Studies On The Iron-Catalyzed 1,2-Acyl Migration Reactions Of α-azidyl Ketones

This dissertation discusses the iron-catalyzed 1,2-acyl migration reaction ofα-azidyl ketones and copper-catalyzed tandem radical addition/cyclization reactions between2-azidyl-N-phenyl acrylamides and trifluoromethyl radical as well as azidyl radical.It contains four chapters:The first chapter is a brief review on the iron-catalyzed amination reactions of organic azides and 1,2-acyl migration reactions.The next three chapters introduce the research works completed during the PhD’s study of the author.They are summarized as follows:（1）It was found that tertiaryα-azidyl phenyl ketones can be transformed into enamides by treatment with FeBr₂ at elevated temperature in DMF.The reaction proceeds via 1,2-benzoyl migration fromα-carbon to the nitrogen atom,accompanied by expulsion of a nitrogen molecule and hydrogen migration.This protocol is suitable for the synthesis of N-（cyclopent-1-en-1-yl）benzamides,N-（cyclohex-1-en-1-yl）benzamides,and N-benzoyl-α-methyl enamines and provides a convenient approach toward isoquinolones.（2）On the basis of the above mentioned result,the reaction conditions were further optimized to improve the result.By using an iron（II）-phosphine complex as catalyst,1,3-dicarbonyl 2-azides were converted in acetonitrile 65 ^oC to an N-acyl imines,which then isomerized to the corresponding enamides.This result confirms that the transformations fromα-azidyl ketones to enamides involve the intermediacy of N-acyl imines.It was also found that 1,3-dicarbonyl azides can be completely converted to enamides under the condition of FeBr₂/Et₃N in acetonitrile at 65 ^oC.A catalytic amount of triethyl amine largely benefits the reaction by rendering the reaction occur at lower temperature as well as raising the yields of the enamides and isoquinolones.（3）The reactions of 2-azido-N-arylacrylamides with trifluoromethyl radicals and azidyl radicals were investigated by using Togni’s reagent and Zhdankin’s reagent as the source of these radicals.Under the catalysis of CuI,Togni’s reagent was firstly convertedintothetrifluoromethylradical,whichthenreactedwith2-azido-N-arylacrylamides to afford the correspondingα-（arylaminocarbonyl）iminyl radicals.The cyclization of the iminyl radicals delivered quinoxalin-2（1H）-one productsinmoderateyields.Asimilarreactiontookplacebetween2-azido-N-arylacrylamides and the azidyl radical.In the latter cases,the reaction produced 3-azidomethyl and 3-cyano-subsituted quinoxalin-2（1H）-ones.This study not only helps to elucidate the factors influencing the cyclization ofα-（arylaminocarbonyl）iminyl radicals,but also provides a new approach towards quinoxalin-2-ones.