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
journal contributionposted 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.