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Experimental and Theoretical Investigation of the Synchronicity of Ambident Silyloxypyrone-Based (5 + 2) Cycloadditions

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posted on 2023-04-14, 14:37 authored by Adam J. Youman, Samantha N. Rokey, Jacob P. Grabowski, Wentao Guo, Qing Sun, Susanna N. Angles, John R. Goodell, Dean J. Tantillo, T. Andrew Mitchell
The reaction pathway of silyloxypyrone-based (5 + 2) cycloadditions was determined to be extremely dependent on the nature of the dipolarophile. Neutral alkenes were the least reactive, whereas both electron-deficient and electron-rich dipolarophiles were more reactive, thus providing evidence for ambident oxidopyrylium intermediates. Qualitative rate studies, Hammett linear free energy relationships, and theoretical calculations combined to provide evidence for a spectrum of reactivity that passes through the borderlands of concerted and stepwise.

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