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Exclusive 5-exo-dig hydroarylation of o-alkynyl biaryls proceeding via C-H activation pathway
Natalia Chernyak1, Vladimir Gevorgyan
1Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
Abstract:
The first example of the palladium-catalyzed exclusive 5-exo-dig hydroarylation of o-alkynyl biaryls has been demonstrated. In contrast to the reported earlier carbocyclizations proceeding via the Friedel-Crafts mechanism, this hydroarylation efficiently proceeds with electron-neutral and electron-deficient arenes, producing fluorene frameworks with defined stereochemistry of the double bond. On the basis of the high reactivity of electron-deficient arenes toward cyclization, high values of inter- and intramolecular kinetic isotope effects, and the exclusive cis-selectivity of cyclization, a mechanism involving a C-H activation motif has been proposed for this transformation.
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