22976-41-6Relevant academic research and scientific papers
Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals
Jiang, Huifang,Lu, Rui,Luo, Xiaolin,Si, Xiaoqin,Xu, Jie,Lu, Fang
supporting information, p. 1292 - 1296 (2020/12/09)
With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.
Novel preparation of N-arylmethyl-N-arylmethyleneamine N-oxides from benzylic bromides with zinc and isobutyl nitrite
Yanai, Kei,Togo, Hideo
, p. 3523 - 3529 (2019/05/24)
Treatment of benzylic bromides with Zn and LiCl, followed by the reaction with i-butyl nitrite gave N-arylmethyl-N-arylmethyleneamine N-oxides in moderate yields. The present reaction is a novel and simple method for the preparation of nitrones from benzylic bromides, although the yields are moderate.
Synthesis and biological evaluation of novel gigantol derivatives as potential agents in prevention of diabetic cataract
Wu, Jie,Lu, Chuanjun,Li, Xue,Fang, Hua,Wan, Wencheng,Yang, Qiaohong,Sun, Xiaosheng,Wang, Meiling,Hu, Xiaohong,Chen, C.-Y. Oliver,Wei, Xiaoyong
, (2015/12/26)
As a continuation of our efforts directed towards the development of natural anti-diabetic cataract agents, gigantol was isolated from Herba dendrobii and was found to inhibit both aldose reductase (AR) and inducible nitric oxide synthase (iNOS) activity, which play a significant role in the development and progression of diabetic cataracts. To improve its bioefficacy and facilitate use as a therapeutic agent, gigantol (compound 14f) and a series of novel analogs were designed and synthesized. Analogs were formulated to have different substituents on the phenyl ring (compounds 4, 5, 8, 14a-e), substitute the phenyl ring with a larger steric hindrance ring (compounds 10, 17c) or modify the carbon chain (compounds 17a, 17b, 21, 23, 25). All of the analogs were tested for their effect on AR and iNOS activities and on D-galactose-induced apoptosis in cultured human lens epithelial cells. Compounds 5, 10, 14a, 14b, 14d, 14e, 14f, 17b, 17c, 23, and 25 inhibited AR activity, with IC50 values ranging from 5.02 to 288.8 μM. Compounds 5, 10, 14b, and 14f inhibited iNOS activity with IC50 ranging from 432.6 to 1188.7 μM. Compounds 5, 8, 10, 14b, 14f, and 17c protected the cells from D-galactose induced apoptosis with viability ranging from 55.2 to 76.26%. Of gigantol and its analogs, compound 10 showed the greatest bioefficacy and is warranted to be developed as a therapeutic agent for diabetic cataracts.
Homo- and hetero-oxidative coupling of benzyl anions
Blangetti, Marco,Fleming, Patricia,O'Shea, Donal F.
experimental part, p. 2870 - 2877 (2012/04/23)
The regioselective benzylic metalation of substituted toluenes using BuLi/KO-t-Bu/TMP(H) (LiNK metalation conditions) with subsequent in situ oxidative C-C coupling has been developed for the facile generation of 1,2-diarylethanes. A range of oxidants can be used for the oxidative coupling step, with 1,2-dibromoethane proving optimal. Heterocouplings can be achieved starting from a mixture of two different toluenes with a bias toward cross coupling achievable by using a 2-fold excess of one toluene starting material. The utility of this approach is illustrated by the synthesis of several biologically active natural products. A distinct advantage is that the synthetic steps typically required to preactivate the coupling substrates are eliminated and no transition metal is required to facilitate the C-C bond formation.
Complete NMR data of methoxylated cis- and trans-stilbenes as well as 1,2-diphenylethanes
Jo, Geunhyeong,Hyun, Jiye,Hwang, Doseok,Lee, Young Han,Koh, Dongsoo,Lim, Yoongho
scheme or table, p. 374 - 377 (2011/12/04)
Resveratrol is a polyphenol isolated from many natural sources including grapes, mulberries, eucalyptus, spruce, lilies, and peanuts. The hydroxyl groups in polyphenols can be substituted with various functional groups, allowing production of multiple derivatives. NMR spectroscopy is used to identify new derivatives. Since the complete NMR data of the known derivatives can be useful for identification of the newly isolated derivatives, here, we report the synthesis of 14 methoxylated stilbenes and four 1,2-diphenylethanes and their NMR data.
Understanding the exceptional hydrogen-atom donor characteristics of water in TiIII-mediated free-radical chemistry
Paradas, Miguel,Campana, Araceli G.,Jimenez, Tania,Robles, Rafael,Oltra, J. Enrique,Bunuel, Elena,Justicia, Jose,Cardenas, Diego J.,Cuerva, Juan M.
supporting information; experimental part, p. 12748 - 12756 (2010/10/21)
In recent years solid evidence of HAT reactions involving water as hydrogen atom source have been presented. In this work we demonstrate that the efficiency of titanocene(III) aqua complexes as an unique class of HAT reagents is based on two key features: (a) excellent binding capabilities of water toward titanocene(III) complexes and (b) a low activation energy for the HAT step. The theory has predictive capabilities fitting well with the experimental results and may aid to find more examples of this remarkable radical reaction.
Regioselective reductive demethoxylation of 3,4,5-trimethoxystilbenes
Azzena, Ugo,Dettori, Giovanna,Idini, Maria Vittoria,Pisano, Luisa,Sechi, Grazia
, p. 7961 - 7966 (2007/10/03)
Selective removal of the 4-methoxy group of 3,4,5-trimethoxystilbenes was performed under electron transfer conditions from Na metal in THF. Careful control of reaction conditions and quenching procedure allowed the synthesis of either (E)-3,5-dimethoxystilbenes or 3,5-dimethoxybibenzyls.
Direct preparation of benzylic manganese reagents from benzyl halides, sulfonates, and phosphates and their reactions: Applications in organic synthesis
Suh, YoungSung,Lee, Jun-Sik,Kim, Seoung-Hoi,Rieke, Reuben D.
, p. 20 - 36 (2007/10/03)
The use of highly active manganese (Mn)*, prepared by the Rieke method, was investigated for the direct preparation of benzylic manganese reagents. The oxidative addition of the highly active manganese to benzylic halides was easily completed under mild conditions. Moreover, benzylic manganese sulfonates and phosphates were prepared by direct oxidative addition of Mn* to the carbon-oxygen bonds of benzylic sulfonates and phosphates. The resulting benzylic manganese reagents were found to undergo cross-coupling reactions with a variety of electrophiles. Most of these reactions were carried out in the absence of any transition metal catalyst under mild conditions. In addition, the use of highly active manganese was also studied for preparation of homo-coupled products of functionalized benzyl halides without transition metal catalysts. These useful approaches provided not only a facile synthetic route to the preparation of resoricinolic lipids but a facile synthesis of functionalized 4-benzylpyridines by regioselective and chemo selective γ-addition of benzylic group to N-alkoxycarbonylpyridinum salts.
1,3-Dimethoxy-5-methylene-1,3-cyclohexadiene Compounds with Leaving Groups at C6: Generation, Solvolytic Reactivity, and Their Importance in the Photochemistry of 3,5-Dimethoxybenzyl Derivatives
DeCosta,Howell,Pincock,Pincock,Rifai
, p. 4698 - 4705 (2007/10/03)
The photochemistry of 3,5-dimethoxybenzyl compounds with the leaving groups acetate (1a), chloride (1b), bromide (1c), iodide (1d), diethyl phosphate (1e), and trimethylamine (1f), as the chloride, was examined by both product studies and flash photolysis. The isomeric triene, 5-methylene-1,3-cyclohexadiene derivative was observed for the acetate (2a), diethyl phosphate (2e) and trimethylammonium chloride (2f). The solvolysis of these derivatives, 2, was examined in alcohol solvents and the rate correlation with YOTS values gave m = 0.47 (2a) and 0.63 (2e), suggesting SN1 reactivity but with an early transition state. Quantum yields for formation of 2a and 2e indicated that these trienes play only a minor role (～16%) in the overall photochemistry of the corresponding arylmethyl substrates.
The Photochemistry of Methoxy-Substituted Benzyl Acetates and Benzyl Pivalates: Homolytic vs Heterolytic Cleavage
Pincock, J. A.,Wedge, P. J.
, p. 5587 - 5595 (2007/10/02)
The multiple methoxy-substituted benzyl acetates (3g-i) and benzyl pivalates (4g-i) have been photolyzed in methanol solution.The products of these reactions are derived from two critical intermediates; the benzyl radical/acyloxy radical pair and the benzyl cation/carboxylate anion pair.As predicted by the meta effect, the yield of ion-derived product, the methyl ether in this case, was enhanced by the presence of the m-methoxy groups.The yield of ether, for the acetate esters, varied from 2percent for the 4-methoxy-substituted ester to 66percent for the 3,4,5-trimethoxy-substituted ester.In contrast, the yield of ether, for the pivalate esters, varied from 1percent for the 4-methoxy-substituted ester to 20percent for the 3,4,5-trimethoxy-substituted one.The meta effect does not explain these differences; electron transfer converting the radical pair to the ion pair is still an important pathway in the mechanism for ion formation.A quantitative analysis of the yield of the ethers was done in order to obtain the electron-transfer rate constants.This analysis revealed that the yield of the ethers was higher than expected based on previous results for other substituted benzyl acetates.A possible explanation for this discrepancy is that internal return of the radical pair to starting material for the acetate esters is more efficient than for the pivalate esters.Also, the esters 3k and 3l, were prepared to study the effect of electron-withdrawing groups in the meta position.For these esters, the benzylic cleavage reactions were inefficient and an isomerization reaction, the benzvalene rearrangement, was competitive.
