41029-45-2Relevant academic research and scientific papers
A unified approach to quinolizinium cations and related systems by ring-closing metathesis
Nunez, Ana,Cuadro, Ana M.,Alvarez-Builla, Julio,Vaquero, Juan J.
, p. 4125 - 4127 (2004)
(Chemical Equation Presented) The first example of an olefin ring-closing metathesis reaction on cationic heteroaromatic systems is described. Dihydroquinolizinium cations and a variety of related cationic systems are synthesized in an efficient approach from N-alkenyl α-vinyl azinium salts using Grubbs' catalysts.
Modification of C-seco taxoids through ring tethering and substituent replacement leading to effective agents against tumor drug resistance mediated by βIII-Tubulin and P-glycoprotein (P-gp) overexpressions
Tang, Yong,Rodríguez-Salarichs, Javier,Zhao, Yu,Cai, Pei,Estévez-Gallego, Juan,Balaguer-Pérez, Francisco,Redondo Horcajo, Mariano,Lucena-Agell, Daniel,Barasoain, Isabel,Díaz, J. Fernando,Fang, Wei-Shuo
, p. 488 - 503 (2017)
In our efforts to improve the efficacy of taxane-based microtubule (MT) stabilizing agents against tumor drug resistance mediated by multiple mechanisms, two clinically relevant factors were focused: i.e., P-glycoprotein and βIII-tubulin overexpression. Based on the structure of C-seco taxoid 1 m (IDN5390) which was believed to more selectively interact with βIII-tubulin than paclitaxel, we prepared a series of C-seco taxoids bearing various 7,9-O-linkages and/or different substituents at C2 and C3′ positions. Some of them exhibited much more potent binding affinity to MTs and cytotoxicity than their C-seco parent compounds in drug resistant cells with both mechanisms. SAR analysis indicated that C2 modifications significantly enhanced MT binding but brought ambiguous influence to cytotoxicity whereas 7,9-linkage and C3′ modifications enhance cytotoxicity more efficiently than improve MT binding. These observations illustrate a better translation of molecular binding effect to cellular activity by C ring closure and C3′ modification than C2 modification in C-seco taxoids.
Synthesis of tertiary alkyl fluorides and chlorides by site-selective nucleophilic ring-opening reaction of α-aryl azetidinium salts
Kawai, Kohei,Tayama, Eiji
, p. 39607 - 39618 (2021/12/27)
Site-selective nucleophilic ring-opening reactions of 2-arylazetidine-2-carboxylic acid ester-derived tetraalkyl ammonium salts2with tetrabutylammonium halides (Bu4NX) to give tertiary alkyl halides are successfully demonstrated. For example, a nucleophilic ring-opening reaction of 2-(o-tolyl) derivative2awith 1.2 equivalents of tetrabutylammonium fluoride (Bu4NF) in THF at 60 °C preferentially proceeded at a more substituted carbon atom (2-position) compared to a less-substituted carbon atom (4-position) and affordedtert-butyl 4-(dimethylamino)-2-fluoro-2-(o-tolyl)butanoate3aain 71% yield as the corresponding tertiary alkyl fluoride. This result was applied to synthesize optically active organofluorine compounds starting from commercially available (R)-1-phenylethylamine.
Ring-Strain Effects in Base-Induced Sommelet–Hauser Rearrangement: Application to Successive Stereocontrolled Transformations
Tayama, Eiji,Watanabe, Kazutoshi,Matano, Yoshihiro
, p. 3631 - 3641 (2016/07/29)
The base-induced Sommelet–Hauser (S–H) rearrangement of azetidine-2-carboxylic acid ester-derived ammonium salts into 2-aryl-substituted derivatives was demonstrated. The ring-strain of four-membered N-heterocycles enables efficient generation of the desired ylide intermediate and enhances the rate of the S–H rearrangement. The asymmetric version of the rearrangement was characterized by excellent levels of successive chirality transmissions. The regio- and stereo-controlled nucleophilic ring opening of the rearrangement products produced quaternary α-aryl amino acid esters with excellent enantiopurities.
Conformationally restricted pyrrolidines by intramolecular [2+2] photocycloaddition reactions
Fort, Diego A.,Woltering, Thomas J.,Nettekoven, Matthias,Knust, Henner,Bach, Thorsten
supporting information, p. 2989 - 2991 (2013/05/09)
Intramolecular [2+2] photocycloaddition reactions of diversely substituted N-Boc protected 4-(allylaminomethyl)-2(5H)-furanones resulted in rigid products (53-75%) with three spatially defined positions for further functionalisation. The Royal Society of Chemistry.
Enantioselective intramolecular [2+2] photocycloaddition reactions of 4-substituted coumarins catalyzed by a chiral Lewis acid
Brimioulle, Richard,Guo, Hao,Bach, Thorsten
supporting information; experimental part, p. 7552 - 7560 (2012/07/30)
Eight coumarins, which carry a terminal alkene tethered by a CH 2XCH2 group to their 4-position (X=CH2, CMe2, O, S, NBoc, NZ, NTs, NBn), were synthesized in overall yields of 51-80 %. Starting materials for the syntheses were either commercially available 4-hydroxycoumarin or 4-formylcoumarin. The intramolecular [2+2] photocycloaddition of these coumarins gave diastereoselectively products with a tetracyclic 3,3a,4,4a-tetrahydro-1H-cyclopenta[2,3]cyclobuta[1,2-c]chromen-5(2H) -one skeleton. Direct irradiation at λ=300 nm in dichloromethane (c=10 mM) led to product formation in good yields for most substrates, presumably via a singlet excited state intermediate. Due to the low coumarin absorption at λ >350 nm the photocycloaddition was slow upon irradiation at λ=366 nm. Addition of a chiral oxazaborolidine-based Lewis acid (50 mol %) increased the reaction rate at λ=366 nm and induced a significant enantioselectivity in the [2+2] photocycloaddition. Six out of eight coumarin substrates (X=CH2, CMe2, O, NBoc, NZ, NTs) gave the respective products in yields of 72-96 % and with 74-90 % enantiomeric excess (ee) upon irradiation in dichloromethane (c=20 mM) at -75 °C. The Lewis acid presumably acts by coordination to the coumarin carbonyl oxygen atom, which leads to a bathochromic shift (redshift) of the UV absorption and which increases the singlet state lifetime. A second electrostatic interaction of the hydrogen atom at C3 with the oxygen atom of the oxazaborolidine is likely. Copyright
Synthesis and polymerization of glycidyl ethers
-
Page/Page column 6-7, (2012/12/13)
The method of preparing novel allyl ethers. Novel glycidyl ethers and their preparation. Polyfunctional poly(glycidyl ethers) their methods of preparation. Novel polyurethanes based on the polyfunctional glycidyl ethers and their method of preparation.
Intramolecular hydride addition to pyridinium salts: New routes to enantiopure dihydropyridones
Donohoe, Timothy J.,Connolly, Matthew J.,Rathi, Akshat H.,Walton, Lesley
supporting information; experimental part, p. 2074 - 2077 (2011/06/22)
The transformation of a simple disubstituted pyridine into a pyridinium ion bearing an exocyclic hydroxyl group, protected as a silane, enabled an intramolecular hydride transfer reaction to take place when fluoride was used as a nucleophile. The addition
Regioselective nucleophilic addition to pyridinium salts: A new route to substituted dihydropyridones
Donohoe, Timothy J.,Connolly, Matthew J.,Walton, Lesley
supporting information; experimental part, p. 5562 - 5565 (2010/02/28)
"Chemical Equation Presented" The regioselective addition of nucleophiles to pyridinium salts generates an intermediate enol-ether, which can be hydrolyzed in situ to provide a range of dihydropyridones. Certain Grignards have shown inherent differences i
28-EPIRAPALOGS
-
Page 50, (2010/02/06)
Methods and materials involving 28-epirapamycin analogs are disclosed.
