Synform Issue 2015/02

Abstract

C o n TA C T Yo ur op ini on ab ou t Sy nf or m is we lco me , ple as e co rre sp on d if yo u lik e: ma rk et ing @t hie me -c he mi str y.c omThis document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. Dear readers,Although this Editorial will be published in the February issue of Synform, the truth is that I am writing it soon after the Christmas and New Year celebrations, which I have spent in Italy. Like most of you, I have eaten and drunk way too much and I suspect I have put on quite some weight as a consequence of the many lunches and dinners with relatives and friends. Now I am facing a period whereby I will necessarily have to keep my gastronomic exuberance under control, which doesn't make me too happy… Let's try to put aside food and drinks for a while then, and focus on something else, if possible. Let's concentrate on good chemistry, such as that described in this new issue of Synform. We start with a novel fluorination procedure discovered by D. Carbon-fluorine bond construction has consistently been of great interest to chemists due to the unique characteristics of fluorinated molecules and the synthetic challenges connected with the introduction of fluorine into organic molecules. Apart from the ipso-fluorination of pre-functionalized substrates, C -H bond fluorination is a prospective alternative and has received a great deal of attention in recent years. However, several challenges, for example, relatively harsh conditions, excess amounts of fluorinating agents (oxidants), narrow substrate scopes and poor selectivity still need to be addressed for this emerging area. Given the broad application of fluorinated compounds in pharmaceuticals, agrochemicals and materials, a mild and versatile C-H bond fluorination protocol is highly desirable. Very recently, a novel and facile nitrate-promoted regioselective fluorination of aromatic and olefinic sp 2 -C -H bonds under mild conditions was described by Professors Dan-Qian Xu and Zhen-Yuan Xu, and Dr. Shao-Jie Lou from Zhejiang University of Technology (P. R. of China).Generally, the fluorination reactions took place under very mild conditions (close to room temperature in most cases). strength of both C-H and C-F bonds, so we were delighted to find that the current palladium-nitrate catalytic system enabled the process in a much milder manner." "A catalytic amount of simple, non-toxic and cheap potassium nitrate served as a highly efficient promoter," said Professor D.-Q. Xu. "Actually, silver nitrate was found to be an efficient additive for this transformation at the outset of this program," she explained. Since silver salts were demonstrated to be incorporated in several C-F bond formation reactions, various silver salts were then screened. However, only silver nitrate and silver nitrite could successfully promote the reaction, whereas other silver salts were ineffective. Professor Z.-Y. Xu said: "The unique counter-anion effect led us to hypo thesize that the nitrate anion might be the pivotal promoter. ...