Tomomi Kinoshita

Chemical Profiling and Gene Expression Profiling during the Manufacturing Process of Taiwan Oolong Tea “Oriental Beauty”

Oriental Beauty, which is made from tea leaves infested by the tea green leafhopper (Jacobiasca formosana) in Taiwan, has a unique aroma like ripe fruits and honey. To determine what occurs in the tea leaves during the oolong tea manufacturing process, the gene expression profiles and the chemical profiles were investigated. Tea samples were prepared from Camellia sinensis var. sinensis cv. Chin-shin Dah-pang while the tea leaves were attacked by the insect. The main volatile compounds, such as linalool-oxides, benzyl alcohol, 2-phenylethanol, and 2,6-dimethylocta-3,7-diene-2,6-diol, increased during manufacture. The gene expression profiles during manufacture were analyzed by differential screening between fresh leaves and tea leaves of the first turn over. Many up-regulated transcripts were found to encode various proteins homologous to stress response proteins. Accordingly, the endogenous contents of abscisic acid and raffinose increased during manufacture. Thus the traditional manufacturing method is a unique process that utilizes plant defense responses to elevate the production of volatile compounds and other metabolites.

Syntheses and racemization via intermolecular prototropy of optically active alkyltropylium ions. A novel scale for the kinetic brønsted basicity of organic solvents

Abstract Optically active (1-methylpropyl)tropylium ion ( 1 ) and (2-bicyclo[2.2.2]octyl)tropylium ion ( 2 ) have been synthesized. The first-order rate constants of racemization via intermolecular prototropy of 1 provide a novel scale for the kinetic Bronsted basicity of organic solvents.

Stereomutation of endo-2-phenyl-endo-6-tropyliobicyclo[2.2.2]octane to the exo-6-tropylio isomer. Steric repulsion between the phenyl and tropylium rings showing intramolecular charge-transfer

Abstract endo-2-Phenyl-endo-6-tropyliobicyclo[2.2.2]octane 2 exhibits intramolecular charge-transfer (CT) interaction, but rearranges to exo-6-tropylio isomer 3 in acetonitrile with the 2/3 ratio of ca.0.07 at equilibrium. This ratio indicates that the steric repulsion between the face-to-face phenyl and tropylium rings at ca.2.5A is estimated to be at least ca.1.6kcal/mol.

The effects of t-butyl substituents on the thermodynamic stability of the cyclopentadienide ion

Abstract The effects have been quantified of t-butyl substituents on the thermodynamic stability of cyclopentadienide ions with no, one, two, and three t-butyl groups, 1 − , 2 − , 3 − and 4 − , respectively. The stability estimated from oxidation potential values decreases in the order 1 − (+ 0.04 V) > 2 − (− 0.16 V) > 3 − (− 0.28 V) > 4 − (−0.45 V). The stability evaluated from p K a values decreases in the same sequence ( 1H : 18.2, 2H : 19.9, 3H : 21.9, and 4H : 25.0 in DMSO). The t-butyl substituent reduces the thermodynamic stability of cyclopentadienide ion in step with increasing number of substituents and this is most probably due to a decrease in solvation and an increase in inductive effect in the carbanion.

Poly-linked cyclopentadienide ions: II. Synthesis and properties of the tetracyclopentadienylmethane tetraanion

The title tetraanion (1d) has been synthesized via ferrocenyl derivatives. Dynamic 1H NMR spectroscopy indicates the most stable conformation of 1d and the barrier to internal rotation of cyclopentadienide rings.

Poly-linked cyclopentadienide ions. 1. Synthesis and properties of tris(cyclopentadienyl)methane trianion

Abstract Tris(cyclopentadienyl)methane trianion has been synthesized via triferrocenylmethyl derivatives. The dynamic 1H NMR spectroscopy indicates the barrier to internal rotation of cyclopentadienido rings.

Gas-phase acidities of cycloheptatrienes: effects of alkyl groups on the stability of carbanions

The gas-phase acidities of 7-alkyl substituted cycloheptatrienes have been determined by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry using a proton-transfer equilibrium method, ΔG0acid (kJ mol−1): methyl 1520.0, ethyl 1516.7, n-propyl acid 1513.3, i-propyl 1512.1, n-butyl 1510.4. The effect of alkyl groups on the acidity of cycloheptatriene is linearly correlated with the polarizability parameters (σα) of substituents, giving a ρα of–55.3 (kJ σ−1α unit). The magnitude of pa is half of that for RCH3 and is significantly larger than that for the fluorene series. These results suggest that the extent of the charge-delocalization in a carbanion plays an important role in determining the susceptibility of the stability of the carbanion to substituent polarizability effects. In addition, comparison of ρ values of acidities of a series of elemental hydrides shows that the numerical value of ρα decreases in the order, C > O ≈ N > S, and that the change of ρα is related to the stability of the respective parent anions (R = H) rather than the atomic electronegativity at the deprotonation center.

The acetolysis of 2,2-dimethyl-1-(p-methoxyphenyl)propyl chloride.—The first example of SN2C+-type solvolysis under typical solvolysis conditions in the absence of additives

The acetolysis of 2,2-dimethyl-1-(p-methoxyphenyl)propyl chloride has been found to be the first example of the SN2C+-type solvolysis under typical SN1 solvolysis reaction conditions, on the basis of its kinetic, stereochemical, and isotopic features.

Quantitative treatment of rate enhancement due to F-strain in the solvolysis of (Z)-2-ethylidene-1-adamantyl mesylate and halides

Abstract The Z:E ratios for the trifluoroethanolysis at 25°C of the title mesylate, chloride, bromide, and iodide are 126, 1020, 2230, and 9680, respectively, whose logarithms are linearly correlated with MM2 steric energies and Hanschs Es values.

Retentive solvolysis. Part 14. The methanol-perturbed phenolysis of optically active 2,2-dimethyl-1-(p-methoxyphenyl)propyl p-nitrobenzoate. The mechanism and the structure of the second ion-pair intermediate

The polarimetric and titrimetric rate constants have been measured for the solvolysis of optically active 2,2-dimethyl-1-(p-methoxyphenyl)propyl p-nitrobenzoate (ROPNB) in phenol–methanol (97:3 w/w). The salt effect of added (Bun)4NClO4 indicates that all products are derived from the second ion-pair intermediate (Int-2), not from the first (Int-1), as for the phenolysis in pure phenol. Competitive solvolysis, i.e., methanol-perturbed phenolysis, produced partially inverted ROPh, o- and p-RC6H4OH, and partially retained ROMe, whereas phenolysis in pure phenol afforded partially retained ROPh and o- and p-RC6H4OH. This stereochemical outcome demonstrates that Int-2, the key intermediate of these phenolyses, has an ion-pair structure shielded by a phenol molecule from the rear-side. The absolute configurations and the maximum rotations of all products have been determined.