The Research Of Cyclization Reaction Based On Ynals

There are many types of nitrogen-containing heterocyclic compounds,which are widely found in natural products with biological activity,pharmaceuticals,agrochemicals,and electronic materials.Due to the excellent application value of nitrogen-containing heterocyclic compounds,the development of efficient and novel synthetic methods has always been one of the hot spots in organic synthesis.Aldehyde group and alkyne triple bonds are the most basic functional groups in organic chemistry,and their chemical properties are relatively active.Ynals are useful intermediates and versatile building blocks.Several mild and convenivent approaches have been developed and thus have increased the attractiveness of this class of compounds in organic synthesis.Based on the concept of green chemistry,this thesis mainly discusses the establishment of methods to synthesize 3-acyl indolizines and1,2,3-triazoles through intermolecular cyclization reaction,including the following three parts.(a)The synthetic methods of ynals and the organic reactions based on ynals are reviewed,such as transition metal catalysis,acid catalysis,organic small molecule catalysis,nitrogen heterocyclic carbene catalysis,photocatalysis and catalyst-free reacitons.(b)A cheap elemental iodine-catalyzed tandem condensation and annulation for the synthesis of 3-acylated indolizines from ynals and 2-alkylpyridines was reported.The merit of this transformation includes precious metal catalyst and additive-free,reacted in air,simple operation,good functional group tolerance,commercially or readily available substrates.Furthermore,water is considered as the source of the carbonyl oxygen in the products,and the functional groups such as cyano,amide and carbonyl groups have a wide range of potential applications in organic synthesis and drug synthesis.(c)A rare earth metal salt as Lewis acid-catalyzed toward polysubstituted1,2,3-triazoles containing aldehyde groups through 1,3-dipolar cycloaddition from ynals and azides in water solvent was developed.The characteristic of the transformation included the triazole isomers can be easily separated,the aldehyde groups can undergo various transformations,water as solvent meets the requirements of green chemistry,rare earth metals as Lewis acid catalysts are highly efficient and inexpensive,good functional group compatibility,simple operation and good yields.