Yaeko Konda

Absolute Configuration of Staurosporine By X-Ray Analysis

Abstract The stereostructure of staurosporine ( 1 ) was determined absolutely to be 2′ S , 3′ R , 4′ R , 6′ R -configurations by means of X-ray crystallographic analysis of 4′- N -methylstaurosporine methiodide ( 2 )

Carbazole alkaloids from Murraya koenigii

Two new alkaloids, 9-carbethoxy-3-methylcarbazole and 9-formyl-3-methylcarbazole, and a known metabolite, 3-methyl-carbazole were isolated from the roots of Murraya koenigii. All three compounds were identified by detailed spectral analyses including 2D NMR studies and their structures confirmed by synthesis. Of the two new metabolites, the 9-formyl compound displayed weak cytotoxicity against both mouse melanoma B16 and adriamycin-resistant P388 mouse leukemia cell lines.

Analysis of Ballpoint Pen Inks by Field Desorption Mass Spectrometry

Destructive identification of ballpoint pen ink was performed using field desorption mass spectrometry (FDMS) to determine the basic dyes in ballpoint pen ink. Seven different brands of black, blue, and red ballpoint pen inks (total: 21 samples) were examined in this study. A 1-mm section was cut from an ink line drawn on paper and used as the sample. Extraction was performed with methanol. Analysis of each extract by FDMS showed the molecular ion peak of each dye and the black, blue, and red inks were then classified into 6, 6, and 6 types, respectively, based on the ions detected. The results indicated that it was possible to distinguish between manufacturers of ballpoint pens. This analysis of ballpoint pen inks was found to be effective and the method was applied to the analysis of an actual forensic sample.

Identification of Pressure-Sensitive Adhesive Polypropylene Tape

Identification of colorless, transparent, pressure-sensitive adhesive polypropylene tape (PP tape) was performed using infrared absorption spectrometry (IR) and pyrolysis gas chromatography mass spectrometry (Py-GC/MS) to determine the pressure-sensitive adhesive. Twenty different products of colorless, transparent PP tapes were examined in this study, and the results of analysis of IR spectra and Py-GC/MS were classified into twelve groups. In addition, the tapes were classified into 14 groups on the basis of IR measurement of release agent present in the backside. The results indicate that colorless, transparent PP tapes can be distinguished in terms of manufacturer, thereby demonstrating that this method of identifying colorless, transparent PP tape is effective. Moreover, the method was applied to the analysis of an actual forensic sample.

Synthesis of 2-amino-2-deoxy-D-hexopyranosides from 4-O-trichloroacetimidyl-D-hex-2-enopyranoside by [3,3]-sigmatropic rearrangement

2-Amino-2-deoxysugars, D-mannosamine and D-altrosamine derivatives were synthesized together with D-idosamine and D-talosamine ones from a 2-deoxy-2-trichloroacetamido-hex-3-enopyranoside. This key intermediate was prepared by regio- and stereoselective [3,3]-sigmatropic rearrangement of 4-O-trichloroacetimidyl-hex-2-enopyranoside.

Macrocyclization by TTN oxidation for the synthesis of chloropeptin left-hand segment

Abstract Cyclic tripeptides containing a diphenylether bond of the Chloropeptin left-hand segment were synthesized with the use of TTN phenolic oxidation in high yield. They were found to exist as equilibrium mixtures of two stable conformers caused by a rotation of the amide bond in solution.

First total synthesis of Mer-N5075A and a diastereomeric mixture of α and β-MAPI, new HIV-I protease inhibitors from a species of Streptomyces

Abstract Mer-N5075A (1) and α-MAPI and β-MAPI (2 and 3) produced from a species of Streptomyces are new anomalous tetrapeptides having potential HIV-I protease inhibitory activity. The first total synthesis of 1 and a diastereomeric mixture of 2 and 3 was achieved simply by a route connecting two dipeptides. The synthetic method is applicable for synthesis of Mer-N5075A analogues, such as GE20372 A and B (4 and 5) and other chemically modified compounds. In addition, the inhibition of HIV-1 Protease and anti HIV activity by the compounds 1, a mixture of 2 and 3, and 24, 25, and 26 were described.

Neat Formic Acid: an Excellent N-Formylating Agent for Carbazoles, 3-Alkylindoles, Diphenylamine and Moderately Weak Nucleophilic Anilines

Abstract Neat formic acid alone efficiently N-formylates carbazoles, 3-alkylindoles, diphenylamine and even moderately weak nucleophilic anilines to furnish the corresponding N-formyl derivatives in 72--87% yields.

Hancokinol, a novel triterpene, from cynanchum hancokianum

Abstract Absolute stereochemistry of hancokinol, a novel triterpene, isolated from Cynanchum hancokianum , has been elucidated by means of spectroscopic and X-ray analyses.

First total synthesis of two new diglycosides, neohancosides A and B, from Cynanchum hancockianum

Abstract Neohancosides A (1) and B (2) are monoterpene diglycosides isolated from Cynanchum hancockianum , which is a Chinese folk medicine having antitumor activity. First total synthesis of 1 and 2 , (3 R )-linaloyl and (3 R )-8-hydroxylinaloyl 3- O - β -d-xylopyranosyl-(1 → 6)-β-d-glucopyranosides were achieved stereoselectively using fluoride 12b as a glycosyl donor. The asymmetry of C-3 in 1 and 2 was introduced efficiently by separating diasteremers of (3 R ), (3 S )-linaloyl and (3 R ), (3 S )-8-benzoyloxylinaloyl 3- O -2,3,4-tri- O -benzoyl-β-d-glucopyranoside, 19 and 21 and 20 and 22 , respectively. Absolute configurations of 1 and 2 were determined by enzymatic degradation of synthetic intermediates 33 and 34 .