Gold-Catalyzed Reactions of Specially Activated Alkynes, Allenes, and Alkenes

Abstract

This review describes the gold-catalyzed reactions of specially activated alkynes, allenes, and alkenes. Such species are characterized by the presence of either electron-donating or electron-withdrawing groups as substituents of the carbon π-system. They are intrinsically polarized, and when compared to their nonspecially activated counterparts can therefore be involved in gold-catalyzed transformations featuring increased regio-, stereo-, and chemoselectivities. The chemistry of specially activated carbon π-systems under homogeneous gold catalysis is extremely rich and varied. The reactivity observed with nonspecially activated unsaturated systems can often be transposed to specially activated ones without loss of efficiency. However, specially activated carbon π-systems also exhibit specific reactivities that cannot be attained with regular substrates. In this family of carbon π-systems, ynamides and their analogs, along with alkynyl carbonyl derivatives, are the classes of substrates that have retained the most attention. This review provides an overview of the chemistry developed with all classes of specially activated carbon π-systems by discussing their general and specific reactivities, presenting and commenting on their gold-catalyzed transformations as well as their applications.

Catalytic Gold Chemistry: From Simple Salts to Complexes for Regioselective C−H Bond Functionalization

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A dicoordinate gold(i)–ethylene complex

“…Homogenous gold catalysis has become one of the most powerful tools in organic synthesis due to the prowess of Au( i ) towards the electrophilic activation of unsaturated hydrocarbons. 1 π-Complexes of gold are generally proposed as key intermediates in the functionalisation of alkenes, alkynes, dienes or allenes in a wide range of catalytic processes, including hydrogenation, hydroamination, oxidation, diarylation, heteroarylation or cycloadditions. 2 Thus, the isolation of gold π-complexes holds an intrinsic interest associated with their catalytic relevance and has provided valuable insight during recent years.…”

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

“…Yet, the last two decades saw the boom of gold catalysis through major breakthroughs, [31–41] thanks to the understanding of fundamental concepts like frontier orbitals, π‐acidity, relativistic effects and redox behaviour [42–52] . In particular, the unique ability of gold catalysts to activate C−C multiple bonds like alkynes, alkenes and allenes has paved the way for the discovery of numerous hitherto unknown organic reactions [53–55] . This is because of the fact that gold catalysts are characteristically soft Lewis acidic in nature, which enable them to interact preferentially with soft Lewis base like C−C multiple bond (a case of ‘‘ like attracts like ’’).…”