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91.
《Optimization》2012,61(5-6):353-360
In the paper an equivalence of Clarke, Dini, α(.)-subgradients and local α(.)-subgradients for strongly α(.)-paraconvex functions is proved 相似文献
92.
93.
V. A. Alfonsov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2637-2644
In this report, we present the application of Pudovik reaction in the synthesis of chiral organophosphorus compounds and shown this reaction to be a promising way to enantiopure aminophosphonic acid derivatives. Cyclization reactions are a new, most efficient strategy for stereoselective synthesis of α-aminophosphonates, namely an intramolecular type of interaction of the P(III) atom and an imino group. 相似文献
94.
Oleg G. Sinyashin Elvira S. Batyeva Oleg V. Ugryumov Ilyas S. Nizamov Olga A. Varnavskaya S. I. Vasyukov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):21-23
Abstract Novel ammonium salts of O,O-dialkyl dithiophosphoric acids were obtained by one-pot synthesis from white phosphorus, elemental sulfur, industrial alcohols or phenols, and amines. Long-chain S-alkyl O,O-dialkyldithiophosphonates were prepared by the reaction of red phosphorus with elemental sulfur, alcohols, and the cheap industrial fractions of С16–С18 and С20–С26 of higher α-olefins in the presence of Lewis acid catalyst. The dithiophosphates obtained possess the high anticorrosion activities toward mild steel. 相似文献
95.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5-6):591-604
Polymerization of methyl methacrylate (MMA) with diphenyl diselenide (DPDSE) in the presence of AIBN at 60°C was investigated. DPDSE was worked as a chain transfer agent (CTA). The chain transfer constant (Ctr) of DPDSE for MMA was estimated to be 1.43. On the other hand, DPDSE was functioned as a photoiniferter for the photopolymerization of MMA. In a limited range of conversion, both the polymer yield and number average of molecular weight ([Mbar]n) increased with the reaction time, and the [Mbar]n linearly increased with the yield. The terminal structure of poly(MMA) was investigated by the 77Se NMR spectrum based on Methyl α-phenylseleno isobutylate (MSEPI) as model compound of the ω-chain end of poly(MMA). Further, photopolymerization of poly (MMA) containing phenylseleno group at ω-chain end as a polymeric photoiniferter with MMA effectively afforded a poly (MMA) having higher molecular weight. 相似文献
96.
Three fluorescent probes were constructed by incorporating an α,β-unsaturated ketone to a coumarin fluorophore. The selective addition of sulfite to the alkene of TSP assisted by cetyltrimethyl ammonium bromide (CTAB) micelle can be visualized by dramatic color and ratiometric fluorescence changes. In CTAB–PBS system, the fluorescence intensity ratio at 465 nm and 592 nm (I465/I592) and the absorbance ratio at 390 nm and 470 nm (A390/A470) were linearly proportional to sulfite concentration in the range of 0.5–150 μM, and the detection limit was 0.2 μM. Good selectivity and competition of TSP1 towards sulfite over several anions and biological thiols were acquired. Probe TSP1 was used to detect sulfite in three realistic samples (mineral water, sugar and white wine) with good recovery. 相似文献
97.
Rudhramyna Gnaneshwar 《合成通讯》2013,43(7):885-890
Abstract Conjugate addition of a silyl ketene acetal [Me2C?C (OMe)OSiMe3] to α,β‐unsaturated lactones (namely, 5,6‐dihydro‐2H‐pyran‐2‐one, 2(5H)‐furanone as Michael acceptor) occurs efficiently at room temperature in the presence of a nucleophilic catalyst, tetra‐n‐butyl ammonium bibenzoate (TBABB), in THF as well as Lewis acid catalysts such as Yb(OTf)3 and I2 in CH2Cl2, giving the corresponding 1,4‐adducts in excellent yields. 相似文献
98.
The C1–8 fragment of autolytimycin was synthesized via a reliable 10-step route capable of delivering 41% overall yield at multi-gram scale. As a key step, a chelation-controlled isopropenylation of α-oxygenated aldehydes was established with a reagent combination of diisopropenylzinc, magnesium halide, and a dichloromethane/toluene mixed solvent. Cram-chelate isopropenylation products dominated for aldehydes with a small α-substituents, such as –OMe and –OBn groups, while the Felkin product could be obtained with a bulky –OTBS group. 相似文献
99.
A three-step synthesis of (R)-7-hydroxycarvone (1), which is anticipated to be a valuable building block for the versatile preparation of natural products, is described. Optimization of the reaction conditions for photooxygenation and migration of (S)-α-pinene 2, tetrapropylammonium perruthenate (TPAP) oxidation of the generated alcohol, and a subsequent ring-opening reaction in the presence of Cu(OTf)2 led to the synthesis of 1 with good reproducibility. The desired product 1 was thus obtained in 46% yield over three steps. 相似文献
100.
N,N-二甲基氨甲酰基三甲基硅烷与一系列N-甲基-N-甲氧甲基α-羰基酰胺在无水无氧、105℃的条件下反应,合成了不对称α-烃基-α-羟基丙二酰胺类化合物或不对称α-烃基-α-三甲基硅氧基丙二酰胺衍生物,收率71%~86%,其结构用元素分析、1H NMR、13C NMR和IR等方法进行了表征.通过研究反应的影响因素发现,反应底物α-羰基酰胺中与α-羰基直接相连的烃基的空间位阻是该加成反应的重要影响因素,而α-羰基直接相连的芳环上取代基的电子效应则主要影响反应完成的时间.并提出了可能的反应机理. 相似文献