Showing papers on "Diazomethane published in 1996"
TL;DR: In this paper, a potential hybrid phosphine ligand with heteroannular soft and hard donor groups was synthesized in 71% yield from 1-phenyl-1-phospha[1]ferrocenophane by ring opening with phenyllithium, followed by reaction with carbon dioxide and acidification.
125 citations
TL;DR: Results suggest that FDVE undergoes biotransformation via the beta-lyase pathway and beta-LYase-catalyzed metabolism may mediate the nephrotoxicity of this compound.
Abstract: The volatile anesthetic sevoflurane is degraded to fluoromethyl 2,2-difluoro-1-(trifluoromethyl)vinyl ether (FDVE), a potent rat nephrotoxin. In rats in vivo, FDVE undergoes glutathione conjugation and metabolism to cysteine conjugates, whose bioactivation by renal cysteine conjugate β-lyase has been implicated by the protective effects of (aminooxy)acetic acid, an inhibitor of cysteine conjugate β-lyase. We specifically tested the hypothesis that FDVE is metabolized via the β-lyase pathway to yield 3,3,3-trifluoro-2-(fluoromethoxy)propanoic acid. Urine of rats administered FDVE (0.3 mmol/kg) was extracted and derivatized with diazomethane. Headspace GC/MS analysis demonstrated a peak whose retention time and mass spectrum were identical to those of synthetic methyl 3,3,3-trifluoro-2-(fluoromethoxy)propanoate. Pretreatment of rats with (aminooxy)acetic acid significantly decreased the amount of 3,3,3-trifluoro-2-(fluoromethoxy)propanoic acid detected in the urine of FDVE-treated animals. The 19F NMR spect...
39 citations
TL;DR: In this paper, the dipole approach mode is determined by the configuration at the sulfinyl group, which strongly increases both the reactivity and the π-facial selectivity.
Abstract: Cycloadditions of diazomethane to (S s )-5-ethoxy-3- p -tolylsulfinylfuran-2(5 H )-ones 1a–b and their corresponding 4-methyl derivatives 3a–b , proceeds in quantitative yields, to give enantiomerically pure 3 H ,6 H ,3a,6a-dihydrofuro[3,4-c]pyrazol-4-ones 2a–b and 4a–b , respectively. The sulfinyl group at C-3 strongly increases both the reactivity and the π-facial selectivity. The dipole approach mode is determined by the configuration at the sulfinyl group. Pyrolysis of pyrazolines 2a or 2b gives the methyl derivatives 3a or 3b in excellent yield.
29 citations
TL;DR: Sodium tetrafluoroborate, tert-butyllithium, and tributyltin hydride react with 3 to afford P-fluoro-P'-hydrogenocarbodiphosphorane 10, P,P'-dihydrogenocbodiph phosphorane 12, and stannyl-substituted methylene salt 15, respectively.
Abstract: Trifluoromethanesulfonic acid reacts at 240 K with bis[bis(diisopropylamino)phosphino]diazomethane, 1, affording the corresponding cationic (phosphino)(P-hydrogenophosphonio)diazomethane derivative 2, which eliminates dinitrogen above 250 K, leading to (phosphino)(phosphonio)carbene 3 isolated in 76% yield (mp 88 °C). Bis(diisopropylamino)phosphenium salt 5a adds at 240 K to P-chlorodiazomethylenephosphorane 4 giving (phosphino)(P-chlorophosphonio)diazo derivative 6a, which leads, after N2 elimination, to the corresponding carbene 7a. Addition of potassium tert-butoxide to 3 gives rise to the transient diphosphinocarbene 8, which rearranges into phosphaalkene 9. Sodium tetrafluoroborate, tert-butyllithium, and tributyltin hydride react with 3 to afford P-fluoro-P‘-hydrogenocarbodiphosphorane 10, P,P‘-dihydrogenocarbodiphosphorane 12, and stannyl-substituted methylene salt 15, respectively. tert-Butyl isocyanide reacts with phosphoniocarbene 3 giving heterocycle 19, whereas with carbene 7 phosphonioketenei...
24 citations
TL;DR: In this article, a new procedure for cyclohexenone annelation was developed, in which 4-isopropylcyclohexanone with allyl bromide gives, over several steps, ketone 8.
Abstract: A new procedure for cyclohexenone annelation has been developed. Thus, alkylation of 4-isopropylcyclohexanone with allyl bromide gives, over several steps, ketone 8. Exposure to (trimethylsilyl)diazomethane and MeLi smoothly cyclized 8 to the cyclopentene 9 by insertion of the intermediate alkylidene carbene into the unactivated methylene CH. On debenzylation, ozonolysis, and subsequent aldol condensation, 9 is transformed into oxo-T-cadinol (1).
21 citations
TL;DR: C-thioxophosphoranyl-N-phosphoranyldiazirine 3, which has been characterized by 31P and 13C NMR spectroscopy, reacts with triisopropylsilyl trifluoromethanesulfonate and trimethylphosphine in 51 and 95% yields, respectively as discussed by the authors.
Abstract: C-[Bis(diisopropylamino)thioxophosphoranyl]-N-[bis(diisopropylamino)phosphino]nitrilimine (1) reacts at −50 °C with tetrachloro-o-benzoquinone (TCBQ) leading to C-thioxophosphoranyl-N-phosphoranyldiazirine 3, which rearranges above −30 °C into heterocycle 4 (84% yield) 1H-Diazirine 3, which has been characterized by 31P and 13C NMR spectroscopy, reacts with triisopropylsilyl trifluoromethanesulfonate and trimethylphosphine, affording N-phosphonionitrilimine 5 and phosphorus ylide 6 in 51 and 95% yields, respectively [Bis(diisopropylamino)thioxophosphoranyl][bis(diisopropylamino)phosphino]diazomethane (8) also reacts with TCBQ leading to 4 (90% yield) via 3 This result is rationalized by the formation of the (thioxophosphoranyl)(phosphoranyl)diazomethane 9, which is in equilibrium with the ion pair thioxophoranyl diazo anion 21/phosphonium 12; attack of the nitrogen end of the diazo anion on the phosphorus cation 12 affords 3 The transient formation of the ion pair 21/12 has been proved by trapping rea
17 citations
TL;DR: In this article, a 1,3-Dipolar cycloaddition of diazomethane to the alpha,beta-unsaturated esters and lactones such as 2-4, 6-8, 10 and 13 occurs in a stereoselective manner affording conjugated Delta(2)-pyrazolines.
16 citations
TL;DR: In this paper, the diazomethane methylation of the common ribonucleosides uridine, cytidine, adenosine, and guanosine and its derivatives was performed to obtain preferentially the 2′-O-methyl isomers.
Abstract: Intensive studies on the diazomethane methylation of the common ribonucleosides uridine, cytidine, adenosine, and guanosine and its derivatives were performed to obtain preferentially the 2′-O-methyl isomers. Methylation of 5′-O-(monomethoxytrityl)-N2-(4-nitrophenyl)ethoxycarbonyl-O6-[2-(4-nitrophenyl)ethyl]-guanosine (1) with diazomethane resulted in an almost quantitative yield of the 2′- and 3′-O-methyl isomers which could be separated by simple silica-gel flash chromatography (Scheme 1). Adenosine, cytidine, and uridine were methylated with diazomethane with and without protection of the 5′ -O-position by a mono- or dimethoxytrityl group and the aglycone moiety of adenosine and cytidine by the 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) group (Schemes 2–4). Attempts to increase the formation of the 2′-O-methyl isomer as much as possible were based upon various solvents, temperatures, catalysts, and concentration of the catalysts during the methylation reaction.
15 citations
TL;DR: In this article, photolysis of matrix-isolated (trimethoxysilyl)diazomethane (1e) leads to the formation of 2e, which was characterized by IR and UV−vis spectroscopy.
14 citations
13 citations
TL;DR: In this paper, a method is described where alkyl esters of both L and D-2-hydroxyglutaric acids are prepared without side lactonization.
Abstract: L-2-Hydroxyglutaric aciduria is a recently discovered inherited neurometabolic disease for which diagnostic identification of the right enantiomer is required. A method is described where alkyl esters of both L-and D-2-hydroxyglutaric acids are prepared without side lactonization. Esterification is achieved at room temperature by reaction with appropriate alkyl chloroformates. This method avoids lactonization, in contrast to esterification with alcohols in acidic media or with diazomethane. The identity of the derivatives is established by HRGC-FTIR and HRGC-MS. Chiral HRGC separation with capillaries coated with 1(R)-trans-N-N'-1,2-cyclohexylenebisbenzamideoligodimethyL-siloxane and with a cyclodextrin is compared. The method is adequate for quantitative determinations.
TL;DR: 1-cyclopropylmethyl-3,7,10-trimethylsilatrane (2a) and 1-cyclopropylmethyltriethoxysilane (3 ) with triethanolamine have been synthesized in the presence of Pd(OAc) 2 as a catalyst.
TL;DR: In this article, the reaction between [PtX 2 L 2 ] (X=Cl, Br, I; L 2 =1,5- cyclo - octadiene (cod), 2PPh 3, 2PMePh 2, Ph 2 PCH 2 PPh 2, S, S -Ph 2 PChMeCH 2 CHMePPh 2 ( SS,-skewphos)) and an excess of Me 3 SiCHN 2 in a CH 2 Cl 2 /Me 2 CO/H 2 O solvent mixture gives the complexes [P
TL;DR: A new betaine, 5,6,6-tributyl-2-diphenylmethylene-3,3,4-triphenyl-1-oxa-3-phosphonia-6-boratacyclohex-4-ene, and 1-(benzoyl(phenyl)methyleneamino]-4,5,5-Tributyl, 2,2,3-, 3,4-, 3.3-, 4.5-, 2.3-diene were synthesized upon interaction of E
Abstract: A new betaine, 5,6,6-tributyl-2-diphenylmethylene-3,3,4-triphenyl-1-oxa-3-phosphonia-6-boratacyclohex-4-ene, and1-(benzoyl(phenyl)methyleneamino]-4,5,5-tributyl-2,2,3-triphenyl-2-phospha-I-azonia-5-boratacyclopenta-1,3-diene were synthesized upon interaction of E-2-dibutylboryl-1-phenyl-1-diphenylphosphinohex-1-ene with diphenylketene and benzoyl(phenyl)diazomethane, respectively. The structure of the latter product was established by IR spectroscopy and X-ray structural analysis.
TL;DR: The structure of the latter heterocycle was confirmed by X-ray diffraction analysis and by comparison of F-19 and C-13 NMR data as discussed by the authors, which was later confirmed by comparison with F-13 and F-20 NMR.
Abstract: The preparation of 3-(2,2,2-trifluoroethylidene)-lactams 7-9 is accomplished by reduction of 3-trifluoroacetyl-substituted lactams 1-3 and subsequent dehydration of trifluoromethylated methanols 4-6. 1,3-Dipolar cycloadditions of compounds 7 with diazomethane and N-methyl-alpha-phenylnitrone give spirocyclic pyrazoline 11 and isoxazolidine 12. The structure of the latter heterocycle is confirmed by X-ray diffraction analysis and by comparison of F-19 and C-13 NMR data.
TL;DR: In this article, the reactivities of 1-chloro-3p-p-tolylsulfinyl acetone (R S )-1 towards diazomethane and of the resulting diastereoisomeric 1 -chloromethyl-1-sulfinylmethyl oxiranes 2 towards O-, N- and C-centred nucleophiles are investigated.
Abstract: The reactivities of 1-chloro-3-p-tolylsulfinyl acetone (R S )- 1 towards diazomethane and of the resulting diastereoisomeric 1-chloromethyl-1-sulfinylmethyl oxiranes 2 towards O-, N- and C-centred nucleophiles are investigated. The synthesis of differently functionalized homochiral chlorinated sulphur-free oxiranes (R)- 15 , (S)- 16 and (R)- 17 has been accomplished in good chemical yields.
TL;DR: In this paper, the SN1 methanolysis of (1-adamantyl)(3-noradamantsantyl)methyl heptafluorobutyrate at 100 °C yielded (1)-adamandyl) methyl ether (17), 2-methoxy-adamide (18), and 4-(1)-methoxideprotoadamantane (19) in a 2 : 65 : 33 ratio.
Abstract: The SN1 methanolysis of (1-adamantyl)(3-noradamantyl)methyl heptafluorobutyrate at 100 °C yielded (1-adamantyl)(3-noradamantyl)methyl methyl ether (17), 2-(1-adamantyl)-1-methoxyadamantane (18), and 4-(1-adamantyl)-3-methoxyprotoadamantane (19) in a 2 : 65 : 33 ratio. The methanolysis of (1-adamantyl)(3-noradamantyl)diazomethane (7) at 0 °C also yielded 17, 18, and 19 in a 4 : 33 : 63 ratio. On the other hand, the photolysis of 7 in 99 : 1 (v/v) hexane–methanol gave 17, 18, 2-(1-adamantyl)-2-methoxyadamantane (25), and 2-(1-adamantyl)-2,4-didehydroadamantane (20) in a 30 : 9 : 36 : 25 ratio. Presence of triethylamine decreased the yields of ethers 17, 18, and 25, and increased the yield of 20 to 46%. The formation of a considerable amount of 17 and the absence of 19 in the photolysis products indicate the generation of (1-adamantyl)(3-noradamantyl)methylidene (8). The formation of 25 and 20 suggests that the generated carbene 8 rearranges to 2-(1-adamantyl)adamantene (3b) and then gives 3-(1-adamantyl)-4-...
TL;DR: In this paper, the extent of deuteration with a quantitative evaluation of the actual species present in any solution of diazomethane could be determined by a GC-MS analysis and 1H NMR spectrometry on a suitable derivative.
Abstract: A multiple D2O–CH2N2 exchange followed by a final anhydrification with K2CO3 gave an alcohol-free low-water-content ether solution of CD2N2. Procedural improvements for the exchange are reported. The extent of deuteration with a quantitative evaluation of the actual species present in any solution of diazomethane could be determined by a GC-MS analysis and 1H NMR spectrometry on a suitable derivative. In addition, a procedure for the quantitative determination of water in diazomethane solutions has been developed.
Abstract: The reactions of solutions of 2,2-ditipylethene-1,1-diol (tipyl = 2,4,6-triisopropylphenyl) (1), which is the enol of ditipylacetic acid, were studied. Oxidation with (p-BrC6H4)3N•+SbCl6- gave a benzofuranone, i.e., a five-membered lactone (5) by cyclization via the oxygen on the ring, and ketonization with loss of aromaticity of the ring. Bromination also gave 5, presumably via an initial oxidation of the oxygen, as well as a bromine-containing six-membered lactone, a benzopyranone (9), formed by cyclization on an o-i-Pr group and ring bromination. No product resulting from reaction of bromine with the double bond was formed. This is ascribed to shielding of the double bond by steric crowding. Attempted etherification of the enolic OH groups did not give the ketene trimethylsilyl or methyl acetals. With diazomethane a bicyclic trienone 13 was formed, presumably by cyclopropanation of the ditipylketene (2) which is in equilibrium with 1, followed by a vinyl cyclopropanone rearrangement to 13. The formatio...
TL;DR: A series of cis-and trans-derivatives of 2-aryl-N, N-dipropylcyclopropylamines and 1-(2-arylcyclopropyl)-N, N -methylamines were synthesized and evaluated for affinity at the 5-HT 1A receptor as mentioned in this paper.
TL;DR: In this paper, the condensation of various arynes with tiglic acid dianion yields (E)-4-aryl-2-methyl-3-butenoic acids exclusively, after proton quench.
TL;DR: In this paper, a method was developed to enforce tolerance levels of cloransulam-methyl in soybeans and soybean forage, hay, and processed commodities using gas chromatography with mass spectrometric detection using electron impact ioniza...
Abstract: Cloransulam-methyl, N-(2-carbomethoxy-6-chlorophenyl)-5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide, is a new broad-spectrum herbicide for use in soybeans. The U.S. Environmental Protection Agency requires that analytical methodology be developed to enforce tolerance levels of pesticides in food crops. This paper describes the method developed to enforce tolerance levels of cloransulam-methyl in soybeans and soybean forage, hay, and processed commodities. The method description includes validation data supporting a lower limit of quantitation of 0.01 μg/g (10 ppb) for cloransulam-methyl in each matrix. Extracts of each matrix are purified using C18 and neutral alumina solid phase extraction. Cloransulam-methyl is derivatized, using (trimethylsilyl)diazomethane, to the N-methylcloransulam-methyl. Quantitation and simultaneous confirmation of residues of cloransulam-methyl as N-methylcloransulam-methyl employ gas chromatography with mass spectrometric detection using electron impact ioniza...
Patent•
18 Sep 1996
TL;DR: In this article, a chymase-inhibitor contains an oxycephem derivative expressed by formula I [X is O, SO2 ; R1 is H, a (substituted) lower alkyl, etc.; R2 is H a lower alyl, a lower alkoxy, etc., R3 is H an a lower ionic, etc; R4 is COR7 (R7 is H), etc.
Abstract: PROBLEM TO BE SOLVED: To obtain the subject medicine useful for preventing and curing cardiac infraction, cardiac failure, rheumatism, etc., by allowing to contain a specific new cephem-based compound. SOLUTION: This chymase-inhibitor contains an oxycephem derivative expressed by formula I [X is O, SO2 ; R1 is H, a (substituted) lower alkyl, etc.; R2 is H, a lower alkoxy, etc.; R3 is H a lower alkyl, etc.; R4 is a lower alkyl, a lower alkoxy, etc.; R5 is COR7 (R7 is H, etc.)] or a cefemsulfone derivative, its pharmaceutically allowable salt or its hydrate. As the compound of formula I, e.g. a compound expressed by formula II (Ra is a (substituted) phenyl, etc.; Rb is H, etc.; Rc is a (substituted) tetrazole, etc.) is cited. The compound of formula I is obtained by reacting a compound of formula III with added biphenyl diazomethane, treating the reaction product with formic acid and reacting with added m-chloroperbenzoic acid and dimethylsulfide.
TL;DR: In this paper, the isomeric methyl phthalaldehydic acids were obtained from phthalides by bromation (NBS) to the 3-bromo derivatives and subsequent hydrolysis with water.
Abstract: The isomeric methyl phthalaldehydic acids11 were obtained from phthalides4 by bromation (NBS) to the 3-bromo derivatives7 and subsequent hydrolysis with water.4 in turn were accessible from dimethyl methyl benzoates1 by dibromination withNBS and subsequent thermical cyclization to the bromo derivatives3 which, on catalytic dehalogenation, afforded the phthalides4. Reaction of11 with methanol or ethanol gave the pseudo-esters13 and14, resp. Short treatment of11 with diazomethane on the other hand yielded the methyl formyl benzoates15b to15e. Prolonged reaction (several hours) gave the oxiranyl compounds17; in addition, the acetonyl derivatives18 were also found, obviously formed by a double methylene insertion into15. All reactions proceeded with good to excellent yields.
TL;DR: In this article, the reaction of 1-methyl-5-nitroimidazole-2-carboxyl chloride (9) with diazomethane afforded 2-diazo-1-(1-memyl-5,nitro-2)-imidrazolyl)ethanone (10).
TL;DR: In both series, the 17-ketones were reduced to 17 beta-hydroxy derivatives, and after benzoylation, the protecting methoxyphenylmethyl group at position 15 was removed with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.
TL;DR: This paper investigated the reaction between chorismic acid and diazomethane in diethyl ether on a larger scale and showed that the previously reported single pyrazoline-based product is accompanied by a stereoisomer that result from the addition of diazmethane to the more hindered α-face of the 1,2-double bond (α:β addition ca. 1:6).
Abstract: Reinvestigation of the reaction between (–)-chorismic acid and diazomethane in diethyl ether on a larger scale has shown that the previously reported single pyrazoline based product is accompanied by a stereoisomer that result from the addition of diazomethane to the more hindered α-face of the chorismate 1,2-double bond (α:β addition ca. 1:6). Thermolysis of the two cycloadducts at 80 °C afforded a pair of cyclopropane derivatives with stereochemistry that could not be confidently assigned using data from coupling constants alone. NOE data allowed a more confident assignment of the stereochemistry of the two cyclopropanes; the β-cyclopropyl derivative was saponified and hydrolysed to yield a bicyclo[4.1.0]hept-2-ene-1-carboxylic acid derivative that was unequivocally shown to possess (1S,4R,5R,6R)-stereochemistry by an X-ray crystallographic study.
Journal Article•