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Dominic Thibeault Jean Legault Charles Gauthier Serge Lavoie Jimmy Bouchard 《合成通讯》2013,43(2):213-221
22(17 → 28)abeo-Lupene derivatives 5a and 6a were obtained after the acid-catalyzed E-ring expansion of 3-acetylbetulin (1a). Glycosylation of these dehydrated triterpenoids using Schmidt's trichloroacetimidate sugar donors in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) provided the new anhydrobetulin saponins 7b–7e in which the terminal olefin C-20(29) isomerizes to form a C-19 tetrasubstituted alkene. The preliminary cytotoxic evaluation revealed that saponins 7b–7d exhibited a moderate cytotoxic activity against A549, DLD-1, and WS1 human cell lines with IC50 ranging from 22 to 49 μM. 相似文献
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We have developed an efficient catalytic enantioselective hydrogenation of pyridine derivatives. Enhanced reactivity was possible by an optimization of the electronic properties of the catalyst through ligand modification. This methodology shows the particular reactivity of N-iminopyridinium ylides that provides access to substituted piperidines in good enantiomeric excesses. 相似文献
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Getia M. Korkotadze T. Moshiashvili G. Tabatadze N. Legault J. Mshvildadze V. 《Chemistry of Natural Compounds》2022,58(5):959-961
Chemistry of Natural Compounds - 相似文献
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A new labdane diterpene from the flowers of Solidago canadensis 总被引:1,自引:0,他引:1
Bradette-Hébert ME Legault J Lavoie S Pichette A 《Chemical & pharmaceutical bulletin》2008,56(1):82-84
A new labdane diterpene, 9alpha,16xi-dihydroxy-6-oxo-7,13-labdadien-15,16-olide (solicanolide, 1) and six known compounds identified as quercetin (2), 3-O-caffeoylquinic acid (3, neochlorogenic acid), 5-O-caffeoylquinic acid (4, chlorogenic acid), 4,5-di-O-caffeoylquinic acid (5), 3,5-di-O-caffeoylquinic acid (6) and 3,4-di-O-caffeoylquinic acid (7) were isolated from the flowers of Solidago canadensis. To our knowledge, compound 7 was isolated for the first time in S. canadensis. This work describes the isolation of compounds 1-7 and the structure elucidation of a new compound identified as compound 1. Solicanolide (1) showed cytotoxic activity against A549 (IC(50): 13+/-2 microM), DLD-1 (IC(50): 26+/-2 microM) and WS1 (IC(50): 17+/-1 microM) cell lines. 相似文献
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This paper investigates the transmission loss of symmetric and asymmetric laminate composite panels periodically reinforced by composite stiffeners. A comprehensive model based on periodic structure theory is developed. First order shear deformation theory is used and the coupling of the in-plane motion of the panel with its out-of-plane motion is taken into account. Stiffeners interact with the panel through three forces (two in-plane, one out-of-plane) and a torsion moment. Three types of cross sections are investigated for the composite stiffeners: I-shaped, C-shaped, and omega-shaped cross-sections. The model is validated numerically by comparison with the finite element/boundary element method. Experimental validations are also conducted. In both cases, excellent agreement is obtained. Numerical results show that the in-plane coupling effect is increased by increasing the panel thickness and the stiffener's eccentricity. The in-plane coupling effect is also found to increase with frequency. 相似文献
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Barrette J Bellwied R Braun-Munzinger P Cleland WE David G Duek E Fatyga M Fox D Gavron A Greene SV Hall J Hemmick TK Heifetz R Herman M Herrmann N Hogue RW Ingold G Jayananda K Kraus D Lissauer D Llope WJ Legault A Ludlam T Majka R Makowiecki D Mark SK Mitchell JT Muthuswamy M O'Brien E Olsen L Polychronakos V Rawool-Sullivan M Rotondo F Sandweiss J Shivakumar B Simon J Sonnadara U Sullivan JP Stachel J Sunier J Takai H Throwe T Van Hecke H Waters L Woody C Wolf K Wolfe D 《Physical review letters》1990,64(11):1219-1222
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Hao C March RE Croley TR Chen S Legault MG Yang P 《Rapid communications in mass spectrometry : RCM》2002,16(6):591-599
Electrospray ionization combined with tandem mass spectrometry has been applied to a study of dopamine and 6-hydroxydopamine, an important neurotransmitter and a well-known neurotoxin, respectively. Both protonated and deprotonated molecules were observed for the two compounds. Upon collision-induced dissociation of protonated and deprotonated 6-hydroxydopamine molecules, the number of fragmentation pathways observed was greater than that observed with protonated and deprotonated dopamine molecules; the greater proclivity to fragment of the former is due to the 6-substituted hydroxyl group, which is para to the 3-OH group and ortho to the CH2CH2NH2 group. Furthermore, 6-hydroxydopamine showed a greater propensity to oxidize than did dopamine when sample solutions were kept uncovered in the air for 24 h prior to mass spectrometric examination. Radical structures of the four main oxidation products of 6-hydroxydopamine have been suggested on the basis of their product ion mass spectra; one or more of these oxidation products may be responsible for the cytotoxic property of 6-hydroxydopamine. 相似文献
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An efficient two-step synthesis of O-(2,4-dinitrophenyl)hydroxylamine is described along with a comparison of its aminating efficiency with O-mesitylenesulfonylhydroxylamine (MSH). It was used in an expedient N-amination/benzoylation procedure involving various substituted pyridines, leading to polysubstituted N-benzoyliminopyridinium ylides, and the scope of its amination power was studied. 相似文献