Aryl boronic acid derivatives are widely used as substrates to synthesize biaryls through Suzuki-Miyaura couplings. However, purifying boronic acid derivatives by conventional silica gel chromatography is not generally easy and causes trouble over the significant loss of isolated yields. Moreover, some boronic acid derivatives are not stable enough under Suzuki-Miyaura coupling conditions.
In this paper, we developed new easy-to-handle boronic acid derivatives. The specific example of our new boronic acid derivative is shown in Figure 1. A single clear spot that corresponds to ArB(Epin) 1a was observed on TLC [Figure 1 (A)]. In contrast, ArB(pin) 1b exhibited an original spot with significant tailing. Moreover, the Suzuki-Miyaura coupling product 2 was obtained with the highest isolated yield >99% from ArB(Epin) 1a, and with much lower yields 2% and 0% from corresponding ArB(pin) 1b and ArB(OH)2 1c, respectively [Figure 1 (B)].
Figure 1. A specific example of new boronic acid derivatives.
This paper was scored 94 by Altmetric, which is in the top 5% of all research outputs, and became the Most Read Article in Organic Letters in a year (7/12/2022).
This paper was selected as cover art. The cover means that the four ethyl groups of the boronate are designed to protect through "space" the empty orbital of the boron atom in a dynamic manner (Figure 2).
Figure 2. The Cover Art of this work in Organic Letters.
This paper is the result of corroborative work with Osaka University. We thank Mr. Naoki Oka from Osaka University carried out this research very hard. We acknowledged Professor Shuji Akai of Osaka University gave advice for preparing the manuscript of this paper.
Literature name : Organic Letters
Article title : Aryl Boronic Esters Are Stable on Silica Gel and Reactive under Suzuki-Miyaura Coupling Conditions
Author list : Naoki Oka, Tsuyoshi Yamada, Hironao Sajiki, Shuji Akai, Takashi Ikawa
Volume and number : Vol. 24, No. 19
Page : 3510-3514
DOI : 10.1021/acs.orglett.2c01174
Laboratory of Organic Chemistry