Multi-substituted DA Cyclopropane Participates In The [3+2] Cycloaddition Reaction Study

Cyclopropane has a special angular tension and torsional tension.It is very easy to open loop.As a class of special compounds involved in the construction of complex organic molecules.The synthesis of poly-substituted D-A cyclopropanes and their applications in organic synthesis are of particular concern to many organic chemists.D-A cyclopropane ring as a 1,3-dipole is very easy with various types of structural units ring reaction to form a five-membered ring,six-ring and so on.Based on the study of cyclopropane compounds and the wide application of cyclopropane compounds in this research group,the isoxazole derivatives,1,3,5-triarylpyrazole derivatives,triarylpyrrole derivatives.Part 1:A new DBU-mediated[3+2]cycloaddition reaction has been developed using readily available donor-acceptor cyclopropanes.This approach provides a straightforward and efficient route to the construction of polysubstituted isoxazole scaffolds in high yields.The optimum reaction conditions were determined by optimizing and screening the conditions.The isoxazole derivatives were obtained by the catalysis of DBU with different substituents of D-A cyclopropane and nitromethane as reaction materials.Nineteen target products were synthesized in a yield of 78-92%.All products were characterized by IR,NMR and LC-MS spectroscopy.Among them,three compounds were characterized by single crystal X-ray diffraction.Part 2:Donor-acceptor cyclopropanes are reacted with arylhydrazines to afford 1,3,5-trisubstituted pyrazoles under the influence of a Bronsted acid.Formally,this transformation can be regarded as a[3 + 2]-cycloaddition of three-membered rings with?-carbonyl and hydrazines.This newly efficient method provides access to a variety of structurally diverse pyrazole derivatives.Twenty target products were synthesized in a yield of 72-84%.All products were characterized by IR,NMR and LC-MS spectroscopy.Among them,three compounds were characterized by single crystal X-ray diffraction.Part 3:The effects of D-A cyclopropane and salicylaldehyde and ammonium acetate on the formation of[3 + 2]cycloaddition reaction,the final synthesis of triaryl pyrrole derivatives.After the reaction conditions were optimized and screened,the optimum reaction conditions were determined.Nineteen target products were synthesized in a yield of 83-90%.All products were characterized by IR,NMR and LC-MS spectroscopy.One of the compounds was characterized by single crystal X-ray diffraction.