Cyclization of Vinyl and Aryl Azides into Pyrroles, Indoles, Carbazoles, and Related Fused Pyrroles

Abstract

This chapter reviews in detail those reactions that form of a new pyrrole ring from vinyl, aryl, and heteroaryl azides via formal C–H insertion processes under thermal, photochemical, and metal‐catalyzed conditions. These reactions proceed via the intermediacy of vinyl or aryl nitrenes (or their metallonitrene equivalents) and generate a wide variety of pyrroles, indoles, carbazoles, and related systems. Methods for the synthesis of the starting azides are summarized, and a comprehensive survey of the cyclization processes is provided.

Unveiling Orthogonal Reactivity of Substituted 2-(2-Azidostyryl)furans: Thermolysis and Photolysis versus Catalysis

“…Today, the Sundberg indole synthesis consists of the thermolysis or photolysis of substituted 2-azidostyrenes to form a wide series of indoles and structurally related analogues (Scheme b). Currently, both fundamental methods of nitrene generation (the deoxygenation of nitro compounds and the decomposition of organic azides) are mutually complementary and widely applied in modern synthetic practice, including total synthesis …”