Atsuko Nishiyama

Sesquiterpenes from Acorus calamus L.

Abstract Five new sesquiterpenes were isolated from Acorus calamus L., in addition to calameone (or calamendiol), the structure of which was revised, and their structures were established. Furthermore, chemical co-relation among these sesquiterpenes was carried out. In particular, the thermal isomerization of shyobunone (I), an elemene-type sesquiterpene, to preisocalamendiol (VI), a germacrone-type compound, should be noted.

Voltammetric and Coulometric Studies on Eugenol and Related Compounds

Abstract Anodic processes were studied for eugenol, isoeugenol and 2,6-dimethoxy-4-allylphenol by cyclic voltammetry at a glassy carbon electrode in methanol. Preparative electrolyses were also applied coulometrically to these phenols, followed by the separation and the determination of the structures of -e, -2e and -4e products. It was indicated that both radical and cationic reactions were controlled by the applied potentials, the solvent media and the substituents on the aromatic rings.

Oxidative dimerization of .ALPHA.-pyran.

Oxidative coupling of α-pyran (1) was examined. Oxidation of α-pyran (1) with manganic tris-(acetylacetonate) resulted in cleavage of the pyran skeleton to three diene dimers (5a, 5b and 6). On the other hand, treatment of α-pyran (1) with vanadium tetrachloride and anodic oxidation gave pyran dimers (7a_??_c and 8a, 8b), respectively.