New Cyclodimerization Reaction of (3,5-Di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetic Acid

2001 ◽  
Vol 66 (8) ◽  
pp. 1250-1256 ◽  
Author(s):  
Peter Nesvadba ◽  
Piotr Rzadek ◽  
Günther Rist
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Structure Elucidation ◽  
Methyl Esters ◽  
Tert Butyl ◽  
Isomeric Methyl

(3,5-Di-tert-butyl-4-oxocyclohexa-2,5-dienylidene)acetic acid 1a underwent on heating a new cyclodimerization reaction affording a 1 : 1 mixture of the racemic cis- and trans-isomeric lactone-acids 2. The decisive structure elucidation of 2 was carried out after its mild esterification with diazomethane and separation of the racemic isomeric methyl esters 3a and 3b. The attempted esterification of 2 with methanol and sulfuric acid gave only the methyl diarylacetate 4. In contrast to 1a, which contains the carboxylic acid functionality no cyclodimerization was observed with the corresponding methyl ester 1b or nitrile 1c.

Improved synthesis of anti-sesquinorbornene

1984 ◽  
Vol 62 (9) ◽  
pp. 1840-1844 ◽  
Author(s):  
Karl R. Kopecky ◽  
Alan J. Miller
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Lead Tetraacetate ◽  
Carboxyl Group ◽  
Silver Acetate ◽  
Benzenesulfonyl Chloride ◽  
Methoxide Ion ◽  
Hydrolysis Of ◽  
Monomethyl Ester

Treatment of methyl hydrogen decahydro-1,4:5,8-exo,endo-dimethanonaphthalene-4a,8a-dicarboxylate with lead tetraacetate in benzene – acetic acid replaces the carboxyl group by an acetoxy group. Hydrolysis of this product with 25% sulfuric acid at 130 °C forms 8a-hydroxydecahydro-1,4:5,8-exo,endo-dimethanonaphthalene-4a-carboxylic acid 10. The reaction between 10 and benzenesulfonyl chloride in pyridine containing triethylamine at 95 °C produces anti-sesquinorbornene 1 in 34% yield. In the absence of triethylamine 1 is converted to the hydrochloride. The iodohydroperoxide of 1 is converted by silver acetate at 0 °C to the diketone in a luminescent reaction. The 1,2-dioxetane could not be isolated. Decahydro-1,4:5,8-exo,exo-dimethanonaphthalene-4a,8a-dicarboxylic anhydride is converted slowly by methoxide ion in methanol at 150 °C to the monomethyl ester which then undergoes demethylation. The isomeric exo,endo anhydride undergoes reaction readily with methoxide ion at 80 °C.

Synthesis of Optically Active Hydroxyalkyl Cycloheptatrienes: A Key Step in the Total Synthesis of 6,11-Methylene-LXB4

Synlett ◽  
2020 ◽  
Vol 32 (01) ◽  
pp. 45-50
Author(s):  
Udo Nubbemeyer ◽  
Analuisa Nava ◽  
Lukas Trippe ◽  
Andrea Frank ◽  
Lars Andernach ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Total Synthesis ◽  
Structure Elucidation ◽  
Butyl Ester ◽  
Optically Active ◽  
Chiral Hplc ◽  
Reaction Conditions ◽  
Acid Product ◽  
Tert Butyl ◽  
Nabh4 Reduction

AbstractStarting from methyl cycloheptatrienyl-1-carboxylate, 6-acylation was successfully achieved employing glutaryl chloride in the presence of AlCl3 under controlled reaction conditions to furnish keto carboxylic acid product. After protection of this keto carboxylic acid as tert-butyl ester, reagent-controlled enantioselective reductions delivered configuration-defined methyl-6-hydroxylalkyl cycloheptatriene-1-carboxylates with up to 80% ee. Whereas simple NaBH4 reduction of the keto carboxylic acid and subsequent lactonization afforded a methyl-6-tetrahydropyranonyl cycloheptatriene-1-carboxylate. Resolution using chiral HPLC delivered the product enantiomers with up to >99% ee Finally, ECD analyses enabled structure elucidation. The products are used as key intermediates in enantioselective 6,11-methylene-lipoxin B4 syntheses.

Juvenile Hormone Analogs in Conifers. II. Isolation, Identification, and Biological Activity of cis-4-[1′(R)-5′-Dimethyl-3′-oxohexyl]-cyclohexane-1-carboxylic Acid and (+)-4(R)-[1′(R)-5′-Dimethyl-3′-oxohexyl]-1-cyclohexene-1-carboxylic Acid from Douglas-fir Wood

1974 ◽  
Vol 52 (7) ◽  
pp. 1192-1199 ◽  
Author(s):  
I. H. Rogers ◽  
J. F. Manville ◽  
T. Sahota
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Juvenile Hormone ◽  
Methyl Esters ◽  
Petroleum Ether Extract ◽  
Douglas Fir ◽  
Ether Extract ◽  
Biological Assays ◽  
Hormone Analogs ◽  
Derivatives Of

The petroleum ether extract from the whole-wood meal of a number of British Columbia Interior-Intermediate variety Douglas-fir trees have yielded two carboxylic acids (+)-todomatuic acid (3b) and cis-dihydrotodomatuic acid (4b) which as their methyl esters are potentially useful juvenile hormone analogs. These compounds possess the R,R and R stereoconfigurations, respectively. The configuration at C-1′ is opposite to that reported by others for "(+)-juvabione" isolated from Abiesbalsamea grown in Czechoslovakia. Whereas (+)-juvabione naturally occurs as and is the methyl ester of (+)-todomatuic acid (4b), in this variety of Douglas-fir these compounds appear as the free acids. Results of biological assays on certain insects indicate that the methyl ester derivatives of these acids are effective ovicides and juvenilizing hormones.

scholarly journals Isolation of oligomers of 5,6-dihydroxyindole-2-carboxylic acid from the eye of the catfish

1974 ◽  
Vol 143 (1) ◽  
pp. 207-217 ◽  
Author(s):  
Shosuke Ito ◽  
J. A. Colin Nicol
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Methyl Esters ◽  
Tricarboxylic Acid ◽  
Oxidation Products ◽  
Molecular Weight Determination ◽  
Mushroom Tyrosinase ◽  
Natural Pigment ◽  
Elemental Analyses ◽  
Tapetum Lucidum

The reflecting material of the tapetum lucidum of the sea catfish (Arius felis) was chromatographed on Sephadex LH-20 in methanol–dimethyl sulphoxide–formic acid. Two components were present: one, showing an absorption maximum at 330nm, was tapetal pigment; the other, at 257nm, was an associated nucleoside. The tapetal pigment was extracted in methanol–HCl and isolated by adsorption chromatography on Sephadex LH-20. It yielded a methoxy methyl ester on treatment with diazomethane, and permanganate oxidation gave pyrrole-2,3,5-tricarboxylic acid. From the information provided by u.v. and i.r. spectra of the pigment and its methoxy methyl ester, from elemental analyses and from the oxidation products, we suggest that the tapetal pigment is derived from oxidative coupling of 5,6-dihydroxyindole-2-carboxylic acid. A molecular-weight determination and chromatography of the methoxy methyl ester indicate that the pigment is a mixture of oligomers, among which the tetramers probably predominate. We consider that the monomers are joined mainly by C-C linkages at positions 4 and 7. A synthetic pigment having spectral properties nearly identical with those of the natural pigment was prepared by enzymic oxidation of 5,6-dihydroxyindole-2-carboxylic acid with mushroom tyrosinase. The identity of the tapetal pigment with the synthetic pigment was further confirmed by comparing u.v. and i.r. spectra of their methoxy methyl esters. Formation of the tapetal pigment from tyrosine and relationships of the tapetal pigment to melanin are discussed.

A useful method for preparation of carboxylic acids from terminal alkynes

1983 ◽  
Vol 61 (10) ◽  
pp. 2423-2424 ◽  
Author(s):  
Suzanne R. Abrams
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Chain Length ◽  
Good Yield ◽  
Terminal Alkynes ◽  
Terminal Acetylenes ◽  
Long Chain ◽  
Acetic Acids

Substituted acetic acids can be prepared in good yield (50–80%) from terminal acetylenes of the same chain length. The alkyne is first converted to the thiophenyl ether, which is treated without purification with mercuric sulfate in acetic acid and 2 N sulfuric acid affording the carboxylic acid. The method is particularly useful in the synthesis of long chain ω-hydroxyalkanoic acids.

Confirmation of Chlorophenoxy Acid Herbicide Residues by Transesterification

1971 ◽  
Vol 54 (2) ◽  
pp. 343-345
Author(s):  
George Yip
Keyword(s):  
Gas Chromatography ◽  
Sulfuric Acid ◽  
Methyl Ester ◽  
Electron Capture ◽  
Organic Phase ◽  
Methyl Esters ◽  
Transesterification Reaction ◽  
Acid Water ◽  
Propyl Esters ◽  
Chlorophenoxy Acids

Abstract Low level residues of 5 chlorophenoxy acids (MCP, 2,4-D, 2,4,5-TP, 2,4,5-T, and 2,4-DB) can be easily confirmed by a transesterification reaction in which the methyl esters are converted to the propyl esters. An aliquot of the methyl ester is heated 5 min with n-propanol and sulfuric acid. Water is added and the organic phase is analyzed by either electron capture or microcoulo metric gas chromatography. A fruit sample fortified with 0.02 ppm 2,4,5-T illustrates the usefulness of the procedure.

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