Pentannulation of Heterocycles by Virtue of Precious Metal Catalysis

Abstract

Pentannulated heterocycles are the key structural subunit of many natural and biologically active compounds. Over the last decades, many precious metal-assisted pentannulations have been described as a consequence of an extensive research. This Focus Review gives an overview of precious metal-catalyzed reactions applied to the synthesis of cyclopenta-fused heterocycles in the last five years.

Regio‐ and Site‐selective Molecular Rearrangements by Homogeneous Gold Catalysis

“…[24][25][26] This being said, the gamut of application of gold catalysis is quite comprehensive to cover the synthesis of an array of important commodities like natural products, [27][28][29][30][31][32][33][34][35] drugs [36] and polymers. [37,38] Gold complexes have been documented to exhibit versatile catalytic efficiency towards a plethora of organic reactions such as CÀ H activation, [39][40][41][42][43] substitution, [44] cycloaddition, [45][46][47][48][49][50] oxidative coupling, [51,52] hydration, [53,54] oxidation, [55][56][57] hydroamination, [58,59] nucleophilic addition, [60] hydrogenation, [61] cross-coupling, [62,63] carbocyclization, [64] heterocyclization, [65][66][67][68][69][70]…”

Construction of Cyclopenta[b]indol-1-ones by a Tandem Gold(I)-Catalyzed Rearrangement/Nazarov Reaction and Application to the Synthesis of Bruceolline H

“…The development of new methods for the synthesis of cyclopenta­[ b ]­indoles is a widely explored research area, as those structures are commonly found in many natural and biologically active compounds. , In particular, gold­(I) catalysis has emerged in the past few years as a powerful tool for the pentannulation of indoles and other N-heterocycles . Cyclization reactions triggered by electrophilic activation of an unsaturated side chain of the heterocycle, sequential gold­(I)-catalyzed hydroamination/cyclization reactions, and cascade gold­(I)-catalyzed rearrangement/cyclization processes have all successfully been employed for the pentannulation of indoles.…”

Cycloisomerization of π‐Coupled Heteroatom Nucleophiles by Gold Catalysis: En Route to Regiochemically Defined Heterocycles

“…Likewise, the focus of this review is to overview the gold‐catalyzed regioselective cycloisomerization of different π‐molecules owning a nucleophilic handle. Although there are a number of excellent reviews which discussed the gold catalyzed cycloisomerization reactions, [84–105] a comprehensive review on this topic that emphasizes regioselectivity is sporadic. To this end, the present review sum up the regioselective heterocyclization by activation of π‐functionality tethered nucleophiles under the catalytic action of gold.…”