本文用分子轨道理论计算表明在一定范围内,β-内酰胺环的锥度增加使活性增加并使环内的张力能和共轭能下降。在h=0.5～0.54×10~(-10)m之间有一个活性最大值。锥形结构造成亲核基团主要对环的β面进攻。这种亲核反应是一种轨道控制反应。在侧链结构相似时,羰基碳原子上正电荷越少,越有利于亲核进攻,从而活性越高。 In this paper, molecular orbital theory calculations show that within a certain range, β-lactam ring taper increase in activity and the ring tension and the conjugate energy can be reduced. There is an activity maximum between h = 0.5 ~ 0.54 × 10 ~ (-10) m. The pyramidal structure causes the nucleophilic groups to primarily attack the β surface of the ring. This nucleophilic reaction is a orbital control reaction. When the structure of the side chains is similar, the less the positive charge on the carbonyl carbon atom, the more favorable to the nucleophilic attack and the higher the activity.