Hiroaki Takayanagi

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 )

Simple and convenient synthesis of tertiary benzanilides using dichlorotriphenylphosphorane

Various tertiary benzanilide derivatives were effectively synthesized from substituted benzoic acid and N-monoalkylated aniline using dichlorotriphenylphosphorane in chloroform. Yields were generally high, even when an electron-withdrawing group substituted the aromatic ring of aniline, or when an electron-donating group substituted the aromatic ring of benzoic acid. Allyl, Boc, MPM and the Z group were unaffected under these conditions.

Pyripyropenes, novel ACAT inhibitors produced by Aspergillus fumigatus. III: Structure elucidation of pyripyropenes E to L

Eight new pyripyropenes, E to L, were isolated from the culture broth of Aspergillus fumigatus FO-1289-2501 selected as a higher producer by NTG mutation. Structural elucidation indicated that all the pyripyropenes have the same pyridino-alpha-pyrone sesquiterpene core as pyripyropenes A to D. Among them, pyripyropene L showed the most potent inhibition against acyl-CoA: cholesterol acyltransferase (ACAT) activity with an IC50 value of 0.27 microM in rat liver microsomes.

Convenient synthesis of 7' and 6'-bromo-D-tryptophan and their derivatives by enzymatic optical resolution using D-aminoacylase

Abstract Compounds 7′ and 6′-bromo- d -tryptophan ( 1 and 2 ) which are important derivatives for the synthesis of the chloropeptin and kistamycin A, respectively, were conveniently synthesized by optical resolution from N-acetyl-7′ and 6′-bromo- dl -tryptophan ((RS)-5 and (RS)-14 ) using d -aminoacylase.

Polymorphism of artemisinin from Artemisia annua

Abstract X-ray crystallography studies have confirmed the discovery of a new polymorphic artemisinin crystal belonging to the triclinic space group, P1. The physicochemical properties of the new polymorph have been compared with those of the previously known orthorhombic P2 1 2 1 2 1 crystal by microscopic examination, density measurements, differential scanning calorimetry, infrared spectroscopy and dissolution studies.

Thermal rearrangement of N-acetyl-N-nitrosoneuraminic acid derivative: Synthesis of 3-deoxy-D-Nonulosonic acid (KDN)

Abstract Thermal rearrangement of N -acetyl- N -nitrosoneuraminic acid derivative followed by deprotection gave 3-deoxy- D -nonulosonic acid (KDN).

Blazeispirol A, an unprecedented skeleton from the cultured mycelia of the fungus Agaricus blazei

Abstract Blazeispirol A, an unprecedented skeleton has been isolated from the cultured mycelia of Agaricus blazei(Agaricaceae). Its structure was elucidated to be the previously unknown spiro [4,10b-ethanonaphtho[1,2-b]pyran-2,2′-furan] skeleton which was established by extensive 1D and 2D NMR spectral data and X-ray analysis.

X-Ray crystal structure of herquline, a new biologically active piperazine from Penicillium herquei Fg-372

Herquline, a biologically active subtance from P. herquei, has been shown by X-ray analysis to have the structure (1).

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.

Synthesis and X-Ray Analysis of 1-Benzyl-6-chlorouracil

1-Benzyl-6-chlorouracil (3) was prepared by benzylation of 6-chlorouracil (2) which was obtained by alkaline hydrolysis of 2,4,6-trichloropyrimidine (1)