455-01-6Relevant academic research and scientific papers
Anti-Markovnikov alkene oxidation by metal-oxo–mediated enzyme catalysis
Hammer, Stephan C.,Kubik, Grzegorz,Watkins, Ella,Huang, Shan,Minges, Hannah,Arnold, Frances H.
, p. 215 - 218 (2017/10/19)
Catalytic anti-Markovnikov oxidation of alkene feedstocks could simplify synthetic routes to many important molecules and solve a long-standing challenge in chemistry. Here we report the engineering of a cytochrome P450 enzyme by directed evolution to catalyze metal-oxo–mediated anti-Markovnikov oxidation of styrenes with high efficiency. The enzyme uses dioxygen as the terminal oxidant and achieves selectivity for anti-Markovnikov oxidation over the kinetically favored alkene epoxidation by trapping high-energy intermediates and catalyzing an oxo transfer, including an enantioselective 1,2-hydride migration. The anti-Markovnikov oxygenase can be combined with other catalysts in synthetic metabolic pathways to access a variety of challenging anti-Markovnikov functionalization reactions.
Antiproliferative activity and SARs of caffeic acid esters with mono-substituted phenylethanols moiety
Xie, Jin,Yang, Fengzhi,Zhang, Man,Lam, Celine,Qiao, Yixue,Xiao, Jia,Zhang, Dongdong,Ge, Yuxuan,Fu, Lei,Xie, Dongsheng
, p. 131 - 134 (2016/12/27)
A series of CAPE derivatives with mono-substituted phenylethanols moiety were synthesized and evaluated by MTT assay on growth of 4 human cancer cell lines (Hela, DU-145, MCF-7 and ECA-109). The substituent effects on the antiproliferative activity were systematically investigated for the first time. It was found that electron-donating and hydrophobic substituents at 2′-position of phenylethanol moiety could significantly enhance CAPE's antiproliferative activity. 2′-Propoxyl derivative, as a novel caffeic acid ester, exhibited exquisite potency (IC50?=?0.4?±?0.02 & 0.6?±?0.03?μM against Hela and DU-145 respectively).
Markovnikov-Selective, Activator-Free Iron-Catalyzed Vinylarene Hydroboration
Macnair, Alistair J.,Millet, Clément R. P.,Nichol, Gary S.,Ironmonger, Alan,Thomas, Stephen P.
, p. 7217 - 7221 (2016/10/14)
Two series of structurally related alkoxy-tethered NHC iron(II) complexes have been developed as catalysts for the regioselective hydroboration of alkenes. Significantly, Markonikov-selective alkene hydroboration with HBpin has been controllably achieved using an iron catalyst (11 examples, 35-90% isolated yield) with up to 37:1 branched:linear selectivity. anti-Markovnikov-selective alkene hydroboration was also achieved using HBcat and modification of the ligand backbone (6 examples, 44-71% yields). In both cases, ligand design has enabled activator-free low-oxidation-state iron catalysis.
A General, Practical Triethylborane-Catalyzed Reduction of Carbonyl Functions to Alcohols
Peng, Dongjie,Zhang, Mintao,Huang, Zheng
supporting information, p. 14737 - 14741 (2015/10/19)
A combination of the abundant and low-cost triethylborane and sodium alkoxide generates a highly efficient catalyst for reduction of esters, as well as ketones and aldehydes, to alcohols using an inexpensive hydrosilane under mild conditions. The catalyst system exhibits excellent chemoselectivity and a high level of functional group tolerance. Mechanistic studies revealed a resting state of sodium triethylalkoxylborate that is the product of the reaction of BEt3 with sodium alkoxide. This borate species reacts with hydrosilane to form NaBEt3H, which rapidly reduces esters.
DEPROTECTION OF BOC-PROTECTED COMPOUNDS
-
Page/Page column 2, (2010/12/29)
Organic compounds having t-butyl ester or BOC carbonate protecting groups are effectively deprotected by heating in a fluorinated alcohol solution.
A novel practical cleavage of tert-butyl esters and carbonates using fluorinated alcohols
Choy, Jason,Jaime-Figueroa, Saul,Lara-Jaime, Teresa
experimental part, p. 2244 - 2246 (2010/05/18)
Thermolytic cleavage of t-butyl esters and t-butyl carbonates was accomplished using TFE (2,2,2-trifluoroethanol) or HFIP (hexafluoroisopropanol) as solvent. Thus, a practical method to cleanly convert t-butyl esters and carbonates into the corresponding carboxylic acids, decarboxylated products, or alcohols in nearly quantitative yields was developed. The product is recovered by a simple solvent evaporation. The practicality of this methodology was demonstrated on alkyl, aryl, and heteroaromatic esters.
Regioselective hydroboration-oxidation and -amination of fluoro-substituted styrenes
Ramachandran, P. Veeraraghavan,Madhi, Sateesh,O'Donnell, Martin J.
, p. 1252 - 1255 (2008/09/20)
Hydroboration of fluorinated styrenes with common hydroborating agents results in polymerization. However, regioselective hydroboration has been achieved by utilizing iodoborane-dimethyl sulfide. A series of fluorinated β-phenethyl alcohols and amines were synthesized via this methodology.
ARTEMISININ-BASED PEROXIDE COMPOUNDS AS BROAD SPECTRUM ANTI-INFECTIVE AGENTS
-
Page/Page column 45-46, (2010/02/07)
Described herein is the synthesis, bioassay results and utility of new C-9 and C-10 substituted artemisinin derivatives with easily functionalizable groups attached to the artemisinin skeleton through carbon chain or heteroatoms. Described also is the demonstration of this class of compounds for their broad-spectrum anti-parasitic activity. Certain of these analogs possess noticeable cytotoxicity deliberately focused on treatment of cancerous diseases.
Structure-activity relationships of the antimalarial agent artemisinin. 7. Direct modification of (+)-artemisinin and in vivo antimalarial screening of new, potential preclinical antimalarial candidates
Avery, Mitchell A.,Alvim-Gaston, Maria,Vroman, Jeffrey A.,Wu, Baogen,Ager, Arba,Peters, Wallace,Robinson, Brian L.,Charman, William
, p. 4321 - 4335 (2007/10/03)
On the basis of earlier reported quantitative structure-activity relationship studies, a series of 9β-16-(arylalkyl)-10-deoxoartemisinins were proposed for synthesis. Several of the new compounds 7 and 10-14 were synthesized employing the key synthetic intermediate 23. In a second approach, the natural product (+)-artemisinic acid was utilized as an acceptor for conjugate addition, and the resultant homologated acids were subjected to singlet oxygenation and acid treatment to provide artemisinin analogues. Under a new approach, we developed a one step reaction for the interconversion of artemisinin 1 into artemisitene 22 that did not employ selenium-based reagents and found that 2-arylethyliodides would undergo facile radical-induced conjugate addition to the exomethylene lactone of 22 in good yield. The lactone carbonyls were removed sequentially by diisobutylaluminum hydride reduction followed directly by a second reduction (BF3-etherate/Et3SiH) to afford the desired corresponding pyrans. Six additional halogen-substituted aromatic side chains were installed via 22 furnishing the bioassay candidates 15-20. The analogues were examined for in vitro antimalarial activity in the W-2 and D-6 clones of Plasmodium falciparum and were additionally tested in vivo in Plasmodium berghei- and/or Plasmodium yoelii-infected mice. Several of the compounds emerged as highly potent orally active candidates without obvious toxicity. Of these, two were chosen for pharmacokinetic evaluation, 14 and 17.
The scope of catalytic asymmetric hydroboration/oxidation with rhodium complexes of 1,1'-(2-diarylphosphino-1-naphthyl)isoquinolines
Doucet, Henri,Fernandez, Elena,Layzell, Timothy P.,Brown, John M.
, p. 1320 - 1330 (2007/10/03)
Preformed cationic Rh complexes of the title ligands are effective for the asymmetric hydroboration/oxidation of vinylarenes at ambient temperature. These vinylarenes may carry E- or Z-β substituents but not a substituents. Enantiomer excesses of up to 97% can be obtained in the most favourable cases. The enantioselectivity is moderately sensitive to the structure of the ligand: the difurylphosphino ligand gave superior results for electron-poor styrenes and the diphenylphosphino ligand the best results for electron-rich reactants. Mechanistic aspects are discussed.
