Efficient access to β- and γ-carbolines from a common starting material by sequential site-selective Pd-catalyzed C-C, C-N coupling reactions

Two efficient and practical approaches are reported for the synthesis of beta- and gamma-carboline derivatives from 3,4-dibromopyridine as a common starting material. The beta-carbolines were prepared by site selective Pd-catalyzed C-C coupling with o-bromophenylboronic acid and subsequent cyclization by double C-N coupling with amines. gamma-Carbolines were prepared from the same starting material by C-N coupling with anilines and subsequent annulation by domino C-C/C-N coupling with o-bromophenylboronic acid. (C) 2019 Elsevier Ltd. All rights reserved.