Takaaki Aratani

Sesquiterpenes of six Porella species (hepaticae)

Abstract The distribution in six Porella species of drimane-, aromadendrane- and pinguisane-type sesquiterpenes and norsesquiterpenes is described. The sharp pungent substance of P. gracillissima , P. fauriei and P. macroloba is (+)-tadeonal.

New substituted bibenzyls of Frullania brittoniae subsp. Truncatifolia

Abstract The two dihydrostilbenes, Brittonin A and Brittonin B, have been isolated from Frullania brittoniae subsp. truncatifolia (F. F. muscicola ). They were identified as 3,4,5,3′,4′,5′-hexamethoxybibenzyl and 3,4,5,3′-tetra- methoxy-4′,5′,-methylenedioxybibenzyl respectively.

Lasiocarpin A, B and C, three novel phenolic triglycerides from Populus lasiocarpa

Abstract The lipophilic excretion of winter buds of many species of Populus contains a variety of flavonoid aglycones. In Populus lasiocarpa , however, neither flavonoids nor free phenolic acids have been detected. Instead we found 3 novel phenolic triglycerides as major components of bud exudate in this species. Their structures have been shown by spectral and chemical evidence to be 1,3-di- p -coumaryl-2-acetyl glycerol, 1- p -coumaryl-3-caffeyl-2-acetyl glycerol, or its antipode, and 1,3-di-caffeyl-2-acetyl glycerol.

The Reaction of Monoketones with Manganese(III) Acetate

When acetone, ethyl methyl ketone (EMK), and cyclohexanone were heated with manganese(III) acetate dihydrate in a mixed solvent of glacial acetic acid and acetic anhydride at 100 °C, acetoxy ketones were obtained as common products. Furthermore, ketone dimers (1,4-diketones) were obtained from acetone and cyclohexanone, which also gave 1,2,3,4-tetrahydrodibenzofuran. When mixtures of these ketones and 1-hexene were heated with the oxidant, saturated and unsaturated ketones and γ-acetoxy ketones were obtained as common products, and 2-propylchromene was obtained as a new product from the cyclohexanone-1-hexene mixture. The formation courses of these reaction products are discussed.

Sacculatal and isosacculatal, two new exceptional diterpenedials from the liverwort, trichocoleopsis sacculata

Abstract The stereostructures of the two new exceptional diterpene dialdehydes from the liverwort, Trichocoleopsis sacculata : sacculatal (1), responsible for the characteristic pungent taste, and isosacculatal (2) have been determined by the spectral evidence and by comparison with polygodial (3), isopolygodial (4), and drimanediol (6) of known relative configurations.

Application of direct spectrophotometry to the analysis of chromatograms : II. Effects of sorbent layer on the bathochromic shift of the absorption maximum of a compound in a thin layer

Abstract Fundamental studies on the analysis of thin-layer chromatograms by direct spectrophotometry are described. Transmittance is more than seven times more sensitive than reflectance. The bathochromic shift of the principal absorption maximum of l -carvone in a silica gel thin layer is discussed.

Application of direct spectrophotometry to the analysis of chromatograms : III. A new micro thin-layer chromatoplate and its application to the analysis of tocopherols

Abstract A method for the more efficient utilization of thin-layer chromatoplates is described. Dipping quartz microscope slides into 46% hydrogen fluoride solution is used to etch plates on which very thin layers (in general above 20 μm thick) can then be spread, and the layers are thin enough to separate very small amounts of materials in a short time. Furthermore, thin layers of sorbent prepared in hollows etched on the quartz plates are protected from mechanical damage and are stable without the need for special storage conditions.