The Role of Gold Acetylides as a Selectivity Trigger and the Importance of gem-Diaurated Species in the Gold-Catalyzed Hydroarylating-Aromatization of Arene-Diynes

Abstract

Terminal 1,2-dialkynylarenes undergo an unexpected cyclization hydroarylation reaction toward naphthalene derivatives in benzene as the solvent. The regioselectivity of the reaction can be controlled by careful catalyst tuning. Also, the preparation of a bench-stable cationic amine complex or simple heterogenization of the catalyst on neutral aluminum oxide, which enables efficient catalyst recycling, was possible. Intensive mechanistic investigations were undertaken, giving new insights into the so-far underestimated role of acetylides in gold chemistry. The gold plays a fascinating dual role serving to both catalyze the reaction and activate the substrate by Au−C-σ bond formation. Evidence of gem-diaurated compounds playing an important part for gold catalysis is also reported.

σ–π-Diauration as an alternative binding mode for digold intermediates in gold(i) catalysis

“…18 The Au1–Au2 distance in 6 , however, was intermediate between the short Fürstner and Hashmi geminally diaurated complexes [2.75 to 2.84 Å], 8,9 and the longer Au–Au distances of the σ–π-diaurated acetylide complexes (3.41 to 3.62 Å). 11 Worth noting in the analogous σ– π-diaurated acetylide chemistry was a rapid interconversion of the two gold units through a process proposed to involve a geminally diaurated acetylide.…”

“…in gold( i )-catalyzed alkyne functionalization reactions. 9 In each case the geminally diaurated products are symmetric in nature.…”

CO‐Extrusion in der homogenen Gold‐Katalyse: Reaktivität von Goldacyl‐Spezies, erzeugt durch Wasser‐Addition an Goldvinylidene

“…[1] Bei diesem Mechanismus wirken nukleophile s-Aktivierung und elektrophile p-Aktivierung der Alkineinheiten von Diin-Systemen bei der Bildung von Goldvinyliden-Zwischenstufen synergetisch zusammen. Seither wurde die hohe Reaktivität dieser Spezies hauptsäch-lich für Insertionsreaktionen in unaktivierte C-HBindungen genutzt.…”

Gold Acyl Complex Formation and Decarbonylation during Indene Synthesis from Catalytically Active Vinylidene Complexes

“…Zhang and coworkers [2] and Hashmi and coworkers, [3] independently, extended the field to include carbophilic gold complexes as precatalysts for dual activation of dialkynes. [4] Despite the high affinity of gold(I) for alkynes as ligands, no tautomeric vinylidene complexes have yet been isolated.…”