- Discriminating non-ylidic carbon-sulfur bond cleavages of sulfonium ylides for alkylation and arylation reactions
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A sulfonium ylide participated alkylation and arylation under transition-metal free conditions is described. The disparate reaction pattern allowed the separate activation of non-ylidic S-alkyl and S-aryl bond. Under acidic conditions, sulfonium ylides serve as alkyl cation precursors which facilitate the alkylations. While under alkaline conditions, cleavage of non-ylidic S-aryl bond produces O-arylated compounds efficiently. The robustness of the protocols were established by the excellent compatibility of wide variety of substrates including carbohydrates.
- Fang, Jing,Li, Ting,Ma, Xiang,Sun, Jiuchang,Cai, Lei,Chen, Qi,Liao, Zhiwen,Meng, Lingkui,Zeng, Jing,Wan, Qian
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supporting information
p. 288 - 292
(2021/07/25)
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- Development of triazine-based benzylating reagents possessing T-butyl group on the triazine core: Thermally controllable reagents for the initiation of reaction
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Benzylating reagents, 4-(4,6-di-t-butyl-1,3,5-triazin-2-yl)-4-benzylmorpholinium triflate, and related derivatives have been developed. The reagents release benzyl triflate as a benzyl cation equivalent upon heating the solution to 40°C under neutral conditions. The O-benzylation of alcohols using a stoichiometric amount of these reagents afforded corresponding benzyl ethers in good to high yields. This was due to the presence of a bulky t-butyl group on the triazine ring of these reagents that prevents the consumption of benzyl triflate via a side reaction with a morpholinotriazine derivative.
- Karuo, Yukiko,Yamada, Kohei,Kunishima, Munetaka
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p. 303 - 308
(2018/03/09)
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- 3α,5α-Cyclocholestan-6β-yl ethers as donors of the holesterol moiety for the electrochemical synthesis f cholesterol glycoconjugates
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3α,5α-Cyclocholestan-6β-yl alkyl and aryl ethers were proved to be efficient cholesteryl donors in the electrochemical synthesis of glycoconjugates. 3α,5α-Cyclocholestan-6β-ol (i-cholesterol) and its tert-butyldimethylsilyl ether can also be used for this
- Tomkiel, Aneta M.,Biedrzycki, Adam,Ploszyska, Jolanta,Narg, Dorota,Sobkowiak, Andrzej,Morzycki, Jacek W.
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supporting information
p. 162 - 168
(2015/02/05)
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- NOVEL VASCULAR LEAK INHIBITOR
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The present disclosure relates to a novel vascular leakage inhibitor. The novel vascular leakage inhibitor of the present disclosure inhibits the apoptosis of vascular endothelial cells, inhibits the formation of actin stress fibers induced by VEGF, enhances the cortical actin ring structure, and improves the stability of the tight junctions (TJs) between vascular cells, thereby inhibiting vascular leakage. The vascular leakage inhibitor of the present disclosure has the activity of not only reducing vascular permeability but also recovering the integrity of damaged blood vessels. Accordingly, the vascular leakage inhibitor of the present disclosure can prevent or treat various diseases caused by vascular leakage. Since the vascular leakage inhibitor of the present disclosure is synthesized from commercially available or easily synthesizable cholesterols, it has remarkably superior feasibility of commercial synthesis.
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Page/Page column 33
(2012/09/21)
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- Cholesterol-derived novel anti-apoptotic agents on the structural basis of ginsenoside Rk1
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Design and synthesis of cholesterol-derived anti-apoptotic agents were described. The synthesized cholesterol analogs designed on the structural basis of ginsenoside Rk1 inhibited the undesirable apoptosis of human endothelial cells, which are induced by
- Lee, Sujin,Maharjan, Sony,Kim, Kyeojin,Kim, Nam-Jung,Choi, Hyun-Jung,Kwon, Young-Guen,Suh, Young-Ger
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scheme or table
p. 7102 - 7105
(2011/01/03)
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- Mix-and-heat benzylation of alcohols using a bench-stable pyridinium salt
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2-Benzyloxy-1-methylpyridinium inflate (1) is a stable, neutral organic salt that converts alcohols into benzyl ethers upon warming. The synthesis and reactivity of 1 are described herein. Benzylation of a wide range of alcohols occurs in good to excellent yield.
- Poon, Kevin W. C.,Dudley, Gregory B.
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p. 3923 - 3927
(2007/10/03)
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- Benzylation of alcohols by using bis[acetylacetonato]copper as catalyst
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Selective O-benzylation of primary hydroxy compounds has been achieved in the presence of bis[acetylacetonato]copper with benzyl chloride. We showed that bis[acetylacetonato]copper was very efficient in promoting the benzylation of primary aliphatic alcohols versus secondary aliphatic alcohols and phenolic hydroxy groups selectively.
- Sirkecioglu, Okan,Karliga, Bekir,Talinli, Naciye
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p. 8483 - 8485
(2007/10/03)
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- Conversion of Esters and Lactones to Ethers via Thionoesters and Thionolactones Using Reductive Radical Desulfurization
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Various thionoesters and thionolactones are readily reduced into the corresponding ethers in high isolated yields by radical desulfuurization with organotin hydrides and Et3B under mild reaction conditions.
- Jang, Doo Ok,Song, Seong Ho,Cho, Dae Hyan
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p. 3479 - 3488
(2007/10/03)
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- Montmorillonite Clay Catalysis. Part 13.1 Etherification of Cholesterol Catalysed by Montmorillonite K-10
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The preparation of cholesteryl ethers from alcohols and phenols with cholesterol is carried out at 50-70 °C by using montmorillonite K-10 as an acid catalyst in chloroform or cyclohexane.
- Lu, Bo,Li, Li-Jun,Li, Tong-Shuang,Li, Ji-Tai
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p. 604 - 605
(2007/10/03)
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- Hypervalent (tert-butylperoxy)iodanes generate iodine-centered radicals at room temperature in solution: Oxidation and deprotection of benzyl and allyl ethers, and evidence for generation of α-oxy carbon radicals
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1-(tert-Butylperoxy)-1,2-benziodoxol-3(1H)-one (1a) oxidizes benzyl and allyl ethers to the esters at room temperature in benzene or cyclohexane in the presence of alkali metal carbonates. Since this reaction is compatible with other protecting groups such as MOM, THP, and TBDMS ethers, and acetoxy groups, and because esters are readily hydrolyzed under basic conditions, this new method provides a convenient and effective alternative to the usual reductive deprotection. Oxidation with 1a occurs readily with C-H bonds activated by both enthalpic effects (benzylic, allylic, and propargylic C-H bonds) and/or polar effects (α-oxy C-H bonds), generating α-oxy carbon-centered radicals, which can be detected by nitroxyl radical trapping. Measurement of the relative rates of oxidation for a series of ring-substituted benzyl n-butyl ethers 2d and 2p-s indicated that electron-releasing groups such as p-MeO and p-Me groups increase the rate of oxidation, and Hammett correlation of the relative rate factors with the σ+ constants of substituents afforded the reaction constant ρ+ = -0.30. The large value of the isotope effect obtained for the oxidation of benzyl n-butyl ether 2d (k(H)/k(D) = 12-14) indicates that the rate-determining step of the reactions probably involves a high degree of benzylic C-H bond breaking. The effects of molecular dioxygen were examined, and the mechanism involving the intermediacy of the tert-butylperoxy acetal 5 and/or the hydroperoxy acetal 32 is proposed. Particularly noteworthy is the finding that (tert-butylperoxy)iodane 1a can generate the tert-butylperoxy radical and the iodine-centered radical 33a, even at room temperature in solution, via homolytic bond cleavage of the hypervalent iodine(III)-peroxy bond.
- Ochiai, Masahito,Ito, Takao,Takahashi, Hideo,Nakanishi, Akinobu,Toyonari, Mika,Sueda, Takuya,Goto, Satoru,Shiro, Motoo
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p. 7716 - 7730
(2007/10/03)
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- Conversion of Thionoesters and Thionolactones to Ethers; a General and Efficient Radical Desulfurisation
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Triphenyltin hydride reduces thionoesters and thionolactones to their corresponding ethers in high yield.
- Nicolaou, Kyriacos C.,Sato, Mitsunobu,Theodorakis, Emmanuel A.,Miller, Neil D.
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p. 1583 - 1586
(2007/10/02)
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- AlCl3-N,N-Dimethylaniline: A Novel Benzyl and Allyl Ether Cleavage Reagent
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A combination system of AlCl3-N,N-dimethylaniline was found to cleave benzyl ethers readily to give parent alcohols in excellent yields.The system also cleaved allyl as well as methyl ethers.Numerous functional groups such as benzoyloxy, phenylthio, and olefinic double bond were not affected.Comparison of AlCl3-N,N-dimethylaniline and AlCl3-anisole were described.
- Akiyama, Takahiko,Hirofuji, Hajimu,Ozaki, Shoichiro
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p. 1932 - 1938
(2007/10/02)
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- CLEAVAGES OF ETHERS BY CHLOROTRIMETHYLSILANE AND ACETIC ANHYDRIDE
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Methyl and benzyl ethers have been cleaved with a combination of reagents consisting of chlorotrimethylsilane and acetic anhydride containing a catalytic amount of concentrated sulfuric acid.Methylthiomethyl ethers yield the correponding acetoxymethyl ethers with chlorotrimethylsilane and acetic anhydride.Comparative study with the borontrifluoride etherate and acetic anhydride method of ether cleavage suggests that chlorotrimethylsilane and acetic anhydride (conc.H2SO4 catalysis) could be a useful alternative to it.
- Sarma, J. C.,Borbaruah, M.,Sarma, D. N.,Barua, N. C.,Sharma, R. P.
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p. 3999 - 4006
(2007/10/02)
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- Elaboration of α-Substituted Benzyl Alkyl Ethers and Sulphides by Suppression of the Wittig and Related Rearrangements via Complexation to Tricarbonylchromium
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Co-ordination of benzyl alkyl ethers and sulphides to tricarbonylchromium allows α-substitution via the corresponding α-carbanions to be achieved by suppression of the Wittig and related rearrangements.Little stereoselectivity was observed in the α-methylation of tricarbonylchromium complexes of benzyl ethers derived from a variety of chiral alcohols.Excellent stereoselectivities were observed in the mono- and di-methylation reactions of tricarbonylchromium where single diastereoisomers of the α-methyl and α,α'-dimethyl complexes were formed.Deprotonation and methylation of tricarbonyl-syn-1-methoxytetralinchromium occured stereospecifically with complete retention of configuration under conditions where the corresponding anti-complex was inert.On treatment with base tricarbonyl-(3-chloropropyl benzyl ether)chromium cyclises to give tricarbonyl-(2-phenyltetrahydrofuran)chromium.Exposure of arenetricarbonylchromium complexes to air and sunlight quantitatively liberates the free arene.
- Blagg, Julian,Davies, Stephen G.,Holman, Nicholas J.,Laughton, Charles A.,Mobbs, Bryan E.
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p. 1581 - 1590
(2007/10/02)
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