- Iridium-catalyzed regiospecific and stereospecific allylic amination for the syntheses of α,β-unsaturated γ-amino esters and the bifurcation of the reaction pathway leading to the formation of oxazolidin-2-ones
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A pair of iridium-catalyzed regiospecific and stereospecific reactions of the carbonates of γ-hydroxy α,β-unsaturated esters were developed. The reaction pathways are strongly affected by the choice of amines employed. A diverse range of γ-substituted α,β-unsaturated γ-amino esters were prepared in excellent yields with various amine nucleophiles such as benzylamine, diallylamine, morpholine, aniline and N-methylaniline. Substitution at the γ-position was well tolerated, encompassing alkyl, aryl and heteroaryl substituents. Enantioenriched (E)-α,β-unsaturated γ-amino esters could also be synthesized from the corresponding enantioenriched allylic carbonates with complete chirality transfer. In sharp contrast, a series of 3,4-disubstituted oxazolidin-2-ones were obtained by using allylamine as a nucleophile.
- Lee, Jun Hee,Lee, Sang-Gi
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Read Online
- Reactions of dimethyl carbonate with aliphatic amines under high pressure
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A facile synthesis of methyl carbamates from primary amines and dimethyl carbonate has been achieved at room temperature using high pressure. High-pressure synthesis of methyl carbamates described herein provides access to the target molecules in an efficient and environmentally friendly way without solvent or catalyst. Better conversion and selectivity than previously published procedures were obtained. Copyright
- Margetic, Davor,Antonac, Irena Zrinski,Glasovac, Zoran,Eckert-Maksic, Mirjana,Maksimovic, Ljiljana
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Read Online
- N-Aryl and N-Alkyl Carbamates from 1 Atmosphere of CO2
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We have successfully isolated and characterized the zinc carbamate complex (phen)Zn(OAc)(OC(=O)NHPh) (1; phen=1,10-phenanthroline), formed as an intermediate during the Zn(OAc)2/phen-catalyzed synthesis of organic carbamates from CO2, amines, and the reusable reactant Si(OMe)4. Density functional theory calculations revealed that the direct reaction of 1 with Si(OMe)4 proceeds via a five-coordinate silicon intermediate, forming organic carbamates. Based on these results, the catalytic system was improved by using Si(OMe)4 as the reaction solvent and additives like KOMe and KF, which promote the formation of the five-coordinated silicon species. This sustainable and effective method can be used to synthesize various N-aryl and N-alkyl carbamates, including industrially important polyurethane raw materials, starting from CO2 under atmospheric pressure.
- Chen, Ming-Yu,Choe, Yoong-Kee,Choi, Jun-Chul,Fukaya, Norihisa,Hamura, Satoshi,Koizumi, Hiroki,Matsumoto, Kazuhiro,Matsumoto, Seiji,Shigeyasu, Shinji,Takeuchi, Katsuhiko,Yuan, Hao-Yu
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supporting information
p. 18066 - 18073
(2021/12/08)
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- METHOD FOR PRODUCING CARBAMATE
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PROBLEM TO BE SOLVED: To provide a method that can produce carbamate with high yield and high selectivity, and excellent economical efficiency, using more different kinds of amines. SOLUTION: A method for producing carbamate has a reaction step where, in the presence of calcium carbide and potassium carbonate, a reaction is induced among amine, methanol, and carbon dioxide. The reaction step is preferably performed at a temperature of 165-180°C. The reaction step is preferably performed at a carbon dioxide pressure of 3-5 MPa. The reaction step is preferably performed using an acetonitrile solvent. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0014-0024
(2021/08/13)
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- Methoxycarbonylation of Alkyl-, Cycloalkyl-, and Arylamines with Dimethyl Carbonate in the Presence of Binder-Free Zeolite
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Abstract: Methyl N-alkyl-, N-cycloalkyl-, and N-arylcarbamates were synthesized by reaction of the correspondingamines with dimethyl carbonate in the presence of binder-free FeHY zeolite. Theoptimal conditions (reactant ratio, amount of the catalyst, temperature,reaction time) were found to afford the target products with high yields.
- Khazipova, A. N.,Khusnutdinov, R. I.,Mayakova, Yu. Yu.,Shchadneva, N. A.
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p. 1228 - 1235
(2020/10/02)
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- Urethanes synthesis from oxamic acids under electrochemical conditions
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Urethane synthesis via oxidative decarboxylation of oxamic acids under mild electrochemical conditions is reported. This simple phosgene-free route to urethanes involves an in situ generation of isocyanates by anodic oxidation of oxamic acids in an alcoholic medium. The reaction is applicable to a wide range of oxamic acids, including chiral ones, and alcohols furnishing the desired urethanes in a one-pot process without the use of a chemical oxidant.
- Ogbu, Ikechukwu Martin,Lusseau, Jonathan,Kurtay, Gülbin,Robert, Frédéric,Landais, Yannick
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supporting information
p. 12226 - 12229
(2020/10/26)
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- O-Alkyl S-(Pyridin-2-yl)carbonothiolates: Operationally Simple and Highly Nitrogen-Selective Reagents for Alkoxy Carbonylation of Amino Groups
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Amino groups are selectively protected in good yields by reaction with O-Alkyl S-(pyridin-2-yl)carbonothiolates in an appropriate solvent at room temperature in air. Even glucosamine, which contains multiple hydroxyl groups, is selectively N-protected in methanol.
- Hashimoto, Yoshimitsu,Morita, Nobuyoshi,Suzuki, Tomoyuki,Tamura, Osamu,Tanaka, Kosaku
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p. 899 - 902
(2020/05/28)
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- Application of Ag/TFPG-DMB COF in carbamates synthesis via CO2 fixation reaction and one-pot reductive N-formylation of nitroarenes under sunlight
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We have designed mesoporous AgNPs decorated COF (Ag/TFPG-DMB COF) nanomaterial which has been formed by an easy ex-situ synthetic method. The synthesized material is characterized by FTIR, PXRD, UV–vis, N2 adsorption–desorption studies, TEM, FESEM and XPS. The material showed the generation of identical mesopore at 3.9 nm. It is observed that the material can perform as both thermally and photochemically active catalyst for carbamate synthesis and one-pot reduction and N-formylation of nitroarenes respectively. The catalytic activity of the Ag/ TFPG-DMB COF nanomaterial is checked for green synthesis of carbamates from different amines and alcohols under 1 atmospheric pressure of CO2 with excellent yield (upto 95 %) as well as with high TOF value (182 h?1) and high selectivity. Additionally, the Ag/ TFPG-DMB COF nanomaterial is also applied as a potentially active photocatalyst for one-pot nitroarene reduction along with N-formylation reaction under sunlight irradiation in green reaction conditions with exceptionally high yield of formylated products upto 99 % as well as with high TOF value (762 h ?1). The catalyst efficiently reduced and formylated para-nitrophenol, a potential water pollutant, which elaborates its scope as an efficient catalyst for water purification also. The catalyst recyclability is also checked for five reaction cycles for both the reactions and the Ag/TFPG-DMB COF material showed outstanding recycling ability without any noticeable leaching of active metal or catalyst degradation.
- Biswas, Surajit,Hazra Chowdhury, Arpita,Hazra Chowdhury, Ipsita,Islam, Sk. Manirul
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- Calcium carbide as a dehydrating agent for the synthesis of carbamates, glycerol carbonate, and cyclic carbonates from carbon dioxide
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Carbon dioxide (CO2) is a nontoxic and inexpensive C1 building block, which can be used for the synthesis of valuable chemicals such as aromatic carbamates from anilines and methanol (MeOH), glycerol carbonate from glycerol, and cyclic carbonates from diols. However, these reactions generate water as the byproduct and suffer from thermodynamic limits, which lead to low yields. Calcium carbide (CaC2) is a renewable chemical, which can be recycled from calcium that is abundant in the Earth's crust. Furthermore, CaC2 rapidly reacts with water. In this work, we used CaC2 as a dehydrating agent for the direct synthesis of carbamates (including polyurethane precursors) from amines, CO2, and MeOH. All reagents were commercially available. In addition, CaC2 was employed for the synthesis of glycerol carbonate from glycerol and CO2 with a zinc catalyst and N-donor ligand. A similar protocol was applied to synthesize cyclic carbonates from diols and CO2.
- Choi, Jun-Chul,Fujitani, Tadahiro,Fukaya, Norihisa,Lin, Xiao-Tao,Sato, Kazuhiko,Yuan, Hao-Yu,Zhang, Qiao
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p. 4231 - 4239
(2020/10/02)
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- A Multicomponent Approach to Oxazolidinone Synthesis Catalyzed by Rare-Earth Metal Amides
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Three-component reaction of epoxides, amines, and dimethyl carbonate catalyzed by rare-earth metal amides has been developed to synthesize oxazolidinones. 47 examples of 3,5-disubstituted oxazolidinones were prepared in 13–97 % yields. This is a simple and most practical method which employs easily available substrates and catalysts, and is applicable to a wide range of aromatic and aliphatic amines, as well as mono-substituted epoxides. Scope of disubstituted epoxides is rather limited, which requires further study. Preliminary mechanistic study reveals two possible reaction pathways through intermediates of β-amino alcohols or amides.
- Zhou, Meixia,Zheng, Xizhou,Wang, Yaorong,Yuan, Dan,Yao, Yingming
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p. 5783 - 5787
(2019/04/14)
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- Electrochemical Hofmann rearrangement mediated by NaBr: Practical access to bioactive carbamates
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An electrochemical Hofmann rearrangement is reported. With the mediation of NaBr, highly corrosive and toxic halogens are avoided. Moreover, this efficient and green approach is well compatible with a broad range of amides, including several commercial medicine derivatives, and provides direct access to synthetically useful carbamates. The synthetic utility of this method is also demonstrated by the preparation of 15N labeling carbamate and gram-scale synthesis of Amantadine.
- Li, Lijun,Xue, Mengyu,Yan, Xin,Liu, Wenmin,Xu, Kun,Zhang, Sheng
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supporting information
p. 4615 - 4618
(2018/07/06)
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- Synthesis of carbamates from carbon dioxide promoted by organostannanes and alkoxysilanes
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A cooperative methoxy transfer between orthosilicate esters and organotin oxides was developed for the synthesis of various N-alkyl and N-aryl carbamates from carbon dioxide in up to 97% isolated yield. The reaction is highly selective and N-alkylated amines are not observed. Density functional theory calculations of the reaction were performed and, together with NMR observations, a plausible mechanism featuring the catalytic regeneration of dialkyltin dialkoxide is proposed.
- Germain, Nicolas,Hermsen, Marko,Schaub, Thomas,Trapp, Oliver
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- Method for preparing methyl carbamate by catalyzing methanol conversion
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The invention discloses a method for preparing methyl carbamate by catalyzing methanol conversion. The method specifically comprises: taking oxygen or air as an oxygen source, taking organic amine as a nitrogen source, taking methanol as a solvent, in the function of a catalyst, allowing methanol to undergo ammoxidation to generate methanamide, and allowing methanamide to undergo in-situ oxidation esterification to obtain methyl carbamate. The method is high in raw material utilization rate. The catalyst is cheap and available, is easy to recycle, can be reused, and is easy to separate from the product. The obtained methyl carbamate is excellent in performance and high in purity. The technical route is of great significance in releasing excess production capacity of methanol and reducing the dependence on highly toxic chemicals.
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Paragraph 0038
(2018/01/09)
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- Iodoarene-catalyzed oxidative transformations using molecular oxygen
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Molecular oxygen serves as a useful oxidant for the glycol scission of 1,2-diols and the Hofmann rearrangement of primary amides using pentamethyliodobenzene as a catalyst. The use of isobutyraldehyde and Lewis basic nitriles under O2 enabled the iodine(i)/(iii) catalytic cycle, where in situ-generated peracid acts as a terminal oxidant.
- Miyamoto,Yamashita,Narita,Sakai,Hirano,Saito,Wang,Ochiai,Uchiyama
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supporting information
p. 9781 - 9784
(2017/09/07)
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- Preparation, Structure, and Reactivity of Pseudocyclic Benziodoxole Tosylates: New Hypervalent Iodine Oxidants and Electrophiles
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New pseudocyclic benziodoxole tosylates were prepared by the treatment of 1-hydroxybenziodoxolones with p-toluenesulfonic acid or via ligand transfer reaction between PhI(OH)OTs (Koser's reagent) and substituted 2-iodobenzoic acids under mild condition. S
- Yoshimura, Akira,Klasen, Scott C.,Shea, Michael T.,Nguyen, Khiem C.,Rohde, Gregory T.,Saito, Akio,Postnikov, Pavel S.,Yusubov, Mekhman S.,Nemykin, Victor N.,Zhdankin, Viktor V.
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supporting information
p. 691 - 695
(2017/01/18)
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- Heterobimetallic dinuclear lanthanide alkoxide complexes as acid-base bifunctional catalysts for synthesis of carbamates under solvent-free conditions
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Heterobimetallic dinuclear lanthanide alkoxide complexes Ln2Na8(OCH2CH2NMe2)12(OH)2 [Ln: I (Nd), II (Sm), III (Yb) and IV (Y)] were used as efficient acid-base bifunctional catalysts for the synthesis of carbamates from dialkyl carbonates and amines as well as the N-Boc protection of amines. The cooperative catalysts showed high catalytic activity and a wide scope of substrates with good to excellent yields under solvent-free conditions. The systems have shown higher catalytic activities due to the noteworthy synergistic interactions of Lewis acid center-Br?nsted basic center. The comparison of catalytic efficiency between mono- and dinuclear heterobimetallic lanthanide alkoxide analogues was also investigated.
- Zeng, Ruijie,Bao, Linquan,Sheng, Hongting,Sun, Lili,Chen, Man,Feng, Yan,Zhu, Manzhou
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p. 78576 - 78584
(2016/09/09)
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- Effective synthesis of dimethylhexane-1,6-dicarbamate from 1,6-hexanediamine and dimethyl carbonate using 3-amino-1,2,4-triazole potassium as a solid base catalyst at ambient temperature
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A new basic catalyst 3-amino-1,2,4-triazole potassium (KATriz) was prepared, characterized and employed for synthesis of dimethylhexane 1,6-dicarbamate (MHDC) by methoxycarbonylation of 1,6-hexanediamine (HDA) and dimethyl carbonate (DMC). Results showed that KATriz exhibited high catalytic activity and selectivity, 100% HDA conversion with nearly 100% MHDC selectivity that could be obtained at room temperature. The catalyst can be reused for several runs without any deactivation. Besides, the influence of reaction conditions, the structure of amines and the possible catalytic mechanism were also investigated.
- Wang, Peixue,Fei, Yuqing,Li, Qinghe,Deng, Youquan
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p. 6681 - 6686
(2018/06/08)
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- One-pot synthesis of carbamates and thiocarbamates from Boc-protected amines
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A highly efficient one-pot procedure for the synthesis of carbamates and thiocarbamates has been described. In the presence of 2-chloropyridine and trifluoromethanesulfonyl anhydride, the isocyanate intermediates were generated in situ for further reactions with alcohols and thiols to afford the desired carbamates and thiocarbamates in high yields.
- Kim, Hee-Kwon,Lee, Anna
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p. 4890 - 4892
(2016/10/21)
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- Evaluation of ethyl: N -(2-phenethyl) carbamate analogues as biofilm inhibitors of methicillin resistant Staphylococcus aureus
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A small molecule library consisting of 45 compounds was synthesized based on the bacterial metabolite ethyl N-(2-phenethyl) carbamate. Screening of the compounds revealed a potent analogue capabale of inhibiting several strains of Methicillin Resistant S. aureus biofilms with low to moderate micromolar IC50 values.
- Stephens, Matthew D.,Yodsanit, Nisakorn,Melander, Christian
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p. 6853 - 6856
(2016/07/21)
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- Hofmann Rearrangement of Carboxamides Mediated by N-Bromoacetamide
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An efficient, one-pot procedure for the Hofmann rearrangement of aromatic and aliphatic amides has been developed. Methyl and benzyl carbamates are produced with N-bromoacetamide in the presence of lithium hydroxide or lithium methoxide, in high yields. β-Phenylamino amides gave five-membered cyclic ureas stereospecifically. Side products of aryl or benzyl bromination were minimized. This procedure offers an easy access to various protected amines or diamines, which represent important synthetic precursors.
- Jevti?, Ivana I.,Do?en-Mi?ovi?, Ljiljana,Ivanovi?, Evica R.,Ivanovi?, Milovan D.
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p. 1550 - 1560
(2016/06/01)
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- L-Proline-TBAB-catalyzed phosgene free synthesis of methyl carbamates from amines and dimethyl carbonate
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The reaction of amines and dimethyl carbonate (DMC) in the presence of catalytic amounts of l-proline and tetrabutylammonium bromide (TBAB) afforded methyl carbamates in good to excellent yields under mild conditions. The presence of both l-proline and TBAB co-catalysts is vital for this transformation.
- Kumar, Subodh,Jain, Suman L.
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p. 2935 - 2938
(2013/09/12)
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- Introducing catalytic lossen rearrangements: Sustainable access to carbamates and amines
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A new, highly efficient and environmentally benign catalytic variant of the Lossen rearrangement is described. Dimethyl carbonate (DMC) as green activation reagent of hydroxamic acids in presence of catalytic amounts of tertiary amine bases {1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8-biazabicyclo 5.4.0 undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane (DABCO), and triethylamine} and small quantities of methanol initiate the rearrangement. Methyl carbamates were obtained in good to moderate yields when aliphatic hydroxamic acids were employed in this catalytic Lossen rearrangement; under the same conditions aromatic hydroxamic acids yielded anilines. Notably, the mixture of DMC/methanol was recycled several times without observing decreased yields, thus minimizing the produced waste. Moreover, several other organic carbonates were successfully employed in the introduced catalytic Lossen rearrangement procedure. Copyright
- Kreye, Oliver,Wald, Sarah,Meier, Michael A. R.
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- Nitrogen-containing organobases as promoters in the cobalt(II)-Schiff base catalyzed oxidative carbonylation of amines
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The use of organic bases as promoters in the cobalt(II)-Schiff base complex catalyzed oxidative carbonylation of amines was investigated. The generality of the reaction was also studied by submitting different amines to the same procedure and by changing the reaction conditions. Very good yields in the corresponding ureas were achieved in toluene with a catalyst loading of 0.5 mol % and using TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene) as promoter. Methyl carbamates were obtained in methanol.
- Saliu, Francesco,Putomatti, Benedetto,Rindone, Bruno
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scheme or table
p. 3590 - 3593
(2012/09/08)
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- PROCESS FOR PREPARING A CARBAMATE COMPOUND
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There is provided a process for preparing a carbamate compound, which is easy and commercially advantageous in that a carbamate compound can be produced with high yield from an amine compound and a carbonate compound. A process for preparing a carbamate compound which comprises the step of reacting an amine compound which has at least one amino group per molecule wherein the amine compound is selected from the group consisting of an aliphatic amine which may be substituted by an alicyclic group or an aromatic group or which may be interrupted by an alicyclic group or an aromatic group, and an alicyclic amine which may be substituted by an aliphatic group, with a carbonate compound in the presence of at least one organic solvent selected from the group consisting of a saturated cyclic hydrocarbon, an unsaturated cyclic hydrocarbon, and a non-cyclic ether by using a hydrolase.
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Page/Page column 9
(2012/12/13)
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- Lewis-acid-mediated ring-exchange reaction of dihydrobenzofurans and its application to the formal total synthesis of (-)-quinocarcinamide
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An unusual Lewis-acid-mediated ring-exchange reaction of dihydrobenzofurans is described. The fused tricyclic ring system is the key structural element for this reaction as it restricts C-N bond rotation and/or destabilizes the benzofuran ring. We achieved the formal total synthesis of (-)-quinocarcinamide using a combination of this reaction and the Au(I)-catalyzed 6-endo-dig hydroamination of an alkyne.
- Chiba, Hiroaki,Sakai, Yuki,Oishi, Shinya,Fujii, Nobutaka,Ohno, Hiroaki
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p. 6273 - 6276,4
(2012/12/12)
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- Lewis-acid-mediated ring-exchange reaction of dihydrobenzofurans and its application to the formal total synthesis of (-)-quinocarcinamide
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An unusual Lewis-acid-mediated ring-exchange reaction of dihydrobenzofurans is described. The fused tricyclic ring system is the key structural element for this reaction as it restricts C-N bond rotation and/or destabilizes the benzofuran ring. We achieved the formal total synthesis of (-)-quinocarcinamide using a combination of this reaction and the Au(I)-catalyzed 6-endo-dig hydroamination of an alkyne.
- Chiba, Hiroaki,Sakai, Yuki,Oishi, Shinya,Fujii, Nobutaka,Ohno, Hiroaki
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p. 6273 - 6276
(2013/01/14)
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- 1,3-oxazinan-2-ones from amines and 1,3-diols through dialkyl carbonate chemistry
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A one-pot green synthesis of 1,3-oxazinan-2-ones from amines and 1,3-diols in the presence of a dialkyl carbonate and potassium tert-butoxide is described. Four dialkyl carbonates were utilised: dimethyl carbonate, diethyl carbonate, diprop-2-yl carbonate, and tert-butyl methyl carbonate. The more hindered the dialkyl carbonate used, the higher the yield of 1,3-oxazinan-2-one. Four 1,3-diols were reacted having primary-primary, primary-secondary, primary-tertiary, and secondary-tertiary functionalities, with the yield of oxazinanone decreasing with increasing hindrance of the diol. In the case of the diols containing primary and either secondary or tertiary functionality, the substituent(s) were selectively found in the 6-position of the so-formed oxazinanone. The optimized conditions were then employed with different nucleophiles, namely phenylhydrazine, aniline, and n-octylamine.
- McElroy, Conrobert,Aricò, Fabio,Tundo, Pietro
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experimental part
p. 1809 - 1815
(2012/08/29)
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- (Tosylimino)phenyl-λ3-iodane as a reagent for the synthesis of methyl carbamates via hofmann rearrangement of aromatic and aliphatic carboxamides
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A new, mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides using (tosylimino)phenyl-λ3-iodane, PhINTs, as a reagent is reported. Because of the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides, which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates or their subsequent conversion to stable carbamates by treatment with alcohols.
- Yoshimura, Akira,Luedtke, Matthew W.,Zhdankin, Viktor V.
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experimental part
p. 2087 - 2091
(2012/05/05)
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- Hypervalent iodine catalyzed hofmann rearrangement of carboxamides using oxone as terminal oxidant
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Hofmann rearrangement of carboxamides to carbamates using Oxone as an oxidant can be efficiently catalyzed by iodobenzene. This reaction involves hypervalent iodine species generated in situ from catalytic amount of PhI and Oxone in the presence of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) in aqueous methanol solutions. Under these conditions, Hofmann rearrangement of various carboxamides affords corresponding carbamates in high yields.
- Yoshimura, Akira,Middleton, Kyle R.,Luedtke, Matthew W.,Zhu, Chenjie,Zhdankin, Viktor V.
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p. 11399 - 11404
(2013/02/23)
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- Highly efficient synthesis of ureas and carbamates from amides by iodosylbenzene-induced hofmann rearrangement
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A simple and efficient method for the synthesis of 1,3-disubstituted ureas and carbamates from amides by using iodosylbenzene as the oxidant is described. Symmetric and asymmetric ureas and carbamates can be prepared by this procedure in up to 98 % yield. Ureidopeptides can also be prepared in good yield by this method. A simple and efficient method for the synthesis of 1,3-disubstituted ureas and carbamates from amides by using iodosylbenzene as the oxidant is described. By using this method, heterocyclic products can be easily obtained in excellent yield. Ureidopeptides can also be prepared in good yield by this procedure. Copyright
- Liu, Peng,Wang, Zhiming,Hu, Xianming
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experimental part
p. 1994 - 2000
(2012/05/05)
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- Heterogeneous CeO2 catalyst for the one-pot synthesis of organic carbamates from amines, CO2 and alcohols
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Heterogeneous CeO2 catalyst can catalyze the one-pot synthesis of methyl benzylcarbamate from benzylamine, CO2 and methanol. The yield of methyl benzylcarbamate reached 92% at >99% benzylamine conversion and 92% benzylamine-based selectivity even in the absence of the dehydrating agents. The catalyst is reusable after the calcination at 873 K for 3 h. Various carbamates can be synthesized with good yield and high selectivity by the reaction of amines + CO2 + alcohols over CeO2. The main formation route of methyl benzylcarbamate is suggested to be the reaction of dimethyl carbonate or the precursor of dimethyl carbonate formation with benzylamine.
- Honda, Masayoshi,Sonehara, Satoru,Yasuda, Hiroshi,Nakagawa, Yoshinao,Tomishige, Keiichi
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supporting information; scheme or table
p. 3406 - 3413
(2012/01/15)
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- Kinetics and mechanism of the aminolysis of O-methyl S-aryl thiocarbonates in acetonitrile
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The aminolysis of O-methyl S-aryl thiocarbonates with benzylamines are studied in acetonitrile at -45.0°C. The βX (βnuc) values are in the range 0.62-0.80 with a negative cross-interaction constant, ρXZ = -0.42, which are interpreted to indicate a concerted mechanism. The kinetic isotope effects involving deuterated benzylamine nucleophiles (XC6H 4CH2ND2) are large, kH/kD = 1.29-1.75, suggesting that the N-H(D) bond is partially broken in the transition state by forming a hydrogen-bonded four-center cyclic structure. The concerted mechanism is enforced by the strong push provided by the MeO group which enhances the nucleofugalities of both benzylamine and arenethiolate from the putative zwitterionic tetrahedral intermediate.
- Oh, Hyuck Keun
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scheme or table
p. 1539 - 1542
(2011/12/04)
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- Green and practical synthesis of carbamates from ureas and organic carbonates
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A practical method for the synthesis of carbamates from ureas and organic carbonates was developed with 100% atom economy using La2O 3/SiO2 as catalyst without any additional solvent. The scope of the protocol is demonstrated in the synthesis of 14 carbamates with various functional groups in excellent yields (76-95%).
- Guo, Xiaoguang,Shang, Jianpeng,Li, Jian,Wang, Liguo,Ma, Yubo,Shi, Feng,Deng, Youquan
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experimental part
p. 1102 - 1111
(2011/05/02)
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- Synthesis of methyl-1-(tert -butoxycarbonylamino)-2- vinylcyclopropanecarboxylate via a hofmann rearrangement utilizing trichloroisocyanuric acid as an oxidant
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A trichloroisocyanuric acid (TCCA) mediated Hofmann rearrangement was utilized to synthesize methyl-1-(tert-butoxycarbonylamino)-2- vinylcyclopropanecarboxylate. A variety of functional groups are tolerated in this reaction including vinyl, cyclopropyl, pyridyl, aryl, benzyl, and nitro groups.
- Crane, Zackary D.,Nichols, Paul J.,Sammakia, Tarek,Stengel, Peter J.
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supporting information; experimental part
p. 277 - 280
(2011/03/20)
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- Parallel synthesis of ureas and carbamates from amines and CO2 under mild conditions
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"Chemical Equation Presented" A mild and efficient library synthesis technique has been developed for the synthesis of ureas and carbamates from carbamic acids derived from the DBU-catalyzed reaction of amines and gaseous carbon dioxide. Carbamic acids derived from primary amines reacted with Mitsunobu reagents to generate isocyanates in situ which were condensed with primary and secondary amines to afford the desired ureas. Similarly, carbamic acids from secondary amines reacted with alcohols activated with Mitsunobu reagents to form carbamates.
- Peterson, Scott L.,Stucka, Sabrina M.,Dinsmore, Christopher J.
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supporting information; experimental part
p. 1340 - 1343
(2010/06/15)
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- Carbamate synthesis from amines and dialkyl carbonate over inexpensive and clean acidic catalyst-Sulfamic acid
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Sulfamic acid has been proved to be the most efficient and recyclable catalyst in carbamate synthesis from alkylamine and dialkyl carbonate. High selectivity, cost-efficiency and simple product separation were the advantageous features obtained in this process. Sulfamic acid could be reused several times and keep its initial activity in the recycle runs. In addition, sulfamic acid has also exhibited the potential catalytic ability for alkylation of aromatic amines.
- Wang, Bo,He, Jing,Sun, Run Cang
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scheme or table
p. 794 - 797
(2011/11/13)
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- Atom-economy synthesis of N-substituted carbamate from urea derivative and dimethyl carbonate catalyzed by La/SiO2: Characterization and activity
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A series of silica gel immobilized lanthanum catalysts were prepared for the atom-economy synthesis of N-substituted carbamates from urea derivatives and dimethyl carbonate. The La/SiO2 catalysts with lanthanum loadings varied from 1.3 wt% to 8.5 wt% were characterized by AES, BET, XRD, TEM, FT-IR, XPS and TPD. According to the characterization, lanthanum species with particle sizes of 5-10 nm on the surface of silica gel were formed. The catalysts were all amorphous and the surface areas were 336.5-530.2 m2/g. NH3-TPD analysis showed that all samples exhibited similar acid strength with different acid amounts. FT-IR measurement indicated that the component of lanthanum species on the catalyst surface were La(OH)3, LaOOH and hydrated La2O3. Also, the peak value of the absolute amount of LaOOH was obtained with 4.3 wt% lanthanum loading. The BET surface area decreased dramatically when the lanthanum loading was above 4.3 wt%. In consideration of the results obtained from the catalytic reactions, it could be concluded that LaOOH was the possible active species and high surface area was important for the high catalytic activity.
- Guo, Xiaoguanga,Shang, Jianpenga,Li, Jiana,Wang, Liguoa,Ma, Yuboa,Shi, Feng,Deng, Youquan
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experimental part
p. 164 - 170
(2010/10/19)
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- Synthesis of carbamates from amines and dialkyl carbonates: Influence of leaving and entering groups
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A number of carbamates were synthesised through a halogen-free process by reacting amines with symmetrical and unsymmetrical carbonates. The results obtained showed a specific trend of preferred leaving groups (in the dialkyl carbonates) depending on whether a catalyst or a base was used. On the other hand, investigations conducted on the preferred entering groups (amines) for the synthesis of carbamates showed the same trend regardless of whether a catalyst or a base was used. Finally, in accordance with the results obtained, it was possible to synthesise sterically hindered carbamates in high yield by transesterification of methyl carbamate with a sterically hindered alcohol. Georg Thieme Verlag Stuttgart New York.
- Tundo, Pietro,McElroy, C. Robert,Aricò, Fabio
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experimental part
p. 1567 - 1571
(2010/09/05)
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- Straightforward carbamoylation of nucleophilic compounds employing organic azides, phosphines, and aqueous trialkylammonium hydrogen carbonate
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In the presence of aqueous trialkylammonium hydrogen carbonate, the Staudinger reaction leads to the intermediate formation of the corresponding isocyanate, which, in turn, reacts further with a nucleophilic reagent also present in the mixture and results in carbamoylation with good yield. On the basis of this reaction a practical carbamoylation procedure was devised and a comparative study on suitability of different solvents and phosphorus (III) derivatives for carbamoylation reaction was conducted. The versatility of the method was demonstrated by examples with different classes of nucleophilic compounds that included the aminomethyl resin and natural compounds that display poor solubility in organic solvents.
- Yagodkin, Andrey,L?schcke, Kerstin,Weisell, Janne,Azhayev, Alex
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scheme or table
p. 2210 - 2221
(2010/04/29)
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- Effect of successive increase in alcohol chains on reaction with isocyanates and isothiocyanates
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The reaction of isocyanates and isothiocyanates with long-chain alcohols, e.g. n-hexanol, n-heptanol and n-octanol, exclusively gave N-aryl-O-alkyl carbamates, while N-aryl-O-alkyl carbamates were formed along with symmetrical 1,3-disubstituted ureas and thioureas when the same reactions were carried out with small-chain alcohols at room temperature without using any solvent.
- Perveen, Shahnaz,Yasmin, Arfa,Khan, Khalid Mohammed
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experimental part
p. 18 - 23
(2010/04/23)
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- Direct fixation of [11C]-CO2 by amines: Formation of [11C-carbonyl]-methylcarbamates
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[11C-Carbonyl]-methylcarbamates can be synthesised directly from [11C]-CO2 and primary or secondary amines in a one-pot, two-step reaction. The use of either diazabicyclo[5.4.0]undec-7-ene (DBU) or 2-tert-butylimino-2-diethylamino-1,3-dimethyl-perhydro-1,3,2-diazaphosphorine (BEMP) enables efficient trapping of [11C]-CO2 in small volumes of DMF as [11C]-carbamate salts. Subsequent reaction with a variety of methylating agents rapidly generates the desired [ 11C-carbonyl]-methylcarbamates in high radiochemical yields. The usefulness of the method is illustrated by the efficient radiosynthesis of a kappa opioid receptor imaging radiotracer, useful in positron emission tomography (PET).
- Wilson, Alan A.,Garcia, Armando,Houle, Sylvain,Vasdev, Neil
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experimental part
p. 428 - 432
(2010/02/16)
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- Hofmann rearrangement of carboxamides mediated by hypervalent iodine species generated in situ from iodobenzene and oxone: Reaction scope and limitations
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Alkylcarboxamides can be converted to the respective amines by Hofmann rearrangement using hypervalent iodine species generated in situ from PhI and Oxone in aqueous acetonitrile. On the basis of this reaction, a convenient experimental procedure for the preparation of alkylcarbamates using Oxone as the oxidant in the presence of iodobenzene in methanol has been developed. An efficient method for direct conversion of substituted benzamides to the respective quinone derivatives by treatment with Oxone and iodobenzene in aqueous acetonitrile has also been found.
- Zagulyaeva, Aleksandra A.,Banek, Christopher T.,Yusubov, Mekhman S.,Zhdankin, Viktor V.
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supporting information; experimental part
p. 4644 - 4647
(2010/12/19)
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- Hindered ureas as masked isocyanates: Facile carbamoylation of nucleophiles under neutral conditions
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Bigger is better: Sterically hindered dialkyl ureas undergo nucleophilic substitution at dramatically faster rates than their less hindered counterparts (see scheme). Steric decompression upon the formation of an intermediate isocyanate can explain this c
- Hutchby, Marc,Houlden, Chris E.,Gair Ford,Tyler, Simon N. G.,Gagne, Michel R.,Lloyd-Jones, Guy C.,Booker-Milburn, Kevin I.
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supporting information; experimental part
p. 8721 - 8724
(2010/01/16)
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- N-Alkylation of carbamates and amides with alcohols catalyzed by a Cp*Ir complex
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New atom-economical catalytic systems consisting of [Cp*IrCl2]2/NaOAc (Cp*=pentamethylcyclopentadienyl) for the N-alkylation of carbamates and amides using alcohols as alkylating agents under solvent-free conditions have been developed. For example, the reaction of n-butyl carbamate with benzyl alcohol in the presence of [Cp*IrCl2]2 (5.0 mol % Ir) and NaOAc (5.0 mol %) at 130 °C under the absence of solvent gives n-butyl N-benzylcarbamate in the yield of 94%. The present catalytic system is applicable to not only carbamates but also amides, and only harmless water is produced as co-product.
- Fujita, Ken-ichi,Komatsubara, Atsuo,Yamaguchi, Ryohei
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experimental part
p. 3624 - 3628
(2009/09/06)
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- Indium-catalyzed reaction for the synthesis of carbamates and carbonates: selective protection of amino groups
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We developed a simple, efficient, and selective method for preparing organic carbamates and carbonates using a catalytic amount of indium. A wide range of carbamates and carbonates were synthesized in high yields. The method is also applicable to the selective protection of amino groups under mild conditions.
- Kim, Joong-Gon,Jang, Doo Ok
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experimental part
p. 2688 - 2692
(2009/08/09)
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- Sc(OTf)3-catalyzed carbomethoxylation of aliphatic amines with dimethyl carbonate (DMC): DMC activation by η1-O(C{double bond, long}O) coordination to Sc(III) and its relevance to catalysis
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The role of metal center in the Sc(OTf)3-catalyzed carbomethoxylation of aliphatic amines with DMC has been investigated. We have shown that the catalytic formation of carbamate ester is promoted by coordination of DMC to scandium(III) ion through the carbonyl oxygen atom. The ability of DMC to coordinate to Sc(III) has been proved by IR and NMR spectroscopy and fully demonstrated also by the isolation, for the first time, of a DMC-metal complex characterized as (η1-O(C{double bond, long}O)-DMC)Sc(OTf)3. A relationship has been shown between the coordination mode of DMC to Sc(III) and the reactivity of coordinated organic carbonate: coordination of DMC to Sc(III) activates both carbonyl group and O-CH3 moieties of the carbonic acid diester and enhances not only the carbomethoxylating but also the methylating activity of the ambident electrophile (DMC), as documented by the different selectivity exhibited by the catalyst in the aminolysis reaction of DMC with benzylamine and aniline, respectively.
- Distaso, Monica,Quaranta, Eugenio
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p. 278 - 288
(2008/09/17)
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- Mild and convenient synthesis of organic carbamates from amines and carbon dioxide using tetraethylammonium superoxide
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A safe and simple method of preparing organic carbamates has been achieved from amines and carbon dioxide using tetraethylammonium superoxide generated in situ. Copyright Taylor & Francis Group, LLC.
- Singh, Krishna Nand
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p. 2651 - 2654
(2008/02/12)
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- A general, facile, and safe procedure for the preparation of S-methyl N-alkylthiocarbamates by methylthiocarbonylation of primary aliphatic amines with S,S-dimethyl dithiocarbonate
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A general procedure is reported for the selective preparation of S-methyl N-alkylthiocarbamates by methylthiocarbonylation of primary aliphatic amines, employing S,S-dimethyl dithiocarbonate as a phosgene substitute. The reactions are carried out in water at room temperature (20-25°C), with S,S-dimethyl dithiocarbonate/amine ratios varying between 1:1.2 and 1:2, and with quantitative recovery of the excess amine. The target products are obtained in exceptionally high yields (generally >95%) and with very high purity (generally >99.5%). Also to be noted is the complete chemoselectivity of the reactions, which can be carried out in the presence of hydroxy or aminophenyl groups. Georg Thieme Verlag Stuttgart.
- Artuso, Emma,Carvoli, Gianni,Degani, Iacopo,Fochi, Rita,Magistris, Claudio
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p. 1096 - 1102
(2008/02/04)
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- Synthesis of carbamates and ureas using Zr(IV)-catalyzed exchange processes
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Equation presented Zirconium(IV)-catalyzed exchange processes have been developed to prepare both carbamates and ureas from dialkyl arbonates and carbamates employing 2-hydroxypyridine (HYP) and 4-methyl-2-hydroxyquinoline (MeHYQ) as catalytic additives, respectively A microwave acceleration effect was observed in Zr(IV)-catalyzed carbamate-urea exchange.
- Han, Chong,Porco Jr., John A.
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p. 1517 - 1520
(2008/02/02)
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