Discussion Of The Stereoselectivity Of Diels-Alder Reactions By ABEEM σπ Model

Under the conditions of light or heated, 1,4 addition reaction could happen between conjugated diene and dienophile, generating circular chemical compound. The reaction of this kind is called Diels-Alder reaction, which is discovered by 0. Diels and K. Alder. Along with the development of the science and technology, Intramolecular Diels-Alder reactions and Hetero-Diels-Alder reactions appear. They are important methods of synthesis of hexatomic ring and hexabasic heterocyclic compound. Because of the good regio- and stereoselectivity, Diels-Alder reaction has become the important tool of synthetic chemistry and significant object of theoretical study.So far, there is no extensive agreement among the scientific community on the factors governing the stereoselectivity for Diels-Alder reactions. In this paper, we studied the stereoselectivity of normal Diels-Alder reactions, Intramolecular Diels-Alder reaction and Hetero-Diels-Alder reaction by ABEEMσ π model. Combined with the Local Hard and Soft Acids and Bases Principle, we made reasonable explanation by calculating the charge distribution and local softness of atom regions. Compared with other methods, such as, Secondary Orbital Interaction (SOI), steric effects, transition state theory and so on, our method is more simple and predictive, and the results are in better agreement with experimental fact.