American Chemical Society
jo1c00331_si_001.pdf (7.21 MB)

The Copper-Catalyzed Reaction of 2‑(1-Hydroxyprop-2-yn-1-yl)phenols with Sulfonyl Azides Leading to C3-Unsubstituted N‑Sulfonyl-2-iminocoumarins

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journal contribution
posted on 2021-06-17, 12:04 authored by Yu Zhao, Zitong Zhou, Lvling Liu, Man Chen, Weiguang Yang, Qi Chen, Michael G. Gardiner, Martin G. Banwell
An operationally simple synthesis of Z-configured and C3-unsubstituted N-sulfonyl-2-iminocoumarins (e.g., 8a) that proceeds under mild conditions is achieved by reacting 2-(1-hydroxyprop-2-yn-1-yl)­phenols (e.g., 6a) with sulfonyl azides (e.g., 7a). The cascade process involved likely starts with a copper-catalyzed alkyne–azide cycloaddition (CuAAC) reaction. This is followed by ring-opening of the resulting metalated triazole (with accompanying loss of nitrogen), reaction of the ensuing ketenimine with the pendant phenolic hydroxyl group, and finally dehydration of the (Z)-N-(4-hydroxychroman-2-ylidene)­sulfonamide so formed.