New progress has been made by Professor Cheng Jinpei's research group in the calibration of the negative hydrogen reaction activity of n-heterocyclophosphate and its application in synthesis

Organic negative hydrogen compounds are a kind of important reducing reagents, which widely exist in nature, organic synthesis and chemical production process Inspired by NADPH in natural system, many non-metallic organic negative hydrogen reagents have been developed In recent years, the chemical research of P-H bond has been paid more and more attention Different from the polarity of the traditional P-H bond (protons are released by heterolysis), the unique framework of 2-h-1,3,2-diazaphospholene makes it show strong activity of releasing negative hydrogen ions This "reverse" activity has brought a new development direction and application prospect for the hydrogen bond chemistry of phosphorus A series of inert polar alkenes, aldehydes, ketones, azo, imines, α, β - unsaturated aldehydes, ketones, CO 2, pyridines, etc were reduced / functionalized by its super hydrogenicity At the same time, the chiral phosphines with similar structure have achieved high stereoselectivity control in asymmetric catalytic reactions In these catalytic reactions, whether the P-H bond can be broken and regenerated is the key factor to control the reduction reaction Although this kind of negative hydrogen reagent has been widely used in synthesis, due to the lack of quantitative scale of its reaction activity, the development of this kind of reagent and related reduction reaction still depends on the traditional trial and error mode This not only causes a lot of waste of resources, but also greatly hinders the rapid development of this field Recently, the nucleophilic parameters (N and Sn) of a series of classical P-H reagents have been determined systematically by kinetic method Using the Mayr kinetic equation logk2 = Sn (n + e) (n is the nucleophilic parameter, Sn is the nucleophilic sensitivity parameter, e is the electrophilic parameter), a series of standard electrophilic reagents were selected to determine the second-order rate constant K2 of the negative hydrogen transfer reaction between the P-H reagent and the standard electrophilic reagent, and the corresponding nucleophilic parameters N and Sn were obtained These nucleophilic parameters (n: 25.54 ~ 13.5) indicate that this kind of negative hydrogen reagent has a strong ability to give negative hydrogen Especially 2-h-1,3,2-diazaphospholene, whose nucleophilic parameter n is 25.54, is the most active non-metallic negative hydrogen reagent determined by Mayr equation It can quickly restore the inert polar unsaturated double bond The structure analysis shows that the strong ability of the compound to give negative hydrogen is mainly due to the aromatic stabilization of the positive phosphorus ions after giving negative hydrogen At the same time, these nucleophilic parameters are further applied to predict the rate of negative hydrogen transfer reaction and the feasibility of the reaction This work provides a reliable theoretical guidance for the design of new P-H negative hydrogen reagents and the development of related reduction reactions The related results were published on angelw Chem Int ed., the corresponding authors were Professor Cheng Jinpei and Dr Yang Jindong, and the first author was Dr Jing Jin (DOI: 10.1002 / anie 201901456).