- Carboamination of Unactivated Alkenes through Three-Component Radical Conjugate Addition
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Two-component Giese type radical additions are highly practical and established reactions. Herein, three-component radical conjugate additions of unactivated alkenes to Michael acceptors are reported. Amidyl radicals, oxidatively generated from α-amido oxy acids using redox catalysis, act as the third reaction component which add to the unactivated alkenes. The adduct radicals engage in Giese type additions to Michael acceptors to provide, after reduction, the three-component products in an overall alkene carboamination reaction. Transformations which can be conducted under practical mild conditions feature high functional group tolerance and broad substrate scope.
- Jiang, Heng,Seidler, Gesa,Studer, Armido
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supporting information
p. 16528 - 16532
(2019/11/11)
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- Introduction of a polar functional group to the lipid tail of 4-epi-jaspine B affects sphingosine kinase isoform selectivity
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Sphingosine kinases (SphKs) are key enzymes that regulate sphingosine 1-phosphate production levels, and are involved in a range of cellular processes. Focusing on a hydrophilic residue in the hydrophobic binding pocket of SphKs, we designed and synthesiz
- Inuki, Shinsuke,Miyagawa, Takashi,Oishi, Shinya,Ohno, Hiroaki
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p. 866 - 872
(2018/09/10)
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- Synthesis and reactivity of N -alkyl carbamoylimidazoles: Development of N -methyl carbamoylimidazole as a methyl isocyanate equivalent
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A high-yielding synthesis of N-methyl carbamoylimidazole from 1,1-carbonyldiimidazole (CDI) and MeNH3Cl is described. The product is a crystalline, readily storable, water-stable compound that reacts as a methyl isocyanate (MIC) substitute. Reaction of N-methyl carbamoylimidazole in the presence of a base such as triethylamine occurs with nucleophiles such as amines, protected and unprotected amino acids, thiols and alcohols. The product N-methylureas, carbamates and thiocarbamates are obtained in good to excellent yields, with reactions occurring in either organic solvents or water. The protocol for the synthesis of N-methyl carbamoylimidazole is both scalable and general, occurring in quantitative yield at scales ranging from 300 mg to 20 g. The success of this method relies upon the reaction of CDI with the ammonium salt rather than the free amine, resulting in a significant improvement in the yield of N-methyl carbamoylimidazole. The reaction presumably involves a proton transfer from MeNH3Cl to the CDI, which results in the release of MeNH2 with simultaneous activation of the CDI as its protonated form. Other primary ammonium hydrochloride salts, including protected α-amino acid salts, give excellent yields of the corresponding N-alkyl carbamoylimidazoles and serve as alkyl isocyanate surrogates. The resultant N-alkyl carbamoylimidazoles can be converted to ureas in high yields without the formation of intermediary isocyanates.
- Duspara, Petar A.,Islam, Md. Sadequl,Lough, Alan J.,Batey, Robert A.
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p. 10362 - 10368
(2013/01/15)
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- Carbamate derivatives of felbamate as potential anticonvulsant agents
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Several monocarbamate compounds derived from felbamate were synthesized and 11 target compounds (1, 4, and 6-14) were initially evaluated in mice MES and PTZ models in our laboratory. Carbamate compounds with varying substituents on the oxygen (1-4) gave anticonvulsant activity with a wide range of ED 50 in MES test from 300 mg/kg (4) and compounds with different groups on the nitrogen (5-14) also were quite active in the range of 15 mg/kg (14) to 170.5 mg/kg (6). This suggested that the spatial limitation in the MES model seemed flexible especially on the nitrogen end. All tested compounds showed some activity against mice scPTZ test, but none had the ED50 value 50 mg/kg. Ten selected compounds (1 and 6-14) for subsequent pharmacological evaluation in NIH all gave positive mice MES activity except 8 and 9, which were unexpectedly active in rats after further evaluations. Among the compounds, 1, 8, and 9 advanced to the quantitative study and 1 and 9 provided the highest PI values, 15 and 21, respectively, in the rat oral MES test.
- Kung, Ching-Hsin,Kwon, Chul-Hoon
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body text
p. 498 - 513
(2011/03/19)
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- One-pot formation of piperidine- and pyrrolidine-substituted pyridinium salts via addition of 5-alkylaminopenta-2,4-dienals to N-acyliminium ions: Application to the synthesis of (±)-nicotine and analogs
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Addition of 5-alkylaminopenta-2,4-dienals onto N-acyliminium ions, generated in situ from α-hydroxycarbamates derived from pyrrolidine or piperidine, in the presence of zinc triflate, followed by dehydrative cyclization, allowed the formation of pyridinium salts substituted at their 3-position by a five- or six-membered nitrogen heterocycle. Subsequent N-dealkylation of the pyridinium moiety and deprotection of the secondary amine or reduction of the carbamate function led to (±)-nicotine and analogs.
- Peixoto, Sabrina,Nguyen, Tuan Minh,Crich, David,Delpech, Bernard,Marazano, Christian
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supporting information; experimental part
p. 4760 - 4763
(2010/12/25)
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- An easy and efficient one-step procedure for the preparation of alkyl and aryl alkylcarbamates from S-methyl N-alkylthiocarbamates
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A general, one-step procedure for the synthesis of alkyl and aryl alkylcarbamates, by the direct reaction of S-methyl N-alkylthiocarbamates with alcohols or phenols in toluene at reflux in the presence of triethylamine, is reported. All the target products were obtained in high yield (15 examples, average yield 94%) and very high purity (>99.2%). The recovery of a co-product of industrial interest, methanethiol, in an amount of one mole for each mole of thiocarbamate, with complete exploitation of the reagent, should also be noted. Georg Thieme Verlag Stuttgart.
- Degani, Iacopo,Fochi, Rita,Magistris, Claudio
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experimental part
p. 2919 - 2924
(2009/04/06)
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- One-pot, three-step preparation of alkyl and aryl alkylcarbamates from S-methyl N-alkylthiocarbamates
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A general procedure for the synthesis of alkyl and aryl alkylcarbamates starting from the corresponding 5-methyl N-alkylthiocarbamates is described. This procedure consists of three steps that are carried out in a one-pot fashion, without isolating the intermediate N-alkylcarbamoyl chlorides or alkyl isocyanates. All the target products were obtained in high yields (16 examples, average yield 91%). To be noted is the recovery of a co-product of industrial interest, dimethyl disulfide, in a half mole amount for each mole of thiocarbamate, with complete exploitation of the reagent. The alkyl isocyanates, if required, can also be isolated in high yields. Georg Thieme Verlag Stuttgart.
- Artuso, Emma,Degani, Iacopo,Fochi, Rita,Magistris, Claudio
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experimental part
p. 1612 - 1618
(2009/04/03)
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- Concomitant Desulfurization and Transesterification of Alkyl Thionocarbamates
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Alkyl carbamate (such as 1) reacts with triphosgene at the nitrogen atom, whereas the analogous thionocarbamates (5) react at the sulfur. Subsequent treatment with various phenols or alcohols leads to the corresponding aryl carbamates or alkyl carbamates
- Joshi, Uday M.,Patkar, Laxmikant N.,Rajappa, Srinivasachari
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- Transesterification of alkyl carbamate to aryl carbamate : Effect of varying the alkyl group
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Phosphorus oxychloride mediated transesterification of four alkyl N-methylcarbamates to several aryl N-methylcarbamates has been studied. Best yields are obtained from benzyl N-methylcarbamate.
- Deshpande, Sunita R.,Likhite, Anjali P.,Rajappa, Srinivasachari
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p. 10367 - 10370
(2007/10/02)
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- Reactions of Carbamyl (Urethanyl) Radicals: Intramolecular Aromatic Additions
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The irradiation of benzyl N-bromo-N-methylcarbamates affords products due to Ar1-5 cyclisation.It has been demonstrated that the intramolecular aromatic cyclisation is regiospecific and is not strongly influenced by electronic effects.
- Dicks, Patrick F.,Glover, Stephen A.,Goosen, Andre,McCleland, Cedric W.
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p. 1243 - 1246
(2007/10/02)
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