Gold-Catalyzed 1,2-Diarylation of Alkenes

Herein, we disclose the gold-catalyzed 1,2-diarylation of alkenes through the interplay of ligand-enabled Au^I/Au^III catalysis with the idiosyncratic π-activation mode of gold complexes. Unlike the classical migratory-insertion-based approach to 1,2-diarylation, the present approach not only circumvents the formation of direct Ar−Ar′ coupling and Heck-type side products but more intriguingly demonstrates reactivity and selectivity complementary to those of previously known metal catalysis (Pd, Ni, or Cu). Detailed investigations to underpin the mechanistic scenario revealed oxidative addition of aryl iodides to an Au^I complex to be the rate-limiting step owing to the non-innocent nature of the aryl alkene.     

Gold‐Catalyzed 1,2‐Diarylation of Alkenes

Herein, we disclose the gold‐catalyzed 1,2‐diarylation of alkenes through the interplay of ligand‐enabled Au^I/Au^III catalysis with the idiosyncratic π‐activation mode of gold complexes. Unlike the classical migratory‐insertion‐based approach to 1,2‐diarylation, the present approach not only circumvents the formation of direct Ar?Ar′ coupling and Heck‐type side products but more intriguingly demonstrates reactivity and selectivity complementary to those of previously known metal catalysis (Pd, Ni, or Cu). Detailed investigations to underpin the mechanistic scenario revealed oxidative addition of aryl iodides to an Au^I complex to be the rate‐limiting step owing to the non‐innocent nature of the aryl alkene.     

Gold(I)/Gold(III) Catalysis that Merges Oxidative Addition and π-Alkene Activation

Heteroarylation of alkenes with aryl iodides was efficiently achieved with a (MeDalphos)AuCl complex through Au^I/Au^III catalysis. The possibility to combine oxidative addition of aryl iodides and π-activation of alkenes at gold is demonstrated for the first time. The reaction is robust and general (>30 examples including internal alkenes, 5-, 6-, and 7-membered rings). It is regioselective and leads exclusively to trans addition products. The (P,N) gold complex is most efficient with electron-rich aryl substrates, which are troublesome with alternative photoredox/oxidative approaches. In addition, it provides a very unusual switch in regioselectivity from 5-exo to 6-endo cyclization between the Z and E isomers of internal alkenols.     

Triflic Acid‐Catalyzed Enynes Cyclization: A New Strategy beyond Electrophilic π‐Activation

The cyclization of enynes, catalyzed by a transition metal, represents a powerful tool to construct an array of cyclic compounds through electrophilic π‐activation. In this paper, we disclose a new and efficient strategy for enynes cyclization catalyzed by triflic acid. The salient features of this transformation includes a broad substrate scope, metal free synthesis, open flask and mild conditions, good yields, ease of operation, low catalyst loading, and easy scale‐up to gram scale. A preliminary mechanism study demonstrated that the activation model of the reaction was σ‐activation, which is different from the transition‐metal‐catalyzed enynes cyclization. Our strategy affords a complementary method to the traditional strategies, which use transition‐metal catalysts.     

Well‐Defined Dinuclear Gold Complexes for Preorganization‐Induced Selective Dual Gold Catalysis

The synthesis, reactivity, and potential of well‐defined dinuclear gold complexes as precursors for dual gold catalysis are explored. Using the preorganizing abilities of the ditopic PN^HP^iPr ( L^H ) ligand, dinuclear Au^I–Au^I complex 1 and mixed‐valent Au^I–Au^III complex 2 provide access to structurally characterized chlorido‐bridged cationic species 3 and 4 upon halide abstraction. For 2 , this transformation involves unprecedented two‐electron oxidation of the redox‐active ligand, generating a highly rigidified environment for the Au₂ core. Facile reaction with phenylacetylene affords the σ,π‐activated phenylacetylide complex 5 . When applied in the dual gold heterocycloaddition of a urea‐functionalized alkyne, well‐defined precatalyst 3 provides high regioselectivities for the anti‐Markovnikov product, even at low catalyst loadings, and outperforms common mononuclear Au^I systems. This proof‐of‐concept demonstrates the benefit of preorganization of two gold centers to enforce selective non‐classical σ,π‐activation with bifunctional substrates.     

Gold(I)/Gold(III) Catalysis that Merges Oxidative Addition and π‐Alkene Activation

Heteroarylation of alkenes with aryl iodides was efficiently achieved with a (MeDalphos)AuCl complex through Au^I/Au^III catalysis. The possibility to combine oxidative addition of aryl iodides and π‐activation of alkenes at gold is demonstrated for the first time. The reaction is robust and general (>30 examples including internal alkenes, 5‐, 6‐, and 7‐membered rings). It is regioselective and leads exclusively to trans addition products. The (P,N) gold complex is most efficient with electron‐rich aryl substrates, which are troublesome with alternative photoredox/oxidative approaches. In addition, it provides a very unusual switch in regioselectivity from 5‐exo to 6‐endo cyclization between the Z and E isomers of internal alkenols.