Rhodium(III)-Catalyzed Alkenyl C-H Bond Functionalization: Convergent Synthesis of Furans and Pyrroles

摘要

Furans and pyrroles are pervasive in natural products and pharmaceuticals.111 For this reason, the synthesis of these five-membered ring heterocycles has been an intense topic for decades with transition-metal-based C-H bond functionalization strategies recently providing powerful annulative approaches for their assembly. Specifically, Glorius and co-workers and Fagnou and co-workers have reported on the synthesis of pyrroles by rhodium(III)-catalyzed coupling of enamides with internal alkynes [Eqs. (1) and (2); Cp~* = C5Me5], and most recently, Lei and co-workers have reported on the synthesis of furans by the silver acetate mediated oxidative coupling of terminal alkynes and 1,3-dicarbonyl compounds [Eq. (3)] . Herein, we report a new type of catalytic C-H bond functionalization with annulation, thus enabling the versatile and efficient synthesis of furans and pyrroles from simple electrophilic coupling partners which serve as very different inputs from those used previously [Eq. (4)] . Additionally, in contrast to the other reported C-H-functionalization-based annulations [Eqs. (1)-(3)], no external oxidant is required.