Gold catalysis: Experimental mechanistic insights into the anellation of phenols with 1,3-dienes

Unlocking the Chain‐Walking Process in Gold Catalysis**

“…To the best of our knowledge, such annulation reaction remain unprecedented in the field of transition metal catalysis. The key features of the present transformation involve the initial migratory insertion step to generate alkyl‐Au(III) intermediate I , followed by a chain‐walking process to form aryl alkene intermediate II which upon intramolecular cyclization through π‐activation affords the annulation [19] product. Overall, such interplay between the chain‐walking process and π‐activation chemistry observed in this transformation underscores the unique reactivity profile offered by gold catalysis compared to other transition metals (Scheme 1b–c vs Scheme 1d).…”

Silver(I)-Catalyzed Intramolecular Cyclizations of Epoxide-Propargylic Esters to 1,4-Oxazine Derivatives

“…However, when 1 a was treated with other metal catalysts, such as Yb(OTf) 3 , Sc(OTf) 3 , Ph 3 PAuCl/Yb(OTf) 3 , Ph 3 PAuCl/AgSbF 6 , or Au‐1 , no desired product was obtained (Table , entries 2–6). The reason for the failure of gold(I) catalysts is that, as compared to the corresponding donor‐substituted alkynes, gold(I) catalysts might be too reactive and can easily or efficiently coordinate to the electron‐rich diene, further enhancing its reactivity and subsequently leading to decomposition of the desired products. Then, various silver(I) catalysts were examined.…”

Gold-Catalyzed Addition of β-Ketoesters to Alkenes: Influence of Electronic and Steric Effects in the Reaction Outcome

“…The gold-promoted nucleophilic additions onto alkynes and allenes have been widely explored for the generation of both new C-heteroatom (N, S, O) bonds and new carbon–carbon bonds [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. In the last few years, gold-mediated activation of alkenes has been developed as well, but in less extension as expected, due to their lower reactivity comparing with the alkynyl and allenyl counterparts [ 27 , 28 , 29 , 30 , 31 ]. In particular, gold catalysis applied to unactivated olefins presents a limited scope of conditions and reagents, and is mainly referred to heteroatom nucleophilic addition, which, in most of the cases, leads to the formation of heterocyclic structures [ 32 , 33 , 34 , 35 , 36 , 37 , 38 ].…”