Acid Γ-lactones Research Articles

3-Alkyl-1,2-cyclopentanediones by Negishi cross-coupling of a 3-bromo-1,2-cyclopentanedione silyl enol ether with alkylzinc reagents: an approach to 2-substituted carboxylic acid γ-lactones, homocitric and lycoperdic acids

Negishi cross-coupling of the silyl-protected 3-bromoenol of 1,2-cyclopentanedione with primary and secondary alkylzinc reagents using Pd-catalysts affords 3-alkyl substituted 1,2-cyclopentanediones in good yield. The method was applied to obtain 3-methylalkoxycarbonyl- and 3(2-Boc-aminoethyl)-alkoxycarbonyl-1,2-cyclopentanediones—homocitric and lycoperdic acid precursors. Homocitric and lycoperdic acids were synthesized using asymmetric oxidation with the Ti(OiPr)4/tartaric ester/tBuOOH complex in two steps from the obtained precursors.

Asymmetric synthesis of 2-alkyl-substituted 2-hydroxyglutaric acid γ-lactones

3-Alkyl-1,2-cyclopentanediones 1 are transformed into 2-alkyl-2-hydroxyglutaric acid γ-lactones 3 in up to 83% isolated yields and up to 96% ee, affording a simple access to many bioactive compounds, including diacylglycerol lactones (DAG-lactones).

Deux nouvelles acetogenines monotetrahydrofuranniques cytotoxiques: L'annomonicine et la montanacine

The structures of annomonicin 1 and montanacin 2, two novel monotetrahydrofuran fatty acid γ-lactones (acetogenins) isolated from Annona montana (Annonaceae), were determined by spectral analysis. Cytotoxic activities were mesured against L1210, P388 and MDA-MB231 cell lines.

(±)-erythro-γ,δ-Dihydroxycarboxylic Acid Lactones from a β-Lithiopropionate Equivalent and α-Chloroaldehydes

Reaction of β-ethylthio-β-lithioacrylate with α-chloroaldehydes furnished predominantly the erythro products I, which were isolated as γ-lactones; At room temperature intermediates I are transformed into the (±)-erythro-γ,δ-dihydroxycarboxylic acid γ-lactones. Raney nickel treatment provided interesting natural γ-lactone derivatives

ChemInform Abstract: Enantioselective Synthesis of α‐Hydroxythioacetals by the Baker′s Yeast Reduction of α‐Ketothioacetals.

AbstractDie cyclischen Acyldithioacetale (I) lassen sich mit Bäcker‐ Hefe (Saccha romyces cerevisiae) in hoher optischer Reinheit zu den Hydroxyalkyldithioacetalen (II) reduzieren.

ENANTIOSELECTIVE SYNTHESIS OF α-HYDROXYTHIOACETALS BY THE BAKER’S YEAST REDUCTION OF α-KETOTHIOACETALS

Abstract Asymmetric reduction of a-ketothioacetals was achieved by fermenting baker’s yeast to afford optically pure α-hydroxythioacetals which play as equivalents of valuable α-hydroxy aldehydes. The utility of the present method was demonstrated in the stereo-selective syntheses of (4S,5S)- and (4S,5R)-4,5-dihydroxydecanoic acid γ-lactones from (S)-(−)-1-(1,3-dithian-2-yl)-1,4-butanediol.

The enantiospecific synthesis of (4S,5R)-and (4S,5S)-4,5-dihydroxydecanoic acid γ-lactones, proposed autoregulators from [formula omitted

Both the (4S,5R)- and (4S,5S)-isomers of 4,5-dihydroxydecanoic acid γ-lactone, natural products and proposed autoregulators of Streptomyces Griseus, have been synthesised directly and in high yield from D-ribose via a common intermediate.

The reactions of norbornyl-type cations derived from the reaction of silver toluene-4-sulphonate with 3-substituted 5-iodonorbornane-2,6-lactones

A series of 3-phenyl- and 3-methyl-substituted 6-endo-hydroxy-5-exo-iodonorborn-2-endo-ylcarboxylic acid γ-lactones and the corresponding acetic acid δ-lactones have been prepared, and their reaction with silver toluene-4-sulphonate studied in acetonitrile solution. In each case the products formed have been isolated and identified, and shown to be derived from the initially formed norobornyl-type cation or the cation derived from Wagner–Meerwein rearrangement. The normal reaction of these cations is capture by toluene-4-sulphonate anion, but in certain cases the cations lose a proton to give an unsaturated or nortricyclene lactone. 3-exo-Substituents reduce the extent of the Wagner–Meerwein rearrangement to a varying degree.

ChemInform Abstract: SYNTHESIS OF ASCARYLOSE FROM 3,6‐DIDEOXY‐L‐ERYTHRO‐HEXOS‐2‐ULOSE

AbstractDie nach einer Vorschrift von E1Khadem et al (Carbohyd.

Synthesis of ascarylose from 3,6-dideoxy-L-erythro-hexos-2-ulose

1. A novel synthesis of 3,6-dideoxy-L-arabino-hexose from L-rhamnose has been performed. 2. The γ-lactones of 3,6-dideoxy-L-arabino- and L-ribo-hexonic acids have been prepared and the13C NMR spectra of aldonic acid γ-lactones have been analyzed.

The lead tetraacetate reaction of alcohols containing a small ring. Part II. Cyclobutane‐methanols and cyclopropane‐ethanols

AbstractThe leadtetraacetate and lead tetraacetate/metal chloride oxidations of cyclobutane‐methanol, cyclopropane‐ethanol and the corresponding α, α‐diniethyl alcohols have been investigated and compared with the oxidative reactions of cyclobutane‐carboxylic acid, cyclopropane‐acetic acid and 4‐pentenoic acid, performed with the same reagents and under similar conditions. It was found that alcohol β‐fragmentation and acid decarboxylation follow a remarkably similar mechanistic course, affording comparable results when the substrates are of the same structural type (1, 2 and 5; 3, 4 and 6) or are converted to the same intermediate alkyl radical fragments (3, 4, 6 and 7). In addition, cyclization products formed from cyclopropane‐ethanol (dihydropyran derivative 31) and 4‐penteuoic acid (γ‐lactones 38) have been isolated and identified.

ChemInform Abstract: PHOTOCHEMICAL ENOLIZATION OF ORTHO‐ALKYLBENZALDEHYDES

AbstractDie o‐Alkylbenzaldehyde (I) reagieren beim Belichten mit einer Quecksilberhochdrucklampe in Benzol mit Acetylendicarbonsäureester (III) über die Enolzwischenstufen (II) zu den Naphthalinderivaten (IV).

Circular Dichroism of Borate Complexes of Aldonic Acid γ-Lactones and Its Application to the Stereochemistry of Vicinal cis-Hydroxyl Groups in Lactone Rings

A method is reported, by chelate formation between borate ion and vic.-cis diols, to determine the configuration at Cβ in aldonic acid γ-lactones. Chelate formation is detected by red shift and decrease in the molar ellipticity of the CD maximum in borate buffer. It was also detected by the decrease in the rate of hydrolysis of the lactone ring at pH 9, as measured by the decrease in the CD maximum.

Photochemical Enolization of ortho-Alkylbenzaldehydes

Irradiation of o-alkylbenzaldehyde, i.e., o-methylbenzaldehyde and o-benzylbenzaldehyde gave the corresponding enoles, which gave dimethyl naphthalene-2, 3-dicarboxylates, 4-hydroxy-1-phenyl-1, 2, 3, 4-tetrahydronaphthalene-2, 3-dicarboxylic acid γ-lactones and phthalides by reaction with dimethyl acetylenedicarboxylate, maleic anhydride and oxygen, respectively.

THE OXYMERCURATION OF 1,4-↑↑-METHYLENE-Δ5-CYCLOHEXENE-2-CARBOXYLIC ACIDS

The oxymercuration of 1,4-↑↑-methylene-Δ5-cyclohexene-2-↑-carboxylic acid yields two diastereomeric hydroxychloromercurials. Their configurations cannot be specified on the basis of information now available with certainty. The oxymercuration of 1,4-↑↑-methylene-Δ5-cyclohexene-2-↓-carboxylic acid also yields two diastereomers, which are designated as 6-↓-hydroxy-5-↓-chloromercuri-1,4-↑↑-methylenecyclohexane-2-↓-carboxylic acid, γ-lactone and 6-↓-hydroxy-5-↑-chloromercuri-1,4-↑↑-methylenecyclohexane-2-↓-dicarboxylic acid, γ-lactone because the former is more easily deoxymercurated than the latter and because their dipole moments match relatively the corresponding moments of the analogous dicarboxylic acid γ-lactones, the configurations of which have been proved chemically. This is the first instance where two diastereomers of opposite configuration have been shown to be formed in an oxymercuration.