title: Iridium(I)-catalyzed C-H Borylation of α,β-Unsaturated Esters with Bis(pinacolato)diboron.
abstract: A new process has been developed for the iridium(I)-catalyzed vinylic C-H borylation of α,β-unsaturated esters with bis(pinacolato)diboron (B2 pin2 ). These reactions proceeded in octane at temperatures in the range of 80-120 °C to afford the corresponding alkenylboronic compounds in high yields with excellent regio- and stereoselectivities. The presence of an aryl ester led to significant improvements in the yields of the acyclic alkenylboronates. Crossover experiments involving deuterated substrates as well as a mixture of stereoisomers confirmed that this reaction proceeds via a 1,4-addition/β-hydride elimination mechanism. Notably, this reaction was also used to develop a one-pot borylation/Suzuki-Miyaura cross-coupling procedure.
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) 11-706-6562.
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) 11-706-6562.
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) 11-706-6562.
authors.forename: Hana
authors.initials: H
authors.lastname: Doi
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) 11-706-6562. ishiyama@eng.hokudai.ac.jp.
authors.forename: Hajime
authors.identifier: 0000-0003-3852-6721
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) 11-706-6562. hajito@eng.hokudai.ac.jp.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Ishiyama
keywords: alkenyl boronates; borylation; diboron; iridium; α,β-unsaturated esters