Showing papers on "Diazomethane published in 1975"
TL;DR: Removal of the ester-protecting group at the C4-carboxyl afforded a select group of cephalosporins with direct halo and methoxy substitution at C3, a number of these compounds are potent antibiotics.
Abstract: The exo-methylene group in esters of 7-acylamido- and 7-amino-3-methylenecephams was ozonized to give 3-hydroxy-3-cephems Conditions are described to effect a selective N-acylation of a 3-hydroxy-3-cephem nucleus ester Vilsmeier reagents converted 7-acylamido-3-hydroxy compounds to 3-halo-3-cephem derivatives Diazomethane converted the 3-hydroxy compounds to 3-methoxy-3-cephem derivatives Removal of the ester-protecting group at the C4-carboxyl afforded a select group of cephalosporins with direct halo and methoxy substitution at C3 A number of these compounds are potent antibiotics
43 citations
34 citations
TL;DR: A humic and a fulvic acid were subjected to four successive hydrolyses with 2 N NaOH solution at 170°C for 3 h as discussed by the authors, and the degradation products were extracted into ethyl acetate, methylated, separated by chromatographic techniques and identified by mass spectrometry and micro-IR spectrophotometry.
26 citations
26 citations
TL;DR: The 3α, 7α, 25-triol triol was identified by mass spectrometry and elemental analysis and was characterized by thin-layer and gas-liquid chromatography as mentioned in this paper.
22 citations
20 citations
17 citations
TL;DR: Extraction of the chlorophenoxy acids 2,4-D and dichlorprop in cereals has been examined by analyzing barley from spraying experiments and results resulted in residues up to ten times lower than found after the combined acid hydrolysis/enzymatic degradation procedure.
Abstract: Extraction of the chlorophenoxy acids 2,4-D and dichlorprop in cereals has been examined by analyzing barley from spraying experiments. A procedure has been set up by combination of acid hydrolysis and enzymatic degradation followed by extraction and clean up on either silica gel or basic aluminum oxide. The final determination is based on reaction with diazomethane and subsequently GLC with ECD. This procedure was compared with two different extraction procedures previously described in the literature. The one comparative procedure uses a mixture of 50% diethyl ether/hexane in presence of sulphuric acid and resulted in residues up to ten times lower than found after the combined acid hydrolysis/enzymatic degradation procedure. In the second comparison a direct extraction was made with a mixture of 65% (v/v) acetonitrile in water. No differences were found between this and the combined acid hydrolysis/enzymatic degradation procedure.
16 citations
TL;DR: In this article, the authors compared the diamagnetic and paramagnetic shielding of the two nitrogens in diazomethane with that of central and terminal nitrogen in other linear triatomic systems [OCN, CNC (isocyano), NNN, NCN (carbodi-imide), and carbon in allene (CCC).
Abstract: Nitrogen-14 n.m.r. measurements of diazirine, diazomethane, diphenyldiazomethane. ethyl diazoacetate, tetra-methyl- and tetraethyl-tetraz-2-ene, and diethyl azodicarboxylate are reported. The diarrsgnetic and paramagnetic shielding of the two nitrogens in diazomethane is compared with that of central and terminal nitrogen in other linear triatomic systems [OCN, CNC (isocyano), NNN, NCN (carbodi-imide), and CCN], and carbon in allene (CCC). The nitrogen shielding is higher in the CH2N2 isomers than in unstrained cis- or trans-diazo-compounds, and for diazirine and molecular N2 it is intermediate between that of the diazomethane nitrogens. These compounds help to define regions in which the absorption of dinitrogen ligands might be expected. The 15N resonances assigned by Bercaw to edge-on and end-on co-ordinated dinitrogen in [Ti(C5Me5)2(N2)] are significantly downfield of the region expected for these, and are in (and downfield of) the region of azo-nitrogen (X–NN–X). An absolute scale for nitrogen shielding is appended, based on DeLucia and Gordy's accurate molecular-beam maser measurement of the spin-rotation constants in NH3, combined with Alei's chemical-shift measurements for 15NH3(g) relative to [15NH4]+(aq).
14 citations
TL;DR: Methylation reactions of 2-amino-5-benzoyl-1,3,4-thiadiazoles 1a-d are reported as a function of alkylating agents as mentioned in this paper.
13 citations
TL;DR: Triethyl orthoformate and boron trifluoride-ether complex convert chroman-4-one into 4-ethoxy-2H-chromen-3-carbaldehyde (II), characterised by conversion into trans-3-(4-hexyl)-1-phenylprop-2-en-1-one (XIV) and thence into the 2phenyl-5H-pyrano[3,2-c][1]benzopyran-1ylium cation (XV).
Abstract: Triethyl orthoformate and boron trifluoride–ether complex convert chroman-4-one into 4-ethoxy-2H-chromen-3-carbaldehyde (II), characterised by conversion into trans-3-(4-ethoxy-2H-chromen-3-yl)-1-phenylprop-2-en-1-one (XIV) and thence into the 2-phenyl-5H-pyrano[3,2-c][1]benzopyran-1-ylium cation (XV). Deethylation of (II) with boron trichloride affords a mixture of 3-hydroxymethylenechroman-4-one (XI) and 3-chloromethylchromone, the latter by a ring-substituent exchange reaction. De-ethylation by cold acids gives (XI) only. Hot acids hydrolyse (XI) to chromanone, air oxidises it to (2-carboxyphenoxy)acetic acid, and silica converts it into 2,3-dihydro- 3,3′-methylenebischromen-4-one (XVIII)via another ring-substitutent exchange reaction followed by an alkylation–hydrolysis sequence. Diazomethane converts (XI) into the 3-methoxymethylene compound (X) which is also obtained by the action of methanol and acid on (II) and therefore represents the thermodynamically stable enol.
TL;DR: The micro determination of stereoisomers of 2-hydroxy and 3-hydroxyl fatty acids has been studied in this paper, where it is possible to determine the enantiomeric composition of microgram amounts of these acids by gas-liquid chromatography of diastereoisomeric derivatives.
Abstract: Publisher Summary This chapter discusses the microdetermination of stereoisomers of 2-hydroxy and 3-hydroxy fatty acids 2-Hydroxy acids and 3-hydroxy acids are intermediates in animal and plant degradation of fatty acids 3-Hydroxy acids are also intermediates in the biosynthesis of fatty acids and 2-hydroxy acids are constituents of brain cerebrosides and of certain waxes It is possible to determine the enantiomeric composition of microgram amounts of these acids by gas-liquid chromatography of diastereoisomeric derivatives 2-Hydroxy acid methyl esters are analyzed as O (–)-menthyloxycarbonyl derivatives About 100 μg of hydroxy acid is methylated with diazomethane and subsequently treated with (–)-menthyl chloroformate 3-Hydroxy acid methyl esters are converted to 2-D-phenylpropionate derivatives About 100 μg of hydroxy acid is methylated with diazomethane and then treated with 2-D-phenylpropionyl chloride
TL;DR: In this paper, the p -(Phenylmethylisopropylstannyl)benzoic acid was prepared and resolved by fractional crystallisation of its (−)-brucine salt from methanol.
TL;DR: In this paper, 1-substituted butadienes follow in their rate constants of diazomethane cycloaddition a linear free energy relationship with Hammett's σp values, ρ=+4.2.
Abstract: 1-Substituted butadienes (R=CH2, CH3, O, C3H5, CO2CH3, CN) and 2-phenylbutadiene accept diazomethane at the 3, 4-bond yielding 3-vinylpyrazoline derivatives. Tautomerization of the 1-to 2-pyrazolines takes place either at room temperature (R=CO2CH3, CN), on heating (R=C6H5) or on acid catalysis (R=H, CH3, OCH3) ; the 2-pyrazolines are characterized as 1-carbamoyl and 1-nitroso derivatives. 1-Substituted butadienes follow in their rate constants of diazomethane cycloaddition a linear free energy relationship with Hammett's σp values, ρ=+4.2. The rates and orientations are discussed in the light of the recent MO perturbation treatment.
TL;DR: A striking example of nucleoside structure specificity is provided and adds support to the depot storage-enzymic cleavage mode of antileukemic activity of 4-(adamantane-1-carbonyloxy)-1-beta-D-ribofuranosyl-2-pyridinone (3d).
Abstract: Treatment of a methanolic solution of 4-hydroxy-1-beta-D-ribofuranosyl-2-pyridinone (3-deazauridine, 1) with diazomethane gave 2-methoxy-1-beta-D-ribofuranosyl-4-pyridinone (2) and 4-methoxy-1-beta-D-ribofuranosyl-2-pyridinone (3a) in an approximate ratio of 1:2. Analogous treatment of 1 with diazomethane in the presence of stannous chloride dihydrate gave eight detected products including 2, 2-methoxy-1-(2-O-methyl-beta-D-ribofuranosyl)-4-phridinone (4), 2-methoxy-1-(3-O-methyl-beta-D-ribofuranosyl)-4-pyridinone (5), 3a, 4-methoxy-1-(2-O-methyl-beta-D-ribofuranosyl)-2-pyridinone (6a), 4-methoxy-1-(3-O-methoxy-beta-D-ribofuranosyl)-2-pyridinone (7a), 2'-O-methyl-3-deazauridine (6b), and 3'-O-methyl-3-deazauridine (7b). For comparison, the 2'-O-methyl derivatives of 2 )4 and 5) and of 3a (6a and 7a), respectively, were prepared in good overall yields by stannous chloride catalyzed methylation of 2 and 3a. Treatment of 1 with benzyl bromide gave 4-benzyloxy-1-beta-D-ribofuranosyl-2-pyridinone (3b). Stannous chloride catalyzed methylation of 4-pivaloxy-1-beta-D-ribofuranosyl-2-pyridinone (3c) gave the corresponding 2'-O-methyl derivative 6c. These compounds were tested in leukemia L1210 culture and against three bacterial strains and were found to be uniformly inactive. This provides a striking example of nucleoside structure specificity and also adds support to the depot storage-enzymic cleavage mode of antileukemic activity of 4-(adamantane-1-carbonyloxy)-1-beta-D-ribofuranosyl-2-pyridinone (3d).
TL;DR: The mouse uterotropic assay revealed that (R)-zearalanone had no activity but a mixture of (R) and (S) gave approximately the same response as (S), suggesting that ( R) has a synergistic effect on the uterotropic activity of (S).
Abstract: A stereoselective synthetic route to (R)-zearalanone was studied to determine the effect of absolute configuration on uterotropic activity. Starting with the naturally occurring (S)-zearalenone the phenolic groups were converted into their respective benzyl ethers followed by ketalization of the carbon-6 carbonyl function using ethylene glycol to give 3 in high yield. The 14-membered lactone could then be opened without racemization of the carbon-10 position by treatment of 3 with sodium hydroxide in dimethyl sulfoxide to yield 4 which was converted to its methyl ester 5 with diazomethane. The reaction of hydroxy ester 5 with p-toluenesulfonyl chloride in pyridine yielded toluenesulfonic ester 6. The reaction of 6 with tetraethylammonium acetate in refluxing methyl ethyl ketone gave 7. The methyl ester in 7 was hydrolyzed to give 8 which was hydrolyzed in aqueous tetrahydrofuran to yield 9. Hydroxy acid 9 was cyclized with trifluoroacetic anhydride in benzene to yield 10 which was reduced and hydrogeneolyzed to give (R)-zearalanone. The mouse uterotropic assay revealed that (R)-zearalanone had no activity but a mixture of (R) and (S) gave approximately the same response as (S) suggesting that (R) has a synergistic effect on the uterotropic activity of (S).
Patent•
11 Jul 1975
TL;DR: A simple method of preparing benzofurylacetic acids in high yield comprising the Wolff rearrangement of corresponding 5-substituted-3-methyl-2-benzofuroyl diazomethane is described in this paper.
Abstract: PURPOSE: A simple method of preparing benzofurylacetic acids in high yield comprising the Wolff rearrangement of corresponding 5-substituted-3-methyl-2-benzofuroyl diazomethane. COPYRIGHT: (C)1977,JPO&Japio
TL;DR: In this article, N-benzyloxyamino acids were prepared using diazomethane, t-butylacetate with perchloric acid and benzyl chloride with ethyl acetoacetate, respectively.
Abstract: Methyl, t-butyl and benzyl esters of N-benzyloxyamino acids were prepared using diazomethane, t-butylacetate with perchloric acid and benzyl chloride with ethyl acetoacetate, respectively. These protected substrates may be used for the unambiguous synthesis of N-hydroxypeptides.
TL;DR: In this paper, the authors developed a rapid, sensitive and specific method for quantification of serum levels of two antidiabetic sulfonylureas, chlorpropamide (I) and tolbutamide (II).
Abstract: We have developed a rapid, sensitive and specific method for the quantitation of serum levels of two antidiabetic sulfonylureas, chlorpropamide (I) and tolbutamide (II). Thermally stable derivatives of I, II and the major products of metabolism of 11, hydroxytolbutamide and carboxytolbutamide, were prepared. Serum levels of I and II were determined following extraction of acidified serum with ethyl acetate, formation of N-methyl derivatives with diazomethane, and then formation of the N-methyl-N′-tri-fluoroacetyl derivatives with trifluoroacetic anhydride. The derivatized compounds were analyzed by gas chromatography/mass spectrometry, and by GLC using flame ionization detection, and quantitated using the internal standard method.
TL;DR: In the presence of an alcohol, oxalic acid esters undergo diazomethane-catalyzed transesterification as mentioned in this paper, in which they undergo transesterization under mild reaction conditions.
Abstract: In the presence of an alcohol, oxalic acid esters undergo diazomethane-catalyzed transesterification. Under mild reaction conditions, esters of homologous dicarboxylic acids and other polycarboxyli...
01 May 1975
TL;DR: When grown on a malt extract-glucose medium, Aspergillus parvulus Smith (ATCC "169911) produced at least four metabolites detectable on thin-layer plates with ferric chloride spray, which determined the structure of O-methylasparvenone by chemical and spectral means and X-ray crystallographic studies of its monoacetate.
Abstract: When grown on a malt extract-glucose medium, Aspergillus parvulus Smith (ATCC "169911) produced at least four metabolites detectable on thin-layer plates with ferric chloride spray. Two of these metabolities, asparvenone (7-ethyl-3,4-dihydro-4,6,8-trihydroxy-1(2H)-naphthalenone) and O-methylasparvenone (7-ethyl-3,4-dihydro-4,8-dihydroxy-6-methoxy-1(2H)-naphthalenone), were isolated and their structures determined. The structure of O-methylasparvenone was determined by chemical and spectral means and X-ray crystallographic studies of its monoacetate. The structure of asparvenone was deduced by spectral and chemical means and by methylation with diazomethane to O-methylasparvenone.
TL;DR: In this article, a mechanism for the betaine reaction was proposed. But it is not shown how to obtain the methyl ester when the iodide anion is replaced by a weaker nucleophile, tetrafluoroborate.
Abstract: The reaction of diazomethane with 3-carboxy-4-fluorophenyltrimethylammonium iodide (1) affords, not the methyl ester, but the betaine 2-fluoro-5-trimethylammoniobenzoate (2). However, when the iodide anion is replaced by a weaker nucleophile, tetrafluoroborate, the methyl ester is obtained. A mechanism for the betaine reaction is outlined.
TL;DR: In this article, an increase in yields of methylene-insertion products in the reactions of diazomethane with arsenic trichloride and arsenic tribromide were achieved through the use of copper catalysis.
Abstract: Dramatic increases in yields of methylene-insertion products in the reactions of diazomethane with arsenic trichloride and arsenic tribromide were achieved through the use of copper catalysis Mono-and bis-insertion products, XCH2AsX2 and (XCH2)2AsX (X = C1 or Br), but no tris-halomethyl arsines were obtained The success of the procedure depends upon the use of ether solvent reclaimed from previous reactions
TL;DR: In this paper, 1-Pyrazoline is formed by the addition of diazomethane to 2-substituted 3-alkylthioinden-1-ones.
Abstract: 1-Pyrazoline are formed by the addition of diazomethane to 2-substituted 3-alkylthioinden-1-ones, and on pyrolysis they yield the corresponding 2-substituted 4-alkylthio-1-naphthols and 3-alkylthiomethylinden-1-ones. Diazomethane adds less readily to 3-methoxy-2-phenylinden-1-one and decomposition of the resulting pyrazoline yields only 4-methoxy-2-phenyl-1-naphthol which is partially converted into 2-phenyl-1,4-naphthoquinone during work-up.
TL;DR: The title compound is produced when the mercaptobutanoate (10) istreated with methanolic sodium methoxide, when the bis(sulphide)(15) is treated with mercury(II) acetate, and when the sulphoxides are heated in benzene.
Abstract: Acetoxymercury(II)(2S)-3-acetoxymercurio(II)thio-2-{(1S,5R)-3-benzyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]-hept-2-en-6-yl}-3-methylbutanoate (9) is converted by hydrogen sulphide into the mercaptobutanoic acid (11), which readily rearranges to a mixture of 2-(2-benzyloxazol-4-ylcarbonylamino)-3-mercapto-3-methylbutanoic acid (17), (3S)-2,3,4,7-tetrahydro-2,2-dimethyl-6-phenylacetamido-7-oxo-1,4-thiazepine-3-carboxylic acid (19), and (2S,5S,6S)-2-(1-mercapto-1-methylethyl)-6-phenylacetamido-4-oxa-1-azabicyclo[3.2.0]heptane-3,7-dione (21).The mercaptobutanoate (10), derived from the acid (11) and diazomethane, reacts with mercury(II) acetate to to give dimethyl 3,3′-mercurio(II)dithiobis-[(2S)-2-{(1S,5R)-3-benzyl-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]-hept-2-en-6-yl}-3-methylbutanoate](15). Diazomethane transforms the mercaptobutanoate (10) into the methylthio-butanoate (13), which is oxidised to a mixture of sulphoxides (14) by m-chloroperbenzoic acid. Compound (13) is also produced when the potassium salt of the acid (11) is treated with methyl iodide. In dimethyl sulphoxide the potassium salt of the acid (11) isomerises to the potassium salt of the thiazepine (20).The title compound is produced when the mercaptobutanoate (10) is treated with methanolic sodium methoxide, when the bis(sulphide)(15) is treated with mercury(II) acetate, and when the sulphoxides (14) are heated in benzene.
TL;DR: In this article, a novel reaction of diazomethane with N-(1-phenylvinyl)morpholines 1 to form N,N′-(3,4-diaza-1,6-diphenyl-ly3,5-hexatriene-l, 6-diyl)dimorpholines 8 and bis(methylsulfonyl)methane (9) is discussed.
TL;DR: In this article, the by-products were formulated as derivatives of methyl 4,7-anhydro-α-d -heptopyranosid-6-ulose dimethy acetal on the basis of p.m. and i.r. spectral data, by analysis of their mass-spectral fragmentation pattern and by chemical transformations.
TL;DR: In this paper, the reduction of 2-methoxy-1-naphthoic acids with 2.4 equiv. of sodium in liquid ammonia leads to the formation of the 1,4-dihydro compounds.
Abstract: The reduction of 2-methoxy-1-naphthoic acids (1) with 2.4 equiv. of sodium in liquid ammonia leads to the formation of the 1,4-dihydro compounds (2). These reduction products on esterification with diazomethane followed by hydrolysis with dilute mineral acids yield methyl 2-oxotetralin-1-carboxylates (5). This constitutes a satisfactory general method of synthesis of (5).