Rhodium(III)-Catalyzed Regioselective C(sp 2 )–H Functionalization of 7‑Arylpyrazolo[1,5‑ a ]pyrimidines with Dioxazolones as Amidating Agents

Rh(III)-catalyzed C–H functionalization of 7-arylpyrazolo[1,5-a]pyrimidines was developed wherein the pyrazolo[1,5-a]pyrimidine moiety is reported for the first time to direct the C–H bond activation. Various 7-arylpyrazolo[1,5-a]pyrimidines underwent smooth C–H amidation with alkyl-, aryl-, and heteroaryl-substituted dioxazolones to afford the products in moderate to good yields. Mechanistic studies suggest that a six-membered rhodacycle intermediate involving N1 might play a key role in the regioselective catalytic cycle.