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1.
Raquel G. Soengas 《Tetrahedron letters》2010,51(1):105-574
Indium-mediated Reformatsky reactions of simple lactones and aldonolactones with ethyl α-bromoisobutyrate allow the synthesis of the corresponding ketals and ulosonic acid esters, respectively, in good yields. 相似文献
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New bianthracene-quaterpyridine ligand 6,6″′-bis(anthracen-9-yl)-2,2′;6′,2″;6″,2″′-quaterpyridine L has been obtained in a multistep synthesis using Suzuki–Miyaura and Stille-type coupling reactions. The dianthracene ligand L has four nitrogen-donor atoms and can form different supramolecular architectures with transition metal ions. Ligand L and intermediate compounds have been characterized by spectroscopic methods and elemental analyses. 2-(Anthracen-9-yl)-6-bromopyridine and 6-(anthracen-9-yl)-6′-bromo-2,2′-bipyridine have been also characterized by X-ray crystallography. 相似文献
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Jari Hovinen 《Tetrahedron letters》2004,45(29):5707-5709
Treatment of 2,6-di(pyridin-2-yl)pyridin-4(1H)-one with various appropriately protected ω-substituted primary alcohols or a nucleoside (3,3′-O-diBz-dUrd) in dry THF in the presence of triphenylphosphine and diisopropylazodicarboxylate gives the corresponding 4′-substituted terpyridines in high yield. 相似文献
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The 2,2′:6′,2″-terpyridines 7a-c were prepared in good yield by reacting α-acetoxy-α-chloro-β-keto-esters 3a-c with bis-amidrazone 4 and 2,5-norbornadiene 6 in ethanol at reflux. Compounds 3a and 3b gave the 2,2′:6′,2″-terpyridines 9a and 9b, respectively, in moderate yield when treated with compound 4 and enamine 8. 相似文献
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The 2,2′:6′,2″-terpyridines 8a and 8b were prepared in good yield by reacting α-acetoxy-α-chloro-β-keto-esters 1 (R1 = nPr and Ph) with the bis-amidrazone 7 and 2,5-norbornadiene 5 in ethanol at reflux. 相似文献
7.
Kenichiro Nagai 《Tetrahedron letters》2004,45(12):2507-2509
4″-Alkoxy avermectin derivatives have been synthesized using O-H insertion reaction with ethyl diazoacetate in the presence of Rh2(OAc)4 as a catalyst. 相似文献
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L. M. Likhosherstov O. S. Novikova V. A. Derevitskaya N. K. Kochetkov 《Russian Chemical Bulletin》1986,35(7):1512-1517
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We investigated the coupling reaction of glycosyl donors N-trichloroethoxycarbonyl-galactosamine-O-trichloroacetimidate (2a) and N-p-nitrobenzyloxycarbonyl-galactosamine-O-trichloroacetimidate (2b) with the 4′-OH of lactose derivatives (3a-d) to synthesize key intermediates of asialo GM2 analogues, and found that the glycosylation yield with 2a was 90% or more in all investigated cases. 相似文献
11.
Naeem B. Hanna Kandasamy Ramasamy Roland K. Robins Ganapathi R. Revankar 《Journal of heterocyclic chemistry》1988,25(6):1899-1903
A simple and high-yield synthesis of biologically significant 2′-deoxy-6-thioguanosine ( 11 ), ara-6-thioguanine ( 16 ) and araG ( 17 ) has been accomplished employing the Stereospecific sodium salt glycosylation method. Glycosylation of the sodium salt of 6-chloro- and 2-amino-6-chloropurine ( 1 and 2 , respectively) with 1-chloro-2-deoxy-3,5-di-O-(p-toluoyl)-α-D-erythro-pentofuranose ( 3 ) gave the corresponding N-9 substituted nucleosides as major products with the β-anomeric configuration ( 4 and 5 , respectively) along with a minor amount of the N-7 positional isomers ( 6 and 7 ). Treatment of 4 with hydrogen sulfide in methanol containing sodium methoxide gave 2′-deoxy-6-thioinosine ( 10 ) in 93% yield. Similarly, 5 was transformed into 2′-deoxy-6-thioguanosine (β-TGdR, 11 ) in 71 % yield. Reaction of the sodium salt of 2 with 1-chloro-2,3,5-tri-O-benzyl-α-D-arabinofuranose ( 8 ) gave N-7 and N-9 glycosylated products 13 and 9 , respectively. Debenzylation of 9 with boron trichloride at ?78° gave the versatile intermediate 2-amino-6-chloro-9-β-D-arabinofuranosyl-purine ( 14 ) in 62% yield. Direct treatment of 14 with sodium hydrosulfide furnished ara-6-thioguanine ( 16 ). Alkaline hydrolysis of 14 readily gave 9-β-D-arabinofuranosylguanine (araG, 17 ), which on subsequent phosphorylation with phosphorus oxychloride in trimethyl phosphate afforded araG 5′-monophosphate ( 18 ). 相似文献
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A clean aqueous Kröhnke reaction process has been accomplished via a one-pot procedure of 2-acetylpyridine with aromatic aldehyde and ammonium acetate under microwave irradiation or conventional heating conditions. This method is convenient, economic and environmental friendly. 相似文献
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A simple glycosylation strategy employing only allyl glycosides is described. In a one-pot fashion, an allyl glycoside is first isomerized to the reactive 1-prop-en-yl glycoside intermediate, which subsequently undergoes glycosylation with a glycosyl acceptor, promoted by NIS at room temperature. 相似文献
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Atropisomerization of 1,1′:5′,1″-ternaphthalene-2,2′,6′,2″-tetrol (TERNOL) is very fast under basic conditions. The stereochemical instability is attributed to the nature of oxide anion of the central 2,6-naphthodiol moiety. Ring-closing metathesis of 7,7″-diallyloxy TERNOL results in intramolecular tethering in a high yield, which intrinsically inhibits the rapid isomerization. Bidentate sites in the tethered TERNOL are proved to have enough structural flexibility as an axial chiral ligand. 相似文献
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[reaction: see text] A series of 2-bromo- and 2-iodo-galactopyranosyl acetates and trichloroacetimidates were evaluated as glycosyl donors for the synthesis of 2-deoxygalactopyranosides. The best selectivity for the beta-glycosidic linkage was achieved by using 6-deoxy-3,4-carbonate-protected galactosyl donors. 相似文献
18.
[reaction: see text] Thioglycosides of natural monosaccharides are readily converted into their corresponding chlorides by diphenylchlorosulfonium chloride. This reagent can likewise effect the conversion of the more stable 4-chlorophenylthio 2-deoxy-2-fluoroglucose derivatives into chloride glycosyl donors. On the basis of this activation strategy, it was possible to assemble unnatural oligosaccharides composed of 2-fluorodeoxy sugars. 相似文献
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