Yoshiharu Okada

Development of chiral phosphine ligands bearing a carboxyl group and their application to catalytic asymmetric reaction

Abstract A new chiral phosphine ligand bearing a carboxyl group, 3-(diphenylphosphino)butanoic acid, was developed and used for palladium catalyzed asymmetric allylic alkylation of cyclic cis-allylic acetates such as 2-cyclopentenyl, 2-cyclohexenyl, and 2-cycloheptenyl acetate. These acetates reacted with triethyl sodiophosphonoacetate in the presence of the palladium catalyst with the ligand to give the corresponding alkylation products in good enantiomeric excesses.

Isolation and identification of flavonoids from Coreopsis lanceolata L. petals

The methanol extract of Coreopsis lanceolata L. petals was acid-hydrolysed, and 7,3′,4′-trihydroxy-8-methoxyflavanone (1) and 6,3′,4′-trihydroxy-7-methoxyaurone (leptosidin) (2) were successfully isolated. The structure of compound 1 is designated to flavanone based on X-ray crystallographic analysis and NMR spectroscopic analysis. Compound 1 showed high-antioxidant effects based on diphenylpicrylhydrazyl radical scavenging assay (94.3% scavenging rate) and superoxide dismutase-like activity assay (23.9% inhibition rate).

Synthesis of phosphine oxide-carboxylic acid esters bearing 9,10-dihydro-9,10-ethanoanthracene moiety

A bulky type of phosphine oxide-carboxylic acid bearing 9,10-dihydro-9,10-ethanoanthracene moiety was synthesized by the Diels-Alder reaction of 2-anthryldiphenylphosphine oxide and methyl acrylate, for which the structure was confirmed on the basis of 1 H NMR spectral data to be dimethyl 2-diphenylphosphinoyl-9,10-dihydro-9,10-ethanoanthracene-11,11- and 12,12-dicarboxylates.

Evaluation of the Fatty Acid Composition of the Seeds of Mangifera indica L. and Their Application

Mango (Mangifera indica L.), an edible fruit, is one of the main agricultural products in many tropical regions. Mango varieties differ in not only fruit shape but also aroma, which is an important characteristic. Although the fruit has many uses, the seeds are discarded as waste. Therefore, this study aimed to estimate the fatty acid content of seed oil of mangoes from different cultivation areas (Miyazaki, Japan, and Taiwan), and to evaluate their application in cosmetics. Five fatty acids were identified in the mango seed oil. Oleic acid and stearic acid were the principal components of mango seed oil obtained from Miyazaki (46.1% and 39.8%, respectively) and Taiwan (43.7% and 40.1%, respectively). As a cosmetic ingredient, mango seed oil showed good deodorizing effect on both 2-nonenal and isovaleric acid. The results indicated the potential applications of mango seed oil in the cosmetic industry.

Convenient Synthesis of 1-(Trimethylsilyl)- and 1-(Trimethylstannyl)vinylphosphonates

Abstract Dimethyl 1,1-bis(trimethylsilyl)methylphosphonate and dimethyl 1-(trimethylsilyl)-1-(trimethylstannyl)methylphosphonate were succeeded to react with aromatic aldehydes in the presence of methyl benzoate as additive to give the corresponding vinylphosphonates in moderate yields. GRAPHICAL ABSTRACT

Convenient Synthesis and Physiological Activities of Flavonoids in Coreopsis lanceolata L. Petals and Their Related Compounds

Chalcones, flavanones, and flavonols, including 8-methoxybutin isolated from Coreopsis lanceolata L. petals, were successfully synthesized with total yields of 2–59% from O-methylpyrogallols using the Horner–Wadsworth–Emmons reaction as a key reaction. Aurones, including leptosidin, were also successfully synthesized with 5–36% total yields using the Aldol condensation reaction as a key reaction. Each chalcone, flavanone, flavonol, and aurone with the 3,4-dihydroxy groups in the B-ring showed high antioxidant activity. Additionally, each of the chalcones, flavanones, flavonols, and aurones with the 2,4-dihydroxy groups in the B-ring showed an excellent whitening ability.

Convenient Synthesis of 1-(Trimethylsilyl)- and 1-(Trimethylstannyl)Vinylphosphonates and Their Synthetic Application

GRAPHICAL ABSTRACT Abstract Dimethyl 1,1-bis(trimethylsilyl)methylphosphonate was succeeded to react with aromatic aldehydes in the presence of methyl benzoate as additive to give the corresponding vinylphosphonates in moderate yields. Michael addition and subsequent Peterson olefination reaction of dimethyl (Z)-2-(3,4-methylenedioxyphenyl)-1-(trimethylsilyl)vinylphosphonate with 3,4,5-trimethoxyphenyllithium and crotonaldehyde afforded the corresponding (2E,4E)-1-(3,4,5-trimethoxyphenyl)-1-(3,4-methylenedioxyphenyl)-2-(dimethylphosphono)hexa-2,4-diene in 36% yield.

Synthesis of Chiral 3-( o -Diphenylphosphinophenyl)-Butanoic Acid and Its Palladium Complex Catalyzed Asymmetric Allylic Alkylation

We report on the synthesis of a novel type of chiral phosphine ligands bearing carboxyl group and have shown that the carboxyl group plays an important role in the asymmetric induction.1 We now report synthesis of chiral 3-(o-diphenylphosphinophenyl)butanoic acid and its palladium complex catalyzed asymmetric allylic alkylation. Reaction of (o-diphenylphosphino)acetophenone 1 with triethyl sodiophosphonoacetate 2 gave ethyl 3-(o-diphenylphosphinophenyl)-but-2enoate 3 in 89% yield. Alkaline hydrolysis of 3 and subsequent hydrogenation in the presence of Rh(PPh3)3Cl under H2 atmosphere