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Weak linear bilevel programming problems: existence of solutions via a penalty method 总被引:1,自引:0,他引:1
Abdelmalek Aboussoror Abdelatif Mansouri 《Journal of Mathematical Analysis and Applications》2005,304(1):399-408
We are concerned with a class of weak linear bilevel programs with nonunique lower level solutions. For such problems, we give via an exact penalty method an existence theorem of solutions. Then, we propose an algorithm. 相似文献
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A new superbasic reagent has been discovered by combining TMSCH2Li and LiDMAE in hexane. This reagent was found highly efficient for the C-2 lithiation of sensitive chloro- and fluoropyridines. The metallation occurred chemo- and regioselectively at 0 °C avoiding the nucleophilic addition or substrate degradation commonly obtained with other alkyllithiums even at lower temperatures. 相似文献
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The first enantioselective total synthesis of the originally assigned structure of lyngbouilloside aglycon has been achieved using a particularly flexible route featuring an acylketene macrolactonization of a tertiary methyl carbinol as the key step. Comparison of the C13 chemical shifts of our synthetic aglycon with the ones pertaining to natural lyngbouilloside and lyngbyaloside C resulted in a possible stereochemical reassignment of the C11 stereogenic center. 相似文献
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Prof. Dr. K. C. Nicolaou Dr. Philipp Heretsch Dr. Abdelatif ElMarrouni Christopher R. H. Hale Dr. Kiran K. Pulukuri Dr. Avinash K. Kudva Dr. Vivek Narayan Prof. Dr. K. Sandeep Prabhu 《Angewandte Chemie (International ed. in English)》2014,53(39):10443-10447
A catalytic asymmetric total synthesis of the potent and selective antileukemic Δ12‐prostaglandin J3 (Δ12‐PGJ3) is described. The convergent synthesis proceeded through intermediates 2 and 3 , formed enantioselectively from readily available starting materials and coupled through an aldol reaction followed by dehydration to afford stereoselectively the cyclopentenone alkylidene structural motif of the molecule. 相似文献
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CNN Pincer Ruthenium Catalysts for Hydrogenation and Transfer Hydrogenation of Ketones: Experimental and Computational Studies 下载免费PDF全文
Prof. Walter Baratta Dr. Salvatore Baldino Prof. Maria José Calhorda Dr. Paulo J. Costa Prof. Gennaro Esposito Dr. Eberhardt Herdtweck Dr. Santo Magnolia Dr. Carlo Mealli Dr. Abdelatif Messaoudi Dr. Sax A. Mason Prof. Luis F. Veiros 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13603-13617
Reaction of [RuCl(CNN)(dppb)] ( 1‐Cl ) (HCNN=2‐aminomethyl‐6‐(4‐methylphenyl)pyridine; dppb=Ph2P(CH2)4PPh2) with NaOCH2CF3 leads to the amine‐alkoxide [Ru(CNN)(OCH2CF3)(dppb)] ( 1‐OCH2CF3 ), whose neutron diffraction study reveals a short RuO ??? HN bond length. Treatment of 1‐Cl with NaOEt and EtOH affords the alkoxide [Ru(CNN)(OEt)(dppb)] ? (EtOH)n ( 1‐OEt?n EtOH ), which equilibrates with the hydride [RuH(CNN)(dppb)] ( 1‐H ) and acetaldehyde. Compound 1‐OEt?n EtOH reacts reversibly with H2 leading to 1‐H and EtOH through dihydrogen splitting. NMR spectroscopic studies on 1‐OEt?n EtOH and 1‐H reveal hydrogen bond interactions and exchange processes. The chloride 1‐Cl catalyzes the hydrogenation (5 atm of H2) of ketones to alcohols (turnover frequency (TOF) up to 6.5×104 h?1, 40 °C). DFT calculations were performed on the reaction of [RuH(CNN′)(dmpb)] ( 2‐H ) (HCNN′=2‐aminomethyl‐6‐(phenyl)pyridine; dmpb=Me2P(CH2)4PMe2) with acetone and with one molecule of 2‐propanol, in alcohol, with the alkoxide complex being the most stable species. In the first step, the Ru‐hydride transfers one hydrogen atom to the carbon of the ketone, whereas the second hydrogen transfer from NH2 is mediated by the alcohol and leads to the key “amide” intermediate. Regeneration of the hydride complex may occur by reaction with 2‐propanol or with H2; both pathways have low barriers and are alcohol assisted. 相似文献
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