Construction Of Nitrogen-containing Heterocyclic Compounds Based On 1,3 Dipolar Cycloaddition Reactio

1,3-dipole cycloaddition reaction is an important method to construct nitrogencontaining heterocyclic compounds,and is widely used in medicine,pesticides,materials,chemical and other fields.This paper mainly introduces the construction of nitrogen-containing heterocyclic compounds by 1,3-dipole cycloaddition,so as to obtain medical intermediates.This paper is mainly divided into the following four parts:The first part describes a wide range of substituted spiro-pyrazoline derivatives containing the pyrrolidinone core are easily accessible by alkalic treatment of 3-benzylidene succinimides and nitrile imines.All the reactions proceeded under mild conditions and the products were isolated by column chromatography in good yields with high diastereoselectivity.Furthermore,this method featured several advantages such as good functional group tolerance and simple scalability.The second part describes the unprecedented synthesis of multi-substituted pyridazines via [4+2] homo-cycloaddition of azoalkenes generated in situ is described.This protocol features broad substrate scope and allows rapid assembly of pyridazines.Notably,this process provides an alternative method for in situ generation of azoalkenes.The third part describes we have developed a simple and efficient synthesis for2-pyrones by [3+3] annulation of cyclopropenones and sulfur ylides in the presence of triethyl amine as base.This reaction features transition-metal free conditions,high yields,and excellent functional group compatibility.A variety of 2-pyrones were prepared in good to excellent yields.The fourth part describes we reported a unique and optionally simple method to assemble 8-azabicyclo[3,2,1]octanes by using oxidopyridinium ions and maleimides as synthons.The features of good to high yields and good functional group tolerance are achieved regularly under mild conditions.Of note,oxidopyridinium ions undergo a [3+2] cycloaddition on its C2 and C6 positions,which was different from the known reported examples.