- Hydroamination and Hydrophosphination of Isocyanates/Isothiocyanates under Catalyst-Free Conditions
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Symmetrical and unsymmetrical N,N’-disubstituted as well as trisubstituted ureas/thioureas by the hydroamination of isocyanates/isothiocyanates, and various phosphathioureas by the hydrophosphination of isothiocyanates have been synthesized in good to excellent yields under catalyst-free and mild conditions. This protocol is also applicable for the efficient synthesis of chiral ureas and thioureas and common herbicides, such as fenuron and monuron.
- Zhu, Xiancui,Xu, Mengchen,Sun, Jinrong,Guo, Dianjun,Zhang, Yiwei,Zhou, Shuangliu,Wang, Shaowu
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p. 5213 - 5218
(2021/10/19)
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- An efficient one-pot synthesis of N,N′-disubstituted phenylureas and N-aryl carbamates using hydroxylamine-O-sulfonic acid
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We have developed an efficient one-pot method for the microwave-assisted synthesis of ureas and carbamates via a proposed Lossen rearrangement. Herein we report the first examples of the direct conversion of benzoyl chlorides into N,N′-disubstituted ureas and N-aryl carbamates using hydroxylamine-O-sulfonic acid as reagent. Using our general method, we have produced 11 examples of N,N′-disubstituted phenylureas in yields up to 95% using various substituted anilines, and primary and secondary amines. Additionally, we were able to generate a series of N-aryl carbamates in moderate yields using primary, secondary and tertiary alcohols.
- Bao, Jennifer,Kuik, Dale,Tranmer, Geoffrey K.
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supporting information
p. 5546 - 5553
(2018/06/12)
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- 2-Picolylamino(diphenylphosphinoselenoic)amide supported zinc complexes: Efficient catalyst for insertion of N–H bond into carbodiimides, isocyanates, and isothiocyanate
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We report here the hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by zinc complexes supported by the ligand 2-picolylamino-(diphenylphosphinoselenoic)amide [{(Ph2P-(?Se)}2NCH2(C5H4N)] (1). A series of zinc complexes [κ2-{(Ph2P-(?Se)}2NCH2(C5H4N)ZnX2] [(X?Cl (2), Br (3a), I (4)] were prepared from ligand 1 and the corresponding zinc dihalide in a 1:1 molar ratio at 60°C in a chloroform solvent. The reaction of ligand 1 and ZnBr2 in methanol yielded another zinc complex [κ2-{(Ph2P-(?Se)}2NCH2(C5H4N)ZnBr2(CH3OH)] (3b). The molecular structures of compounds 3a, 3b, and 4 were established through single-crystal X-ray diffraction analyses. The solid-state structures of all the complexes revealed a κ2- chelation through pyridine nitrogen and selenium atoms of ligand 1 to the zinc ion. Complex 2 proved to be a competent pre-catalyst for the addition of the amine N–H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanate and phenylisothiocyanate in toluene solvents, which proceeded rapidly at room temperature with 5 mol% catalyst loading to yield (up to 99%) the corresponding derivatives of urea and thio-urea. However, a temperature of 90°C was needed for the hydroamination of N,N′ dicyclohexylcarbodiimide. We also report the most plausible mechanism of the hydroamination reaction.
- Harinath, Adimulam,Bano, Kulsum,Ahmed, Shakil,Panda, Tarun K.
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supporting information
p. 23 - 32
(2017/09/25)
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- Scalable, One-Pot, Microwave-Accelerated Tandem Synthesis of Unsymmetrical Urea Derivatives
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We report a facile, microwave-accelerated, one-pot tandem synthesis of unsymmetrical ureas via a Curtius rearrangement. In this method, one-pot microwave irradiation of commercially available (hetero)aromatic acids and amines in the presence of diphenylphosphoryl azide enabled extremely rapid (1-5 min) construction of an array of unsymmetrical ureas in good to excellent yields. We demonstrate the utility of our method in the efficient, gram-scale synthesis of key biologically active compounds targeting the cannabinoid 1 and α7 nicotinic acetylcholine receptors.
- Kulkarni, Abhijit R.,Garai, Sumanta,Thakur, Ganesh A.
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p. 992 - 999
(2018/06/18)
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- Pd/C Catalyzed Carbonylation of Azides in the Presence of Amines
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A facile and efficient Pd/C-catalyzed carbonylation of both aliphatic and aromatic azides in the presence of amines is reported. Serving as the widely existed fragments in an array of biological pharmaceuticals, functionalized unsymmetrical ureas were str
- Zhao, Jin,Li, Zongyang,Yan, Shuaihu,Xu, Shiyang,Wang, Ming-An,Fu, Bin,Zhang, Zhenhua
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p. 1736 - 1739
(2016/05/19)
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- Preparation method for alkyl/benzyl/aryl urea compounds through heterogeneous-phase catalysis
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The invention discloses a preparation method for formula (I) compounds, and the compounds are obtained by reacting a formula (II) compound with a formula (III) compound in a solvent in carbon monoxide atmosphere under catalysis of a heterogeneous-phase pa
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Paragraph 0063-0071; 0072; 0073; 0074; 0076; 0078; 0082
(2016/10/09)
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- Imidazolin-2-iminato Ligand-Supported Titanium Complexes as Catalysts for the Synthesis of Urea Derivatives
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The reactions of tetrakis(dimethylamido)titanium(IV) [Ti(NMe2)4] with three different imidazolin-2-imines (ImRNH; R = tert-butyl (tBu), mesityl (Mes), and 2,6-diisopropylphenyl (Dipp)) afforded the corresponding titanium i
- Naktode, Kishor,Das, Suman,Bhattacharjee, Jayeeta,Nayek, Hari Pada,Panda, Tarun K.
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supporting information
p. 1142 - 1153
(2016/02/09)
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- Hydroamination of carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(IV) complex
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The hydroamination of heterocumulenes such as carbodiimides, isocyanates, and isothiocyanates by a bis(phosphinoselenoic amide) supported titanium(iv) complex as a precatalyst is reported here. The titanium(iv) complex [{Ph2P(Se)NCH2CH2NPPh2(Se)}Ti(NMe2)2] (1) was synthesised by the reaction of tetrakis-(dimethylamido)titanium(iv) [Ti(NMe2)4] with [{Ph2P(Se)NHCH2CH2NHPPh2(Se)}] in toluene at ambient temperature. Titanium complex 1 proved to be a competent pre-catalyst for the addition of an amine N-H bond to carbodiimides, isocyanates, and isothiocyanates. The reaction scope was expanded to reactions of aliphatic and aromatic amines with phenylisocyanates and phenylisothiocyanates in toluene solvents proceeding rapidly at room temperature with 5 mol% catalyst loadings to yield the corresponding urea and thio-urea derivatives up to 99%. However, ambient temperature was needed for hydroamination of 1,3-dicyclohexylcarbodiimide. The amine addition reactions with isocyanates showed first order kinetics with respect to catalyst 1 as well as substrates. The most plausible mechanism for the hydroamination reaction was established by isolating 1,1-dimethylphenyl urea as a side product.
- Bhattacharjee, Jayeeta,Das, Suman,Kottalanka, Ravi K.,Panda, Tarun K.
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supporting information
p. 17824 - 17832
(2016/11/18)
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- Curtius rearrangement of aromatic carboxylic acids to access protected anilines and aromatic ureas
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(Diagram presented) The reaction of a chloroformate or di-tert-butyl dicarbonate and sodium azide with an aromatic carboxylic acid produces the corresponding acyl azide, presumably through the formation of an azidoformate. The acyl azide undergoes a Curtius rearrangement to form an isocyanate derivative which is trapped either by an alkoxide or by an amine to form the aromatic carbamate or urea. The reaction conditions are compatible with a variety of functional groups and allow the synthesis of a number of aniline derivatives containing alkyl, halide, nitro, ketone, ether, and thioether substituents.
- Lebel, Helene,Leogane, Olivier
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p. 5717 - 5720
(2007/10/03)
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- A study on the stability of 5,5-diamino-substituted- 1,4,2- oxathiazoline derivatives
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5,5-Diamino-substituted-1,4,2-oxathiazoline derivatives 3 as potential prodrugs, which were easily prepared from hydroximoyl chlorides I and the appropriate thiourea derivatives 2, were decomposed instantaneously into isothiocyanates 4 and the corresponding urea derivatives 5 irrespective of the substituents.
- Jung, Keum Shin,Lee, Hong Jung,Song, Hyun Nam,Kim, Jae Nyoung
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p. 1879 - 1884
(2007/10/03)
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- Ureas from N-Chloroamidines; An Aza-Analogous Hofmann Degradation
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N-Chlorination and subsequent treatment with alkali of suitably substituted benzamidines yields ureas with phenyl or alkyl migration.Under the same conditions, 2-iminopyrrolidine is converted into 2-oxohexahydropyrimidine with ring enlargement.
- Sonnenschein, Helmut,Schmitz, Ernst
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p. 443 - 444
(2007/10/02)
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- The Nitrile Oxide-Isocyanate Rearrangement
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The thermal rearrangement of 2,4,6-trimethylbenzonitrile N-oxide to the corresponding isocyanate has been investigated by double isotopic labelling and kinetic experiments.Rearrangement proceeds with exchange of oxygen atoms, and this exchange occurs exclusively between nitrile oxide molecules.Kinetic results suggest that the pathway involves a polymerisation, catalysed either by electrophiles or by nucleophiles, followed by decomposition of the polymer.The rearrangement is catalysed at room temperature by trifluoracetic acid.A synthesis of (18)O-labelled hydroxylamine is reported.
- Taylor, Giles A.
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p. 1181 - 1184
(2007/10/02)
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