Synthesis Of Ureas And Isocoumarin Derivatives Based On Rh-catalyzed Organic Reactions Of Cyclic Daizo-1,3-diketones

It is well known that diazo compounds are generate metal-carbene species that undergo diverse conversions catalyzed by transition-metal,including addition,insertion,1,3-dipolar cycloaddition,rearrangement,cyclization reactions,C-H activation,and other reactions.Based on literatures,ureas and isocoumarins were synthesized via cyclic diazo-1,3-diketones by Rh(II)or Rh(III)catalyzed has been developed.The discussion and results are listed as follows.A methodology of forming ureas derivatives via the reactions of cyclic diazo-1,3-diketones,carbodi-imides and DXE catalyzed by Rh2(OAc)4 was developed.The reaction was followed by the insertion of C-X(X=Cl,Br,I)bond,nucleophilic addition and rearrangement reaction.A total of 22 novel compounds were synthesized and characterized by NMR,IR,HRMS and X-Ray.The effects of solvents,temperature,reaction time and catalyst on the reaction were investigated,and a possible reaction mechanism is presented.An efficient([Cp*RhCl2]2)-catalyzed C-H activation/ esterification reaction for the synthesis of isocoumarins has been developed.This procedure uses readily available benzoic acids and cyclic diazo-1,3-diketones as starting materials,and involves domino intermolecular C-H activation in combination with intramolecular esterification to give the corresponding isocoumarins in moderate to excellent yields.This process provides a facile approach for the construction of isocoumarins containing various functional groups without any additives.A total of 42 novel compounds were synthesized and characterized by NMR,IR,HRMS and X-Ray.On the basis of the experimental results,a plausible mechanism was proposed.In summary,a novel and efficient route for the synthesis of ureas and isocoumarins via Rh-catalyzed C-X insertion reaction of cyclic2-diazo-1,3-diketones under mild conditions has been developed.The described protocol is superior to previous methods due to several advantageous features,including readily available starting materials,a broad substrate scope with moderate to excellent yields,no inert gas protection and an additive-free workup process.The high atom economy are the most attractive parts of this reaction.We believe that the results will inspire the use of C-X insertion reaction to construct other potential bioactive compounds in a variety of future applications.And further enriched diazo organic reaction based on transition metal catalyzed.