Hydroxy-containing cyclic ethers react with thermally generated benzynes to produce aryl ethers. Diverse reactivity was observed. Cleavage of the cyclic ether was involved in most of the pathways. The transformations are rationalized via initial formation of oxonium ion-containing 1,3-zwitterions arising from preferential nucleophilic attack on the benzyne by the ether oxygen. Pinacol-like rearrangements, including ring expansion, to yield aldehydes or ketones and oxirane fragmentations to generate aryl enol ethers were main competing events.
Bibliographical noteFunding Information:
Support for this research was provided by the National Institutes of General Medical Sciences of the U.S. Department of Health and Human Services (R35 GM127097). Some of the NMR data were obtained with an instrument acquired with funds from the NIH Shared Instrumentation Grant program (S10OD011952).
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