Absolute stereostructure

Matsuda H, Morikawa T, Toguchida 1, Harima S, Yoshikawa M. (2002) Medicinal flowers. VI. Absolute stereostructures of two new flavanone glycosides and a phenylbutanoid glycoside from the flowers of Chrysanthemum indicum L. Their inhibitory activities for rat lens aldose reductase. Chem Pharm Bull 50 972-975. 

SCHEME 6. Richardson s proof of the absolute stereostructure of mycaminose in 1961 and his contribution to R.B. Woodward s final structure elucidation of magnamycin. 

ZO079 Yamahara, ]., S. Hatakeyama, K. Taniguchi, M. Kawamura, and M. Yoshikawa. Stomachic principles in ginger. II. Pungent and anti-ulcer effects of low polar constituents isolated from ginger, the dried rhizoma of Zingiber officinale Roscoe, cultivated in Taiwan. The absolute stereostructure of a new diarylheptanoid. Yakugaku Zasshi 1992 112(9) 645-655. 

Yoshikawa, M. et al.. Bioactive constituents of Chinese natural medicines. III. Absolute stereostructures of new dihydroflavonols, hovenitins I, II and III, isolated from Hoveniae Semen Sen Eructus, the seed and fruit of Hovenia dulcis Thumb. (Rhamnaceae) inhibitory effect on alcohol-induced muscular relaxation and hepatoprotective activity, Yakugaku Zasshi, 117, 108, 1997. 

Matsuda, H., T. Kageura, I. Toguchida, T. Murakami, A. Kishi, and M. Yoshikawa. 1999. Effects of sesquiterpenes and triterpenes from the rhizome of Alisma orientate on nitric oxide production in lipopolysaccharide-activated macrophages absolute stereostructures of alismaketones-B 23-acetate and -C 23 acetate. Bioorg. Med. Chem. Lett. 9 3081-3086. 

Halichlorine (1) (Fig. 11.1) is an alkaloid which was isolated from the marine sponge H. okadai Kadota (Kuramoto et ah, 1996). This compound was revealed to be a novel alkaloid containing an azaspiro[4.5]decane skeleton clarified by detailed spectroscopic analyses. The absolute stereostructure was confirmed by many synthetic studies (Arimoto et ah, 1998 Clive et ah, 2005 Liu et ah, 2009 Trauner et ah, 1999). Halichlorine was shown to inhibit the induction of vascular cell adhesion molecule-1 (VCAM-1) in cultured human umbilical vein endothelial cells. Drugs that block the inflammatory stimuli-induced expression of VCAM-1 may be useful for treating atherosclerosis, coronary artery diseases, angina, and noncardiovascular inflammatory diseases (Kock et ah, 1995). We introduce here the recent aspects of the biological and physiological activities of halichlorine. 

Fig. (2). Determination of the absolute stereostructure of broussonetine C (1) by the benzoate chirality method.

The yellow pigment halenaquinol sulfate (410) has been isolated from the Okinawan sponge Xestospongia sapra and is a pentacyclic hydroquinone [345]. The absolute stereochemistry was determined to be 6S by comparing the CD spectrum of a derivative with a theoretically calculated spectrum [346]. Theoretical calculation of CD spectra of halenaquinol sulfate (410) isolated from X. exigua and X. sapra determined that the absolute stereostructure was 12bS [347]. The pentacyclic compound, xestoquinol sulfate (411) has been isolated from an Okinawan collection of X. sapra and its structure was elucidated on the basis of spectroscopic data and a chemical conversion [348]. 

The absolute stereostructures of the hallucinogenic diterpenes Salvinorin A and B have been... 

Kitagawa I, Fukuda Y, Taniyama T, Yoshikawa M (1995) Chemical Studies on Crude Drug Processing. VEI. On the Constituents of Rehmanniae Radix. (2) Absolute Stereostructures of Rehmaglutin C and Glutinoside Isolated from Chinese Rehmanniae Radix, the Dried Root of Rehmannia glutinosa Libosch. Chem Pharm Bull 43 1096... 

Amagata T, Doi M, Ohta T, Minoura K, Numata A (1998) Absolute Stereostructures of Novel Cytotoxic Metabolites, Gymnastatins A-E, from a Gymnascella Species Separated from a Halichondria Sponge. J Chem Soc Perkin Trans 1 3585... 

Kitagawa, I., Kobayashi, M., Katori, T., Yamashita, M., Tanaka, J., Doi, M., and Ishida, T., Absolute stereostructure of swinholide A, a potent cytotoxic macrolide from the Okinawan marine sponge Theonella swihnoei, J. Am. Chem. Soc., 112, 3710, 1990. 

Along similar lines, we secured access to herbarumin II 21 and have also been able to prepare a comprehensive set of stereoisomers of pinolidoxin (13). Among them, compound 22 turned out to be identical to the natural product, thereby correcting the relative and absolute stereostructure of this herbicidal agent which had been misassigned in the original publications (11). 

The relationship between the absolute stereostructure and the CD S] characteristics was elucidated by calculation for F-2 and F-4 [30]. Althoug] calculated wavelengths of the maximum Cotton effects were not very acci the shapes of the spectra were nicely reproduced. 

The absolute stereostructures of halenaquinone (+)-l, halenaquinol (+)-2, halenaquinol sulfate (-i-)-3, xestoquinone (+)-4, and xestoquinol 62, novel pentacyclic marine natural products isolated from tropical marine sponges, were theoretically determined to be 12bS, respectively, on the basis of the calculation of the CD spectra of naphthalene-diene derivatives by the re-electron SCF-CI-DV MO method. These studies also clarified that the theoretical CD method was applicable to such complex natural products. 

It is well known that the absolute configuration of chiral compounds was first determined by the Bijvoet using X-ray crystallography [1]. In X-ray crystallography, since the anomalous dispersion effect of heavy atoms can be measured accurately under proper conditions, the absolute stereostructure obtained is unambiguous and reliable. In addition, the molecule can be projected as a three-dimensional structure, and, therefore, the method has been employed extensively. However,... 

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