title: Hypervalent Activation as a Key Step for Dehydrogenative ortho C-C Coupling of Iodoarenes.
abstract: Building on earlier results, a direct metal-free α-arylation of substituted cyclic 1,3-diones using ArI(O2CCF3)2 reagents has been developed; unlike other arylative approaches, the arylated products retain the iodine substituent ortho to the newly formed C-C bond. The mechanism is explored by using DFT calculations, which show a vanishingly small activation barrier for the C-C bond-forming step. In fact, taking advantage of an efficient in situ hypervalent activation, the iodoarenes are shown to undergo a cross-dehydrogenative C-C coupling at the C-H ortho to the iodine. When Oxone is used as terminal oxidant, the process is found to benefit from a rapid initial formation of the hypervalent ArI(OR)2 species and the sulfate-accelerated final coupling with a ketone. This method complements the ipso selectivity obtained in the metal-catalyzed α-arylation of carbonyl compounds.
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona (Spain).
authors.forename: Yichen
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona (Spain).
authors.forename: Ismael
authors.initials: I
authors.lastname: Arenas
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona (Spain).
authors.forename: Lewis Marc
authors.initials: LM
authors.lastname: Broomfield
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona (Spain).
authors.forename: Eddy
authors.initials: E
authors.lastname: Martin
authors.affiliation: Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona (Spain). ashafir@iciq.es.
authors.forename: Alexandr
authors.initials: A
authors.lastname: Shafir
keywords: CH functionalization; arylation; cross-coupling; cross-dehydrogenative coupling; hypervalent iodine