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31.
Madan G. Barthakur 《Tetrahedron letters》2006,47(28):4925-4927
An efficient one-pot synthesis of substituted 4H-thiopyrans has been accomplished from a three-component reaction of α,β-unsaturated ketones, Lawesson’s reagent and alkynes under microwave irradiation. 相似文献
32.
α-取代氨基氟代苯基膦酸酯衍生物的合成、晶体结构与抗癌活性 总被引:4,自引:0,他引:4
利用席夫碱与亚磷酸酯反应, 合成了新型O,O'-二烷基-α-(6-甲氧苯并噻唑-2-基氨基)-4-氟苯基膦酸酯化合物, 结构经元素分析, IR, 1H NMR, 13C NMR和X单晶衍射确认. X单晶衍射测试结果表明: 化合物3d分子属于四面体晶系, 空间群I4(1)/a, a=2.1055(3) nm, b=2.1055(3) nm, c=2.0521(5) nm, α=90.00°, β=90.00°, γ=90.00°, V=0.9098(3) nm3,
Z=16, Dc=1.321 mg/m3, =0.250 mm-1, F(000)=3808. 化合物还存在着1个分子内氢键[N(2)—H(2)…O(1)]. 生物测定表明化合物3f在20 g/mL浓度下对PC3细胞的抑制率为84.3%. 相似文献
33.
Treatment of phenyl 2,3-O-cyclic ketene acetal- and 2,3-O-thionocarbonyl-1-thio-mannopyranosides with TMSOTf and MeOTf, respectively, gave the corresponding 2,3-O-cyclic dioxonium intermediates, which proceeded via 1→2 migration and concurrent glycosidation in the presence of alcohols to provide the corresponding 2-S-phenyl glycosides stereoselectively. While the former donors were too labile, the latter donors have proved superior for the present purpose. The X-ray crystallographic structures of phenyl 4-O-methyl-2,3-O-thiocarbonyl-1-thio-α-l-rhamnopyranoside (1), a typical donor for the present reaction, and its anomeric azide analogue (6), which could not undergo the present reaction under similar conditions, are provided. 相似文献
34.
The Diels-Alder reaction of enantiomerically pure (E)-γ-keto-α,β-unsaturated p-tolylsulphoxides 3 with cyclopentadiene give four easily separable diastereomers. The effect of several Lewis acids on the reaction was studied, finding a high endo selectivity with respect to the carbonyl group and moderate π-diastereoselectivity using BF3·Et2O as catalyst. The reactivity of compounds 3 as well as their endo selectivity are both higher than those observed for the corresponding (E)-3-sulfinylacrylates. 相似文献
35.
36.
N. Suryakiran 《Tetrahedron letters》2007,48(5):877-881
The synthesis of α-halo β-keto-sulfones using potassium halide and hydrogen peroxide as a chemoselective mono halogenation reagent and the synthesis of α,α-symmetrical and asymmetrical dihalo β-keto-sulfones and α-halo, α-alkyl and β-keto-sulfones is described. Base induced cleavage of α-halo β-keto-sulfones, α,α-dihalo β-keto-sulfones, and α-halo, α-alkyl β-keto-sulfones afforded the corresponding halomethyl sulfones, dihalomethyl sulfones and haloalkyl sulfones. 相似文献
37.
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39.
An unprecedented N-transacylation reaction on 2-acetamido-2-deoxy-α-d-glucopyranosides was disclosed in the presence of acyl chloride and DMAP under reflux in pyridine. 相似文献
40.
A simple and efficient one-step, regioselective, enzymatic glucosylation of arbutin by α-glucosidase
4-Hydroxyphenyl-β-isomaltoside has been synthesized by α-glucosidase assisted transglycosylation between arbutin as acceptor and sucrose as donor molecules, respectively. Optimum conditions for the transglucosylation reaction were 40 °C for 20 h with 10 mM arbutin and 1.5 M sucrose in a 100 mM sodium citrate/phosphate buffer at pH 5.0. The new glucoside was obtained in a 50% molar yield with respect to arbutin. 相似文献