General approaches for fluorination, trifluoromethylation, and trifluoromethylthiolation were developed based on the electrophilic nature of arynes. In these reactions, the addition of fluorine-containing nucleophiles onto aryne intermediates was efficiently promoted by either silver catalysts or silvercontaining stoichiometric reagents. Contrary to known methods that require aromatic precursors, our new approach enables efficient non-traditional synthesis of Ar-F, Ar-CF 3 and Ar-SCF 3 from nonaromatic building blocks under relatively mild conditions.Scheme 1 Unprecedented reactivity of arynes in the presence of a silver complex.

Arynes generated directly from alkyne building blocks in the presence of silver catalysts effectively activate primary, secondary, and tertiary alkane C-H bonds. This C-H insertion requires only a catalytic amount of silver complex and modest heating compared to harsh conditions and extra promoters including directing groups, oxidants, and bases in typical transition-metal-based C-H bond functionalizations. Preliminary mechanistic studies suggest that the C-H bond-breaking and new bond-forming events take place in a concerted manner, rendering a formal 1,2-addition of C-H bond across the π-bond of arynes.

Efficient Alder-ene reactions of various arynes generated directly from bis-1,3-diynes are described. The reactivity of ene donors with different tethers was examined under thermal and metal-catalyzed conditions, which indicates that both the formation of aryne intermediates and their ene reactions are less sensitive to the catalyst than to the structural features of the substrates.

P age 1940. The structures of 3m and 3n in entries 2 and 3 of Table 2 are inadvertently represented as indolines. Their correct structures should be the corresponding isoindolines.We thank a reader who brought this to our attention.

A new biaryl synthesis via silver-catalyzed hydroarylation of arynes from acyclic building blocks with unactivated arenes in intra- and intermolecular manners has been developed. The previously observed Diels-Alder reactions of arynes with arene were not observed under the current silver-catalyzed conditions. Deuterium scrambling and DFT calculations suggest a stepwise electrophilic aromatic substitution mechanism through the formation of a Wheland-type intermediate followed by a water-catalyzed proton transfer in the final step of the hydroarylation.