title: Catalyst-controlled regiodivergent C-H borylation of multifunctionalized heteroarenes by using iridium complexes.
abstract: The regiodivergent C-H borylation of 2,5-disubstituted heteroarenes with bis(pinacolato)diboron was achieved by using iridium catalysts formed in situ from [Ir(OMe)(cod)]2 /dtbpy (cod=1,5-cyclooctadiene, dtbpy: 4,4'-di-tert-butyl-2,2'-bipyridine) or [Ir(OMe)(cod)]2 /2 AsPh3 . When [Ir(OMe)(cod)]2 /dtbpy was used as the catalyst, borylation at the 4-position proceeded selectively to afford 4-borylated products in high yields (dtbpy system A). The regioselectivity changed when the [Ir(OMe)(cod)]2 /2 AsPh3 catalyst was used; 3-borylated products were obtained in high yields with high regioselectivity (AsPh3 system B). The regioselectivity of borylation was easily controlled by changing the ligands. This reaction was used in the syntheses of two different bioactive compound analogues by using the same starting material.
authors.affiliation: Division of Chemical Process Engineering and Frontier Chemistry Center (FCC), Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo, Hokkaido 060-8628 (Japan), Fax: (+81) 117066562.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Sasaki
authors.affiliation: Division of Chemical Process Engineering and Frontier Chemistry Center (FCC), Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo, Hokkaido 060-8628 (Japan), Fax: (+81) 117066562.
authors.forename: Jumpei
authors.initials: J
authors.lastname: Taguchi
authors.affiliation: Division of Chemical Process Engineering and Frontier Chemistry Center (FCC), Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo, Hokkaido 060-8628 (Japan), Fax: (+81) 117066562.
authors.forename: Shotaro
authors.initials: S
authors.lastname: Hiraki
authors.affiliation: Division of Chemical Process Engineering and Frontier Chemistry Center (FCC), Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo, Hokkaido 060-8628 (Japan), Fax: (+81) 117066562. hajito@eng.hokudai.ac.jp.
authors.forename: Hajime
authors.initials: H
authors.lastname: Ito
authors.affiliation: Division of Chemical Process Engineering and Frontier Chemistry Center (FCC), Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8 Kita-ku, Sapporo, Hokkaido 060-8628 (Japan), Fax: (+81) 117066562. ishiyama@eng.hokudai.ac.jp.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Ishiyama
keywords: CH activation; borylation; heterocycles; iridium; regioselectivity