Expedient Access to Polyaromatic Biaryls by Unconventional Ag-Catalyzed Cycloaromatization of Alkynylthiophenes and Au-Catalyzed Double C–H Activation

Abstract

An unconventional approach for the regioselective synthesis of polyaromatic biaryls via site-selective Ag-catalyzed twofold electrophilic cycloisomerization followed by Au-catalyzed double C−H activation is described. The developed process allows the synthesis of highly decorated biaryls with excellent regioselectivity. As revealed by DFT computations, the reaction represents a rare example of C1−C5 endo-exo and C1−C6 endo-endo cycloaromatization. The formation of the 6-membered ring is predicted to be the fruit of an uncommon SEAr on a vinyl carbocation.

Gold(I)‐Catalyzed Bis‐Cyclization of Allenynes for the Synthesis of Strained and Planar Polycyclic Compounds

“…This reaction constructs a strained tetracyclic scaffold during the vinyl cation formation step. Quite recently, Verma and co‐workers reported a silver‐catalyzed generation of vinyl cation species from diynes, followed by intramolecular arylation to construct a thiophene‐fused indenes (Scheme 3B) [7b] . This reaction does not require the regioselective formation of a vinyl cation using substrates with a symmetrical structure.…”