4383-07-7Relevant academic research and scientific papers
Asymmetric Retro-Claisen Reaction by Synergistic Chiral Primary Amine/Palladium Catalysis
Han, Yanfang,Zhang, Long,Luo, Sanzhong
supporting information, p. 7258 - 7261 (2019/10/02)
We described herein a chiral primary amine/palladium catalyzed asymmetric retro-Claisen reaction of β-diketones with salicylic carbonates. A series of chiral α-alkylated ketones and macrolides were obtained with good yields and excellent enantioselectivities upon a sequence of decarboxylative benzylation, retro-Claisen cleavage, and enamine protonation. This strategy features broad substrate scope, mild conditions, as well as high atom economy with salicylic carbonates as the o-quinone methide precursors.
Synthesis of Monofunctionalized Calix[5]arenes
Ingenfeld, Bj?rn,Straub, Steffen,Fr?mbgen, Christopher,Lützen, Arne
, p. 676 - 684 (2017/11/16)
Seven OH-free and O -permethylated monofunctionalized calix[5]arenes carrying either additional methyl or tert -butyl groups are prepared following fragment condensation protocols. This strategy proves to be superior to previous approaches. Calix[5]arenes with free OH groups all adopt a cone conformation stabilized by a seam of hydrogen bonds at the lower rim. Post-condensation modifications, i.e., methylation of phenolic OH groups or functional group interconversions can also be achieved. Bulky tert -butyl groups are also found to stabilize the cone conformations of O -methylated compounds. These compounds offer versatile functional groups that make these concave molecules interesting building blocks for the synthesis of more sophisticated molecular architectures.
Lewis Base Catalyzed Intramolecular Reduction of Salicylaldehydes by Pinacol-Derived Chlorohydrosilane
Assoah, Benedicta,Vale, Jo?o R.,Kalenius, Elina,Veiros, Luis F.,Candeias, Nuno R.
supporting information, p. 2910 - 2917 (2018/06/27)
A newly developed stable chlorohydrosilane derived from pinacol is herein described. This was successfully used in the reduction of salicylaldehydes in reasonable to excellent yields (51–97 %). The ability of the hydrosilane to react as a reducing agent is increased upon the in situ formation of a trialkoxyhydrosilane and activation with a Lewis base, as further indicated by density functional theory studies. 1,3-Dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) was identified to be a suitable catalyst for this metal-free reduction, promoting the regio- and chemoselective reduction of aldehydes in ortho-position to phenols, despite the presence of vicinal ketones. The performance of pinacol-derived chlorohydrosilane in the reduction of salicylaldehydes was further observed to be superior to that of well-established commercially available chlorohydrosilanes.
Indanol-Based Chiral Organoiodine Catalysts for Enantioselective Hydrative Dearomatization
Hashimoto, Takuya,Shimazaki, Yuto,Omatsu, Yamato,Maruoka, Keiji
supporting information, p. 7200 - 7204 (2018/06/15)
Rapid development in the last decade has rendered chiral organoiodine(I/III) catalysis a reliable methodology in asymmetric catalysis. However, due to the severely limited numbers of effective organoiodine catalysts, many reactions still give low to modes
MAO inhibitory activity of bromo-2-phenylbenzofurans: Synthesis,: in vitro study, and docking calculations
Delogu,Pintus,Mayán,Matos,Vilar,Munín,Fontenla,Hripcsak,Borges,Vi?a
, p. 1788 - 1796 (2017/09/29)
Monoamine oxidase (MAO) is an enzyme responsible for metabolism of monoamine neurotransmitters which play an important role in brain development and function. This enzyme exists in two isoforms, and it has been demonstrated that MAO-B activity, but not MAO-A activity, increases with aging. MAO inhibitors show clinical value because besides the monoamine level regulation they reduce the formation of by-products of the MAO catalytic cycle, which are toxic to the brain. A series of 2-phenylbenzofuran derivatives was designed, synthesized and evaluated against hMAO-A and hMAO-B enzymes. A bromine substituent was introduced in the 2-phenyl ring, whereas position 5 or 7 of the benzofuran moiety was substituted with a methyl group. Most of the tested compounds inhibited preferentially MAO-B in a reversible manner, with IC50 values in the low micro or nanomolar range. The 2-(2′-bromophenyl)-5-methylbenzofuran (5) was the most active compound identified (IC50 = 0.20 μM). In addition, none of the studied compounds showed cytotoxic activity against the human neuroblastoma cell line SH-SY5Y. Molecular docking simulations were used to explain the observed hMAO-B structure-activity relationship for this type of compounds.
Porous Ge@C materials via twin polymerization of germanium(II) salicyl alcoholates for Li-ion batteries
Kitschke, Philipp,Walter, Marc,Rüffer, Tobias,Seifert, Andreas,Speck, Florian,Seyller, Thomas,Spange, Stefan,Lang, Heinrich,Auer, Alexander A.,Kovalenko, Maksym V.,Mehring, Michael
supporting information, p. 2705 - 2719 (2016/02/20)
The germylenes, germanium(ii) 2-(oxidomethyl)phenolate (1), germanium(ii) 4-methyl-2-(oxidomethyl)phenolate (2) and germanium(ii) 4-bromo-2-(oxidomethyl)phenolate (3) were synthesized and their thermally induced twin polymerization to give organic-inorganic hybrid materials was studied. The compounds 1-3 form oligomers including dimers, trimers and tetramers as a result of intermolecular coordination of the benzylic oxygen atom to germanium. The structural motifs were studied by single crystal X-ray diffraction analysis and DFT-D calculations. Thermally induced twin polymerization of these germylenes gave hybrid materials based on germanium-containing phenolic resins. Carbonization of these resins under reductive conditions resulted in porous materials that are composed of germanium and carbon (Ge@C materials), while oxidation with air provided non-porous germanium dioxide. The porous Ge@C materials were tested as potential anode materials for rechargeable Li-ion batteries. Reversible capacities of 540 mA h g-1 were obtained at a current density of 346 mA g-1 without apparent fading for 100 cycles, which demonstrates that germanium is well accessible in the hybrid material.
2-Phenylbenzofuran derivatives as butyrylcholinesterase inhibitors: Synthesis, biological activity and molecular modeling
Delogu, Giovanna L.,Matos, Maria J.,Fanti, Maura,Era, Benedetta,Medda, Rosaria,Pieroni, Enrico,Fais, Antonella,Kumar, Amit,Pintus, Francesca
, p. 2308 - 2313 (2016/04/20)
A series of 2-phenylbenzofurans compounds was designed, synthesized and evaluated as cholinesterase inhibitors. The biological assay experiments showed that most of the compounds displayed a clearly selective inhibition for butyrylcholinesterase (BChE), while a weak or no effect towards acetylcholinesterase (AChE) was detected. Among these benzofuran derivatives, compound 16 exhibited the highest BChE inhibition with an IC50 value of 30.3 μM. This compound was found to be a mixed-type inhibitor as determined by kinetic analysis. Moreover, molecular dynamics simulations revealed that compound 16 binds to both the catalytic anionic site (CAS) and peripheral anionic site (PAS) of BChE and it displayed the best interaction energy value, in agreement with our experimental data.
Water-promoted ortho-selective monohydroxymethylation of phenols in the NaBO2 system
Li, Hui-Jing,Wu, Ying-Ying,Wu, Qin-Xi,Wang, Rui,Dai, Chun-Yang,Shen, Zhi-Lun,Xie, Cheng-Long,Wu, Yan-Chao
, p. 3100 - 3107 (2014/05/06)
Water-promoted ortho-selective monohydroxymethylation of phenols in the NaBO2 system generates salicyl alcohols in 65-97% yields. A remarkable rate-enhancement by water was observed, and NaBO2 appeared to serve the dual role of a suitable base and an efficient chelating reagent. This protocol possesses many advantages such as short reaction times, expanded substrate scope, and high mono- and regio-selectivities. The experimental results were explained by the calculations based on local ionisation energy minima, leading to a possible reaction mechanism.
MAO Inhibitory Activity of 2-Arylbenzofurans versus 3-Arylcoumarins: Synthesis, invitro Study, and Docking Calculations
Ferino, Giulio,Cadoni, Enzo,Matos, Maria Joao,Quezada, Elias,Uriarte, Eugenio,Santana, Lourdes,Vilar, Santiago,Tatonetti, Nicholas P.,Yanez, Matilde,Vina, Dolores,Picciau, Carmen,Serra, Silvia,Delogu, Giovanna
, p. 956 - 966 (2013/07/27)
Monoamine oxidase (MAO) is an important drug target for the treatment of neurological disorders. Several 3-arylcoumarin derivatives were previously described as interesting selective MAO-B inhibitors. Preserving the trans-stilbene structure, a series of 2-arylbenzofuran and corresponding 3-arylcoumarin derivatives were synthesized and evaluated as inhibitors of both MAO isoforms, MAO-A and MAO-B. In general, both types of derivatives were found to be selective MAO-B inhibitors, with IC50 values in the nano- to micromolar range. 5-Nitro-2-(4-methoxyphenyl)benzofuran (8) is the most active compound of the benzofuran series, presenting MAO-B selectivity and reversible inhibition (IC50=140nM). 3-(4′-Methoxyphenyl)-6-nitrocoumarin (15), with the same substitution pattern as that of compound 8, was found to be the most active MAO-B inhibitor of the coumarin series (IC50=3nM). However, 3-phenylcoumarin 14 showed activity in the same range (IC50=6nM), is reversible, and also severalfold more selective than compound 15. Docking experiments for the most active compounds into the MAO-B and MAO-A binding pockets highlighted different interactions between the derivative classes (2-arylbenzofurans and 3-arylcoumarins), and provided new information about the enzyme-inhibitor interaction and the potential therapeutic application of these scaffolds.
Substituent effects on oxidation-induced formation of quinone methides from arylboronic ester precursors
Cao, Sheng,Christiansen, Robin,Peng, Xiaohua
, p. 9050 - 9058 (2013/07/26)
A series of arylboronic esters containing different aromatic substituents and various benzylic leaving groups (Br or N+Me3Br -) have been synthesized. The substituent effects on their reactivity with H2O2 and formation of quinone methide (QM) have been investigated. NMR spectroscopy and ethyl vinyl ether (EVE) trapping experiments were used to determine the reaction mechanism and QM formation, respectively. QMs were not generated during oxidative cleavage of the boronic esters but by subsequent transformation of the phenol products under physiological conditions. The oxidative deboronation is facilitated by electron-withdrawing substituents, such as aromatic F, NO2, or benzylic N+Me 3Br-, whereas electron-donating substituents or a better leaving group favor QM generation. Compounds containing an aromatic CH 3 or OMe group, or a good leaving group (Br), efficiently generate QMs under physiological conditions. Finally, a quantitative relationship between the structure and activity has been established for the arylboronic esters by using a Hammett plot. The reactivity of the arylboronic acids/esters and the inhibition or facilitation of QM formation can now be predictably adjusted. This adjustment is important as some applications may benefit and others may be limited by QM generation. Tunable quinone methide formation: Aromatic substituents and the benzylic leaving group strongly affect the H 2O2-induced formation of quinone methides (QMs) from arylboronic esters (see scheme). The reactivity of arylboronic esters can be predictably adjusted by varying substituents. Copyright
