- Chlorination of oximes with aqueous H2O2/HCl system: Facile synthesis of gem-chloronitroso- and gem-chloronitroalkanes, gem-chloronitroso- and gem-chloronitrocycloalkanes
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Chlorination of cyclic and linear ketone oximes with aqueous H 2O2/HCl in a two-phase dichloromethane-water system selectively affords gem-chloronitroso compounds in yields of up to 94%. One-pot oxidation of the resulting gem-chloronitroso compounds with peracetic acid, prepared in situ, gives gem-chloronitroalkanes and cycloalkanes in yields of up to 82%. The advantages of the method are that it is facile and environmentally benign and does not require gaseous chlorine. Georg Thieme Verlag Stuttgart.
- Terent'ev, Alexander O.,Krylov, Igor B.,Ogibin, Yuri N.,Nikishin, Gennady I.
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p. 3819 - 3824
(2008/02/09)
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- Motuporamines, anti-invasion and anti-angiogenic alkaloids from the marine sponge Xestospongia exigua (Kirkpatrick): Isolation, structure elucidation, analogue synthesis, and conformational analysis
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Extracts of the sponge Xestospongia exigua collected in Papua New Guinea were positive in a new assay for anti-invasion activity. Bioassay-guided fractionation led to the identification of the three known motuporamines A (1), B (2), and C (3) along with the new motuporamines D (4), E (5), and F (6) and a mixture of G, H, and I (15). Motuporamines A (1), B (2), and C (3) and the mixture of G, H, and I (15) were responsible for the anti-invasion activity of the crude extract. Motuporamine C (3) has also been found to be anti-angiogenic. A series of analogues of the motuporamines have been synthesized and evaluated for anti-invasive activity. These SAR results revealed that a saturated 15-membered cyclic amine fused to the natural motuporamine diamine side chain (13) represented the optimal structure for anti-invasive activity in this family. Single-crystal X-ray diffraction analysis of one of the analogues 20 showed that in the solid state its 16-membered macrocyclic amine fragment adopted the [4444] quadrangular conformation predicted by calculations to be the lowest energy conformation for the corresponding cycloalkane, cyclohexadecane. These data along with literature X-ray data and conformational analysis for derivatives of azacyclotridecane have been used as precedents for predicting the lowest energy ring conformations of other motuporamines. The SAR data from the natural and synthetic motuporamines have been combined with the conformational analyses to provide an outline of the functionality and shape required for activity in this family of alkaloids and to design a new analogue 49 that showed good anti-invasion activity.
- Williams, David E.,Craig, Kyle S.,Patrick, Brian,McHardy, Lianne M.,Van Soest, Rob,Roberge, Michel,Andersen, Raymond J.
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p. 245 - 258
(2007/10/03)
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