共查询到20条相似文献,搜索用时 15 毫秒
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《Tetrahedron letters》1996,37(42):7529-7532
Several new protecting groups were introduced at the Nin-position of tryptophan, and their reactivities were examined under the conditions used for peptide synthesis by Boc-strategy. Among them, the cyclohexyloxycarbonyl (Hoc) group was found to be the most suitable in terms of stability during elongation of the peptide chain and removability at the final HF reaction without resorting to the use of thiols. 相似文献
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The fast, selective and mild removal of levulinyl groups with hydrazine from galactose, which also carries hydroxyl functions protected with acetyl groups, enables, under Koenigs-Knorr conditions, the synthesis of a trimer containing β-linked galactoses. 相似文献
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Cumyl ester is an optimal C-terminal protecting group for glycine benzophenone imine in asymmetric alkylation reactions catalyzed by Cinchona chiral phase-transfer catalysts. High levels of enantioselectivity have been obtained (up to 94% ee) with this substrate, which provides an attractive alternative to the analogous tert-butyl ester. N-terminal imines and the C-terminal esters can be cleaved from alkylation products by hydrogenolysis, while maintaining acid-labile side chain protecting groups. 相似文献
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[reaction: see text] 6-Bromo-4-(1,2-dihydroxyethyl)-7-hydroxycoumarin (Bhc-diol) can be used under simulated physiological conditions as a photoremovable protecting group for aldehydes and ketones. The single- and two-photon-induced release of benzaldehyde, piperonal, acetophenone, and cyclohexanone is demonstrated. 相似文献
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Y Kanaoka K Tanizawa E Sato D Yonemitsu Y Ban 《Chemical & pharmaceutical bulletin》1967,15(5):593-598
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James P. Tam Tai-Wai Wong Mark W. Riemen Foe-S. Tjoeng R.B. Merrifield 《Tetrahedron letters》1979,20(42):4033-4036
Boc-Asp(OHex) and Boc-Glu(OHex) were synthesized and used in solid phase peptide synthesis. Hex ester is stable to TFA, cleavable by HF and minimizes aspartimide formation and α,β-rearrangement of aspartyl peptides in acid and particularly in base. 相似文献
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A novel protecting group for NH functionality of heterocycles, a thietane ring, was proposed. It can be readily introduced by alkylation of NH-heterocycles with 2-chloromethylthiirane. Removal of the thietane protecting group is performed via oxidation to thietane 1,1-dioxide with hydrogen peroxide in acetic acid and subsequent treatment with sodium alkoxide. 相似文献
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Zajac MA 《The Journal of organic chemistry》2008,73(17):6899-6901
Efforts to couple 4 with 12 employing base mediation are problematic due to the formation of 6. To circumvent this issue, 12 was converted to the pyridine borane complex (13). Alkylation of 4 with 13 provided 3 after removal of the borane under acidic conditions and saponification of the ester. 相似文献
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[reaction: see text]. N-Benzhydryl aziridines-2-carboxylates can be readily obtained from the catalytic asymmetric aziridination reaction from N-benzhydrylimines and ethyl diazoacetate. Cleavage of the benzhydryl group by hydrogenolysis leads to ring opening when R = aryl. Surprisingly, ozone will selectively oxidize the benhydryl group in these aziridines even when R is an aryl group. This allows for a new deprotection strategy for these aziridines whose generality is explored. 相似文献
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Selective modification of electrode surfaces is a vital step in the development of many practical applications of self-assembled monolayers (SAMs). This paper describes a protection-deprotection strategy similar to that commonly utilized in organic synthesis, with gold oxide as a protecting layer, to direct self-assembly on one gold electrode in the presence of another. 相似文献
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Wilden JD Geldeard L Lee CC Judd DB Caddick S 《Chemical communications (Cambridge, England)》2007,(10):1074-1076
2,4,6-Trichlorophenol (TCP) sulfonate esters undergo effective aminolysis under conventional heating and microwave irradiation; the reactivity of these species is such that chemoselective transformations of PFP sulfonate esters can be achieved. 相似文献
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Kazuteru Umetsu 《Tetrahedron letters》2008,49(49):7046-7049
Treatment of ortho-alkynylbenzoic acid esters with excess amounts of EtOH in the presence of a gold catalyst results in the liberation of alcohols or phenols in high yields under mild conditions. The protection of alcohols and phenols proceeds smoothly by use of ortho-alkynylbenzoic acid or ortho-iodobenzoyl chloride. Highly chemoselective deprotections are described. 相似文献
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The trifluoroacetyl moiety has been used as a new protecting group for guanidine functionality. The protecting group is easily cleaved under mild basic conditions and is complementary to the Boc, Cbz, and Ddpe protecting groups. The protecting group can be applied to peptide synthesis in solution as well as on a solid phase as it is orthogonal to a Boc and Cbz strategy and semiorthogonal to an Fmoc strategy. 相似文献
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Carboxylic acids were protected as their corresponding 3-butenyl esters. Deprotection was carried out via ozonolysis and β-elimination of the resultant 3-acyloxypropanal. 相似文献
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The 2,5-dimethylphenacyl chromophore, a new photoremovable protecting group for carboxylic acids, is proposed. Direct photolysis of various 2,5-dimethylphenacyl esters in benzene or methanol at 254-366 nm leads to the formation of the corresponding carboxylic acids in almost quantitative isolated yields. The photodeprotection is based on efficient intramolecular hydrogen abstraction without the necessity of introducing a photosensitizer. 相似文献