Showing papers on "Diazomethane published in 2011"
TL;DR: A convenient iron-catalyzed procedure to prepare trifluoromethylated vinyl- and alkynylcyclopropanes in a chemo- and diastereoselective manner is presented.
112 citations
TL;DR: A novel 1,3,4-substituted 1,2,3-triazolium salt was found to function as an effective precursor for the synthesis of the first structurally characterized cationic silver(I) and ruthenium(II)carbene complexes of overall 1:2 ligand-to-metal stoichiometry.
72 citations
TL;DR: Direct access to 3-trifluoromethyl-substituted benzofuranols is presented, which are obtained in good yields from commercially available salicylaldehydes by using in situ generated trifluorsized diazomethane and boron triffluoride as an activator.
46 citations
34 citations
TL;DR: In this article, a series of N -arylsulfonyl-α-amino acid methyl esters bearing different substituents at the 4-position of the sulfonamide aromatic ring were compared with diazomethane and trimethyloxonium tetrafluoroborate in N-methylation processes.
31 citations
TL;DR: In this paper, single-walled carbon nanotubes (SWCNTs) were purified by treatment with concentrated nitric acid and then subjected to Soxhlet extraction with tetrahydrofuran (THF).
20 citations
TL;DR: In this article, it was shown that diazomethane undergoes a facile 1,3-dipolar cycloaddition with both dithiobenzoate RAFT agents and the DBSs of polymers formed by RAFT polymerization.
Abstract: It has been found that diazomethane undergoes a facile 1,3‐dipolar cycloaddition with both dithiobenzoate RAFT agents and the dithiobenzoate end‐groups of polymers formed by RAFT polymerization. Thus, 2‐cyanoprop‐2‐yl dithiobenzoate on treatment with diazomethane at room temperature provided a mixture of stereoisomeric 1,3‐dithiolanes in near quantitative (>95%) yield. A low‐molecular‐weight RAFT‐synthesized poly(methyl methacrylate) with dithiobenzoate end‐groups underwent similar reaction as indicated by immediate decolourization and a quantitative doubling of molecular weight. Higher‐molecular‐weight poly(methyl methacrylate)s were also rapidly decolourized by diazomethane and provided a product with a bimodal molecular weight distribution. Under similar conditions, the trithiocarbonate group does not react with diazomethane.
17 citations
TL;DR: In this article, the reactions of diazomethane and its derivatives with aldehdyes and ketones are discussed in detail, and the reaction is most often carried out by either allowing the carbonyl compound to react with an ethereal solution of the dihedral derivative with or without the addition of a catalyst, or by treating a methanol solution with a nitrosoalkylurethane in the presence of a base.
Abstract: Diazomethane and its derivatives react with aldehdyes and ketones usually under very mild conditions to yield a variety of interesting and often useful products. The reaction is most often carried out by either allowing the carbonyl compound to react with an ethereal solution of the diazomethane derivative with or without the addition of a catalyst, or by treating a methanol solution of the carbonyl compound with a nitrosoalkylurethane in the presence of a base, Only the reactions of diazomethane and its alkyl and aryl derivatives are discussed in detail.
Keywords:
diazoemethane;
derivatives;
aldehydes;
ketones;
aliphatic diazo compounds;
quinones;
isolation of products;
identification;
safety considerations;
experimental conditions
14 citations
TL;DR: Optically active cyclopropanes bearing a trifluoromethyl group are obtained with high enantioselectivities by reaction of styrene derivatives with trifloromethsyl diazomethane generated in situ as discussed by the authors.
Abstract: Optically active cyclopropanes bearing a trifluoromethyl group are obtained with high enantioselectivities by reaction of styrene derivatives with trifluoromethyl diazomethane generated in situ.
13 citations
TL;DR: Gas Chromatographic method has been developed and recovery of metsulfuron methyl from soil was above 70%.
Abstract: Gas Chromatographic method has been developed for the determination of metsulfuron methyl residues from soil. Due to the thermal unstability of this herbicide and its mono methyl derivative, it was derivatized to a dimethyl derivative using diazomethane. Structure of the derivatized product was confirmed by GC–MS. Time for methylation reaction was standardized and 24 h was found to be the optimum time in ethylacetate solvent. Using this method, recovery of metsulfuron methyl from soil was above 70%. Limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.1 μg mL−1 and 0.2 μg g−1 respectively.
7 citations
TL;DR: In this paper, N -Vinyl 2,2-bisphosphonoaziridines are formed by treatment of 1,1-bisophosphono-2-aza-1,3-dienes with diazomethane.
TL;DR: A number of chalcones with the (+)- and (−)-usnic acid moieties were synthesized by the following sequence: the reaction of these acids with phenylhydrazine, reduction of the C(1)=O group with sodium borohydride, O-methylation of the intermediate compounds with diazomethane, and subsequent condensation with substituted benzaldehydes at the acetyl group as mentioned in this paper.
Abstract: A number of chalcones with the (+)- and (−)-usnic acid moieties were synthesized by the following sequence: the reaction of these acids with phenylhydrazine, reduction of the C(1)=O group with sodium borohydride, O-methylation of the intermediate compounds with diazomethane, and subsequent condensation with substituted benzaldehydes at the acetyl group.
TL;DR: The reaction of the organozinc reagent prepared from methylene iodide and zinc-copper couple with substituted unsaturated compounds has proved to be a versatile and convenient method for the synthesis of cyclopropanes as discussed by the authors.
Abstract: The reaction of the organozinc reagent prepared from methylene iodide and zinc-copper couple with substituted unsaturated compounds has proved to be a versatile and convenient method for the synthesis of cyclopropanes. The synthesis is stereospecific with regard to the stereochemistry of the unsaturated compound and is usually free from serious side reactions; it can be carried out under mild conditions in diethyl and affords cyclopropanes often in good yields. This method can be easily adapted to large-scale preparations. Two useful variations of the cyclopropanation reaction have appeared which involve the same or a similar organozinc intermediate: (1) diazomethane reacts with iodide in ether to form a reagent which converts unsaturated compounds to cyclopropanes; (2) methlyene iodide and diethyl zinc react in ether in the presence of unsaturated compounds to cyclopropanes. Processes are known in which a divalent carbon fragment adds to carbon-carbon double bonds either as a free carbene or as an organometallic complex.
Keywords:
cyclopropanes;
methylene iodide;
zinc-copper couple;
alkenes;
zinc reagent;
hydroxyalkenes;
allenes;
angular methylation;
experimental conditions
TL;DR: The quantitative determination of the 15‐epimer content of prostaglandins by formation of their isotopically‐labelled methyl esters is described and evidence for the uncatalysed reaction of diazomethane with the alcoholic hydroxyl groups of prostglandin molecules, which could be significant in other prostaglandsin analysis techniques (e.g. g.l.c.) which depend on quantitative esterification with this reagent.
Abstract: The quantitative determination of the 15‐epimer content of prostaglandins by formation of their isotopically‐labelled methyl esters is described. Either [3H]dimethyl sulphate or [14C]diazomethane are used as esterification reagents. The reaction products are separated by thin layer chromatography and the epimer ratio determined by scintillation counting of the labelled ester zones. The accuracy of the technique is illustrated by the determination of 15‐epimer in ICI 74 205, a close analogue of PGF2α. Evidence for the uncatalysed reaction of diazomethane with the alcoholic hydroxyl groups of prostaglandin molecules, which could be significant in other prostaglandin analysis techniques (e.g. g.l.c.) which depend on quantitative esterification with this reagent, is also presented.
TL;DR: The Arndt-Eistert synthesis as mentioned in this paper is a procedure for converting an acid to its next highest homolog or to a derivative of the homologous acid, and an ester and an amide.
Abstract: The Arndt-Eistert synthesis is a procedure for converting an acid to its next highest homolog or to a derivative of the homologous acid, and an ester and an amide. The synthesis, which is applicable to both, aliphatic and aromatic acids involves the following three operations; formation of the acid chloride; reaction of the acid chloride with diazomethane to yield a diazoketone; and rearrangement of the diazoketone in the presence of suitable reagents and a catalyst (colloidal silver, platinum, copper). An acid is formed in the presence of water, and ester is produced in an alcohol, and am amide results when ammonia or an amine is used.
Keywords:
Arndt-Eistert synthesis;
diazomethane;
acids;
amides;
esters;
experimental conditions
01 Jan 2011
TL;DR: In this paper, 13 pyrazoline derivatives from eudesmanolides and guaianolides were synthesized and the structure of each compound was elucidated by spectroscopic techniques including IR, 1 H NMR and 13 C NMR spectra.
Abstract: To introduce a methyl group at C-16 instead of C-13, dehydrocostus lactone was allowed to react with an ethereal solution of diazoethane. To obtain structure- biological activity data, thirteen new pyrazoline derivatives from eudesmanolides and guaianolides were synthesised. The carbon chain at C-13 was extended by treating a 13- methyl derivative of dehydrocostus lactone with diazomethane and diazoethane to form substituted pyrazolines. The same sequence of reactions was performed on alantolactone, isoalantolactone and isodehydrocostus lactone, which formed substituted pyrazolines. The structure of each compound was elucidated by spectroscopic techniques including IR, 1 H NMR and 13 C NMR spectra. All thirteen generated compounds were subjected to biological evaluation as plant growth regulators. The results demonstrate an overall increase in effectiveness compared to the parent compounds.
TL;DR: In this paper, direct Sonogashira coupling of 6-halopurines with methyl propiolate and with propargyl aldehyde was not successful, but the corresponding orthoester and proparagyl aldhyde diethylacetal reacted smoothly.
Abstract: While direct Sonogashira coupling of 6-halopurines with methyl propiolate and with propargyl aldehyde was not successful, the corresponding orthoester and propargyl aldehyde diethylacetal reacted smoothly. Such prepared orthoester was then converted to the desired methylester by methanolysis, the acetal was too stable to be hydrolyzed. The obtained 6-ethynylpurines, bearing orthoester, acetal, methoxycarbonyl and for comparison also the phenyl substituent on the ethynyl group, were subjected to the cycloaddition reaction with cyclopentadiene, diazomethane and phenylazide. Electron deficient alkynylpurines were considerably more reactive in this reaction compared to the not activated phenylethynyl derivative. The prepared alkynylpurines exhibited medium cytostatic activity (IC 50 = 2.6–15 μM), while the cycloadducts were inactive.
TL;DR: New derivatives of (+)-usninic acid including products of ring expansion, methylation of enol and phenol hydroxyls, and formation of an oxirane ring in addition to products with pyran and furan rings annelated to ring A of (+-USNIC acid were prepared by reaction of (+−USINIC acid and its pyrazole derivatives with diazomethane as discussed by the authors.
Abstract: New derivatives of (+)-usninic acid including products of ring expansion, methylation of enol and phenol hydroxyls, and formation of an oxirane ring in addition to products with pyran and furan rings annelated to ring A of (+)-usninic acid were prepared by reaction of (+)-usninic acid and its pyrazole derivatives with diazomethane.
TL;DR: By the reaction of isatin with heterocyclic ketones (N-tert-butoxycarbonyl derivatives of pyrrolidin-3-one, piperidin4-one and piperidine-4-1) in the presence of KOH (the Pfitzinger reaction) was synthesized quinoline-4 carboxylic acids [4,3]fused with the respective heterocycles.
Abstract: By the reaction of isatin with heterocyclic ketones (N-tert-butoxycarbonyl derivatives of pyrrolidin-3-one, piperidin-4-one, piperidin-3-one, 1,2,3,4-tetrahydroquinolin-4-one, 8-azabicyclo[3.2.1]octan-3-one, tetrahydropyran-4-one, tetrahydrobenzopyran-4-one) in the presence of KOH (the Pfitzinger reaction) were synthesized quinoline-4-carboxylic acids [4,3]fused with the respective heterocycles. These acids were involved in the reactions with diazomethane and amines at the carboxy group leading to methyl esters and amides, respectively. The esters obtained reacted with hydrazine hydrate affording the acid hydrazides, which entered in the condensation with benzaldehyde to form phenylhydrazones. The esters and amides containing N-tert-butoxycarbonyl fragment lost the tert-butoxycarbonyl group easily to form the secondary amines dihydrochlorides, the [4,3]fused quinoline-4-carboxylic acid derivatives.
TL;DR: In this paper, a cycloaddition reaction of chalcone (I) with hydrazine hydrate or cycloadding reactions of I with diazomethane and nitrile oxide generated from oxime (V) is described.
Abstract: via condensation of chalcone (I) with hydrazine hydrate or cycloaddition reactions of (I) with diazomethane and nitrile oxide generated from oxime (V)
TL;DR: Experimental and theoretical data on the reactions of different diazo compounds (diazomethane, its derivatives, cyclic diazzo compounds and diazocarbonyl compounds) with fullerenes are summarized in this paper.
Abstract: Experimental and theoretical data on the reactions of different diazo compounds (diazomethane, its derivatives, cyclic diazo compounds and diazocarbonyl compounds) with fullerenes are summarized. The structures and stereochemistry of cycloadducts formed in these reactions are considered.
TL;DR: In this article, it was demonstrated that treatment of azadienes of type (I) and (VI) with diazomethane provides aziridines as main products.
Abstract: It is demonstrated that treatment of azadienes of type (I) and (VI) with diazomethane provides aziridines as main products.