Structurally Divergent Lithium Catalyzed Friedel–Crafts Reactions on Oxetan‐3‐ols: Synthesis of 3,3‐Diaryloxetanes and 2,3‐Dihydrobenzofurans |
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Authors: | Rosemary A Croft Dr James J Mousseau Chulho Choi Dr James A Bull |
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Institution: | 1. http://www3.imperial.ac.uk/people/j.bull;2. Department of Chemistry, Imperial College London, South Kensington, London, UK;3. Pfizer Global Research and Development, Groton, USA |
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Abstract: | The first examples of 3,3‐diaryloxetanes are prepared in a lithium‐catalyzed and substrate dependent divergent Friedel–Crafts reaction. para‐Selective Friedel–Crafts reactions of phenols using oxetan‐3‐ols afford 3,3‐diaryloxetanes by displacement of the hydroxy group. These constitute new isosteres for benzophenones and diarylmethanes. Conversely, ortho‐selective Friedel–Crafts reactions of phenols afford 3‐aryl‐3‐hydroxymethyl‐dihydrobenzofurans by tandem alkylation–ring‐opening reactions; the outcome of the reaction diverging to structurally distinct products dependent on the substrate regioselectivity. Further reactivity of the oxetane products is demonstrated, suitable for incorporation into drug discovery efforts. |
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Keywords: | carbocations homogeneous catalysis lithium oxetanes oxygen heterocycles |
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