Denitrogenative Pd/Cu‐catalyzed Suzuki‐type Cross‐
coupling of Aryltrifluoroborates with Arylhydrazine
Hydrochlorides in Water under Room Temperature
| Mengting Meng
| Liping Deng
| Kai Cheng
| Chenze Qi
Zhejiang Key Laboratory of Alternative
Technologies for Fine Chemicals Process,
Shaoxing University, 312000 Shaoxing,
People's Republic of China
Universität Heidelberg, Im Neuenheimer
Feld, 270 69120 Heidelberg, Germany
Kai Cheng and Chenze Qi, Zhejiang Key
Laboratory of Alternative Technologies for
Fine Chemicals Process, Shaoxing
University, 312000 Shaoxing People's
Republic of China.
A water‐soluble palladium‐catalyzed Suzuki‐type cross‐coupling of
aryltrifluoroborates with arylhydrazide hydrochlorides was efficiently devel-
oped under mild and environmentally benign conditions, in water without
any ligand. The newly developed Pd/Cu co‐catalyzed denitrogenative reaction
gave a range of structurally diverse substituted biaryls with good to excellent
yields, in which the byproduct was nitrogen.
arylhydrazide hydrochlorides, aryltrifluoroborates, Suzuki‐type cross‐coupling, water, water‐soluble
1 | INTRODUCTION
Transition‐metal‐catalyzed cross‐coupling reactions have
made a great contribution to the recent growth of organic
synthesis. A great diversity of carbon‐carbon/heteroatom
bonds can now be easily generated by transition‐
metal‐catalyzed protocols that find wide applications in
the synthesis of substances such as natural products,
agrochemicals, materials, dyes, and pharmaceuticals.
From a ‘green and sustainable chemistry’ perspective,
water is a particularly environmentally safe and attractive
alternative solvent in synthetic chemistry. Water, as a
hydrogen source, is undoubtedly one of the most
suitable and promising routes for constructing com-
pounds. Water is a renewable resource that is
nontoxic, nonflammable, and cost‐effective. The primary
motivations to carry out cross‐coupling reactions in aque-
ous solvents have been economic and environmental.
The Suzuki−Miyaura reaction, among all cross‐coupling
reactions, is especially important because one of the
coupling partners, the organoboron counterpart, is
generally more readily available and environmentally
friendlier than most other available organometallics.
Moreover, organoboron reagents such as boronic
acids exhibit moisture, air, and heat stability, thus
allowing cross‐couplings to be performed under
convenient reaction conditions. Organoboronic acids are
hard to determinate the precise stoichiometry because
the existence of dimeric and trimeric anhydrides with loss
of water. Otherwise, organoboronic acids are easier to
give deboronation and homocoupling by‐products, and
sensitive to many commonly used reagents in organic
Boronic acids and boronate esters can be replaced
effectively by the corresponding organotrifluoroborates in
transmetallation reactions, rendering many advantages
over the former. Trifluoroborates are increasingly important
reagents because of their favorable physical and chemical
properties; additionally, they offer an alternative to toxic
organometallic species such as organostannanes.
The tetracoordinate nature of the trifluoroborates
makes them resistant to a variety of reaction conditions.
This characteristic allows one to build complexity into a
molecule while leaving the carbon−boron bond intact.
Received: 4 October 2017 Revised: 27 October 2017 Accepted: 30 October 2017
Appl Organometal Chem. 2018;32:e4203.
Copyright © 2017 John Wiley & Sons, Ltd.wileyonlinelibrary.com/journal/aoc 1of9