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Bunyathaworn P.,Natural Products and Organic Synthesis Research Unit NPOS | Boonananwong S.,Natural Products and Organic Synthesis Research Unit NPOS | Kongkathip B.,Natural Products and Organic Synthesis Research Unit NPOS | Kongkathip N.,Natural Products and Organic Synthesis Research Unit NPOS
Steroids | Year: 2010

A series of new polyoxygenated steroid derivatives with various steroid skeleton moieties were synthesized. Antitumor activity of the compounds against three tumor cell lines (Breast cancer MCF7, lung cancer NCI and oral cancer KB) were evaluated. Compounds with aromatic A ring of this series exhibited the most potent cytotoxicities in all tested cells. The absence of OH at C-16 or lack of cholesterol like side chain at C-20 in the steroid skeleton apparently result in decreased cytotoxicity. The compound became inactive when the side chain contains double bond at C-24-C-25. When hydroxyl group at C-3 was protected no cytotoxicities against MCF7 and NCI and considerable low cytotoxicity against KB cell lines were observed. © 2010 Elsevier Inc. All rights reserved. Source


Wichienukul P.,Natural Products and Organic Synthesis Research Unit NPOS | Akkarasamiyo S.,Natural Products and Organic Synthesis Research Unit NPOS | Kongkathip N.,Natural Products and Organic Synthesis Research Unit NPOS | Kongkathip B.,Natural Products and Organic Synthesis Research Unit NPOS
Tetrahedron Letters | Year: 2010

An efficient synthesis of the influenza neuraminidase inhibitor prodrug oseltamivir phosphate (Tamiflu) from cheap, commercially available d-ribose is described. The main features of this approach comprise a metal (Zn, In)-mediated domino reaction and ring-closing olefin metathesis (RCM) of the resultant functionalized dienes to produce the Tamiflu skeleton. The synthesis described in this Letter represents a new and efficient transformation of a shikimic acid derivative into a 1,2-diamino compound which involved oxidation of an alcohol followed by reductive amination, regioselective ring opening of an amino pentylidene ketal and stereospecific nucleophilic replacement of a triflate with an azide. © 2010 Elsevier Ltd. All rights reserved. Source

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