Nobuyuki Mase

Aerobic copper/TEMPO-catalyzed oxidation of primary alcohols to aldehydes using a microbubble strategy to increase gas concentration in liquid phase reactions

An efficient method for the synthesis of aldehydes was achieved by using air-microbubble techniques in aerobic copper/TEMPO-catalyzed oxidation of primary alcohols. Use of air-microbubbles to improve gas absorption into liquid phase is proven to be highly beneficial for gas/liquid phase reactions.

Enantioselective alkylation using a new C3 symmetric amine-based chiral phase-transfer catalyst

Abstract A new C 3 symmetric amine-based chiral phase-transfer catalyst was synthesized. Application of the chiral PTC (1 mol%) in the alkylation of a tert -butyl glycinate-benzophenone Schiff base under mild reaction conditions provided an alkylated product with up to 58% enantiomeric excess.

Organocatalytic Knoevenagel condensations by means of carbamic acid ammonium salts.

The Knoevenagel condensation between an active methylene compound and an aromatic aldehyde with a carbamic acid ammonium salt used as an organocatalyst gave the desired Knoevenagel products in up to 98% yield. The reaction occurred at rt and in a short reaction time under solvent-free conditions. In addition, no extraction, wash, or chromatography steps were needed to obtain a high-purity Knoevenagel product.

Characterisation of odorant compounds and their biochemical formation in green tea with a low temperature storage process

We produced low temperature (15 °C) processed green tea (LTPGT) with higher aroma contents than normal green tea (Sencha). Normal temperature processed green tea (NTPGT), involved storing at 25 °C, and Sencha had no storing process. Sensory evaluation showed LTPGT had higher levels of floral and sweet odorants than NTPGT and Sencha. Aroma extract dilution analysis and gas chromatography-mass spectrometry-olfactometry indicated LTPGT had 12 aroma compounds with high factor dilution values (FD). Amongst LTPGTs 12 compounds, indole, jasmine lactone, cis-jasmone, coumarin, and methyl epijasmonate contributed to floral, fruity and sweet characters. In particular, indole increased initially, peaking at 16 h, then gradually decreased. Feeding experiments suggested [(15)N]indole and [(15)N]oxygenated indoles (OX-indoles) were produced from [(15)N]anthranilic acid. We proposed the increase in indole was due to transformation of anthranilic acid during the 16 h storage and the subsequent decline in indole level was due to its conversion to OX-indoles.

Novel strategic lipase-catalyzed asymmetrization of 1,3-propanediacetate in supercritical carbon dioxide

Abstract In lipase-catalyzed asymmetrization of 1,3-propanediacetate no enantioselectivity was observed in conventional organic solvents, whereas in supercritical carbon dioxide (scCO2) enantioselectivities were observed up to 50% ee, which probably arose from a conformational changing of lipase at the active site due to a transformation of the amino group of lysine into carbamic acid.

Organocatalytic α-hydroxymethylation of cyclopentanone with aqueous formaldehyde: Easy access to chiral δ-lactones

Optically active lactones are important synthons in perfume and aroma manufacturing. Therefore, developments of efficient asymmetric syntheses are desired. Organocatalytic asymmetric alpha-hydroxymethylations of cyclopentanone with aqueous formaldehyde have been developed, to furnish the corresponding alpha-(hydroxymethyl)cyclopentanone with high enantioselectivity. Further chemical transformation of alpha-(hydroxymethyl)cyclopentanone gave the key intermediate for jasmine lactone, which is widely found in fruits and flowers.

Determination of volatile compounds in four commercial samples of japanese green algae using solid phase microextraction gas chromatography mass spectrometry

Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings.

Reverse enantioselectivity in the lipase-catalyzed desymmetrization of prochiral 2-carbamoylmethyl-1,3-propanediol derivatives

Abstract Enantioselective acetylation of 2-carbamoylmethyl-1,3-propanediol derivatives was catalyzed effectively by lipase PS to give monoacetates with high enantioselectivity: The enantioselectivity depended on the 2-carbamoylmethyl groups. The reaction of N -monoalkylcarbamoylmethyl-1,3-propanediol afforded the monoacetate with the ( S )-configuration, whereas N , N -dialkylcarbamoylmethyl-1,3-propanediol gave the monoacetate with the ( R )-configuration.

First synthesis of (R)-(−)-5-hydroxy-3-methyl-3-pyrrolin-2-one (jatropham) by lipase-catalyzed kinetic resolution

Abstract Jatropham, ( R )-(−)-5-hydroxy-3-methyl-3-pyrrolin-2-one, is synthesized in three steps from citraconic anhydride. Highly regioselective reduction of citraconimide gives racemic jatropham in high yield. Kinetic resolution of racemic jatropham using lipase is also described.

Convenient Synthesis of Pulchella-lactam, a CD45 Protein Tyrosine Phosphatase Inhibitor from the Marine Fungus Corollospora pulchella, and Its Related Compounds

Convenient synthesis of pulchellalactam (1a) and its related compounds was accomplished. Total yields of (Z)-pulchellalactam and (E)-pulchellalactam were 55% for 5 steps and 43% for 8 steps from commercially available andinexpensive citraconic anhydride, respectively.