Synthesis of Indoles and Indolines from α-Phosphoryloxy Enecarbamates

Significance

Interesting intra- and intermolecular Pd-catalyzed coupling routes to 2-substituted indoles and indolines from acyclic α-phosphoryloxy enecarbamates is reported. The α-phosphoryloxy enecarbamate A shows remarkable chemoselectivity in the Suzuki-Miyaura cross-coupling reaction with aryl and heteroaryl boronic acids. Subsequent Heck-type cyclization of B to form C was achieved efficiently by employing Et₃N as a base. In situ cross-coupling/cyclization cascades of α-phosphoryloxy enecarbamates A to indoles C were also achieved. An 5-endo-trig aryl radical ­cyclization of cross-coupled product N-(o-bromophenyl) enecarbamate B leading to indoline D was also reported.