focused on developing safer, more sustainable alternative routes for classical transformations while ameliorating the associated environmental impact. Nucleophilic substitution is one of the most widely used classes of reactions in synthetic chemistry as it enables molecular construction by the formation of carbon–carbon and carbon–heteroatom bonds. However, these reactions generate considerable waste, not only during the reaction, but also in the upstream manufacture of the necessary reagents. This class of reaction relies heavily upon electrophilic halogenation reagents and organophosphorus compounds, the industrial manufacture of which are energy intensive processes that generate large quantities of halogenated waste. The ability to reliably construct carbon(sp³)–heteroatom bonds from readily available materials with minimal waste generation, both at source and during the reaction, would culminate in the greenest possible process in the broadest sense.
In this project, diphenyl H-phosphonate was demonstrated to be a general reagent to enable the activation of alcohols towards substitution by a wide range of nucleophiles in one-pot. Importantly, diphenyl H-phosphonate can be formed by a phosphorus trichloride-free route, minimising the upstream waste generated in the manufacture of this reagent. This methodology was applied in the deoxygenative functionalisation of alcohols to construct various bonds of synthetic importance, namely C–I, C–Br, C–Cl, C–N and C–P bonds. The scopes of the carbon(sp³)–heteroatom bond forming protocols described in this work were demonstrated in the synthesis of a broad range of compounds, including targets of pharmaceutical importance. The deoxygenative functionalisation methodologies described herein exhibit improved sustainability and safety profiles, good functional group tolerance and use commercially available reagents, culminating in a protocol that is primed for broad synthetic application.
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Keywords
Alcohol substitution , Deoxygenative halogenation , Deoxygenative amination , H-phosphonate , Alkyl halides , Low waste
Citation
Cregan, A. 2024. H-phosphonate-enabled deoxygenative functionalisations of alcohols. PhD Thesis, University College Cork.