22 Tricyclic Diterpene(Aromatic C-Ring)系のConformation

抄録

(I). Preferred Conformation of Dehydroabietic Acid(Cis A/B Ring System) Type Compound. Recently there has been an interesting discussion on whether the preferred conformation of a cis ring-fused system is of the steroid or nonsteroid type. In this paper, the conformation of cis 17-norditerpene (15) is discussed in comparison with that of cis 12-methyl compound (24). Analysis of their NMR, IR spectra and reactions leads to conclude that the steroid type conformation of 12-methyl series is preferred to the nonsteroid-type conformation having the 1,3 diaxial nonbonding interaction between the 12- and 1-methyl and, conversely, nonsteroid type conformation is preferred in the 17-nor-compound where the 12-proton is only present. (II). Preferred Conformation of 10 Oxy-podocarpic Acid Type Compound. Conformation of 10β- and 10α-oxy deoxypodocarpic acid derivatives and the corresponding lactones is discussed by their NMR and IR spectrum analysis. The NMR analysis is performed especially on the ABX type proton system as observed between 9-methylene and 10-methine protons.