114 Volume 3 • Issue 1 • 1000117 Madridge J Nov Drug Res.
ISSN: 2641-5232
Madridge
Journal of Novel Drug Research
Research Article Open Access
Regioselective C-H Borylation of C (sp
2
)-H Bond
Hua-Qing Jing, Jon C Antilla and Hong-Liang Li*
Institute for Molecular Design and Synthesis, School of Pharmaceutical Science and Technology, Health Science Platform, Tianjin University,
Nankai District, Tianjin, China
Article Info
*Corresponding author:
Hong-Liang Li
Institute for Molecular Design and Synthesis
School of Pharmaceutical Science and
Technology
Health Science Platform, Tianjin University
Nankai District, Tianjin
China
E-mail: lhl522508@126.com
Received: January 30, 2019
Accepted: February 19, 2019
Published: February 26, 2019
Citation: Jing HQ, Antilla JC, Li HL.
Regioselective C-H Borylation of C (sp
2
)-H
Bond. Madridge J Nov Drug Res. 2019; 3(1):
114-119.
doi: 10.18689/mjndr-1000117
Copyright: © 2019 The Author(s). This work
is licensed under a Creative Commons
Attribution 4.0 International License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the
original work is properly cited.
Published by Madridge Publishers
Abstract
C-H activation reactions have become a powerful method to direct functionalization
of alkyl, alkenyl, and aryl C-H bonds over the past few decades. Among of them, Iridium
catalyzed transformation of aryl C-H bonds to C-B bonds is one of the most useful
method. However, a central challenge in these reactions is controlling their site selectivity.
Over the past decade, some methods have been developed to accomplish regio-
selective C-H borylation by catalysts or substrates modification. In this paper, some
methods developed in recent years to realize ortho-, meta-, and para-selective C-H
borylation will be summarized and their strategy and mechanism of these methods will
be discussed.
Keywords: Iridium; Regioselective; C-H borylation; Non-covalent bond interaction.
Introduction
Carbon-Carbon bond are the molecular “bricks and mortar” from which diverse
architectures in living organisms and manmade materials are constructed. In the field of
organic chemistry, there are numerous methods for carbon-carbon bond construction,
which have been developed, ranging from traditional nucleophilic reaction to metal
catalyzed reaction for formation of C-C bond. Among of them, Suzuki-Miyaura reaction
has become one of the most powerful method for the construction of C-C bond since
its discovery in 1979 [1]. Arylboron is an important reagent for participating in this
reaction. In addition, organoboron reagents as versatile intermediates have been
extensively used in synthetic chemistry because it can be converted to more complex
molecules by further transformations, such as Chan-Lam-Evans coupling, [2-4] and
oxidation [5-7]. Therefore, developing a highly effective method for synthesis of
organoboron reagents is very desirable.
Traditional methods to obtain organoboron reagents are these three methods
(Scheme 1), which contains synthesis from organolithium or organomagnesium,
hydroboration of alkenes or alkynes and haloboration of terminal alkynes [8]. However,
there are some limitations of these methods. For example, the synthesis from
organometallics usually requires stoichiometric amounts of strong base such as n-BuLi
and a harsh lower temperature to use in the reaction. As for the reactions of hydroboration
and haloboration, boron atom always adds to the terminal position of alkenes or
alkynes. It is difficult to obtain internal boron reagents form these two methods. Besides,
these three methods also are not in accordance with the rule of atomic economy. The
development of transition metal catalyzed C-H borylation provides a good way for
preparation of organoboron reagents, especially for aromatic boron reagents.
ISSN: 2641-5232