A Novel and Efficient Coupling Reaction of Sodium Tetraphenylborate with Hypervalent Iodonium Salts

Abstract

The novel coupling reaction of sodium tetraphenylborate with hypervalent iodonium salts was achieved in acidic water, providing an efficient and rapid method for the formation of carboncarbon bonds in excellent yield.The Suzuki reaction is one of the most versatile and utilized reactions for the selective construction of carboncarbon bonds, in particular for the formation of biaryls. 1 These coupling reactions are utilized extensively in the synthesis of pharmaceuticals, herbicides, and natural products as well as conducting polymers and liquid crystalline materials because they use nontoxic readily available organoboranes, yield easily removable nontoxic byproducts, and tolerate many functional groups. However, the use of heavy metals as catalysts leads to the generation of waste, which can have a number of problems associated with it, thus the eradication of the catalyst from the Suzuki reaction offers significant advantages. Recently, Leadbeater and Marco reported the first catalyst-free Suzuki coupling reaction under microwave irradiation. 2 They investigated the coupling of aryl halides with arylboronic acids, which afforded biaryls in excellent yields when aryl bromides were reacted with arylboronic acids in water under microwave heating at 150 °C for five minutes. However, due to the development of pressure and the need for specialized sealed vessels this method is not suitable for organic reactions carried out at atmospheric pressure and it is also difficult to apply on an industrial scale. In order to extend the scope of the catalyst-free Suzuki reaction the development of mild, efficient, and environmentally more benign metal-catalyst-free conditions are required.During the past few years the chemistry of hypervalent iodine compounds has experienced an unprecedented growth. 3 As powerful electrophilic reagents, hypervalent iodine compounds, in particular, hypervalent iodonium salts have found synthetic application due to their high reactivity toward various nucleophiles, their ready availability, and their nontoxic properties. They have been widely used in the Suzuki reaction to replace aryl halides or triflates affording products in excellent yield under mild reaction conditions. 4 As part of a program to investigate the catalyst-free Suzuki reaction, we explored the coupling reaction of sodium tetraphenylborate with iodonium salts in acidic water. In this paper, we would like to report a novel and efficient coupling reaction of sodium tetraphenylborate with iodonium salts in acidic water. This method was successfully applied to the synthesis of biaryls, and to the best of our knowledge, the metal-catalyst-free Suzuki-type coupling reaction of sodium tetraphenylborate with iodonium salts in acidic water has not been reported.Initially, we investigated the catalyst-free coupling reaction of phenylboronic acid with diphenyliodonium chloride in water by traditional heating methods. We found that the coupling was difficult to effect and the desired biphenyl was not obtained either in the presence or absenc...

Chemistry of Polyvalent Iodine

“…In more recent papers, the electrophilic arylations of sodium arenesulfinates,725 potassium carbonotrithioates,726 and benzazoles727 using diaryliodonium salts in ionic liquids, and the arylations of anilines,728 sodium tetraphenylborate729 and vinylindiums730 have been reported.…”

Aryl Diazonium versus Iodonium Salts: Preparation, Applications and Mechanisms for the Suzuki–Miyaura Cross‐Coupling Reaction

“…The same group also reported that similar reactions could be carried out without using either a palladium catalyst or a base. In water, iodonium salts could be coupled either at room temperature under ultrasonic irradiation60 or at 50 °C in acidic conditions 61. Both organic fragments of the iodonium were coupled at 100 °C in water using microwave irradiation 62.…”

Microwave Assisted Novel Efficient Pd-free Catalyst for Suzuki C-C Coupling Reaction

“…Leadbeater and Marco [12,13] claimed that the Suzuki Miyaura coupling of boronic acids and aryl halides is possible without the need for a transition-metal catalyst ( Table 1, Entry 14-17). In order to investigate the possibility of catalyst-free Suzuki reaction, Yan and his co-workers reported in 2006 a novel and efficient method for coupling reaction of sodium tetraphenylborate with iodonium salts in acidic water [14]. This method was simple, mild, high-yielding, and more environmentally benign ( Furthermore, a class of anionic clay is called layered double hydroxides (LDHs) or hydrotalcite (HTs) has attracted considerable interest from industrial and academic fields.…”