- An efficient one-pot synthesis of: N, N ′-disubstituted ureas and carbamates from N -acylbenzotriazoles
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A facile and high-yielding one-pot synthesis of carbamates and N,N′-disubstituted symmetrical ureas from N-acylbenzotriazoles has been devised. It is believed that, the intermediate acyl-azide undergo Curtius rearrangement and in different solvents gives different products i.e. carbamates in alcohols and N,N′-disubstituted symmetrical urea in THF.
- Singh, Anoop S.,Kumar, Dhananjay,Mishra, Nidhi,Tiwari, Vinod K.
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p. 84512 - 84522
(2016/10/12)
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- Design and synthesis of novel stiripentol analogues as potential anticonvulsants
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A series of stiripentol (STP) analogues namely, 2-[(1E)-1-(1,3-benzodioxol- 5-yl)-4,4-dimethylpent-1-en-3-ylidene]-N-(aryl/H)hydrazinecarboxamides 7a-h, (±)-(5RS)-N-(aryl/H)-(1,3-benzodioxol-5-yl)-3-tert-butyl-4, 5-dihydro-1H-pyrazole-1-carboxamides (±)-8a-h, and (±)-[(5RS)-(1, 3-benzodioxol-5-yl)-3-tert-butyl-4,5-dihydro-1H-pyrazol-1-yl](aryl)methanones (±)-13a-f was synthesized by adopting appropriate synthetic routes and was pharmacologically evaluated in the preliminary anticonvulsant screens. The selected bioactive new chemical entities were subjected to ED50 determination and neurotoxicity evaluation. The most active congeners are 7h in MES screen and (±)-13b in scPTZ screen which displayed ED50 values of 87 and 110 mg/kg, respectively, as compared to that of STP (ED 50 = 277.7 and 115 mg/kg in MES and scPTZ, respectively).
- Aboul-Enein, Mohamed N.,El-Azzouny, Aida A.,Attia, Mohamed I.,Maklad, Yousreya A.,Amin, Kamilia M.,Abdel-Rehim, Mohamed,El-Behairy, Mohammed F.
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experimental part
p. 360 - 369
(2012/03/11)
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- Facile double-lithiation of a transient urea: Vicarious ortho -metalation of aniline derivatives
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A convenient one-pot method for the conversion of phenylisocyanate into ortho-functionalized aniline derivatives has been developed. The reaction proceeds via the selective ortho-metalation of a transient labile urea, which can be considered as a synthetic equivalent of 2-lithio-phenylisocyanate, a highly improbable intermediate.
- Houlden, Chris E.,Lloyd-Jones, Guy C.,Booker-Milburn, Kevin I.
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supporting information; experimental part
p. 3090 - 3092
(2010/09/05)
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- Unexpected Reaction of Oximinoacetoacetate with Amines: A Novel Synthesis of Carbamates
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The synthesis of alkyl carbamates by a solvent-free reaction of oximinoacetoacetate and amine at 130C is reported. A preliminary mechanism to this unexpected reaction is also given.
- Elghamry, Ibrahim
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experimental part
p. 3010 - 3015
(2009/12/01)
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- Pyrazolinols
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The use of pyrazolinols formula (I) in which A, Q, R1, R2, R3, R4 and R5 are as defined in the description for controlling pests, novel pyrazolinols and a plurality of processes for preparing these co
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- PYRAZOLINOLS USED AS PESTICIDES
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The invention relates to the use of pyrazolinols of formula (I), in which A, Q, R1, R2, R3, R4 and R5 are defined as cited in the description, for controlling pests. The invention also relates to nove
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Page/Page column 67
(2008/06/13)
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- Ultrasound promoted 'one pot' conversion of nitrocompounds to carbamates
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An efficient ultrasound promoted novel direct conversion of nitro compounds to N-(tert-butoxycarbonyl) amines and N-(ethoxycarbonylamines) is achieved using Sn-NH4Cl for the first time.
- Chandrasekhar,Narsihmulu,Jagadeshwar
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p. 771 - 772
(2007/10/03)
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- The Biodegradation of Low-molecular-weight Urethane Compounds by a Strain of Exophiala jeanselmei
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To further analyze the biodegradation of polyurethane polymers, we investigated the biodegradation of low-molecular-weight N-tolylcarbamate model compounds with structures closely resembling the urethane linkages found in polyurethanes based on tolylene-diisocyanate (TDT). Soil microflora were screened for microorganisms that were able to utilize toluene-2,4-dicarbamic acid, diethyl ester (compound 1) as the sole source of carbon, and the soil fungus Exophiala jeanselmei strain REN-11A was selected as the most effective strain. Several N-tolylcarbamate compounds were used, and it was found that REN-11A was able to degrade compound 1, as well as the related compound toluene-2,6-dicarbamic acid, diethyl ester, very efficiently. Further investigation showed that compound 1 was biodegraded to tolylene-2,4-diamine via the aromatic amine intermediates carbamic acid, (3-amino-4-methylphenyl)-, ethyl ester and carbamic acid, (5-amino-2-methylphenyl)-, ethyl ester.
- Owen, Stephen,Otani, Takahito,Masaoka, Satoshi,Ohe, Tatsuhiko
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p. 244 - 248
(2007/10/03)
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- Process for the preparation of urethanes
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A process for the preparation of urethanes. Urethanes having the general formula R1 (NHCOOR2)n are reacted with an alcohol at a temperature of 120° to 400° C. in amounts such that, for every mol of the urethane, at least o
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- Electrophilic Aromatic N-Substitution by Ethoxycarbonylnitrenium Ion generated from Ethyl Azidoformate in the Presence of Trifluoroacetic Acid
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Thermal reactions of ethyl azidoformate with aromatic compounds in the presence of trifluoroacetic acid (TFA) gave ethyl N-arylcarbamates.Toluene, nitrobenzene, or naphthalene was selectively attacked on the ortho- and para-positions, on the ortho- and meta-positions, or in the 1- and 2-positions, respectively.The yields were ca. twice as high as those for thermolysis ( a nitrene-azepine route) in the absence of TFA with the subsequent addition of TFA at room temperature.The positional selectivities for toluene and naphthalene were lower for the former thermolysis than for the latter.The reactivity of cyclohexane or toluene relative to benzene was greater in the latter thermolysis than the former.A Hammett plot with ρ - 1.7 was obtained for the formation of ethyl N-arylcarbamates in the former thermolysis in TFA-nitrobenzene (8:2 v/v); the value was more negative than that (-1.32) for the disappearance of substituted benzenes in the reaction with ethoxycarbonylnitrene.The results suggest that the thermolysis in the presence of TFA involves an electrophilic aromatic N-substitution by ethoxycarbonylnitrenium ion.
- Takeuchi, Hiroshi,Mastubara, Eiji
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p. 981 - 985
(2007/10/02)
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- PLATINUM COMPLEX CATALYZED REDUCTIVE N-CARBONYLATION OF NITROARENES TO THE CARBAMATES.
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The platinum catalyst combined with triphenylphosphine, tin(IV) chloride, and triethylamine showed high activity for the reductive N-carbonylation of nitroarene in ethanol at 180 degree C under carbon monoxide of 60 kg cm** minus **2. From nitrobenzene, ethyl phenylcarbamate was obtained in 83% yield. Iron(III) chloride, aluminum chloride and titanium(IV) chloride could be used as Lewis acids in place of tin(IV) chloride. Various nitroarenes were transformed into corresponding carbamate in moderate to excellent yields with the platinum catalyst.
- Watanabe,Tsuji,Takeuchi,Suzuki
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p. 3343 - 3348
(2007/10/02)
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- Electrophilic Aromatic Substitution by Ethoxycarbonylnitrenium Ion. Reactions of Ethyl Azidoformate with Aromatics in the Presence of Trifluoroacetic Acid
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Electrophilic aromatic substitution by ethoxycarbonylnitrenium ion occurs in reactions of ethyl azidoformate with aromatics in the presence of trifluoroacetic acid, giving ethyl n-arylcarbamates.
- Takeuchi, Hiroshi,Koyama, Kikuhiko
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p. 226 - 228
(2007/10/02)
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