Mechanistic Insights Into the Transition‐Metal‐Catalyzed Dual Reactivity Mode of Vinyl Ethylene Carbonates With Anilines

A study into a catalyst-controlled chemodivergent strategy to access 2-vinyl indolines and indole-2-acetates is presented herein. This strategy overcomes the usual allylic reactivity of vinyl ethylene carbonates (VECs) via a tandem C─H/C─O bond activation sequence. The methodology provides useful molecular scaffolds by following two distinct pathways in a highly step- and atom-economical manner and features a challenging β-hydroxide elimination. In the Rh-catalyzed transformation, unusual competing pathways were observed, such as a regioselective insertion of a Rh-OMe species into the "C═C" bond of the vinyl segment, a regioselective C─H activation of the vinyl indoline, and an interesting oxidative addition of MeOH into Rh(I). Detailed mechanistic insights through a combination of experimental and computational studies unveil a unique reactivity mode of VECs, thereby opening up a new avenue for transition metal catalysis. Synthetic utility of the annulated products demonstrates an additional advantage of the methodology.