[reaction: see text] A study concerning the synthesis of new phosphine gold(I) complexes using the bis(trifluoromethanesulfonyl)imidate moiety as a weakly coordinating counter-anion is described. These new air-stable complexes are more convenient to prepare, store, and handle and are exceedingly active for the catalysis of a wide range of enynes cycloisomerizations.

International audienceA study concerning the synthesis of new N-heterocyclic carbene gold(I) complexes using the bis(trifluoromethanesulfonyl)imidate moiety (Tf2N-) as a weakly coordinating counteranion is described. These new air-stable (NCH)AuNTf2 complexes are convenient to prepare, stoe, and handle and proved to be active in a range of gold(I)-catalyzed transformations

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.

International audienceWe thank the Natural Sciences and Engineering Research Council (for Accelerator and Discovery grants to L.B.) and the University of Ottawa (for a University Research Chair to L.B.) for support of this research. We also thank Prof. Derek Pratt (University of Ottawa) for insightful discussion

Striking gold: A series of variously functionalized propynyl arenes was smoothly converted into indan‐2‐ones by a new gold(I)‐catalyzed oxidative cyclization process. [LAu]NTf2 (Tf=trifluoromethanesulfonyl) is a superior catalyst both in terms of yield and kinetics for the present transformation.

An element of surprise: A series of functionalized 2‐alkynyl arylazides has beed converted into 3‐substituted indoles or 2,2‐disubstituted indolin‐3‐ones in the presence of a gold(I) complex. Various oxygen or aryl nucleophiles can be used in this process to trap the intermediate α‐imino gold carbene. The structural motifs of the products are found in a large variety of biologically active compounds and natural products.

A series of benzyl propargyl ethers react with a gold(I) catalyst to furnish variously substituted allenes via a 1,5-hydride shift/fragmentation sequence. This transformation is rapid and practical. It can be performed under very mild conditions (room temperature or 60 degrees C) using terminal as well as substituted alkyne substrates bearing a primary, secondary, or tertiary benzyl ether group. The allenes thus formed can be reacted in situ with an internal or external nucleophile, corresponding to an overall reductive substitution process, to produce more functionalized compounds.

The gold(I) catalyzed rearrangement of 5-en-2-yn-1-yl acetates into functionalized acetoxy bicyclo[3.1.0]hexenes is described. The mild reaction conditions employed allow the efficient and rapid synthesis of a variety of such bicyclic compounds via a sequence of two gold(I)-catalyzed isomerization steps. Acetoxy bicyclo[3.1.0]hexenes products can be further transformed to 2-cycloalkenones by simple methanolysis.