Showing papers on "Diazomethane published in 2003"
TL;DR: The results and the analysis of reported data suggest that the outcome of the reaction between a diazoalkane and a late transition metal complex can be anticipated considering steric requirements relevant to eta(1)-C diazos complex formation.
Abstract: PCP ligand (1,3-bis-[(diisopropyl-phosphanyl)-methyl]-benzene), and PCN ligand ({3-[(di-tert-butyl-phosphanyl)-methyl]-benzyl}-diethyl-amine) based rhodium dinitrogen complexes (1 and 2, respectively) react with phenyl diazomethane at room temperature to give PCP and PCN−Rh carbene complexes (3 and 5, respectively). At low temperature (−70 °C), PCP and PCN phenyl diazomethane complexes (4 and 6, respectively) are formed upon addition of phenyl diazomethane to 1 and 2. In these complexes, the diazo moiety is η1 coordinated through the terminal nitrogen atom. Decomposition of complexes 4 and 6 at low temperatures leads only to a relatively small amount of the corresponding carbene complexes, the major products of decomposition being the dinitrogen complexes 1 and 2 and stilbene. This and competition experiments (decomposition of 6 in the presence of 1) suggests that phenyl diazomethane can dissociate under the reaction conditions and attack the metal center through the diazo carbon producing a η1-C bound di...
99 citations
TL;DR: N-Nosyl-alpha-amino acid methyl esters are methylated quantitatively with diazomethane and coupled with N-Fmoc amino acid chlorides to afford the corresponding dipeptides.
Abstract: N-Nosyl-α-amino acid methyl esters are methylated quantitatively with diazomethane. After proper deprotection of the amino function by treatment with the reagent system mercaptoacetic acid/sodium methoxide, the obtained N-methyl amino acid methyl esters are coupled with N-Fmoc amino acid chlorides to afford the corresponding dipeptides. The obtained products do not show any detectable extent of racemization by 1H NMR and HPLC.
47 citations
TL;DR: The discussion focuses on the basic derivatisation reactions used to convert herbicides to derivatives to make them analysable by gas chromatography, and possibly to reduce detection limits and/or increase extraction recovery from aqueous samples.
Abstract: This paper reviews derivatisation processes applied in chromatographic determination of acidic herbicides (with carboxyl and phenol groups), mainly in aqueous environmental samples. The discussion focuses on the basic derivatisation reactions used to convert herbicides to derivatives to make them analysable by gas chromatography, and possibly to reduce detection limits and/or increase extraction recovery from aqueous samples. The reactions are transesterification, esterification, silylation, alkylation, and extractive and pyrolytic alkylation. The reagents used to conduct the reactions are numerous. Diazomethane is a very efficient methylation reagent but explosive and toxic. Methyl iodide also ensures rapid and efficient methylation. Benzyl bromide can be used directly in water but derivatisation yield is low and reproducibility is poor. Butyl chloroformate and dimethyl sulfite can also be used for derivatisation in water, and acetic anhydride can be used for in-situ derivatisation of phenolic herbicides. For increasing selectivity of GC detection pentafluorobenzyl bromide (for ECD) and (2-cyanethyl)dimethyl(diethylamino)silane (for NPD) have been applied. Very characteristic ions are produced in mass spectra if silyl groups are introduced, e.g. by using bis(trimethylsilyl)trifluoroacetamide. Tetramethylammonium, trimethylphenylammonium, tetraalkylammonium, and trimethylsulfonium hydroxides and salts can by used for derivatisation at elevated temperature in the GC injection port. Extractive alkylation is relatively efficient if tetraalkylammonium salts with long chain alkyl groups are used.
43 citations
TL;DR: Chiral bis(oxazoline)-copper(I) complexes were found to be effective catalysts for the enantioselective cyclopropanation reaction of trans-cinnamate esters exploiting an argon flow mediated diazomethane addition method as discussed by the authors.
Abstract: Chiral bis(oxazoline)–copper(I) complexes were found to be effective catalysts for the enantioselective cyclopropanation reaction of trans-cinnamate esters exploiting an argon flow mediated diazomethane addition method. After optimization of the catalyst structure, good yields and enantiomeric excesses were obtained with electron-poor methyl cinnamate derivatives. Sterically demanding esters gave lower yields and enantioselectivities. The correlation between the product enantiopurities and the σ+ values of the aromatic para-substituents was shown to be linear in a Hammet-type plot.
39 citations
TL;DR: A useful serinal derivative, 1,1-dimethylethyl (S)-4-formyl-2,2-dimethyl-3-oxazolidinecarboxylate, is a serinal additive derivative as discussed by the authors.
Abstract: 1,1,-dimethylethyl (S)- or (R)-4-formyl-2,2-dimethyl-3-oxazolidinecarboxylate: A useful serinal derivative
reactant: N-Boc-L-serine
intermediate: N-Boc-L-serine methyl ester
intermediate: 3-(1,1-Dimethylethyl) 4-methyl (S)-2,2-dimethyl-3,4-oxazolidinedicarboxylate
product: 1,1-Dimethylethyl (S)-4-formyl-2,2-dimethyl-3-oxazolidinecarboxylate
Keywords:
acetal (and thioacetal) formation;
acylation;
alkylation, N-alkylation;
alkylation, O-alkylation;
alkylation, O-alkylation;
annulation, heterocyclic-[5];
cyclization, condensation;
esterification, of substituted monobasic acids;
protection, nitrogen;
reduction, CO2R CHO;
toluene;
benzene;
diazomethane, explosive, toxic;
N,N-dimethylformamide, cancer suspect agent;
dioxane, cancer suspect agent;
methyl iodide;
nitrosomethylurethane, warning
28 citations
TL;DR: In this paper, it was shown that the reactions of dimethyl phosphonate with diols to form polyphosphonate oligomers with only methyl phosphonates end groups are plagued by a serious side reaction that forms phosphonic acid end groups.
25 citations
TL;DR: The synthesis of pyrimidine was also achieved via 1,3-dipolar cycloaddition of methyl 2-bromo-3-phenyl-2H-azirine-2-carboxylate with an azomethine ylide as discussed by the authors.
22 citations
TL;DR: In this paper, the authors showed that trimethylsilyl-diazomethane can significantly improve the diastereoselectivities of cyclopropanation catalysts.
22 citations
TL;DR: (S)-3-(tert-butyloxycarbonylamino)-1-diazo-4-phenylbutan-2-one, potential explosive as discussed by the authors, potential explosive.
Abstract: (S)-3-(tert-Butyloxycarbonylamino)-4-phenylbutanoic acid
R Boc-phenylalanine
I (S)-3-(tert-Butoxycarbonylamino)-1-diazo-4-phenylbutan-2-one
P (S)-3-(tert-Butyloxycarbonylamino)-4-phenylbutanoic acid
Keywords:
ketones, monoketones, diazo ketones;
diazo compounds;
carbamates;
acylation;
(s)-3-(tert-butyloxycarbonylamino)-1-diazo-4-phenylbutan-2-one, potential explosive;
triethylamine;
ethyl chloroformate;
diazo compounds;
diazomethane, toxic, explosive;
diazomethane;
carbamates;
acids, substituted, amino acids;
rearrangements;
metal-catalyzed reactions, silver;
silver trifluoroacetate;
trifluoroacetic acid;
esters, of unsubstituted monobasic acids, amino esters;
esters, of substituted monobasic acids, hydroxy esters;
acids, substituted, amino acids;
carbamates
19 citations
TL;DR: In this article, it was shown that N-metallated 9, the kinetic product of the reaction, irreversibly rearranges at high temperature in solution to give the thermodynamically preferred C-lithiated isomer.
Abstract: (Trimethylsilyl)diazomethane (1-H) reacts with nBuLi in THF at elevated temperature to afford (previously reported) 1-Li·3/2THF. However, reaction in hexane/TMEDA at low temperature affords instead the N-lithiate Me3SiCNNLi·TMEDA (9), which is a novel “open” pseudo-cubic tetramer in the solid state. Variable-temperature NMR spectroscopy suggests that N-metallated 9, apparently the kinetic product of the reaction, irreversibly rearranges at high temperature in solution to give the thermodynamically preferred C-lithiated isomer. These observations, supported by DFT calculations, influence our understanding of the reactivity of lithiated diazomethanes towards aryl isothiocyanates, suggesting as they do that previously observed product selectivity in these reactions is critically dependent on temperature control exercised during the process. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
17 citations
TL;DR: In this article, a simple and mild method to prepare α-diazoketones from carboxylic acids is presented, which involves the reaction of carboxyl acids with triphenylphosphine/NBS and subsequent treatment with diazomethane.
TL;DR: In this article, it was shown that Enaminone 5 reacted with potassium cyanide in the presence of 18crown-6 to afford benzyl 4-cyanomethyl-5-oxo-2,5-dihydrofuran-3-ylcarbamate.
Abstract: Benzyl (3S,4E)-4-[(dimethylamino)methylidene]-5-oxotetrahydrofuran-3-ylcarbamate 5 was prepared in 4 steps from L-aspartic acid 1 Acid-catalysed treatment of 5 with amines 6 gave the dimethylamine substitution products 7 Benzyl (3S,4E)-4-[(arylamino)methylidene]-5oxotetrahydrofuran-3-ylcarbamates 7c–n were prepared by parallel solution phase synthesis from 5 and anilines 6c–n in 45–94% yields Enaminone 5 reacted with potassium cyanide in the presence of 18-crown-6 to afford benzyl 4-cyanomethyl-5-oxo-2,5-dihydrofuran-3-ylcarbamate 9 Upon reaction of 9 with nitrile oxide 10 the 1,2,4-oxadiazole derivative 11 was isolated in poor yield, while treatment of 9 with diazomethane 12 furnished the methylation products 13 and 14
TL;DR: In this paper, the reaction of pentacyclo with diazomethane (9a) and 2-diazopropane(9b) gave the 1,3,4-thiadiazolines 12a and 12c, which subsequently were used as precursors of reactive thiocarbonyl ylides 13a,b, respectively.
Abstract: Reaction of pentacyclo[5.4.0.02,6.0 3 , 1 0 .0 5 . 8 ]undecane-8-thione (7) with diazomethane (9a) and 2-diazopropane (9b) afforded the 1,3,4-thiadiazolines 12a and 12c, which subsequently were used as precursors of reactive thiocarbonyl ylides 13a,b, respectively. Diphenyldiazomethane reacted rapidly with 7 to yield thiirane 14c as the final product. When decomposition of 12a or 12c was carried out in the presence of dipolarophiles, such as TCNE, DMAD or N-methylmaleinimide, new cage-functionalized heterocvcles were obtained.
TL;DR: In this article, 2-pyrazolines were obtained by cycloaddition of diazomethane to bis(arylsulfonylethenyl)-sulfones (3) and 1-aryls-ulfonyl-2-styryls-polygonal-2 -stylonylnets (2-Styryls, 2-styloenlethenes) with chloranil.
TL;DR: In this paper, 2H-Pyran-2-ones were transformed with various hydrazines into (E)- or (Z)-α,β-didehydro-α-amino acid (DDAA) derivatives containing a highly substituted pyrazolyl moiety attached at the β-position.
Abstract: 2H-Pyran-2-ones 1 were transformed with various hydrazines into (E)- or (Z)-α,β-didehydro-α-amino acid (DDAA) derivatives 4 (and 7) containing a highly substituted pyrazolyl moiety attached at the β-position. With heterocyclic hydrazines, the products 4 were accompanied also by decarboxylated enamines E-6. In order to separate (E/Z)-mixtures of acids, they were transformed to the corresponding methyl esters 9 and 10 by the application of diazomethane. Catalytic hydrogenation under high pressures with Pd/C as a catalyst resulted in the formation of racemic alanine derivatives 11.
TL;DR: In this paper, the cycloaddition of diazomethane, cyclocondensation of hydrazine hydrate, and cyclopropanation of TMSOI to 1-aroyl-2-styrylsulfonylethenes were studied and different novel products thereby obtained were characterized with spectral parameters.
Abstract: The cycloaddition of diazomethane, cyclocondensation of hydrazine hydrate, and cyclopropanation of TMSOI to 1-aroyl-2-styrylsulfonylethenes were studied and different novel products thereby obtained were characterized with spectral parameters. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:155–159, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10117
TL;DR: The tin(II) chloride catalyzed reactions of diazodiphenylmethane with the cis- and trans-1,2-cyclohexanediols and R,S-1-2-propanediol in 1, 2-dimethoxyethane and the identification of the monodipenylmethyl ethers formed are reported.
TL;DR: Complexed cyclopropyl-3,4-dihydroxyphenylalanine (∇ DOPA) were synthesized by diazomethane cycloprocessanation of the appropriate diene(tricarbonyl)iron complexes linked to azlactones as discussed by the authors.
TL;DR: The cycloaddition of diazomethane to bis(1-aryl-2-propen-1-one) sulfides/sulfones (1/2) and cyclocondensation of 1/2 with hydrazine hydrate has been studied as mentioned in this paper.
TL;DR: The reaction of 3-acetyl-6,6-dimethyltetrahydrothiopyran-2,4-dione with diazomethane furnishes a mixture of 3.
Abstract: The reaction of 3-acetyl-6,6-dimethyltetrahydrothiopyran-2,4-dione with diazomethane furnishes a mixture of 3-acetyl-6,6-dimethyl-4-methoxy-5,6-dihydro-2H-thiopyran-2-one and 3-acetyl-6,6-dimethyl- 2-methoxy-5,6-dihydro-2H-thiopyran-4-one in 2:3 ratio, whereas in reaction with dimethyl sulfate in the presence of potassium carbonate forms a mixture of the same products in 9:1 ratio. In both reactions the overall yield of ethers amounts to 50%. Treating of regioisomeric enol methyl ethers with pyrrolidine, o-toluidine, and allylamine provides the corresponding endocyclic enaminodiketones.
TL;DR: In this paper, the reaction of [o-(trifluoromethyl)phenyl] and [bis(diisopropylamino)phosphino]diazomethane with tetracarbonylbis(μ-chloro)dirhodium(I) ([Rh(CO)2(μ -Cl)]2] affords the monometallic complex 2 at low temperature and the dinuclear complex 3 upon warming to 0 °C.
TL;DR: In this article, the chemical properties of the starting compounds 3-amino-6-chloro-4-phenyl-1H-quinolin-2-one (1) and 3amino,4-methyl-1 H-quinoline-2 -one (2) were investigated.
TL;DR: The 1,3-dipolar cycloaddition of diazomethane to levoglucosenone was found to occur regio-and stereoselectively to form optically active 9,11-dioxa-4,5-diazatricyclo[6.2.1.02,6]undec-4-en-7-one.
Abstract: The 1,3-dipolar cycloaddition of diazomethane to levoglucosenone was found to occur regio- and stereoselectively to form optically active 9,11-dioxa-4,5-diazatricyclo[6.2.1.02,6]undec-4-en-7-one. Levoglucosenone was found to react with methyldiazoacetate to give the 2:1 adduct.
TL;DR: In this article, enolized enol forms of diazo esters with diazomethane were obtained by O-methylation of enol form of DIAZO esters, which undergo heterocyclization into 3,5-disubstituted 4-hydroxypyrazoles.
Abstract: Ethyl 5-aryl-2-diazo-3,5-dioxopentanoates and 1,5-diaryl-2-diazopentane-1,3,5-triones are partially enolized in solutions. By O-methylation of enol forms of diazo esters with diazomethane ethyl 5-aryl-2-diazo-5-methoxy-3-oxopent-4-enoates were prepared. Concurrently with the O-methylation the diazo esters undergo heterocyclization into 3,5-disubstituted 4-hydroxypyrazoles which under the reaction condition suffer O- and N-methylation by excess diazomethane. 3,5-Diaroyl-4-hydroxypyrazoles were also obtained from diazopentanetriones but here triethylamine served as the cyclization reagent.
TL;DR: A simple, efficient and stereospecific approach by the Arndt-Eistert method employing Fmoc-/Boc-alpha-amino acid and 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyl-uronium hexafluorophosphate mixture for the acylation of diazomethane synthesizing the key intermediates FmOC-/ Boc-
Abstract: A simple, efficient and stereospecific approach for the homologation of urethane-protected alpha-amino acids to beta-amino acids by the Arndt-Eistert method employing Fmoc-/Boc-alpha-amino acid and 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyl-uronium hexafluorophosphate mixture for the acylation of diazomethane synthesizing the key intermediates Fmoc-/Boc-alpha-aminodiazomethanes as crystalline solids is described.
Patent•
13 Feb 2003
TL;DR: In this paper, the problem of obtaining a sulfonyl diazomethane compound suitable as a photo-acid generator for chemical amplification-type resist materials, or the like, for making integrated circuits sensitive to radiations including ultraviolet radiation, far-ultraviolet radiation, electron beams, X-rays, excimer laser, γ-rays and synchrotron radiation, was solved.
Abstract: PROBLEM TO BE SOLVED: To obtain a sulfonyl diazomethane compound suitable as a photo-acid generator for chemical amplification-type resist materials, or the like, for making integrated circuits sensitive to radiations including ultraviolet radiation, far-ultraviolet radiation, electron beams, X-rays, excimer laser, γ-rays and synchrotron radiation, to obtain such a photo-acid generator, to obtain such a resist material containing the sulfonyl diazomethane compound, and to provide a method for pattern formation using the resist material. SOLUTION: The sulfonyl diazomethane compound is represented by formula(1)( wherein, R is H or a 1-4C alkyl or alkoxy; G is SO 2 or CO; R 3 is a 1-10C alkyl or 6-14C aryl; (p) is 1 or 2, and (q) is 0 or 1, wherein p+q=2; (n) is 2 or 3; (n') is 0 or 1; (m) is an integer of 3-11; and (k) is an integer of 0-4 ). COPYRIGHT: (C)2004,JPO&NCIPI
TL;DR: In this paper, a cyclic substituent was added to cephalosporin sulfoxides to synthesize enone-or dienone-type moieties.
Abstract: Cephalosporin sulfoxides 1 and 2 containing an enone- or dienone-type moiety at position 2 were treated with 2,3-dimethylbuta-1,3-diene or diethyl azodicarboxylate to synthesize, in DielsAlder reactions, the new cephalosporin derivatives 4 and 5 with a cyclic substituent (Scheme 1). Under the same conditions, ethyl diazoacetate and diazomethane reacted differently: while reactions of 1 and 3 with the former lead to compounds 7–10 corresponding to the 1,3-dipolar cycloaddition route (Scheme 2), diazomethane produced only enol ethers 12 and 13, respectively (Scheme 3). This difference could be rationalized by assuming two different reaction pathways: an orbital-symmetry-controlled concerted cycloaddition and an ionic one.
TL;DR: In this article, the cycloaddition of diazomethane, cyclocondensation of hydrazine hydrate, and cyclopropanation of TMSOI to 1-aroyl-2-styrylsulfonylethenes were studied and different novel products thereby obtained were characterized with spectral parameters.
Abstract: The cycloaddition of diazomethane, cyclocondensation of hydrazine hydrate, and cyclopropanation of TMSOI to 1-aroyl-2-styrylsulfonylethenes were studied and different novel products thereby obtained were characterized with spectral parameters. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:155–159, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10117
TL;DR: In this article, the synthesis of indazol-4,7-dione derivatives via 1,3-dipolar cycloaddition of diazomethane with 2,3dimethyl-1,4-benzoquinone (2) and 1,4naphthoquinone(7) followed by N-alkylation of the pyrazol nitrogen atom of the corresponding quinones (3) and (8) with methyl chloroacetate is described.
Abstract: The synthesis of new indazol-4,7-dione derivatives via 1,3-dipolar cycloaddition of diazomethane with 2,3-dimethyl-1,4-benzoquinone (2) and 1,4-naphthoquinone (7) followed by N-alkylation of the pyrazol nitrogen atom of the corresponding quinones (3) and (8) with methyl chloroacetate is described. A series of amides from esters (5) and (10) were also obtained. These compounds were tested in vitro as potential anti-trypanosomal agents. Compounds (4) and (8) were found to have significant activity.
TL;DR: In this article, a six-step radioactive synthesis from diethyl [carboxylate-14C1,2] oxalate was described, which yielded a 6.8 µCi/mg with a radiochemical purity of > 99% as determined by HPLC.
Abstract: Carbon-14 labeled (R)-3-fluoro-4-(2′-(5′′, 6′′, 7′′, 8′′-tetrahydro-5′′, 5′′, 8′′, 8′′-tetramethyl-2′′-naphthyl)-[2′-hydroxy-14C])[carbonyl-14C]acetamidobenzoic acid, 1, was prepared in a six step radioactive synthesis from diethyl [carboxylate-14C1,2] oxalate. The penultimate compound was purified by chiral HPLC, which following deprotection yielded 1 in an overall radiochemical yield of 6.8%. The specific activity of the final product was found to be 24.5 µCi/mg with a radiochemical purity of > 99% as determined by HPLC. Derivatization of 1 via trimethylsilyl diazomethane to the corresponding methyl ester 9, followed by chiral HPLC analysis, demonstrated that 1 had an optical purity of > 99% ee. Copyright © 2002 John Wiley & Sons, Ltd.