Recent developments in the group-1B-metal-catalyzed synthesis of pyrroles

Abstract

Pyrroles are important synthetic targets as a result of their occurrence in numerous biologically active molecules, their important roles in diverse living processes, and their utility as versatile intermediates. As a consequence, numerous efforts focused on the development of concise and efficient methods for the construction of pyrroles. Compared with other transition metals, the group 1B metals (Cu, Ag and Au) are probably more versatile and widely used for the synthesis of pyrroles in organic chemistry. Considering the importance of both topics in organic synthesis, here we summarize recent achievements in the synthesis of pyrroles catalyzed by monometallic systems which belong to the group 1B metals (Cu, Ag and Au).

Modular Domino Process toward Highly Functionalized Pyrroles via Pd-Catalyzed [4 + 1] Annulation under Mild Conditions

“…Updated synthetic strategies advanced significantly including those of multicomponent coupling reactions 6 and transition metal-catalyzed cyclizations. 7 Amines are commercially available with versatile functionalities, thus offering an ideal N-source toward the formation of pyrroles through [4C + 1N] cyclization. In this respect, the exploration for suitable 4C synthon or its equivalent, which enables subsequent cyclization with either aryl or aliphatic amines, is of great importance.…”

Synthesis of Polycarbonyl Pyrroles via K2S2O8-Mediated Oxidative Cyclization of Enamines

“…The classic Paal–Knorr and Hantzsch reactions have been frequently used to assemble pyrroles with a single carbonyl group on the ring. In the past several decades, novel methods such as transition-metal-catalyzed coupling and multicomponent reactions have been established for the synthesis of functional multicarbonyl pyrroles. Following these strategies, one or two carbonyl groups can be introduced into the pyrrole compound.…”

Skeletally Tunable Seven-Membered-Ring Fused Pyrroles

“…Pyrrole and its derivatives dominate synthetic and medicinal chemistry because of their bioactive and therapeutic properties. , The traditional Paal–Knorr and Hantzsch reactions and the more recent synthetic approaches tolerate various functionalized and substituted pyrroles through different starting materials. − However, the chemistry and applications of several pyrrole derivatives are underdeveloped because reliable synthetic protocols are not in place. Specifically, seven-membered-ring fused pyrroles (7-mrFPs) are a subclass of pyrroles that have received less attention, and only sporadic examples are known. , This limited number of 7-mrFPs can be synthesized via metal-catalyzed − or microwave- or thermal-assisted processes. , The former method encompasses the multistep formation of a structurally complex molecule, which, in turn, transforms to the fused derivative (Scheme A).…”