D-APIOSE

1958 ◽  
Vol 36 (3) ◽  
pp. 480-485 ◽  
Author(s):  
P. A. J. Gorin ◽  
A. S. Perlin
Keyword(s):  
Lead Tetraacetate ◽  
Open Chain ◽  
Naturally Occurring ◽  
Chain Form

Naturally-occurring apiose is shown by synthesis to be the D-isomer in the open-chain form. In this synthesis 3-O-benzyl-D-fructose is cyanohydrated and the resulting heptonic lactones are reduced to 3-O-benzyl-2-C-(hydroxymethyl)-D-arabo-hexitol. The latter is oxidized with lead tetraacetate affording 2-O-benzyl-3-C-(hydroxymethyl)-D-glycero-tetrose which, on debenzylation, gives 3-C-(hydroxymethyl)-D-glycero-tetrose (D-apiose).

scholarly journals Specificity of 2-keto-3-deoxygluconate-6-P aldolase for open chain form of 2-keto-3-deoxygluconate-6-P.

1977 ◽  
Vol 252 (10) ◽  
pp. 3486-3492
Author(s):  
C F Midelfort ◽  
R K Gupta ◽  
H P Meloche
Keyword(s):  
Open Chain ◽  
Chain Form

Lead Tetraacetate Oxidations in the Sugar Group. V.1The Rates of Oxidation of Open-Chain Polyalcohols in Dry Acetic Acid Solution2

1944 ◽  
Vol 66 (3) ◽  
pp. 467-468 ◽  
Author(s):  
Robert C. Hockett ◽  
Margaret T. Dienes ◽  
Hewitt G. Fletcher ◽  
Hugh E. Ramsden
Keyword(s):  
Acetic Acid ◽  
Lead Tetraacetate ◽  
Open Chain ◽  
Group V

Bridged Xanthenes. II. An Intramolecular Cycloaddition Route

1975 ◽  
Vol 53 (14) ◽  
pp. 2054-2063 ◽  
Author(s):  
D.J. Bichan ◽  
Peter Yates
Keyword(s):  
Carboxylic Acid ◽  
Acrylic Acid ◽  
Ethylene Glycol ◽  
Structural Features ◽  
Lead Tetraacetate ◽  
Gambogic Acid ◽  
Similar Treatment ◽  
Intramolecular Cycloaddition ◽  
Naturally Occurring ◽  
Acid Lactone

Oxidation of mesitol (8) with lead tetraacetate in acrylic acid followed by gentle heating gives 6-hydroxy-4,6,7-trimethyl-5-oxobicyclo[2.2.2]oct-7-ene-2-carboxylic acid lactone (13), which is considered to be formed via intramolecular cycloaddition of 6-acryloxy-2,4,6-trimethyl-2,4-cyclohexadienone (11). Similar treatment of 4-methylxanthen-3-o1 (7) gives the corresponding bridged xanthene keto lactone 5. Ketalization of this with ethylene glycol, followed by treatment with methylmagnesium iodide, hydrolysis, and pyrolysis gives the bridged xanthene keto ether 4, which possesses many of the structural features of the nucleus of the naturally occurring coloring matters morellin and gambogic acid.

Structure and Acid Strength of Opianic Acid and Its N-Methyl Oxime

1963 ◽  
Vol 16 (4) ◽  
pp. 709
Author(s):  
BH Korsch ◽  
NV Riggs
Keyword(s):  
Carboxylic Acid ◽  
Equilibrium Mixture ◽  
Acid Strength ◽  
Carboxyl Group ◽  
Open Chain ◽  
C 30 ◽  
Chain Form

In water, undissociated opianic acid exists as an equilibrium mixture containing c. 30% of lactol form (Ia) in equilibrium with open-chain form (IIa); the carboxyl group is therefore a stronger acid by c. 0.5 pK units than the measured value (pK 3.06 � 0.03) indicates. Opianic acid N-methyl oxime exists largely as the classical nitrone carboxylic acid (IIIa) in water, and is slightly weaker (pK 2.6-2.7) than opianic acid. Both compounds exist largely as cyclic forms, (Ia) and (IV), respectively, in chloroform.

2-pyrone-4,6-dicarboxylic acid, a catabolite of gallic acids in Pseudomonas species

1982 ◽  
Vol 152 (3) ◽  
pp. 1154-1162
Author(s):  
P J Kersten ◽  
S Dagley ◽  
J W Whittaker ◽  
D M Arciero ◽  
J D Lipscomb
Keyword(s):  
Dicarboxylic Acid ◽  
Gallic Acid ◽  
Gel Filtration ◽  
Sulfhydryl Group ◽  
Hydrolytic Activity ◽  
Major Product ◽  
Open Chain ◽  
Ring Fission ◽  
Single Subunit ◽  
Chain Form

2-Pyrone-4,6-dicarboxylate hydrolase was purified from 4-hydroxybenzoate-grown Pseudomonas testosteroni. Gel filtration and electrophoretic measurements indicated that the preparation was homogeneous and gave a molecular weight of 37,200 for the single subunit of the enzyme. Hydrolytic activity was dependent upon a functioning sulfhydryl group(s) and was freely reversible; the equilibrium position was dependent upon pH, with equimolar amounts of pyrone and open-chain form present at pH 7.9. Since the hydrolase was strongly induced when the nonfluorescent organisms P. testosteroni and P. acidovorans grew with 4-hydroxybenzoate, it is suggested that 2-pyrone-4,6-dicarboxylate is a normal intermediate in the meta fission degradative pathway of protocatechuate. Laboratory strains of fluorescent pseudomonads did not metabolize 2-pyrone-4,6-dicarboxylate, but a strain of P. putida was isolated from soil that utilized this compound for growth; the hydrolase was then induced, but it was absent from extracts of 4-hydroxybenzoate-grown cells that readily catabolized protocatechuate by ortho fission reactions. 2-Pyrone-4,6-dicarboxylic acid was the major product formed when gallic acid was oxidized by purified protocatechuate 3,4-dioxygenase. Protocatechuate 4,5-dioxygenase gave only the open-chain ring fission product when gallic acid was oxidized, but the enzyme attacked 3-O-methylgallic acid, giving 2-pyrone-4,6-dicarboxylic acid as the major product. Cell suspensions of 4-hydroxybenzoate-grown P. testosteroni readily oxidized 3-O-methylgallate with accumulation of methanol.

scholarly journals Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

2016 ◽  
Vol 12 ◽  
pp. 2731-2738 ◽  
Author(s):  
Markus Menke ◽  
Pardha Saradhi Peram ◽  
Iris Starnberger ◽  
Walter Hödl ◽  
Gregory FM Jongsma ◽  
...  
Keyword(s):  
Mass Spectrum ◽  
Double Bond ◽  
Fragmentation Pathway ◽  
Ring Closing Metathesis ◽  
Grubbs Catalyst ◽  
Open Chain ◽  
Naturally Occurring ◽  
Products Analysis ◽  
First Time ◽  
Gular Glands

The contents of the gular glands of the male African reed frog Hyperolius cinnamomeoventris consist of a mixture of aliphatic macrolides and sesquiterpenes. While the known macrolide gephyromantolide A was readily identified, the structure of another major component was suggested to be a tetradecen-13-olide. The synthesis of the two candidate compounds (Z)-5- and (Z)-9-tetradecen-13-olide revealed the former to be the naturally occurring compound. The synthesis used ring-closing metathesis as key step. While the Hoveyda–Grubbs catalyst furnished a broad range of isomeric products, the (Z)-selective Grubbs catalyst lead to pure (Z)-products. Analysis by chiral GC revealed the natural frog compound to be (5Z,13S)-5-tetradecen-13-olide (1). This compound is also present in the secretion of other hyperoliid frogs as well as in femoral glands of male mantellid frogs such as Spinomantis aglavei. The mass spectra of the synthesized macrolides as well as their rearranged isomers obtained during ring-closing metathesis showed that it is possible to assign the location of the double bond in an unsaturated macrolide on the basis of its EI mass spectrum. The occurrence of characteristic ions can be explained by the fragmentation pathway proposed in the article. In contrast, the localization of a double bond in many aliphatic open-chain compounds like alkenes, alcohols or acetates, important structural classes of pheromones, is usually not possible from an EI mass spectrum. In the article, we present the synthesis and for the first time elucidate the structure of macrolides from the frog family Hyperoliidae.

Ring–Chain Tautomerism of Hydroxyketones

1971 ◽  
Vol 49 (23) ◽  
pp. 3799-3806 ◽  
Author(s):  
Josephine E. Whiting ◽  
J. T. Edward
Keyword(s):  
Organic Solvents ◽  
Cyclic Form ◽  
Open Chain ◽  
Chain Form

A study of the u.v., i.r., and n.m.r. spectra of 5-hydroxy-2-pentanone and of 6-hydroxy-2-hexanone has shown that in most organic solvents there is a slight preference for the open-chain form of the hydroxyketone over the cyclic hemiketal. Increase in temperature and in polarity of solvent further favors the open-chain tautomer; in water there was no evidence of any cyclic form.

scholarly journals Flavonoids from Ulex Species

2000 ◽  
Vol 55 (7-8) ◽  
pp. 506-510 ◽  
Author(s):  
Patrícia Máximo ◽  
Ana Lourenço ◽  
Sónia Savluchinske Feio ◽  
Jose Carlos Roseiro
Keyword(s):  
Antifungal Activity ◽  
Open Chain ◽  
Active Compounds ◽  
Cladosporium Cucumerinum ◽  
Naturally Occurring ◽  
Nmr Data ◽  
Bioautographic Method ◽  
C Nmr

Abstract Nine flavonoids have been isolated from Ulex jussiaei and U. minor (Leguminosae). From both species the isoflavonoids ulexin A and the new naturally occurring ulexin B have been identified, together with isoderrone, the pterocarpans (-)-maackiain and (-)-4-methoxymaackiain, and the chalcone isobavachromene. The pterocarpan (-)-2-methoxymaackiain was only present in the first species and the isoflavones isolupalbigenin and ulexone A have been identified in the second one. 13C NMR data of isobavachromene, isolupalbigenin and ulexone A are also included. The antifungal activity of the isolated compounds was tested by the bioautographic method against Cladosporium cucumerinum. The most active compounds were the pterocarpans, the chalcone and the isoflavones with non-hydroxylated open chain prenyl substituents.

Reaction of open-chain conjugated nitrones with lead tetraacetate and

1973 ◽  
Vol 14 (29) ◽  
pp. 2711-2714 ◽  
Author(s):  
Nazar Singh ◽  
Kewal Krishan
Keyword(s):  
Lead Tetraacetate ◽  
Open Chain
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