Ruthenium-Catalyzed Heteroatom-Directed Regioselective C–H Arylation of Indoles Using a Removable Tether

Abstract

A new approach to C-2 arylated indoles has been developed by utilizing a ruthenium-catalyzed, heteroatom-directed regioselective C-H arylation. The reaction is highly site-selective and results in very good yields. The highlight of the work is the use of a removable directing group and compatibility of the catalytic system with halogen functional groups in the substrates.

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…This method provides good substrate scope and yields, although requiring stoichiometric amounts of both Cu and Ag ( Scheme 109J ). 647 Ackermann recently reported the arylation of peptide-substituted indoles using aryl bromides. This procedure afforded good yields of arylated products, with no racemisation and good robustness.…”

Copper‐Catalyzed Direct Arylation of Indoles and Related (Hetero)arenes: A Ligandless and Solvent‐free Approach

“…The usefulness of our developed protocol was demonstrated by the smooth removal of 2‐pyridinyl group to obtain synthetically advantageous C‐2 arylated free NH indoles (Scheme ) . Thus, the C‐2 arylated indoles 3 aa , 3 ba , and 3 ca were treated with MeOTf, followed by the reaction in NaOH (2.0 M), led to the formation of free NH indoles 4 aa , 4 ba , and 4 ca , respectively, in excellent yields.…”

Cobalt‐Catalyzed C−H Nitration of Indoles by Employing a Removable Directing Group

“…The deuterated substrate 1 a [D 1 ] was prepared according to the procedure reported in the literature …”