62522-73-0Relevant academic research and scientific papers
Direct trifluoroacetylation across a trimethylsilyloxy system as a stereospecific, chemo- and regioselective approach to C3-vicinal halohydrins
Stamatov, Stephan D.,Stawinski, Jacek
, p. 439 - 442 (2007)
Trifluoroacetylation across the silyloxy system of 1-acyl-2-O- trimethylsilyl-3-haloglycerols with trifluoroacetic anhydride (TFAA) in the presence of a halide anion (e.g. Bu4NX; X = Cl, Br or I), followed by removal of the trifluoroacetyl tran
A One-Pot Reaction of α-Imino Rhodium Carbenoids and Halohydrins: Access to 2,6-Substituted Dihydro-2 H-1,4-oxazines
Comninos, Elena,Jones, Kieran D.,Miura, Tomoya,Moggach, Stephen A.,Murakami, Masahiro,Nutt, Michael J.,Sobolev, Alexandre N.,Stewart, Scott G.
supporting information, (2020/04/21)
Herein, we report a Rh(II)-catalyzed reaction between 1-tosyl-1,2,3-triazoles and halohydrins to provide 2,6-substituted 3,4-dihydro-2H-1,4-oxazines under basic conditions. The reaction is proposed to undergo a rhodium carbenoid 1,3-insertion into O-H followed by an annulation. The scope includes phenyl or alkenyl C4-substituted triazoles and a range of halohydrins using catalytic Rh2Oct4 and K2CO3. A synthesis of the antimicrobial natural product (±)-chelonin C is also reported using this novel methodology.
Environmental Polymer Degradation: Using the Distonic Radical Ion Approach to Study the Gas-Phase Reactions of Model Polyester Radicals
Taggert, Bethany I.,O'Hair, Richard A. J.,Wille, Uta
, p. 5290 - 5300 (2017/07/28)
A novel precursor to the distonic O- and C-centered radical cations Oxo+O? and Oxo+C? was designed and synthesized, which represents model systems for radicals produced during polyester degradation. The precursor is equipped with a nitrate functional group, which serves as a masked site for these alkoxyl and carbon radicals that are unleashed through collision-induced dissociation (CID). Oxo+O? and Oxo+C? feature a cyclic carboxonium ion as permanent charge tag to enable monitoring their ion-molecule reactions on the millisecond to second time scale in the ion trap of the mass spectrometer. The reactions of Oxo+O? and Oxo+C? with cyclohexene, cyclohexadiene, ethyl acetate, 1,1-dimethoxyethane, and 1,2-dimethoxyethane, which exhibit structural features present in both intact and defective polyesters, were explored through product and kinetic studies to identify "hot spots" for radical-induced damage in polyesters. All reactions with Oxo+O? were extremely fast and proceeded predominantly through HAT. Oxo+C? was about two orders of magnitude less reactive and did not noticeably damage aliphatic ester moieties through hydrogen abstraction on the time scale of our experiments. Radical addition to alkene π systems was identified as an important pathway for C-radicals, which needs to be included in polymer degradation mechanisms.
Regioselective and stereospecific opening of an oxirane system mediated by trifluoroacetic acid and halide anions. A new direct approach to C3-vicinal halohydrins
Stamatov, Stephan D.,Stawinski, Jacek
, p. 1887 - 1889 (2007/10/03)
Glycidol derivatives bearing ester, ether or silyl functionality upon treatment with trifluoroacetic acid (TFA) in the presence of a halide anion (e.g., Bu4NX; X = Cl, Br or I) at room temperature undergo regioselective and stereospecific openi
An Efficient Method for the Chemoselective Preparation of Benzoylated 1,2-Diols from Epoxides
Khalafi-Nezhad,Soltani Rad,Khoshnood
, p. 2552 - 2558 (2007/10/03)
A very efficient and highly regioselective ring-opening reaction of epoxides with benzoic acid and its derivatives in the presence of cat. amount of tetrabutylammonium bromide (TBAB) in anhydrous acetonitrile has been developed. This effective method is useful for the preparation of selectively protected diols as precursor for many organic syntheses such as those of acyclic nucleosides and other synthetic purposes. The advantages of this method are efficiency, selectivity, low cost, and the applicability in large-scale synthesis of β-benzoyloxyalkanols.
Solvent-free organic reactions on silica gel supports. Facile transformation of epoxides to β-halohydrins with lithium halides
Kotsuki, Hiyoshizo,Shimanouchi, Tomoyasu,Ohshima, Reiji,Fujiwara, Shunsuke
, p. 2709 - 2722 (2007/10/03)
The reaction of epoxides with lithium halides was efficiently promoted on the surface of silica gel in the absence of any solvent to give the corresponding β-halohydrins. The reactivity of lithium halides was shown to follow the order LiI > LiBr >> LiCl, and the reactivity of LiCl was dramatically increased by adding an equivalent amount of water to this system. On the other hand a similar reaction with α,β-epoxyketones produces the α-haloenone derivatives, presumably via halohydrin intermediates. The epoxide-opening reaction of (R)-(+)-styrene oxide was also investigated to clarify the stereochemical features of this reaction.
Bioactivation of 6,7-dimethyl-2,4-di-1-pyrrolidinyl-7H-pyrrolo[2,3- d]pyrimidine (U-89843) to reactive intermediates that bind covalently to macromolecules and produce genotoxicity
Zhao, Zhiyang,Koeplinger, Kenneth A.,Padbury, Guy E.,Hauer, Michael J.,Bundy, Gordon L.,Banitt, Lee S.,Schwartz, Theresa M.,Zimmermann, David C.,Harbach, Philip R.,Mayo, Judy K.,Aaron, C. Sidney
, p. 1230 - 1239 (2007/10/03)
U-89843 is a novel pyrrolo[2,3-d]pyrimidine antioxidant with prophylactic activity in animal models of lung inflammation. During preclinical safety evaluation, U-89843 was found to give a positive response in the in vitro unscheduled DNA synthesis (UDS) assay, an assay which measures DNA repair following chemically-induced DNA damage in metabolically competent rat hepatocytes. Incubation of [14C]U-89843 with liver microsomes resulted in covalent binding of radioactive material to macromolecules by a process that was NADPH-dependent. U-89843 has been shown to undergo C-6 methylhydroxylation to give U-97924, in rat both in vivo and in vitro, in a reaction catalyzed by cytochrome P450 2C11. Synthetical U-97924 is chemically reactive and undergoes dimerization in aqueous solution. The dimerization of U-97924 was significantly inhibited by addition of nucleophiles such as methanol, glutathione, and N-acetylcysteine. Characterization of the corresponding methanol, glutathione, and N-acetylcysteine adducts of U-97924 supported the hypothesis of a reaction pathway involving reactive iminium species formed via dehydration of U-97924. The metabolism-dependent irreversible covalent binding of radioactive material to liver microsomal protein and DNA also is dramatically reduced in the presence of reduced glutathione (GSH). A trifluoromethyl analog of U-89843 was prepared in an effort to block the corresponding metabolic hydroxylation pathway. This new compound (U-107634) was found to be negative in the in vitro UDS assay, and its metabolic susceptibility toward hydroxylation at the C-6 methyl group was eliminated. These observations suggest that the positive in vitro UDS results of U-89843 are mediated by the bioactivation of U-89843, leading to reactive electrophilic intermediates derived from the (hydroxymethyl)pyrrole metabolite U-97924.
