Carbonylated Indoles from PdII-Catalyzed Intermolecular Reactions of Indolyl Cores

Abstract

This review summarizes palladium-catalyzed carbonylation, transmetalation, and cross-coupling reactions that lead to carbonylated indoles from indoles and indolyl compounds. Special attention is drawn to procedures involving the C(sp2)–H substitution of free (NH)-indoles or (N-substituted)-indoles. Proposed mechanisms are described with, in some cases, personal comments.1 Introduction2 Carbonylative Reactions2.1 Indolyl Halides as Starting Substrates2.2 Indolyl Iodides as Intermediates2.3 Indolylborates as Intermediates2.4 C(sp2)–H Reactions2.4.1 Carboxylation2.4.2 Carbonylative Alkoxylation2.4.3 Carbonylative Arylation2.4.4 Carbonylative Alkenylation2.4.5 Carbonylative Alkylation2.4.6 Double Carbonylation3 Cross-Coupling of Stannyl- or Mercurioindoles4 Cross-Coupling of Indoles4.1 Aldehydes4.2 Alcohols4.3 α-Diketones4.4 α-Oxo Esters4.5 α-Oxocarboxylic Acids4.6 Nitriles4.7 Isocyanides4.8 Isothiocyanates and Isocyanates4.9 α-Aminocarbonyl Compounds4.10 Vinyl Ethers or Vinyl Amides4.11 Toluene and Substituted Toluenes4.12 Bromodichloromethane5 Conclusion