25 ラクタム環コンホメーションとCotton効果の関係

抄録

A rule about the n-π* Cotton effect of seven-membered lactam ring (lactam rule) was investigated from ORD and CD spectra of A-azatetrahydro-α-santonins and A-azasteroids derived from their oximes by the Beckmann Rearrangement. From this rule, the seven-membered lactam was classified into two types A and B. Type A should have the negative and type B should have the positive Cotton effect. Further applications of the lactam rule to four-membered lactam, azetidinones, and five-membered lactam, camphorolactams and pyrrolidones are discussed. This rule was applied to simple seven-membered lactams, (-)-menthone lactam, N-methyl-(-)-menthone lactam, and N-methyl-A-azatetrahydro-α-santonins. Conformational equilibrium of these compound was discussed on the basis of the lactam rule.