Jun'ichi Katakawa

2-(2,3-Naphthalimino)ethyl trifluoromethanesulphonate as a highly reactive ultraviolet and fluorescent labelling agent for the liquid chromatographic determination of carboxylic acids

Abstract The use of 2-(2,3-naphthalimino)ethyl trifluoromethanesulphonate in the preparation of 2-(2,3-naphthalimino)ethyl ester derivatives of carboxylic acids for ultraviolet and fluorescent detection in high-performance liquid chromatography is described. The reagent is easily synthesized in two steps from 2,3-naphthalenedi-carboxylic anhydride and is stable at least for 6 months at room temperature. Reactions of carboxylate potassium salts (10 −5 M ) with a 10-fold equivalent excess amount of the reagent proceed to completion within 10 min in acetonitrile at room temperature in the presence of 18-crown-6 as a catalyst. The derivatization procedure with this reagent has been applied succesfully to the determination of some carboxylic acids in mouse brain. The detection limits (signal-to-noise ratio = 3) with ultraviolet and fluorescent detection are 100 fmol (at 259 nm) and 4 fmol (λ ex = 259 nm, λ em = 394 nm), respectively.

Synthesis of an amaryllidaceae alkaloid, (±)-hippeastrine

Synthese stereoselective a partir du [benzodioxole-1,3yl-5]-5 methoxycarbonylamino-6 cyclohexene-3acetate de methyle

Crystal and molecular structure of 10,20-epoxy-grayanotoxin-II

The photooxidation with HgO in benzene and the hydrolysis with 2%-KOH in methanol of the grayanotoxin (GTX) derivative (4) gave a 10,20-epoxy-grayanotoxin-II(5). The crystal structure of (5) has been determined by X-ray diffraction at room temperature. The crystal is monoclinic, space group P21, with a = 14.248(10) Å, b = 6.670(10) Å, c = 9.990(10) Å, α = 105.507(8)°, V = 914.9(2) Å3, Z = 2. The structure was solved by direct methods and refined by full-matrix least squares methods to a final R1 = 0.046 (wR2 = 0.0833) for 1161 independent reflections. The molecule has a pentacyclic structure consisting of two five-membered, one six-membered, one seven-membered, and one three-membered rings. The three-membered ring is connected with the seven-membered ring by spiro-type bond.

Crystal and molecular structure of a new diterpenyl glycoside from Pteris cretica L.

The crystal and molecular structure of a new diterpenyl glycoside, Ptr-1, is presented. The crystal is triclinic, space group P1, with a = 8.2414(8) Å, b = 13.0826(9) Å, c = 6.1427(8) Å, α = 95.345(9)°, β = 111.589(8)°, γ = 96.726(7)°, V = 604.9(1) Å3, Z = 1. The structure was solved by direct methods and refined by full-matrix least-squares methods to a final R = 0.049 (Rw = 0.099) for 1872 independent reflections. The molecular structure is based on a glycopyranosyl group and a tetracyclic group. The glycopyranosyl group is β-D-allopyranosyl group. The tetracyclic group consists of 1 five-membered and 3 six-membered rings.

New stereoselective synthesis of 9-methyl-cis-decalin derivatives by double Michael reaction of 3,5-dimethyl-4-methylenecyclohex-2-enone and dimethyl 3-oxoglutarate; X-ray crystal and molecular structure of two of the products

Double Michael reaction of 3-methyl-, 2,3-dimethyl-, and 3,5-dimethyl-4-methylenecyclohex-2-enone with dimethyl 3-oxoglutarate in dimethyl sulphoxide in the presence of potassium fluoride as a catalyst gave stereoselectively 9-methyl-, 1,9-dimethyl-, and 4,9-dimethyl-6,8-dimethoxycarbonyl-2,7-dioxo-cis-decalin, respectively.