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1.
Sahar Ben Youssef Job Tchoumtchoua Maria Halabalaki Noureddine Allouche 《Journal of carbohydrate chemistry》2016,35(4):224-237
The use of precipitation followed by acetylation procedures and preparative TLC purification allowed a facile isolation of four carbohydrates from the methanol extract of Pinus halepensis seeds. The isolated oligosaccharides exhibited high degree of purity. They were identified as α-D-galactosyl-(1→1)-myo-inositol nonaacetate (1), α-D-glucosyl-(1→2)-β-D-fructosyl octaacetate (2), α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl undecaacetate (3), and α-D-galactosyl-(1→6)-α-D-galactosyl-(1→6)-α-D-glucosyl-(1→2)-β-D-frutosyl tetradecaacetate (4) and were isolated for the first time from this plant. The 1H and 13C NMR assignments for compounds 2, 3, and 4 were detailed herein for the first time. 相似文献
2.
《Analytical letters》2012,45(4):279-287
Abstract Calibration curves are presented for several different types of amino acids to illustrate the quantitation of these compounds by in situ fluorescence densitometry on thin layer plates. 相似文献
3.
O. I. Kolodiazhnyi D. B. Golokhov S. N. Ustenko 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract NMR and chemical studies have shown that α-halogenoalkyl-phosphines 1 and P-halogenoylids 2 exist as halogenotropic tautoineric systems. The position of the equilibrium depends on the used solvent, temperatures and substituents at the α-carbon atom. For example, the equilibrium 1 2 shifts towards the phosphine from 1 if the substituents at the α-carbon atom are electron-donating (R = H, Me, Pr, i-Pr). These compunds, existing preferably in the phosphine form, undergo typical reactions both for tervalent phosphorus compounds and P-halogenoylids. Tervalent phosphorus compounds, α-halogenoalkylphosphines 1 add sulfur and react with anhydrous HCl to convert into the dichlorophosphines -4. Like the P-halogenoylids, they add alcohols and phenols forming the phosphonium salts 5, 6, react with primary amines and aniline to yield the iminophosphonates 7 They also form the 2-halogenoalkylphosphonates 8 in the reaction with aldehydes. 相似文献
4.
Ahmed Djellal et Abdelhafid Djerourou 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1123-1129
The protection of the hydroxy group of p-cresol 1 by o-silylation gives derivatives 2 and 3 , the methyl group of which can be brominated by NBS. The phase transfer catalysis applied to 4 and 5 is a good way which permits the mild introduction of the allylthio group ( 6 and 7 ). Hydroboration applied to silylated compounds 8 and 9 , followed by methanolysis and hydrolysis leads to target acids 10 and 11 in a good yield. La protection du groupement hydroxy du p-crésol 1 par o-silylation donne les dérivés 2 et 3 ce qui permet de bromer le substituant méthyle par le N-bromosuccinimide (NBS). La catalyse par transfert de phase (CTP) appliquée aux produits 4 et 5 est une bonne méthode pour introduire un groupement allylthio (composés 6 , 7 ). L'hydroboration des composés silylés 8 et 9 , suivie d'une méthanolyse et d'une hydrolyse permet d'accéder aux acides cibles 10 et 11 avec de bons rendements. 相似文献
5.
Abstract Prolonged treatment of tetra-O-acetyl-1, 5-anhydro-hex-1-enitols (“tetra-O-acetyl-hydroxy-glycals”) 3 and 5 with BF3 in CH2Cl2 at RT lead to anomeric mixtures of the title compounds 2 and 4a, the α-anomer 4a dominating. Reaction of 5 gave the higher yields of 4a (71%) and 2 (12%), the results being accounted mechanistic grounds. The same reaction performed in an aromatic solvent, like toluene, gave rise to competing C-alkylation., The ortho and para-tolyl derivatives 6 and 7, also with enone structure, were isolated in a combined maximum yield of 40% from 5. β-Enone 2 was also prepared in moderate yield by thermolysis of β-d-glucopyranose pentaacetate (1). In this case no α-anomer 4a was detected. 相似文献
6.
Sylvie Pochet Patrice Allard Tam Huynh-dinh J. Igolen 《Journal of carbohydrate chemistry》2013,32(3):277-288
Abstract A scheme of asymmetric synthesis of C-glycosyl α-glycines is described. Reductive hydrolysis of 2-deoxy-3,5-di-O-p-toluoyl-β D-erythropentofuranose 1-cyanide (4) in the presence of N,N-diphenylethylenediamine gave the imidazolidine 5, which was converted to 2,5-anhydro-3-deoxy-4,6-di-O-p-toluoyl-β-D-allose (3)by acid hydrolysis. The aldehyde (3), chiralamine, benzoic acid and t-butyl isocyanide four component condensation afforded in good yield two diastereomeric adducts (6a and 6b), which were separated by column chromatography and deblocked to furnish 2-deoxy-β-D-erythropentofuranosyl R and S-glycines (1a) and (1b). 相似文献
7.
Alicia Fernández Cirelli Marcos Sznaidman Lucio Jeroncic Rosa M. de Lederkremer 《Journal of carbohydrate chemistry》2013,32(2):167-176
Abstract Partial benzoylation of l-rhamnono-l,4-lactone (1) gave 2,5-di-O-benzoyl-l-rhamnono-1,4-lactone (2) as the main product. In similar conditions, d-mannono-l,4-lactone (3) gave preferentially 2,5,6-tri-O-benzoyl-d-mannono-l,4-lactone (4). 2,3,5,6-Tetra-O-benzoyl- (5) and 3,6-di-O-benzoyl-d-mannono-1,4-lactone (6) were isolated in low yield from the reaction mixture. The structures of the partially benzoylated compounds 2, 4 and 6 were assigned on the basis of spectroscopic data. 相似文献
8.
Abstract Addition of enol esters to acetylated 1,5-anhydro-D-hex-1-enitols (acetylated-D-glycals) in the presence of a Lewis acid catalyst yields acetylated 3-deoxy-α-D-hex-2-enopyranosyl compounds which can serve as starting materials for the synthesis of other C-(α-D-hexopyranosyl) compounds. 相似文献
9.
Abstract The reaction of N-phenyliminoketenylidenetriphenylphosphorane [a] (1), with 2-benzylidene-1, 3-indandione (2), 1,2-diphenyl-3,4-pyrazolidenedione (3)and/or 5-benzylidene barbituric acid (4) has been investigated. When ylide 1 was allowed to react with compounds 2, 3 or 4 in THF at ambient temp. the corresponding new pyrano-phosphoranylidenes 5, 6 or 7 were obtained. The elemental microanalyses, IR, 1H NMR, 31P NMR and MS data agree with the structure of the cyclic iminophosphoranes by [4+2]-cycloaddition and exclude 4-membered ring structure by [2+2]-cycloaddition. When the Wittig reaction was carried on the pyrano-phosphoranes 5, 6 or 7 using p-nitrobenzaldehyde, the exocyclic olefins together with triphenylphosphine oxide were isolated. 相似文献
10.
Noureddine Raouafi Khaled Boujlel Mohamed Lamine BenKhoud 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1387-1395
The condensation of N1-benzimidazolyl amidines 1 with tris(dimethy- lamino)phosphine leads to the corresponding [1,2a]Benzimidazolo-1,3,5,2-triazaphosphorines 3 . The N2-phosphoroamidine intermediates 2′ are isolated and yielded the corresponding cyclic compounds 4 upon heating. The oxidation by sulfur of the compounds 3 gives the thiooxide derivatives 4 . The structure of these compounds is unambiguously confirmed by IR, 1H, 31P, and 13C NMR spectroscopy and by MS for some products. 相似文献
11.
F. M. Soliman Kh. M. Khalil G. Abd-el-naim 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract The reaction of 1,2-benzo [a] phenazine-8, 9-dione 1 and/or 1,2,3-indantrione 2, with phosphonium ylides has been studied. When 1 was reacted with two molar amounts of methoxy-(3a) and/or ethoxycarbonylmethylenetriphenylphosphorane (3b), in THF, at the reflux temp, for 3 hrs, dimethyl (4a) and/or diethyl 1,2-dihydrobenzo a furo [3,2-h] phenazine-1,2-dicarboxylate (4b), along with triphenylphosphine oxide and triphenylphosphine were obtained. On the other hand, reaction of equimolar amounts of ylides 3 with the red trione 2 in THF at room temp., afforded colourless crys tals of 2′,4′-dihydroxyspiro [indan-2,3′ (2′H)-indeno [1,2-b] pyran]-1,3,5′(4′H)-trione diacetate (5a) or dipropionate (5b), together with triphenylphosphine oxide. Formation of 6-membered dihydro aromatic ring like 5, is considered as a new reaction of phos phoranes. The structure of the new compounds 4 and 5 was confirmed and the reaction mechanisms are discussed. 相似文献
12.
Azaiez Ben Akacha Salim Barkallah Belgacem Baccar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):163-166
Abstract Under the normal conditions, the reaction of hydrazine and methylhydrazine with OO-diethyl 1 oxoalkane phosphonates 1 proceeds by cleavage of the phosphorus-carbon bond and leads to the formation of diethylphosphite 2 and N-acylhydrazide 3 . A procedure has been developed for the synthesis of new primary hydrazone of OO-diethyl 1-oxoalkane phosphonates 4 . A mechanism is proposed. The structure of those compounds 4 was confirmed by NMR and IR spectroscopy. 相似文献
13.
Makoto Kiso Yuji Ogawa Yushun Fujishima Minoru Fujita Shinji Tanaka Akira Hasegawa 《Journal of carbohydrate chemistry》2013,32(4):625-638
Abstract In order to elucidate further the relationship between the composition of the fatty acyl groups in the nonreducing-sugar subunit of bacterial lipid A and its biological activity, 3-O-[(3R)-3-(acyloxy)tetradecanoyl]-2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-4-O-phosphono-D-glucose [GLA-63(R, R) and GLA-64(R, R)], and 3-O-[(3R)-3-(acyloxy)tetradecanoyl]-2-deoxy-4-O-phosphono-2-tetradecanamido-D-glucose [GLA-67(R), GLA-68(R) and GLA-69(R)] have been synthesized. Benzyl 2-[(3R)-3-(benzyloxymethoxy)tetradecanamido]-2-deoxy-4,6-O-isopropylidene-β-D-glucopyranoside (5) and benzyl 2-deoxy-4,6-O-isopropylidene-2-tetradecanamido-β-D-glucopyranoside (6) were each esterified with (3R)-3-dodecanoyloxytetradecanoic acid (1), (3R)-3-tetradecanoyloxytetradecanoic acid (2) or (3R)-3-hexadecanoyloxy-tetradecanoic acid (3), to give 7-11, which were then transformed, by the sequence of deisopropylidenation, 6-O-tritylation and 4-O-phosphorylation, into a series of desired compounds. 相似文献
14.
Abstract Treatment of methyl 3,4-di-O-acyl-2,6-dideoxy-α-D-ribo-hexo-pyranoside 1 or 2 with trimethylsilyl halide leads to the formation of a complex mixture of α-D-ribo-hexopyranosyl halides 3 or 5 together with the educts 1 or 2 as well as their β-anomers 8 or 9. The bromides 3 and 5, suitable for glycosidations, are preferably obtained by reaction of the digitoxose acetate derivatives 6 and 7, respectively, which in turn are prepared from 1 and 2 by mild acetolysis. Further reaction of the halides 3 to 5 with trimethylsilyl halides gives rise to a quantitative formation of the 2,3,6-trideoxy-4-0-acyl-3-halo-α-D -arabino-hexopyranosyl halides 10 to 12. In another reaction sequence starting with the olivose triacetate 20 the formation of 10 via the halide 13 is demonstrated. Structural evidence for the halides 10 to 12 is given by 1H NMR data as well as by analyses of their glycosides 14 to 19. The results support a mechanistic interpretation for the formation of 10 to 12 via a 3,4-acetoxonium ion as the key intermediate obtained from 3 by an SNfi and from 13 and SN2i step. Final conversion into the terminal halodeoxy compounds 10 to 12 proceeds by and SN2 reaction with the halide ion. 相似文献
15.
Abstract The title compound was synthesized in four steps from D-glucono-1,5-lactone. Reduction of 2,4,6-tri-O-benzoyl-3-deoxy-D-arabino-hexono-1,5-lactone (1) with disiamylborane afforded 2,5,6-tri-O-benzoyl-3-deoxy-D-arabino-hexopyranoae (2) which, on debenzoylation, gave 3-deoxy-D-arabino-hexoae (3). Tautomeric equilibrium of 3 was studied by 1H and 13C NMR spectroscopy. 相似文献
16.
Nitrones 2a , 2b obtained from the aldehydes 1a , 1b , are used for the syntheses of the N-ethoxy iminium salts 4a and 4b . In the following procedure 4a and 4b react to several esters of phosphinic acids 6a - 6d . 相似文献
17.
A fews representatives (1b-d) of a novel group of structurally related morphine-antagonist compounds have been prepared in stereochemically homogeneous form. The employed procedures involve O-demethylation either of the corresponding codeine derivatives 2b-d, or those of the N-alkylated analogues 2b-c synthesized from N-demethylthebaine (7a) by means of N-alkylation and subsequent transformations of 7b, d–compounds selected from the resulting functionalized thebaines 7b-exs. 相似文献
18.
Ernst Peter Müller Paul Peringer Roland Aeschimann Thomas Maetzke Walter Petter 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Reaction of the 2-azidoalcohol 1 with 2-phenyl1-1,3,2-dioxaphospholane leads to a 4:1 mixture of the pentacoordinate phosphorane 3 and the diazadiphosphetidine 4. In solution, these compounds are in equilibrium, presumably involving the not detectable iminophosphorane 2. A single X-ray analysis carried out on 3 proves the structure of this type of compound which has been postulated earlier as intermediate in the synthesis of aziridines from azidoalcohols1,2 相似文献
19.
Rajan N. Shah José Baptista Guillermo R. Perdomo Jeremy P. Carver Jiri J. Krepinsky 《Journal of carbohydrate chemistry》2013,32(4):645-660
Abstract Selective acetolysis of methyl 2, 3, 4, 6-tetra-O-benzyl-α-D-manno-pyranoside (2) allows for easy preparation of 1-acetates of 2, 3,4, 6-tetra-O-benzyl (5), 6-O-acetyl-2, 3, 4, tri-O-benzyl-(6), 4, 6-di-O-acetyl-2,3-di-O-benzyl-(7), 3, 4, 6-tri-O-acetyl-2-O-benzyl-(8), and 2, 4, 6-tri-O-acetyl-3-O-benzyl-D-mannopyranoside (9). 8 and 9 formed are separated by preparative HPLC in 30-60g scale. The time course of previously described acetolyses of 3, 4, 6-tri-O-benzyl- 1, 2-O-(1-methoxyethyidene)-β-D-mannopyranose (3), and methyl 2, 3-dt-O-benzyl-4, 6-O-benzylldene-α-D-mannopyranoside (4) giving 9, 1, 2, 6-tri-O-acetyl-3, 4-di-O-benzyl-(10), and 1, 2-di-O-acetyl-3, 4, 6-tri-O-benzyl-(11) α-D-mannopyranose as well 7 have been studied. 相似文献
20.
Suresh Chander Suri Angelica C. Cabrera Edward J. Wucherer Stephen L. Rodgers 《合成通讯》2013,43(5):841-851
A mixture of 1-methyl- and 2-methyl-1,4,4a,8a,-tetrahydro-endo-1,4-methano-naphthalene-5,8-diones ( 2 & 3 ) was chemically transformed into separable methyl substituted tricyclo[5.2.1.02,6]decadienones 7 , 8 & 9 . The structure of 8 & 9 were elucidated via Cope rearrangement of their corresponding allylic alcohols ( 10 & 11 ) to furnish 12 & 13 respectively. 相似文献