Studies On Transition-Metal Catalyzed Tandem Reactions Of Isocyanides Involving Diazo Compounds

Isocyanides are versatile building blocks for the synthesis of nitrogen-containingcompounds.In this field,the transition-metal catalyzed insertion reaction of Isocyanides has been widely concerned and achieved many important results.However,the uncontrollable over insertion of isocyanides,the tandem cyclization reactions and the difficult of the insertion of oxygen are serious issues for it.Therefore,developing a simple insertion reaction of isocyanides that used molecular oxygen as terminal oxidant and oxygen-atom source without cyclization is a challenge.Most of the reactions between isocyanides and diazo compounds were concentrated in the insertion reaction of diazobin with isocyanides.However,the reaction of the isocyanides with 2,2,2-trifluoroethane has never been reported.Therefore,the tandem insertion reaction of isocyanides with 2,2,2-trifluoroethane and various nucleophiles,and developing of a new transition-metal catalyzed reaction of isocyanides with diazo compounds are very exciting.Based on the transition-metal catalyzed reaction involving diazo compounds,studies on the insertion reaction of the isocyanate as the core,this paper focuses on the insertion reaction of isocyanides with various nucleophilic reagents used oxygen as an oxidant and oxygen-atom source,the tandem insertion reaction of isocyanides with 2,2,2-trifluoroethane and various nucleophiles and the new cyclization reaction of isocyanate with diazo compounds.The specific research contents are as follows:1)We have developed a novel Rh-catalyzed aerobic oxidative insertion reactions of isocyanides with various alcohols or amines for the first time.More importantly,the reaction employs molecular oxygen as the terminal oxidant and oxygen-atom source and provides a simple,general and efficient approach to N-arylcarbamates and ureas in an atom-economic manner.The reaction features readily available starting materials,easy operation under mild reaction conditions,good to excellent yields and broad substrate scope.Moreover,this research also provides a new model of activation for transition metal catalyst systems using ?-diazocarbonyls as carbene ligands and will further expand the application of ?-diazocarbonyls in organometallic chemistry.2)We have developed a novel strategy for the rapid and highly efficient synthesis of trifluoroethyl substituted imidates and amidines through rhodium-catalyzed tandem reaction of isocyanides with 2,2,2-trifluorodiazoethane and various oxygen nucleophiles,or amines.More importantly,using ketenimine generated in situ from the reaction of vinyl isocyanides and 2,2,2-trifluorodiazoethane as key intermediate,a simple and highly efficient synthetic route to 1-trifluoroethyl isoquinolines has been developed.3)We have developed a novel copper-catalyzed multicomponent cyclization reactions of isocyanides with ?-diazocarbonyls as N-terminal electrophiles.The reaction provides a very efficient and simple modular approach to a range of functionalized imidazolines and biimidazoles through a copper-catalyzed tandem process,involving intermolecular nucleophilic addition/[3+2] cycloaddition/intramolecular cyclization-ring-opening/elimination sequence.The findings described herein represent a significant advance in application of the electrophilic capability of ?-diazoesters and will open up a novel way to access the diversity of diazo chemistry.