摘要：In an earlier paper2) of this series, experimental evidence was presented that the methine base obtained by the Hofmann degradation of O-methylanhydrodemethyloxy-acanthine (III), a trilobine-type base derived from oxyacanthine (I, R=H), was identical with trilobine methyl methine or isotrilobine methyl methine. On this basis it was suggested that trilobine and isotrilobine are optical isomers, both having the common structure (III). In the present series of experiments, it was confirmed that although so far trilobine was considered to possess two N-CH3 groups, actually one of the two nitrogen atoms is present as N-CH3, and the other, as an NH group (see Table I). It follows, therefore, that isotrilobine should be represented by the structure of (IX, R1=R2=CH3), whereas trilobine by (IX, R1=H, R2=CH3 or R1=CH3, R2=H). Furthermore, it was suggested that the stereochemical arrangments about the two asymmetric centers in these bases are both of (-, +) type.
