Anionic Indole N-Carbamoyl N → C Translocation. A Directed remote Metalation Route to 2-Aryl- and 2-Heteroarylindoles. Synthesis of Benz[a]carbazoles and Indeno[1,2-b]indoles

A new LDA-induced anionic N-C carbamoyl migration of 2-arylindoles (7) is reported. Treatment of N-carbamoylindoles 10 and 13, readily available by direct and ipso-borodesilylative Suzuki-Miyaura cross-coupling routes from 8 and 12, respectively, provides a general route to functionalized 2-arylindoles 11 and 14, respectively (Tables 1 and 2). The reaction has been applied to the synthesis of benzo[ a]carbazoles 16 and indeno[1,2- b]indoles 18, and its intramolecularity has been established by a crossover experiment (Scheme 4).