This work was supported by Pusan National University (PNU; the Financial Supporting Project of Long-term Overseas Dispatch of PNU’s Tenure-track Faculty, 2021).
In this study, gold(III)-catalyzed cyclization reactions of alkynyl norbornene derivatives were developed to provide benzofused (hetero)arenes with substitutions at the benzocyclic ring. The combination of Au(OAc)3 and AgNTf2 allowed for the annulation of (hetero)arenes by intramolecular hydro(hetero)arylation followed by retro-Diels–Alder reactions to afford fully conjugated benzofused (hetero)arenes in yields higher than those obtained by our previously developed Pd(OAc)2-catalyzed protocol. Furthermore, when Au(OAc)3 was replaced with AuCl3, (hetero)arenes with the norbornene bridge installed at the more electron-rich and sterically demanding position underwent a rearrangement to afford the corresponding regioisomeric products in a divergent manner. The results indicate that the rigid norbornene ring creates a steric effect, in addition to placing two reactive sites in close proximity and serving as an acetylene synthon. This illustrates the importance of steric effects in addition to the electronic effects of the catalyst and the substrate on the rearrangement.
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Rogge T,
Kaplaneris N,
Chatani N,
Kim J,
Chang S,
Punji B,
Schafer LL,
Musaev DG,
Wencel-Delord J,
Roberts CA,
Sarpong R,
Wilson ZE,
Brimble MA,
Johansson MJ,
Ackermann L.
Nat. Rev. Methods Primers 2021; 1: 43
15
Ahlsten N,
Cambeiro XC,
Perry GJ. P,
Larrosa I.
C–H Functionalisation of Heteroaromatic Compounds via Gold Catalysis. In Au-Catalyzed Synthesis and Functionalization of Heterocycles. Bandini M., Springer; Cham: 2016: 175-226
