Hiroo Ueda

An Efficient Synthetic Method for (±)-Malyngolide and Its Optical Resolution

A convenient synthetic method for (±)-malyngolide (1), an antibiotic from the marine bluegreen alga Lyngbya majuscula GOMONT, is described. The compound (±)-1 was synthesized from 2-methylglutaric ...

Synthesis of β-Ketosulfoxides by the Condensation of Aliphatic Dicarboxylic Acid Esters with Methyl Sulfinyl Carbanion

The synthetic method of β-ketosulfoxides from aliphatic dicarboxylic acid esters, especially low molecular esters, has been extensively studied. Methyl sebacate, methyl azelate, methyl suberate, methyl pimerate and methyl adipate were allowed to react with methyl sulfinyl carbanion and afforded to the corresponding bis-β-ketosulfoxides. On the other hand, methyl glutarate and methyl α-alkyl glutarate gave the cyclic ketosulfoxides. The structural elucidation of the cyclic ketosulfoxides could be substantiated by chemical evidences and spectroscopic data. The mechanisms for the reaction are also discussed

Studies on the Reduction of Terpenes with Sodium in Aqueous Ammonia: Part XIII. On the Reduction of p-Mentha-1,3-dien-7-al

The reduction of p-mentha-1,3-dien-7-al (II) with sodium in aqueous ammonia afforded trans- and cis-p-menthan-7-ol via 1-p-menthen-7-al (phellandral) and trans- and cis-p-menthan-7-al, respectively, in which the trans forms were obtained predominantly due to the stereoelectronic requirement.

Studies on Menthol Derivatives:Part I. Synthesis of (-)-Menthyl Carbinol

(–)-Menthyl carbinol (1-(R)-methyl-3-(R)-hydroxymethyl-4-(S)-isopropylcyclohexane) (4) was prepared stereospecifically in good yield by treatment of formaldehyde with the Grignard reagent from (–)-menthyl chloride (2), which was prepared from (–)-menthol-(1-(R)-methyl-3-(R)-hydroxy-4-(S)-isopropylcyclohexane) (1) by chlorination using the Lucas reagent (HCl+ZnCl2). The configuration of 4 was assigned by the chemical method.

Syntheses of Terpenes by the Condensation of Aliphatic Compounds: Part II. Self-Condensation of Mesityloxide and Structures of Isomeric Isoxylitones

Treatment of mesityloxide with basic condensing agents resulted in formation of isoxylitones-A, B, C and D and isophorone. These compounds were purely isolated and assigned their structures from spectroscopic and chemical evidences. Isoxylitone-A and isoxylitone-B were conformers of 1-acetyl-2, 4, 6, 6-tetramethyl-1, 3-cyclohexadiene separated by the rotational barrier of acetyl group and interconversional barrier of cyclohexadiene ring. Isoxylitone-C was 4-isopropenyl-1, 5, 5-trimethyl-1-cyclohexen-3-one. Isoxylitone-D was 5, 5-dimethyl-3-(1-isobutenyl)-2-cyclohexen-1-one.

Syntheses of Terpenes by the Condensation of Aliphatic Compounds: Part I. Synthesis of Piperitenone by the Condensation of Mesityloxide with 4-Diethylaminobutanone-(2)

The condensation of mesityloxide with 4-diethylaminobutanone-(2) in the presence of potassium t-butoxide gave the products containing piperitenone together with isoxylitones, which were identified by gas chromatography and chemical methods. The effects of the combination of condensing agent, solvent, molar ratio of reagents and reaction temperature on the components in the condensation products were studied. It was found that piperitenone was able to obtain in an yield of 51% on the basis of 4-diethylaminobutanone-(2) by the use of Triton-B as a condensing agent. Also piperitenone can be isolated from the condensation products by the treatment with semicarbazide.

Studies on Kojic Acid and its Related γ-Pyrone Compounds: Part VII. The Alkylation of Kojic Acid and Pyromeconic Acid through their Mannich Base (Synthesis of Maltol-(1))Part VIII. Synthesis of Comenic Acid from Kojic Acid (Synthesis of Maltol (2))

The Mannich reaction of kojic acid in both acidic and basic media was studied. Mono-Mannich derivatives (substitution at position 6) were obtained; the reactivity in basic medium was found to be somewhat greater than in acidic medium. Reduction of the Mannich derivatives with zinc dust and acetic acid gave a 6-methyl kojic acid (6-methyl-5-hydroxy-2-hydroxymethyl-γ-pyrone).Mono-Mannich base of pyromeconic acid was also prepared in a manner similar to that of kojic acid. From this Mannich base, maltol (2-methyl-3-hydroxy-γ-pyrone) was obtained by the reduction with zinc dust and acetic acid.

3-Octanone as a Principal Component of an European Mentha arvensis L.:Studies on the Essential Oils of the Interspecific Hybrids in the Genus Mentha , Part IV.

Sir: It has been well established that Mentha arvensis L. var. piperascens MAL. (Japanese mint) contains (-) menthol predominantly. However, we have as yet very little information as to the chemical components of the essential oil of Mentha arvensis L., which is wildly distributed over Europe and called corn-mint. This investigation was undertaken to examine the components of the European Mentha arvensis oil. The seed materials used in our experiments were sent from Hortus Botanicus Antwerpen, Belgium, and cultivated in Okayama University, Japan. Chromosome number of European M. arvensis was established to be 2n=72, and that of Japanese M. arvensis, 2n=96 in our previous report1). The essential oils obtained from the strains of European origin have the following properties:

Studies on the Reduction of Terpenes with Sodium in Aqueous-ammonia:Part IV. On the Reduction of (+)-Pulegone

In regard of the reduction of (+)-pulegone with sodium in aqueous-ammonia, application of infra-red analyses and chemical methods revealed the product to be composed of 75% (−)-menthol and 25% (+)-isomenthol.

Studies on the Reduction of Terpenes with Sodium in Aqueous-ammonia:Part V. Syntheses of (-)-Isopulegol and (+)-Neo-isopulegol

(−)-Isopulegol and (+)-neo-isopulegol were isolated by a partial esterification of isopulegol mixture, obtained by the hydrolysis of the condensation product of (+)-citronellal with acetic anhydride. From the infrared spectra and optical rotation, it has been shown that isopulegol synthesized from (+)-citronellal mainly consists of (−)-isopulegol and (+)-neo-isopulegol in approximately equal amounts, but the presence of other isomers is negligible.