Diels-Alder反应是双键对共轭二烯的1,4加成,形成六节环化合物,所以又称4+2环加成反应。通式常写成: Z和Z’是—CHO,—COR,—COOH等吸电子基。实验证明,亲双烯试剂具有吸电子基,二烯分子存在供电子基时,反应较易进行。此反应具有协同反应的特征,故可用前线轨道理论加以讨论。二烯和亲双烯试剂分子都有HOMO(最高占据轨道)和LUMO(最低空轨道),彼此 The Diels-Alder reaction is the 1,4-addition of a double bond to a conjugated diene to form a six-membered ring compound, which is also known as a 4 + 2 cycloaddition reaction. Often written as: Z and Z ’are -CHO, -COR, -COOH and other electron-withdrawing groups. Experiments show that the dienophilic reagent has an electron-withdrawing group. When the diene molecule exists for the electron-donating group, the reaction is easy to carry out. This reaction has a synergistic reaction characteristics, it can be discussed using frontier orbital theory. Both diene and dienophile reagents have HOMO (highest occupied orbital) and LUMO (lowest empty orbital), each other