共查询到20条相似文献,搜索用时 31 毫秒
1.
A.A.Leslie Gunatilaka Subramaniam Sotheeswaran H.T.Badra Sriyani Eric S. Waight 《Tetrahedron letters》1982,23(29):2987-2990
Hermonionic acid and its decarboxylated product have been isolated from . 13C NMR spectral and chemical evidence indicate that hermonionic acid is 2-0-[2-(3-methylbut-2-enyl)-3-methoxy- 4-hydroxy-5-(3,7-dimethylocta-2,6-dienyl]-4-methoxy-5-(3-methylbut-2-enyl-6-hydroxybenzoic acid. The previously assigned dienone structure for this acid is incorrect. 相似文献
2.
Upasiri Samaraweera Subramaniam Sotheeswaran M. Uvais S. Sultanbawa 《Tetrahedron letters》1981,22(50):5083-5086
Calozeylanic acid has been isolated from the bark of three species: (= ), and . Its structure has been established as 2(R),3(R)-2,3-Dimetyl- 5-hydroxy-6-(3-methylbutanyl)-6-(3,7-dimethylocta-3,6-dienyl)-7-oxo-8- (2-carboxy-1-phenylethyl)-2,3,6,7-tetrahydrobenzo-4-pyrone. 相似文献
3.
Synthesis of the two isomers , of the mono coenzyme A ester of o-succinylbenzoic acid (, OSB, i.e. 4-(2-carboxyphenyl)-4-oxobutanoic acid) and enzymic conversion of , to 1,4-dihydroxy-2-naphthoic acid shows that as opposed to previous assumptions the “aliphatic” rather than the “aromatic” carboxyl group in o-succinylbenzoic acid is activated during vitamin K2 biosynthesis in Escherichia coli and Mycobacterium phlei. 相似文献
4.
The synthesis of - and -N-(4-amino-3, 3-dimethyl-2-hydroxybutyryl)- β-alanine () is described. Compound is an analog of pantothenic acid in which the 4′-hyroxy group is replaced by amino group. The synthetic sequence leading to involved the synthesis L-4-amino-3,3-dimethyl-2-hydroxybutyric acid and its resolution. Coupling of N-benzyloxycarbonyl N-hydroxysuccinimide ester () with β-alanine and followed by removal of the protecting group gave . 相似文献
5.
()-5-Hydroxy-6--8,11,14--eicosatetraenoic acid (5-HETE) (1) and its enantiomer are readily available by a chemical synthesis from arachidonic acid which includes a chromatographic separation of diastereomeric urethanes (3) made from (±)-5-HETE methyl ester and the isocyanate 4 derived from dehydroabietylamine. 相似文献
6.
The aldol reaction of formaldehyde with the dicyclopentylborinyl enolate derived from -(or -) 1-tert-butyldimethylsilyloxy-l-cyclohexylbutan-2-one, followed by desilylation and sodium meta-periodate oxidation, provides -(or -) β-hydroxyisobutyric acid. 相似文献
7.
Tatsuhiko Kanmera Sannamu Lee Haruhiko Aoyagi Nobuo Izumiya 《Tetrahedron letters》1979,20(46):4483-4486
A series of cyclo (Δaminoacyl-L-Ala) () (Δ=α,β-dehydro) were prepared from cyclo(Gly-L-Ala) and corresponding aldehyde, and hydrogenated with Pd black in MeOH. Chiral inductions producing cyclo (L-aminoacyl-L-Ala) () from were 96–99% in the case of L-Aba (2-aminobutanoic acid), L-Val, L-Leu, and L-App (2-amino-5-phenylpentanoic acid) as an L-aminoacyl moiety in . Pure L-Leu, L-Aba, and L-App were synthesized in preparative scale from corresponding through asymmetric hydrogenation and acid-hydrolysis. 相似文献
8.
The structure of a new metabolite isolated from has been shown to be (2S)-4-oxo-1-azabicyclo[3.3.0]octa-5,7-diene-2-carboxylic acid by means of its spectroscopic properties and total synthesis. 相似文献
9.
Reaction of mucochloric and mucobromic acid with (ethoxycarbonylmethylene) triphenyl-phosphorane affords the ethyl ester of (2, 4 -4,5-dichloro- and (2, 4) -4, 5-dibromo-2,4-pentadienoic acid respectively; in the latter case ethyl (2 -5-bromo-2-penten-4-ynoate is formed concomittantly. 相似文献
10.
Michael J. Kukla 《Tetrahedron letters》1982,23(44):4539-4540
Reexamination of the reported (1) synthesis of β-ketosulfoxides from acid chlorides and reagent revealed that the products formed were actually methylthiomethyl esters (). 相似文献
11.
A stereocontrolled synthesis of C16-PAF () from (S)-(?)-malic acid (), employing regioselective hydrogenolytic cleavage of benzylidene acetal derivatives of (S)-1,2,4-butanetriol () with borane-tetrahydrofran complex, is described. 相似文献
12.
Compounds and prepared from eugenol () and safrole () respectively were submitted to ozonation in methanol at 0°C. The 3-alkyl muconic acid dimethyl esters were produced from (~ 45%), while starting from the 3-alkyl muconic acid monomethyl esters were obtained regiospecifically (~ 75%). These latter compounds were transformed (~ 85%) into the 4,4-dialkyl butenolides . 相似文献
13.
Claudine Augé Serge David Christine Gautheron Alain Veyrières 《Tetrahedron letters》1985,26(20):2439-2440
Condensation of 2-acetamido-6--acetyl-2-deoxy-D-mannose with pyruvic acid in the presence of immobilized acylneuraminate pyruvate lyase (2.8 units) gave 5-acetamido-9--acetyl-3,5-dideoxy-D--D--2-nonulopyranos-1-onic acid (-acetyl-9--acetylneuraminic acid) on the 0.3 mmole scale. 相似文献
14.
(+)-Thalictrifoline () has been synthesized from an optically resolved (+)-8-oxo-13-carboxytetrahydroprotoberberine () whose absolute configuration was established by correlation with (+)-. This determines the absolute configurations of (+)-thalictrifoline () as 13R, 14R aria (+)-corydalic acid methyl ester () as 3R, 4R. 相似文献
15.
3-(t-Butoxycarbonyl)-2-(trifluoromethyl)imidazo[1,2-]-pyridine, prepared from trifluoroacetonitrile and pyridinium t-butoxycarbonylmethylide, reacts smoothly with trifluoroacetic acid to provide 2-(trifluoromethyl)imidazo[1,2-]pyridine-3-carboxylic acid, which gives 2-(trifluoromethyl)imidazo[1,2-]-pyridine when heated. 3-Cyano-2-(trifluoromethyl)imidazo[1,2-]pyridine can be obtained treatment of trifluoroacetonitrile with pyridinium cyanomethylide, which is sufficiently reactive to effect nucleophilic displacement of fluorine from pentafluoropyridine under mild conditions [→pyridinium cyano(tetrafluoro-4-pyridyl)methylide]. 相似文献
16.
The α-anions of 2-substituted 1,3-dioxolan-4-ones derived from chiral mandelic and lactic acid (, ; ; , ) were alkylated with high stereoselectivity. The products formed were hydrolysed to α-hydroxy acids with 65–85% e.e. ((S)(+)-,,, (R)(–)-). 相似文献
17.
Françoise Barrière Jean-Claude Barrière Derek H.R. Barton Jeanine Cleophax Alice Gateau-Olesker Stephan D. Géro Fatemeh Tadj 《Tetrahedron letters》1985,26(26):3121-3124
A cyclopentanoid building block has been synthesized in “one pot” cyclization process from epoxides - (which are readily accessible from (R,R)-(+) tartaric acid) with the carbanion derived from phenylthioacetonitrile (PhS-CH2-CN). 相似文献
18.
Peter C. Cherry Derek N. Evans Christopher E. Newall Nigel S. Watson Peter Murray-Rust Judith Murray-Rust 《Tetrahedron letters》1980,21(6):561-564
1,4-Addition of sulphur nucleophiles to the diene () derived the pen-2-em () from clavulanic acid provides the thiadeoxa analogues (–). X-ray analysis of the ester () shows the thermodynamically stable isomers to have the same relative stereochemistry as clavulanic acid. 相似文献
19.
Structure of an alkaline hydrolysis product of heavenly blue anthocyanin was determined to be -4-0-(6-0-(-3-0-(β-D-glucopyranosyl)caffeyl)-β-D- glucopyranosyl)caffeic acid (). 相似文献
20.
A six-step synthesis is reported of -3-amino-2-piperidone-6-carboxylic acid from -homoserine lactone and the --butyl ester on -benzyloxycarbonylaminomalonic acid. Evidence of chiral integrity is discussed. 相似文献