Rhodium-Catalyzed Reactions Of 3-Diazoindolin-2-Imines With Aryl Allylic Alcohols And Nitrosobenzenes

Transition metal carbenes have both unique and rich reactivities,which make them play an important role in organic synthesis.In recent years,the synthesis and transformations of novel carbene precursors have attracted the interest of chemists.In particular,under the appropriate transition metal catalysis,tri azoles and 3-diazoindolin-2-imine compounds can be converted into ?-imine metal carbene intermediates,which can react with nucleophiles to obtain nitrogen compounds with diverse structures.In this paper,3-diazoindolin-2-imine,as a precursor of carbene,was studied.?-imine rhodium carbene was formed under divalent rhodium catalysis and then reacted with O-containing nucleophiles of 1-aryl-substituted allylic alcohols.The experimental results showed that the reaction condition is mild,the yield is moderate to good,and the functional group compatibility is wide.In addition,the mechanism of the reaction was discussed by DFT calculations.Calculation results showed that after the formation of ?-imino rhodium carbene intermediate,the hydroxyl of the aryl allylic alcohol substrates reacts with the carbene more easily than the olefin part,and the H atom of the hydroxyl was transferred from O to N atom of imine group to form the alloxygen-containing intermediate.The formed intermediate underwent cl aisen rearrangement to obtain the rearrangement intermediate,which then disassociated the TsNH2 to yield the final product under the assistance of the catalyst anion.In addition,?-imine rhodium carbene intermediate was produced from divalent rhodium catalyzed 3-diazoindolin-2-imine,can react with N-containing nucleophile of nitrosobenzenes to produce nitrone compounds.This reaction combines the advantages of the drug application 'of indoles skeleton and the richness reaction of nitrone intermediate,both make the product have great potential research value.In this reaction,DFT calculation results show that N atom of the nitroso group attacked the carbene to form nitrone product directly.