Synthesis of Indazolones via Friedel–Crafts Cyclization of Blocked (Masked) N‑Isocyanates
journal contributionposted on 22.08.2017, 00:00 by Eslam B. Elkaeed, Jing An, André M. Beauchemin
Nitrogen-substituted isocyanates (N-isocyanates) are rare amphoteric reagents with high, but underdeveloped synthetic potential. Herein, we study the formation of indazolones by Friedel–Crafts cyclization of N-isocyanates using blocked (masked) N-isocyanate precursors: the effect of the masking group and the reaction scope have been delineated. Substrate synthesis has also been improved using a reported copper-catalyzed coupling of arylbismuth(V) reagents that is compatible with the hemilabile OPh blocking group.