Constructions Of Several N-heterocyclic Compounds Via Tandem Reactions

It is well-known that the isoquinoline and quinoline skeletons are found in manynatural products and pharmaceuticals that exhibit remarkable biological activities.The thesis is mainly focused on the diversity-oriented synthesis (DOS) of diversenatural product-liked compounds such as isoquinoline and quinoline derivatives viatandem reactions.Firstly, a multi-component reaction of2-alkynylbenzaldehyde, carbodiimide, andbromine catalyzed by silver triflate under mild conditions is described, affording theN-(((4-Bromo-3-phenylisoquinolin-1-yl)(cyclohexyl)amino)(cyclohexylamino)methylene)-4-methylbenzenesulfonamides in good yields. The compounds could be furtherelaborated via the Pd-catalyzed cross-coupling reactions with aryboronic acids togenerate the functionalized isoquinolines.Secondly, the synthesis of H-pyrazolo[5,1-a]isoquinolines via tandem reactionsof N’-(2-alkynylbenzylidene)hydrazide with tertiary amine under cooperativecatalysis is developed. The reaction proceeds through6-endo cyclization, nucleophilicaddition, intramolecular condensation, and aromatization to generate theH-pyrazolo[5,1-a]isoquinolines in good to excellent yields.Subsequently, a palladium-catalyzed tandem reaction of2-alkynylaniline with2-alkynylvinyl bromide is reported, which provides an efficient route for the assemblyof cyclopenta[c]quinolin-3-ols. A double insertion of triple bonds is the key stepduring the transformation.