Iridium(I)-catalyzed C-H Borylation of α,β-Unsaturated Esters with Bis(pinacolato)diboron

Ikuo Sasaki; Jumpei Taguchi; Hana Doi; Hajime Ito; Tatsuo Ishiyama

doi:10.1002/asia.201600078

Iridium(I)-catalyzed C-H Borylation of α,β-Unsaturated Esters with Bis(pinacolato)diboron

Chem Asian J. 2016 May 6;11(9):1400-5. doi: 10.1002/asia.201600078. Epub 2016 Apr 5.

Authors

Ikuo Sasaki¹, Jumpei Taguchi¹, Hana Doi¹, Hajime Ito², Tatsuo Ishiyama³

Affiliations

¹ 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.
² 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. [email protected].
³ 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. [email protected].

PMID: 26929021
DOI: 10.1002/asia.201600078

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.

Keywords: alkenyl boronates; borylation; diboron; iridium; α,β-unsaturated esters.

Publication types

Research Support, Non-U.S. Gov't