- Monomeric Cinchona Alkaloid-Based Catalysts for Highly Enantioselective Bromolactonisation of Alkynes
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The cinchona alkaloid dimer (DHQD)2PHAL has been shown to be a broadly applicable catalyst for asymmetric halogenations. However, this catalyst does not have to be dimeric and a class of monomeric quinidine and quinine-derived catalysts was prepared, often showing superior selectivity in bromolactonisations of terminal alkynoic acids. Mechanistic investigations show that these organocatalysts act as host molecules that can bind carboxylic acid-based substrates as guests with substantial binding constants. Based on these findings, it is proposed that this class of catalysts is bifunctional in nature activating the halogenating agent as well as the nucleophile in electrophilic halogenation reactions.
- Wilking, Michael,Daniliuc, Constantin G.,Hennecke, Ulrich
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p. 18601 - 18607
(2016/12/16)
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- Base-induced cyclization of derivatives of bispropargylated acetic acid to m -toluic acid
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A base-induced cyclization reaction of 1,1-bispropargyls has been examined. Alkali treatment of 2,2-bispropynyl acetic acid derivatives in aqueous ethanol mostly provided 3-methylbenzoic acid. Investigations on substituent effects indicate the requirement of an electron-withdrawing group causing CH acidity and the center of the dipropargylic structure. Besides, an intramolecular hydrogen transfer causing the rearrangement of one terminal alkyne into a corresponding allene appears to be essential. Despite an unsatisfying conversion yield of below 40%, the reaction is interesting due to the mild cyclization conditions.
- Ali, Tammar Hussein,Heidelberg, Thorsten,Hussen, Rusnah Syahila Duali
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p. 1361 - 1364
(2015/06/16)
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- Oxidative rearrangement of malondialdehyde: Substrate scope and mechanistic insights
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A novel oxidative rearrangement of malondialdehyde was described. Under the effect of H2O2, malondialdehyde smoothly transferred to carboxylic acid with C-C bond cleavage in good to excellent yields. Mechanistic studies showed that this reaction proceeded via the formation of a 1,2-dioxolane intermediate, followed by concert C-C, O-O, C-H bond cleavage and a hydride shift.
- Yu, Xin,Liu, Zheng,Xia, Zilei,Shen, Zhigao,Pan, Xixian,Zhang, Hui,Xie, Weiqing
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p. 53397 - 53401
(2015/01/16)
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- POLYMER CONJUGATE FOR DELIVERY OF A BIOACTIVE AGENT
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The present invention relates in general to polymer-bioactive agent conjugates for delivering a bioactive agent to a subject. The polymer-bioactive agent conjugates contain triazole moieties in the polymer backbone and a bioactive moiety selected from prostaglandin analogues, β-blockers and mixtures thereof. The present invention also relates to methods for preparing the polymer conjugates using click chemical reactions, to monomer-bioactive agent conjugates suitable for preparing the polymer conjugates, and to pharmaceutical products comprising the polymer conjugates for the treatment of glaucoma.
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Paragraph 416
(2014/09/29)
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- BINDING-SITE MODIFIED LECTINS AND USES THEREOF
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In one aspect, the disclosure provides cross-linked materials that include multivalent lectins with at least two binding sites for glucose, wherein the lectins include at least one covalently linked affinity ligand which is capable of competing with gluco
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Page/Page column 99
(2010/08/09)
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- 2-AMINOINDANS AS SELECTIVE DOPAMINE D3 LIGANDS
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Compounds and their pharmaceutically acceptable salts suitable for treating central nervous system disorders associated with the dopamine D3 receptor activity of Formula I: wherein R 1 and R 2 are independently H, C 1-8 alkyl or C 1-8 alkylAryl; X is CH 2 R. sub.3 or NHSO 2 R 4 ; Y is hydrogen, CH 2 R 3, NHSO. sub. 2 R 4, CONR 1 R 2, SO 2 NR 1 R 2, SO 2 CH. sub.3, halogen, OSO 2 CF 3, SCH 3 or OCH 3 ; R 3 is NHSO 2 R 4, SO 2 R 4, CONR 1 R 2 or Aryl; and R. sub.4 is NR 1 R 2, C 1-C 8 alkyl, Aryl or C 1-C. sub.8 alkylAryl.
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- SELECTIVITY OF NUCLEOPHILIC ADDITION TO AND SUBSTITUTION AT ISOTHIOCYANATOCARBONYL GROUP. REACTIONS OF 4-PENTINOYL- AND 2-(2-PROPINYL)-4-PENTINOYL ISOTHIOCYANATE WITH AMINES AND METHANOL
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4-Pentinoyl isothiocyanate reacts with primary and secondary amines by either nucleophilic addition to N=C=S group to yield the corresponding thioureas, or a nucleophilic substitution at the carbonyl group to give 4-pentinoic acid amides.The less nucleophilic diphenylamine reacts selectively to afford the product of nucleophilic addition only. 2-(2-Propinyl)-4-pentinoyl isothiocyanate, having a sterically hindered carbonyl group, furnished with primary amines a mixture of amides and thioureas, whereas the bulkier secondary amines react selectively to form thioureasonly.Both isothiocyanates afford with methanol as a nucleophile axclusively the corresponding O-methyl monothiocarbamates.
- Kutschy, Peter,Kristian, Pavol,Dzurilla, Milan,Koscik, Dusan,Nadaskay, Robert
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p. 995 - 1005
(2007/10/02)
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- Intramolecular Reactions of N-Nitrenes with Alkynes: Conformational Anchoring in Spiro-fused 2H-Azirines
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Oxidations of N-aminoquinazolin-4(3H)-ones (7)-(11) with lead tetra-acetate in dichloromethane results in the intramolecular addition of the N-nitrene to the triple bond in each case and azirines (20), (22), (17), (23), and (30), respectively, are isolated with (31) identified as a by-product in the oxidation of compound (11).An X-ray crystal structure determination on compound (17) reveals a remarkable deformation of bond angles at the spiro centre and this feature appears to be common to all azirines.The five membered ring in the azirines (17), (20), (22), and (23) has the envelope conformation (26) and the six-membered ring in the azirine (30) has the twist-boat conformation (32): a possible explanation for this conformational anchoring is offered.
- Atkinson, Robert S.,Grimshire, Michael J.
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p. 1215 - 1224
(2007/10/02)
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