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1.
A practical synthetic method for the direct synthesis of unsymmetrically substituted ureas from N-Alloc-, N-Cbz-, and N-Boc-protected amines is described. In this study, efficient direct conversion of the Alloc-, Cbz-, and Boc-carbamate compounds to ureas was achieved in the presence of DABAL-Me3, an air stable and easily handled reagent. Using this reaction method, both protected aromatic and aliphatic amines were successfully transformed into various trisubstituted and tetrasubstituted ureas with high yields without side product. Our findings offer promising guidelines for direct preparation of useful ureas from N-Alloc-, N-Cbz-, and N-Boc-carbamates. 相似文献
2.
P. R. Latthe P. S. Shinge Bharati V. Badami P. B. Patil S. N. Holihosur 《Journal of Chemical Sciences》2006,118(3):249-256
3-[4-(Azidocarbonyl)]phenylsydnone (2) obtained from 3-(4-hydrazinocarbonyl) phenylsydnone (1) on Curtius rearrangement with alcohols, water and amines afforded the corresponding carbamates (3a-h), 4,4′-(sydnone-3-yl) diphenyl urea (4) and 4-(heterocyclyl)phenyl ureas (5a-l). Compounds (5a-l) on one-pot ring conversion yielded the 1,3,4-oxadiazolin-2-one derivatives (6a-l), which on reaction with N2H4 gave the 4-amino-1,2,4-triazolin-3-ones (7a-l). All these compounds exhibited moderate antimicrobial activity against the few microbes tested. The carbamates have been
found to be more toxic against fourth instar larvae ofAedes aegypti, in particular, then-butyl derivative (3e). 相似文献
3.
A. Yu. Aksinenko T. V. Goreva T. A. Epishina A. N. Pushin V. B. Sokolov 《Russian Chemical Bulletin》2006,55(6):1052-1055
Cyclocondensation of N-substituted imines of methyl trifluoropyruvate with monosubstituted ureas afforded novel 5-amino-5-trifluoromethylhydantoins.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1014–1017, June, 2006. 相似文献
4.
Pankrushina N. A. Nikitina I. A. Anferova N. V. Osadchii S. A. Shakirov M. M. Shults E. E. Tolstikov G. A. 《Russian Chemical Bulletin》2003,52(11):2490-2499
Efficient procedures were developed for N-deethylation of lappaconitine to give N(20)-deethyllappaconitine. Alkyl derivatives of N(20)-deethyllappaconitine, including labeled lappaconitine, and N(20)-acetoxy-N(20)-deethyllappaconitine were prepared for the first time. The assignments of the signals for the carbon atoms in the 13C NMR spectra of lappaconitine and related lappaconine were refined using 13C—13C 2D INADEQUATE and 2D 13C—1H correlation experiments. 相似文献
5.
Hexa-n-butyl- and hexaisopentyldigermoxanes but not hexaphenyldigermoxane react with O-trimethylsilyl N,N-diethylcarbamate and trimethylsilyl piperidinocarboxylate to give O-triorganylgermyl carbamates. 相似文献
6.
I. V. Ovchinnikov A. S. Kulikov M. A. Epishina N. N. Makhova V. A. Tartakovsky 《Russian Chemical Bulletin》2005,54(5):1346-1349
Earlier unknown N-trinitroethyl derivatives of acetylhydrazine, 4-amino-1,2,4-triazole, and 2,4,6-triamino-1,3,5-triazine, which are potential
components for gas-generating formulations, were synthesized.
Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1306–1309, May, 2005. 相似文献
7.
Reactions of O-(organylstannyl) carbamates with alcohols afford alkoxystannanes and proceed most completely on heating in an excess of alcohol. The reactions provide a new approach to the synthesis of difficultly accessible alkoxystannanes. 相似文献
8.
L. B. Kulikova G. I. Ezhova N. E. Kravchenko O. V. Dorofeeva A. S. Kulikov A. G. Zavozin 《Russian Chemical Bulletin》2007,56(8):1631-1636
Conditions for N-acylation of 2-amino-5-aryl-6H-1,3,4-thiadiazines with trifluoroacetic anhydride and halogen-substituted carboxylic acid halides with retention of the initial
heterocyclic system were found. 5-Aryl-2-haloacylamino-6H-1,3,4-thiadiazines were obtained in preparative yields. Their reactions with hetarenethiols afforded N-hetarylthioacyl derivatives.
Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1570–1575, August, 2007. 相似文献
9.
A one-pot synthesis of N-substituted 3,3,3-trifluoroalanine esters from alkyl trifluoropyruvates and carboxamides or substituted ureas was developed. 相似文献
10.
A precise, reliable, sensitive, and selective method for the determination of titanium(IV) is described. Titanium(IV) reacts withN
1-hydroxy-N
1,N
2-diphenylbenzamidine (HDPBA) and thiocyanate to form an orange-coloured mixed-ligand complex of stoichiometry 112 (Ti SCN– HDPBA). The complex is quantitatively extractable into toluene from 0.05–0.15M hydrochloric acid. The spectrum of the complex exhibits an absorption maximum at 400 nm with a molar absorptivity of 20000M
–1 cm–1 and the coloured system obeys Beer's law in the concentration range 0.20–3.0 gml–1 titanium. The effects of foreign ions and of various experimental parameters have been studied to establish the optimum conditions for the extraction and determination of titanium. The precision of the method has been evaluated and the relative standard deviation has been found to be 0.53%. The method has been successfully applied to the determination of titanium in synthetic matrices corresponding to titanium-containing ores, minerals, and alloys. 相似文献
11.
o-Alkyl derivatives of N-acetylaminobenzo-12-crowns-4 4a—f were prepared by Pd—Cu-catalyzed alkynylation of 5"-N-acetylamino-4"-iodobenzo-12-crown-4 (2). Cyclization of compounds 4a—f afforded the corresponding substituted 5,6-indolo-12-crowns-4 5a—c. 相似文献
12.
Diphenylphosphoryl azide (DPPA) mediated one-pot synthesis of Nα-Fmoc/Bsmoc/Boc/Z-protected ureidopeptides and peptidyl ureas as well as phenyl/succinimidyl (Nα-urethane protected) methyl carbamates starting from Nα-protected amino acids is reported. The formation of an azide, its rearrangement and coupling with an amino component is accomplished in a sequence of one-pot operations. The protocol has incorporated urea linkages in a sterically hindered peptide. 相似文献
13.
Interaction of cellulose with amine oxide solvents 总被引:1,自引:3,他引:1
Cellulose I, mainly as ramie or as Avicel microcrystalline cellulose, has been monitored by optical microscopy and by 13C CPMAS NMR, over the course of its dissolution in hot N-methylmorpholine N-oxide solvent. Its interaction with the near-solvent N-ethylmorpholine N-oxide and related non-solvents has also been investigated. NMR shows that N-methylmorpholine N-oxide partly converts crystalline cellulose I into amorphous solid cellulose. The changes in chemical shift imply increased flexibility at the glycosidic bonds. In contrast, N-ethylmorpholine N-oxide converts cellulose I to cellulose IIII, without dissolution. Microscopy shows that the ramie fibres swell laterally, and at least some also shorten longitudinally, during dissolution. Model studies using methyl--d-glucopyranose show no evidence from 13C chemical shifts for different modes of binding with different solvents. However, N-methylmorpholine N-oxide binds more strongly to methyl--d-glucopyranose in DMSO than does N-ethylmorpholine N-oxide, whereas N-ethylmorpholine N-oxide binds better to H2O. Also, 13C T
1 values for aqueous cellobioside show increasing rotational freedom of the –CH2OH sidechains as N-methylmorpholine N-oxide is added. Together, these observations imply the initial penetration of solvents and near-solvents between the molecular cellulose sheets. Subsequently, N-methylmorpholine N-oxide breaks H-bonds, particularly to O-6, just sufficiently to loosen individual chains and then dissolve the sheets. 相似文献
14.
Lipunova G. N. Nosova E. V. Mochul"skaya N. N. Andreiko A. A. Chasovskikh O. M. Charushin V. N. 《Russian Chemical Bulletin》2002,51(4):663-667
The interaction of C-aryl-substituted amidrazones and S-methylisothiosemicarbazide with 3-ethoxy-2-polyfluorobenzoylacrylates results in corresponding N-(quinolin-1-yl)amidines that undergo conversion into derivatives of 1,2,4-triazino[5,6,1-i,j]quinoline by heating in acetic anhydride. 相似文献
15.
L. A. Musina E. E. Shul’ts L. A. Krichevskii S. M. Adekenov M. M. Shakirov G. A. Tolstikova 《Russian Chemical Bulletin》2006,55(2):331-337
The oxidation of N-acetyl-and N-benzoylanabasine with the tert-butyl hydroperoxide (TBHP)— MoCl5 system or MCPBA proceeds selectively at the nitrogen atom of the pyridine ring. The oxidation of N-methylanabasine under similar conditions gives a mixture of stereo-isomeric N-oxides at the piperidine nitrogen atom, their ratio depending on the reagent used. The oxidation of anabasine by TBHP— MoCl5 or MCPBA is accompanied by dehydrogenation and results in anabaseine N-oxide. The reactions of anabasine and anabaseine pyridine N-oxides with acetic anhydride were investigated. The substituted 1H-3-pyridin-2-ones were prepared.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 322—328, February, 2006. 相似文献
16.
Ahmad R. Massah Davood Azadi Hamid Aliyan Ahmad R. Momeni Hamid Javaherian Naghash Foad Kazemi 《Monatshefte für Chemie / Chemical Monthly》2008,139(3):233-240
Summary. The preparation of N-acylsulfonamides is described using primary amines, arylsulfonyl chlorides and acyl chlorides. Reaction of primary aryl amines
with arylsulfonyl chlorides in the presence of NaHCO3 produced N-arylsulfonamides, which reacted in situ with benzoyl chloride furnishing the corresponding N-benzoyl-N-arylsulfonamides in 72–96% yields. Accordingly, 4-nitrobenzoyl chloride and 3,5-dinitrobenzoyl chloride were used as acylating
agents. All the reactions were carried out under solvent-free conditions at room temperature and the products were isolated
after simple work-up in high yields and purity. 相似文献
17.
Summary.
N-Glycosides of Asn and homologues have been synthesized starting from hexafluoroacetone-protected -activated Asp, Glu, and Aad derivatives and glycosylamines. The synthetic value of the new building blocks was demonstrated by the concise incorporation of N-glycosylated Asn, Gln, and Aad -amides into glycopeptides. 相似文献
18.
Roznyatovsky V. A. Gerdov S. M. Grishin Yu. K. Laikov D. N. Ustynyuk Yu. A. 《Russian Chemical Bulletin》2003,52(3):552-556
A new method for quantification of the relative distribution of deuterium in molecules is proposed. The technique is based on the lineshape analysis in the 2H NMR spectra obtained at the natural abundance level of deuterium with allowance for inhomogeneity of the magnetic field. The equilibrium thermodynamic H/D isotope effects for hindered rotation about the C—N bond in the N,N-dimethylformamide molecule and for prototropic exchange in the cyclopentadiene molecule were determined. The results obtained agree with those of DFT calculations of the vibrational energies. 相似文献
19.
R. A. Novikov I. P. Klimenko E. V. Shulishov V. A. Korolev Yu. V. Tomilov 《Russian Chemical Bulletin》2008,57(8):1718-1724
Cyclopropylazoarenes containing methoxy groups in the aromatic ring give the corresponding N-arylpyrazolines on the reflux in o-dichlorobenzene or on SnCl2 catalysis at 80 °C in good yields. The products can be smoothly oxidized into the corresponding pyrazoles. Thermolysis of
cyclopropylazoarenes containing hydroxy groups in the aromatic ring proceeds more complicated. Thus in the case of resorcin
azo derivative, strong resinification of the reaction mixture is observed and the corresponding N-arylpyrazoline is isolated only in −40% yield. Under similar conditions, thermolysis of 1-cyclopropyl- and 1-(1-methylcyclopropyl)azo-2-naphthol
proceeds otherwise and unexpectedly leads to naphtho[1,2-d]oxazole derivatives with degradation of the cyclopropane ring.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1686–1692, August, 2008. 相似文献
20.
Godin JP Faure M Breuille D Hopfgartner G Fay LB 《Analytical and bioanalytical chemistry》2007,388(4):909-918
We describe a new method of assessing, in a single run, 13C isotopic enrichment of both Val and Thr by gas chromatography–combustion–isotope-ratio mass spectrometry (GC–C–IRMS). This
method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo
samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers (13C-valine or 13C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at
natural abundance and at low 13C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5%
at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard
amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32‰. The
13C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural
abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis. 相似文献