Decomposition of N-Sulfonylhydrazones to Diazoalkanes Goes to Room Temperature and Application to [2+1] Cyclopropenation with Alkynes
Xihe Bi describes the decomposition of N-sulfonylhydrazones to diazoalkanes at room temperature.
It is well known that diazo compounds are outstanding building blocks in organic synthesis. Since their discovery over 100 years ago, these reagents have been frequently employed in a variety of processes, starting from homologation reactions to metal-catalyzed C–H insertions. However, due to their toxic and explosive nature, direct use of diazo compounds in many of these chemically interesting reactions and their utilization in large-scale production has been very difficult. To avoid these difficulties, chemists have developed a range of diazo surrogates as an alternative diazo source in numerous organic transformations. N-Tosylhydrazones have proved to be some of the most useful diazo surrogates, because of their rapidly expanding repertoires of organic transformations. However, their high dissociation temperature remains an inherent drawback, and severely limits their use in synthetic areas where low reaction temperatures are generally employed. Recently, this challenging issue has been addressed by the research group of Professor Xihe Bi at the Northeast Normal University (P. R. of China), who discovered for the first time the room-temperature decomposable property of N-nosylhydrazones.