Showing papers on "Diazomethane published in 1969"

Partial asymmetric synthesis of methylenecyclopropanes and spiropentanes

Abstract: Reaction of substituted allenes and diazomethane gives rise to optically active methylenecyclopropane and spiropentane derivatives in the presence of dissymmetric copper chelates, bis[N-(R and S)-α...

Studies on the syntheses of heterocyclic compounds. Part CCCII. Alternative total syntheses of (±)-nandinine, (±)-canadine, and berberine iodide

Abstract: Mannich reaction of 1-(2-bromo-5-hydroxy-4-methoxybenzyl)-1,2,3,4-tetrahydro-6,7-methylenedioxyisoquinoline (IX) gave 12-bromonandinine (II) which was debrominated to afford (±)-nandinine (I). Methylation of (±)-nandinine with diazomethane gave (±)-canadine (III), dehydrogenation of which with iodine afforded berberine iodide (XI).

Studies on L-ascorbic acid derivatives. II. L-Ascorbic acid 3-phosphate and 3-pyrophosphate.

Abstract: Phosphorylation of 5, 6-isopropylidene-L-ascorbic acid with phosphorus oxychloride gave mainly a mixture of four phosphates. Column chromatography on Dowex-1-bicarbonate with a solution of sodium bicarbonate as a developer was found suitable for the separation of these phosphates for the preparative purpose. Consequently, L-ascorbic acid 3-phosphate and 3-pyrophosphate were isolated as the magnesium salts. Treatment of the former with diazomethane, followed by successive amidation and ozonization gave methyl oxamate, and this provided evidence that the starting ester was the 3-phosphate. The latter ester, on treatment with acid or alkali, afforded quantitatively the same product, i.e., L-ascorbic acid 3-phosphate. These facts, together with the elemental analysis and potentiometric analysis, determined the structure of the latter to be L-ascorbic acid 3-pyrophosphate.

A spectroscopic study of the photodecomposition of diazomethane.

Abstract: — The decomposition of diazomethane by photolytic means has been studied both in inert gas matrices near 4°K and in the gas phase near 295°K. The direct detection of the diazomethyl radical, HCNN and DCNN, and evidence for the participation of methanal azine, H2C=-N=CH2, by vibrational spectroscopy proved that both species play a significant role in the decomposition schemes under the conditions of investigation. The present results make possible the reinterpretation of the data from earlier published experiments to conform to these schemes. The isomerisation of diazomethane is also discussed, and evidence is presented for the production of both diazirine and isodiazomethane under certain photolytic conditions, the former by an intramolecular process and the latter by the recombination of the diazomethyl radical with a hydrogen atom. The vibronic absorption spectra of gaseous diazomethane at 295°K are presented, and deductions concerning photochemical processes are drawn.

Cyclitols. XXVIII. Methyl esters of inositol phosphates. The structure of phytic acid

Abstract: Methylation of phytic acid with diazomethane gives a crystalline dodecamethyl ester; a similar crystalline ester was also obtained from scyllo-inositol hexaphosphate. The methyl esters of many myo-inositol polyphosphates can be separated from each other by thin-layer or column chromatography. Phosphate migration occurs when the hydroxyl groups of partially phosphorylated inositols are methylated.

Cycloadditions. Part I. Steric effects in the addition of diazoalkanes to αβ-unsaturated esters

Abstract: The addition of 2-diazopropane to methyl acrylate and its methyl-substituted analogues normally (i.e., when electronic effects are dominant) gives methyl 1-pyrazoline-3-carboxylates, of which those bearing a hydrogen atom at C(3) tautomerise readily to the Δ2-isomers. The orientation of addition is reversed in the reactions of methyl 3-methylbut-2-enoate with 2-diazopropane and diazoethane. Methyl 4,4-dimethylpent-2-enoate undergoes reverse addition with 2-diazopropane, but not with diazoethane or diazomethane. The reversals are attributed to the presence of unfavourable eclipsing interactions in the transition state for normal addition.

Changes in Molecular Weight of Pectin During Methylation with Diazomethane

Abstract: SUMMARY– Acid and enzymatic demethylation procedures suggest that the change in molecular weight during methylation is a result of depolymerization and that a change in the percent methoxyl groups probably has very little effect on the change in molecular weight during methylation or demethylation with pectins having an ester content between 60% and 95%. Samples of a commercially prepared citrus pectin were acid washed, dissolved and neutralized to different levels with dilute NaOH. These samples were treated with isopropanol to yield an open gel-like precipitate, the alcohol was replaced with ether and the pectin treated with diazomethane at < −30°C. The samples methylated to 70%, 85% and 95% had molecular weight values which decreased with increasing degrees of esterification. Molecular weight was determined by measuring the viscosity of a 0.1 % sol in 1 % Calgon.

A contribution to esterification of carboxylic acids for their separation by means of gas chromatography

Abstract: The separation, identification, and determination of carboxylic acids by means of gas chromatography is most satisfactorily undertaken through their esters. A kinetic study was therefore worked out to determine the optimum conditions for esterification of carboxylic acids by means of diazomethane, methylalcohol under catalytic action of boron trifluoride, and trimethylchlorsilane. It was shown by the results obtained that esterification with excessive diazomethane, in the presence of minor quantities of methylalcohol, is in all cases faster than esterification of the same acids by means of methanol under the catalysis of boron trifluoride. For gas chromatographic purposes the classical esterification using methanol and sulphuric acid has proved to be unsuitable, the same applying to the formation of trimethylsilyesters.

Evidence for equatorial approach by diazomethane to the carbonyl group of 5α-3-oxosteroids

Abstract: Comparisons of the diazomethane and Tiffeneau–Demjanov ring expansion reactions on 17β-hydroxy-5α-androstan-3-one and its derivatives have indicated equatorial approach of diazomethane to the C-3 carbonyl and have confirmed that for the corresponding addition of cyanide ion under equilibrating conditions the axial cyano-epimer expected to be favoured thermodynamically is the predominant product

Researches on acetylenic compounds. Part LXVI. Base catalysed interconversions between pent-2-ynoic, penta-2,3-dienoic, and pent-3-ynoic acids—a mechanistic study

Abstract: The sodium salts of pent-2-ynoic (I), penta-2,3-dienoic (II), and pent-3-ynoic (III) acids are interconverted on heating in aqueous sodium hydroxide. The reaction was followed by g.c. analysis of the methyl esters after methylation of the acid mixtures with diazomethane at –70°. Rate and equilibrium constants for the individual steps were obtained, allowance being made for a competing hydration reaction. Solvent isotope effects k(D2O)/k(H2O) for the conversion of (I) into (II), 1·4, and of (II) to (III), 1·6, were found, and are interpreted as evidence for a carbanion intermediate. The isomerisations in deuterium oxide have also been studied by n.m.r., and the observation that pent-3-ynoate underwent deuteriation at C-2 faster than it isomerised to (II) is consistent with a carbanion mechanism for the isomerisation.

A Reinvestigation of the Reaction of α, β-Unsaturated Acid Chlorides with Diazomethane

Abstract: With two equivalents of diazomethane, 3-(5-nitro-2-furyl) acryloyl chloride (Ia) gave 3-diazoacetyl-4-(5-nitro-2-furyl)-1-[3-(5-nitro-2-furyl) acryloyl]-2-pyrazoline (Va) in good yield, which was converted to the corresponding bromide (VIa (X=Br)), chloride (VIa (X=Cl)) and thiocyanate (VIIIa) in the usual methods. To confirm the results described above, cinnamoyl chloride (Ib) was treated with various amounts of diazomethane. With excess, two equivalents of, and an equimolar amount of diazomethane Ib gave 3-diazoacetyl-4-phenyl-2-pyrazoline (IVb), 1-cinnamoyl-3-diazoacetyl-4-phenyl-2-pyrazoline (Vb) and the mixture of Vb and 3-chloroacetyl-1-cinnamoyl-4-phenyl-2-pyrazoline (VIb) respectively. Furthermore, the same mixture of Vb and VIb was obtained by the treatment of IVb with an equimolar amount of Ib. Antimicrobial activities of nitrofuran derivatives are listed in the table.

Photolytic synthesis of methyl sterculate containing mixture from methyl stearolate and diazomethane

Abstract: A method for synthesis of a mixture containing methyl sterculate is described. The presence of the cyclopropene compound was verified by Halphen Test, infrared absorption and the effect on fatty acid distribution in egg yolks produced by hens consuming the synthetic product.

Methyl isocyanate as a contaminant in the diazomethane prepared from nitrosomethylurea

Abstract: Ethereal diazomethane solutions prepared from nitrosomethylurea contain varying amounts of methyl isocyanate, the presence of which may cause undesirable side reactions

1,3-Cycloaddition reactions of the para-bonded valence isomer of a substituted benzene: hexafluorobicyclo[2,2,0]hexa-2,5-diene as a dipolarophile, and phenyl azide and diazomethane as dipoles

Abstract: The para-bonded valence isomer of hexafluorobenzene is a good dipolarophile and reacts readily with phenyl azide and diazomethane.

Novel dibasic acid compounds and means for the production thereof

Abstract: 1,182,518. Aspartic acid derivatives. PARKE, DAVIS & CO. 1 Nov., 1968, No. 51867/68. Heading C2C. [Also in Division A2] Novel compounds of Formula I wherein one of R 1 and R 2 is the L-form of a group of formula and the other of R 1 and R 2 is H, C 1-4 alkyl or C 1-4 alkoxy and M is H or a salt forming cation and acid addition salts of the dibasic compounds are prepared by hydrolysing the corresponding compound of Formula I above, wherein one of R 1 and R 2 is a group of formula wherein Z is a group hydrolysable to a carboxyl group optionally with or followed by salt formation or exchange. Intermediate alkyl esters of the above Formula I (Z=-COO alkyl) are prepared by reduction of a mixture of an appropriately substituted-N- [p - aminobenzoyl] - L - aspartic acid dialkyl ester and a compound of Formula I, wherein one of R 1 and R 2 is cyano which has itself been prepared either by diazatization of the compound, wherein one of R 1 and R 2 is amino followed by treatment with an alkali metal cyanide or by condensation of guanidine with the appropriately substituted α-(cyanophenyl)-#-alkoxyacrylonitrile to form the pyrimidine. α - (3(4) - Cyano - 4(3) - R - phenyl)-#- alkoxyacrylonitrile, where R is H, alkoxy or alkyl is prepared by action of either diazomethane or an alkyl orthoformate on the corresponding α- cyano - α - 3(4) - cyano - 4(3)R - phenyl acetaldehyde which is prepared by action of the corresponding acetonitrile with ethyl formate and sodium alkoxide. 4 - Cyano - 3 - methylphenylacetonitrile is prepared by action of NaCN on the methanesulphonate ester of 4 -{hydroxymethyl) - o - tolunitrile which is prepared by action of methanesulphonyl chloride on the 4-(hydroxymethyl)-otolunitrile obtained by KBH 4 /LiCl reduction of 4-cyano-m-toluic acid methyl ester prepared by action of CuSO 4 .5H 2 O followed by KCN on diazotized 4-amino-m-toluic acid ester. 3 - Cyano - 4 - methoxyphenylacetonitrile is prepared by action of NaCN on 3-cyano-4-methoxybenzyl chloride prepared by action of thionyl chloride on 3-cyano-4-methoxy-benzyl alcohol itself prepared by reduction of methyl 3-cyano-4- methoxybenzoate which is prepared by action of cuprous cyanide on 3-bromo-4-methoxybenzoic acid methyl ester. The novel compounds have bacteriostatic and antimetabolic properties.