Masanobu Iguchi

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.

Biomimetic reactions of germacrenes

The biomimetic reactions of epoxygermacrene-D (1) with basic alumina afforded three new interesting compounds (4, 5, and 6), two of which (4 and 6) have the same carbon skeleton as that of periplanone-A (3), a sexual stimulant for the American cockroach. The remaining one (5) is a bicyclo[3.1.0]hexane derivative, from whch an axisonitrile-3 type compound (14) has been produced. Finally, preisocalamendiol (2) was also converted into 6.

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.

The Stereostructure of Acetylparabenzlactone and Its Conversion to a Lariciresinol-type Lactone

Acetylparabenzlactone (1), an acetylation product of (−)-parabenzlactone (2), has been newly isolated from Parabenzoin trilobum Nakai, and the stereostructures of these two piperolignanolides have also been elucidated. Furthermore, the chemical conversion of 1 to a lariciresinol-type lactone (3) has been carried out.

Chirality recognition by 1,1′-binaphthyl-2,2′-diyl phosphoryl chloride—determination of configuration of asymmetric carbon atom attached to the hydroxy methylene group

Abstract Chirality of the asymmetric carbon atom attached to the hydroxy methylene group can be determined with high sensitivity by derivation into the 1,1′-binaphthyl-2,2′-diyl phosphate [( R,S )-BNP ester]. Consistent result with the sign of the CD spectra and the chirality of the asymmetric carbon atom was obtained by the introduction of a novel sequence rule.

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.

Biogenetic model reactions of epoxygermacrone

Treatment of the epoxygermacrone (II) with 80% HCO2H, AlCl3, ButOK, or basic alumina afforded various cyclization products; in particular, (II) gave a cis-selinane sesquiterpene (IV) with 80% HCO2H.

Biogenetic model reactions of germacrone-type sesquiterpenes

Acid catalysed conversion of germacrone-type sesquiterpenes into cadinene-type compounds has been carried out by using 80% aq. AcOH or AlCl3 in dry ether, and Iµ-cadinene has been synthesized from preisocalamendiol in two steps.