- A mild and efficient THP protection of indazoles and benzyl alcohols in water
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A mild and efficient method for THP protection of indazoles and benzyl alcohols has been developed in water, the most environmentally friendly solvent, in which Tween 20 (2% w/w) was added to form aqueous micelles to increase the solubility of starting materials. This aqueous protocol allowed the reaction to proceed smoothly at room temperature and with only 1.2 equiv of DHP, providing moderate to good yields of THP protected products for a wide scope of substrates. In addition, the methodology was highly practical in the large-scale synthesis (1 g synthesis of 2c as an example), wherein the convenient work-up and purification procedure (simple filtration) made the protocol even more attractive.
- Zhan, Yang,Ding, Xiao,Wang, Hailong,Yu, Haihua,Ren, Feng
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supporting information
p. 2150 - 2153
(2018/05/08)
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- Selective tetrahydropyranylation of alcohols and phenols using titanium(IV) salophen trifluoromethanesulfonate as an efficient catalyst
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Titanium(IV) salophen trifluoromethanesulfonate, [TiIV(salophen)(OSO2CF3)2], as a catalyst enables selective tetrahydropyranylation of alcohols and phenols with 3,4-dihydro-2H-pyran. Using this catalytic system, primary, secondary and tertiary alcohols, as well as phenols, were converted to their corresponding tetrahydropyranyl ethers in high yields and short reaction times at room temperature. Investigation of the chemoselectivity of this method showed discrimination between the activity of primary alcohols in the presence of secondary and tertiary alcohols and phenols. This heterogenized catalyst could be reused several times without loss of its catalytic activity. Copyright
- Yadegari, Maryam,Moghadam, Majid
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p. 872 - 875
(2016/09/20)
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- Inhibition of secreted phospholipase A2. 4-Glycerol derivatives of 4,5-dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one with broad activities
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Secreted phospholipases A2 (sPLA2s) have been reported to play an important role in various inflammatory conditions and thus represent an attractive therapeutic target. Previous SAR studies from our laboratory have revealed certain important features of our recently discovered specific hGIIA sPLA2 inhibitors, and we report here the synthesis and biological activities of glycerol-containing derivatives of our lead compound III (Figure 1). Efficient and selective synthesis methods have been developed to make glycerol trisubstituted by different groups on desired positions. In terms of biological activities, the best compounds (A3, A6, and A15) are more active than III (Figure 1), as potent as Me-Indoxam, an sPLA2s inhibitor of reference, against hGIIA, hGV, and hGX sPLA2s and at least 10 times less active toward the GIB enzymes in two in vitro assay systems. By synthesis of enantiopure (S)-A6, we demonstrated that no important improvement of the inhibitory potency could be achieved by this approach. Furthermore, the results show that the global lipophilicity is likely responsible for the anti-PLA 2 activity and two oxadiazolone moieties seem too big to be accommodated by the active site of the hGIIA enzyme.
- Touaibia, Mohamed,Djimdé, Atimé,Cao, Fei,Boilard, Eric,Bezzine, Sofiane,Lambeau, Gérard,Redeuilh, Catherine,Lamouri, Aazdine,Massicot, France,Chau, Fran?ois,Dong, Chang-Zhi,Heymans, Fran?oise
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p. 1618 - 1626
(2008/02/02)
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- Chemoselective tetrahydropyranylation of primary alcohols under freezing water pressure
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A highly efficient environmentally friendly method for selective tetrahydropyranylation of primary alcoholic groups under pressure exerted by freezing water has been described.
- Boruwa, Joshodeep,Bhuyan, Ranjana,Gogoi, Naminita,Barua, Nabin C.
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p. 331 - 334
(2007/10/03)
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- Chemoselective tetrahydropyranylation of alcohols and their detetrahydropyranylation using silicasulphuric acid as a reusable catalyst
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A simple, mild, and efficient protocol for chemoselective protection of alcohols over phenols as tetrahydropyranyl ethers and their deprotection using silicasulphuric acid as a reusable solid acid catalyst is described.
- Pore,Desai, Uday V.,Mane,Wadgaonkar
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p. 2135 - 2142
(2007/10/03)
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- A mild and efficient selective tetrahydropyranylation of primary alcohols and deprotection of THP ethers of phenols and alcohols using PdCl 2(CH3CN)2 as catalyst
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Primary alcohols were selectively tetrahydropyranylated in good to excellent yields at room temperature using PdCl2(CH 3CN)2 as catalyst in tetrahydrofuran (THF) in the presence of phenols, secondary, and tertiary alcohols. The tetrahydropyranyl (THP) group could be efficiently removed using PdCl2(CH 3CN)2 as catalyst in CH3CN, while other protection groups such as p-toluenesulfonyl (Ts), tert-butyldiphenylsilyl (TBDPS), benzyloxycarbonyl (Cbz), allyl, benzyl (Bn), and benzoyl (Bz) remained intact under these conditions.
- Wang, Yan-Guang,Wu, Xiao-Xing,Jiang, Zhi-Yong
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p. 2973 - 2976
(2007/10/03)
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- RuCl3, a mild and efficient catalyst for tetrahydropyranylation of alcohols and deprotection of tetrahydropyranyl ethers
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Catalytic amount of anhydrous ruthenium trichloride in dry acetonitrile catalyzes efficiently tetrahydropyranylation of different types of alcohols to afford the corresponding tetrahydropyranyl ethers in high yields. Deprotection of tetrahydropyranyl ethers can also be achieved efficiently in the presence anhydrous ruthenium trichloride in wet acetonitrile.
- Kazemi,Kiasat,Ebrahimi
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p. 2888 - 2889
(2007/10/03)
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- A Highly Efficient and Chemoselective Synthetic Protocol for Tetrahydropyranylation/Depyranylation of Alcohols and Phenols
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Various alcohols and phenols can be converted efficiently to the corresponding tetrahydropyranyl (THP) ethers in good yields using catalytic amounts of bromodimethylsulfonium bromide (0.005-0.02 equivalent) at room temperature. On the other hand, various THP ethers can also be deprotected to the parent alcoholic or phenolic compounds in CH2Cl2/ MeOH (5:2) by employing 0.05 equivalent of the same catalyst. Some of the major advantages of this procedure are its mild conditions, that it is highly selective and efficient, high yielding, and cost-effective, that it needs no solvent and is compatible with the presence of other protecting groups. Furthermore, no brominations occur at a double or triple bond, at an allylic position or even at an aromatic ring. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Khan, Abu T.,Mondal, Ejabul,Borah, Ballav M.,Ghosh, Subrata
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p. 4113 - 4117
(2007/10/03)
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- A mild, efficient and selective cleavage of aryl tert-butyldimethysilyl ethers using KOH in ethanol
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An efficient and selective method for the deprotection of aryl tert-butyldimethysilyl (TBS) ethers is described. The protecting group TBS could be cleaved from aryl silyl ethers in the prensence of alkyl TBS ethers using KOH in ethanol at room temperature to give the corresponding phenols in excellent yields (87-99%).
- Jiang, Zhi-Yong,Wang, Yan-Guang
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p. 568 - 569
(2007/10/03)
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- A mild, efficient and selective deprotection of t-butyldimethylsilyl-protected phenols using cesium carbonate
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A mild and efficient method for the deprotection of aryl t-butyldimethysilyl (TBS) ethers is described. The protecting group TBS could be cleaved from aryl silyl ethers using cesium carbonate in DMF-H2O at room temperature to give the corresponding phenols in excellent yields. The reaction conditions allowed selective deprotection of aryl TBS-protected phenols in the presence of TBS, phenyloxycarbonyl or tetrahydropyranyl-protected alcohols.
- Jiang, Zhi-Yong,Wang, Yan-Guang
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p. 3859 - 3861
(2007/10/03)
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- LiBF4: A mild and efficient catalyst for the tetrahydropyranylation of alcohols and their detetrahydropyranylation
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Catalytic amount of lithium tetrafluoroborate in dry acetonitrile catalyzes an efficient tetrahydropyranylation of different types of alcohols to afford the corresponding tetrahydropyranyl ethers in high yields. Deprotection of tetrahydropyranyl ethers can also be achieved efficiently in the presence of lithium tetrafluoroborate in methanol. The chemoselectivity was observed in the protection of alcoholic function in the presence of phenolic function.
- Kazemi,Kiasat,Ebrahimi
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p. 2483 - 2487
(2007/10/03)
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- A mild procedure for rapid and selective deprotection of aryl acetates using natural kaolinitic clay as a reusable catalyst
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A variety of aryl acetates are selectively cleaved to the corresponding phenols using natural kaolinitic clay in methanol under mild conditions (25°C).
- Bandgar,Uppalla,Sagar,Sadavarte
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p. 1163 - 1165
(2007/10/03)
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- Dicyanoketene ethylene acetal as a mild and efficient catalyst for tetrahydropyranylation of alcohols
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Alcohols can react with 3,4-dihydro-2H-pyran in the presence of a catalytic amount of dicyanoketene ethylene acetal under neutral conditions to afford the corresponding tetrahydropyranyl ethers in good yields.
- Miura,Masaki
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p. 1981 - 1987
(2007/10/02)
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