- Phase-separable aqueous amide solutions as a thermal history indicator
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Aqueous solutions of several new amide compounds for use as simple thermal history indicators in the low-temperature transport of food and other products were synthesized. The phase transition temperatures of the aqueous solutions can be freely adjusted by changing the amide-water ratio in solution, the sodium chloride concentration of the water, and the type of amide compound. It is expected that these aqueous solutions can be applied as new thermal history indicators.
- Kitsunai, Makoto,Miyajima, Kentaro,Mikami, Yuzuru,Kim, Shokaku,Hirasawa, Akira,Chiba, Kazuhiro
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- Deuterium exchange as an indicator of hydrogen bond donors and acceptors
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Hydrogen-deuterium exchange has been used to determine the hydrogen bonding preferences of a select group of small peptides in organic solvents. This kinetic analysis permitted comparison of hydrogen bond strengths in relation to controls and also indicated the identity of both hydrogen bond donors and hydrogen bond acceptors. Copyright
- Steffel, Lauren R.,Cashman, Timothy J.,Reutershan, Michael H.,Linton, Brian R.
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Read Online
- Intramolecular hydrogen bonding and conformation of small peptides: Variable-temperature FTIR study on N-acetyl-L-Pro-L-Leu-Gly-NH2 and related compounds
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Intramolecular hydrogen bonding and conformation of tripeptide amides in CDCl3 solutions have been examined by variable-temperature FTIR spectroscopy. Absorption in the NH stretching region of N-acetyl-L-Pro-L-Leu-Gly-NH2 was decomposed into some component bands by least-squares fitting. Two broad bands at around 3350 and 3290 cm-1 were assigned to intramolecularly hydrogen-bonded NH groups in different conformers. The other relatively sharp bands were assigned to hydrogen-bond-free NHs of the three different amide groups by referring to spectra of analogous amide compounds. From temperature dependence of the band intensities, it is concluded that the C-terminal amide group takes part in the hydrogen bonding in both hydrogen-bonded conformers. From comparison with spectra of N-trifluoroacetyl-L-Pro-L-Leu-Gly-NH2 and L-Pro-L-Leu-Gly-NH2, the 3290-cm-1 band has been assigned to a 13-membered ring with the hydrogen bond between NH of the C-terminal amide group and CO of the N-terminal acetyl group. The 3350-cm-1 band, on the other hand, has been assigned to a 10-membered hydrogen-bonded ring between the C-terminal amide NH and a prolyl carbonyl group. A van't Hoff analysis shows that the 13-membered hydrogen-bonded ring is lly more favorable but entropically less favorable than the 10-membered hydrogen-bonded ring.
- Tonan, Kenji,Ikawa, Shun-Ichi
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- An unexpected copper-catalyzed carbonylative acetylation of amines
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A novel copper-catalyzed carbonylative acetylation of amines has been developed. With peroxide as the oxidant as well as the methyl source with a copper catalyst under CO pressure, good yields of N-acetyl amides could be obtained. Notably, this is the first example of carbonylative acetylation.
- Li, Yahui,Wang, Changsheng,Zhu, Fengxiang,Wang, Zechao,Fran?ois Soulé, Jean,Dixneuf, Pierre H.,Wu, Xiao-Feng
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- N-acyl and N-alkoxycarbonyl derivatives of 1H-1,2,3-triazolo-[4,5-c] pyridine; preparation and application
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The N-acylating and N-alkoxycarbonylation ability of the N-substituted 1,2,3-triazolo[4,5-c]pyridines 1a-e have been investigated. The alkoxycarbonyl triazolopyridine derivatives (1c-e) were readily prepared in 81-96% yield (the corresponding tetrafluoroborate > 95%). Triazolo[4,5-c]pyridine (1) has been shown to work as a good leaving group by the formation of amido- and carbamate protected derivatives of primary amines. The method was also successful for the N-tert-butoxycarbonyl (N-BOC) protection of the amino acid, phenylalanine. The synthetic transformations are facilitated by the one-pot preparation of 1a-e followed by the direct reaction with the amines or amino acid. The present method thus offers an efficient and convenient protocol for the in situ preparation of triazolopyridine reagents to be used directly for the protection of amines and amino acids. N-Acyl- and N-alkoxycarbonyl triazolopyridines (1a-e) were readily prepared in 4 steps from 4-aminopyridine (4) by amine protection, pyridine nitration, nitro reduction and diazotizations/cyclizations. All reactions offer the advantages of rapid conversions in high yields under very mild conditions.
- Holt, Jarle,Fiksdahl, Anne
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Read Online
- CONFORMATIONAL STUDIES BY DYNAMIC NMR-25 STEREOMUTATIONS IN TRIALKYLAMINES
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The trend toward steric acceleration for N-inversion and steric deceleration for C-N rotation has been verified in an homogeneous series of tertiary isopropylamines.Unambiguous evidence has been obtained that in a crowded amine (3-pentyl diisopropylamine) the barrier to rotation becomes higher than that to inversion.It has also been shown that this amine adopts an eclipsed, rather than a staggered dynamic conformation.
- Lunazzi, Lodovico,Macciantelli, Dante,Grossi, Loris
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Read Online
- A 2-aminopyrimidine heterocyclic compound and its applications
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The present invention discloses a 2-aminopyrimidine heterocyclic compound having a general formula I structure and its applications, which are kinase CDK4, CDK6 and / or CDK9 inhibitors, can be more widely used in the treatment of a variety of cancers, ha
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Paragraph 0086; 0094-0095
(2022/01/12)
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- A piperazine-containing aminopyrimidine derivative and its application
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The present invention discloses a piperazine-containing aminopyrimidine derivative having a general formula I. structure, which belongs to kinase CDK4, CDK6 and / or CDK9 inhibitors, can be more widely used in the treatment of a variety of cancers, has gr
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Paragraph 0124-0127
(2022/01/12)
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- A pyrimidine compound and its application
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The present invention discloses a pyrimidine amine compound having a general formula I structure and its applications, the class of compounds belongs to the kinase CDK4, CDK6 and / or CDK9 inhibitors, can be more widely used in the treatment of a variety
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Paragraph 0084; 0091-0095
(2022/01/12)
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- Phenysilane and Silicon Tetraacetate: Versatile Promotors for Amide Synthesis
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Phenylsilane was reevaluated as a useful coupling reagent for amide synthesis. At room temperature, a wide range of amides and peptides were obtained in good to excellent yields (up to 99 %). For the first time, Weinreb amides synthesis mediated by a hydrosilane were also documented. Comparative experiments with various acetoxysilanes suggested the involvement of a phenyl-triacyloxysilane. From this mechanistic study, silicon tetraacetate was shown as an efficient amine acylating agent.
- Morisset, Eléonore,Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 388 - 392
(2020/01/24)
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- AMINO PYRIMIDINE COMPOUND FOR INHIBITING PROTEIN TYROSINE KINASE ACTIVITY
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An amino pyrimidine compound for inhibiting protein tyrosine kinase activity, a pharmaceutical composition thereof, preparation therefor, and an application thereof. Specifically, an amino pyrimidine compound represented by formula (I), R1, R2, L, Y, R6, W, A, m, and n being defined in the specification, and a pharmaceutically acceptable salt, a stereoisomer, a solvent compound, a hydrate, a polymorphism, a prodrug, or an isotope variant thereof. The compound can be used for treating and/or preventing protein tyrosine kinase-related diseases such as cell proliferative diseases, cancers, and immune diseases.
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Paragraph 0302-0303
(2019/06/07)
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- An Ammonium-Formate-Driven Trienzymatic Cascade for ω-Transaminase-Catalyzed (R)-Selective Amination
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(R)-Amination mediated by (R)-specific ω-transaminases generally requires costly d-alanine in excess to obtain the desired chiral amines in high yield. Herein, a one-pot, trienzymatic cascade comprising an (R)-specific ω-transaminase, an amine dehydrogenase, and a formate dehydrogenase was developed for the economical and eco-friendly synthesis of (R)-chiral amines. Using inexpensive ammonium formate as the sole sacrificial agent, the established cascade system enabled efficient ω-transaminase-mediated (R)-amination of various ketones, with high conversions and excellent ee (>99%); water and CO2 were the only waste products.
- Chen, Fei-Fei,Liu, Lei,Wu, Jian-Ping,Xu, Jian-He,Zhang, Yu-Hui,Zhang, Zhi-Jun,Zheng, Gao-Wei
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p. 14987 - 14993
(2019/12/02)
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- Deuterium-modified Abemaciclib derivative
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The invention belongs to the field of medicinal chemistry and specifically relates to a deuterium-modified Abemaciclib derivative, a preparation method of the derivative, a pharmaceutical composition containing the deuterium-modified Abemaciclib derivative, and application of the deuterium-modified Abemaciclib derivative and the pharmaceutical composition in the preparation of a medicine for treating cell proliferative diseases. In comparison with Abemaciclib, some compounds of the invention (especially compounds in the embodiment) have more excellent pharmacokinetic properties. It is expected that clinical dosage will be reduced. Thus, treatment cost is reduced so as to benefit more patients.
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Paragraph 0071; 0072; 0073; 0074; 0075
(2017/08/02)
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- Substituted benzimidazole derivatives
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The invention belongs to the field of pharmaceutical chemistry, particularly relates to substituted benzimidazole derivatives as well as a preparation method and pharmaceutical composition thereof and further relates to an application of the substituted b
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Paragraph 0042; 0044; 0045
(2018/01/09)
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- Doping of copper (I) oxide onto a solid support as a recyclable catalyst for acetylation of amines/alcohols/phenols and synthesis of trisubstituted imidazole
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A study of copper-mediated C-heteroatom especially C-N and C-O bond formations using simpler methodologies has been carried out. In the present work, acetylation of various substrates such as amines, phenols and alcohols; synthesis of 2,4,5-trisubstituted imidazole is done using simple and easily available starting materials. Copper (I) oxide was synthesized in situ by the reduction of Fehling's solution with glucose followed by its anchoring onto different supports like silica, HAP, basic alumina and cellulose. Comparison and contrasts between the reactivity of copper (I) oxide supported onto different supports for these reactions are made. The reactivity of copper (I) oxide seems to be largely dependent on the nature of support and the most active catalyst for a particular reaction was further characterized by different spectroscopic techniques such as FTIR, XRD, TGA, XPS, SEM, TEM and AAS. The catalysts were found to be stable, easily recyclable without any significant loss in activity. Graphical abstract: Applications of solid supported copper (I) oxides (where solid support is silica, HAP, cellulose and basic alumina) are studied for various organic transformations with special emphasis on C-N and C-O bond formation reactions.[Figure not available: see fulltext.]
- Gupta, Manjulla,Gupta, Monika
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p. 231 - 241
(2016/01/09)
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- KINASE INHIBITOR AND USE THEREOF
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The invention relates to a CDK4/6 kinase inhibitor, or a pharmaceutically acceptable salt, ester, or solvate thereof, or their isomers; a pharmaceutical formulation, pharmaceutical composition and kit comprising said CDK4/6 kinase inhibitor, or a pharmaceutically acceptable salt, ester, or solvate thereof, or their isomers, and use of said CDK4/6 kinase inhibitor, or a pharmaceutically acceptable salt, ester, or solvate thereof, or their isomers. For example, the compounds of the invention are useful for reducing or inhibiting the activity of CDK4/6 kinase in a cell, and/or treating and/or preventing a cancer-related disease mediated by CDK4/6 kinase.
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Paragraph 0171; 0172
(2016/11/21)
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- Me2AlCl-mediated carboxylation, ethoxycarbonylation, and carbamoylation of indoles
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Various 1-methyl-, 1-triisopropylsilyl-, and 1-benzylindoles are carboxylated under CO2 pressure (3.0 MPa) with the aid of 1.0 molar equiv of Me2AlCl to give 1-substituted indole-3-carboxylic acids in good to excellent yields. Mechanistic studies suggest that the intermediate, an indol-3-ylaluminum ate complex, was reversibly formed by electrophilic addition of Me2AlCl to the substrate followed by deprotonation of the resulting adduct. This method is successfully extended to alkoxycarbonylation with ethyl chloroformate and carbamoylation with naphthalen-1-yl isocyanate, which afford ethyl indole-3-carboxylates and N-naphthalen-1-ylindole-3-carboxamides, respectively.
- Nemoto, Koji,Tanaka, Shinya,Konno, Megumi,Onozawa, Satoru,Chiba, Masafumi,Tanaka, Yuuki,Sasaki, Yosuke,Okubo, Ryo,Hattori, Tetsutaro
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p. 734 - 745
(2016/01/15)
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- COMBINATION THERAPY FOR CANCER
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The present invention provides preparation of medicaments for use in treating and methods of treating non-small cell lung cancer in a patient comprising: [5-(4-ethyl-piperazin-1-ylmethyl)-pyridin-2-yl]-[5-fluoro-4-(7-fluoro-3-isopropyl-2-methyl-3H- benzoimidazol-5-yl)-pyrimidin-2-yl]-amine, or a pharmaceutically acceptable salt thereof, in combination, as further described herein, with an anti-VEGFR2 antibody, preferably, ramucirumab.
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Page/Page column 28-29
(2015/09/28)
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- Direct Preparation of Amides from Amine Hydrochloride Salts and Orthoesters: A Synthetic and Mechanistic Perspective
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The conversion of a wide range of primary and secondary aliphatic and a few arylamine hydrochloride salts to their corresponding acetamides with trimethyl orthoacetate is described. Mechanistic studies using NMR and gas chromatography-mass spectrometry techniques indicate these reactions proceed via an O-methylimidate intermediate that undergoes in situ demethylation by chloride, affording the corresponding acetamides. Synthetically, this reaction represents a practical, high-yielding protocol with a simple workup for the rapid conversion of amine hydrochloride salts to acetamides.
- Di Grandi, Martin J.,Bennett, Caitlin,Cagino, Kristen,Muccini, Arnold,Suraci, Corey,Saba, Shahrokh
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supporting information
p. 2601 - 2607
(2015/11/28)
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- Ritter reactions between alcohols and acetonitrile mediated by the conducting polymer poly-(3,4-ethylenedioxy thiophene) (Pedot)
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Herein, we report new reactivity of the conducting polymer, poly-(3,4-ethylenedioxy thiophene) (PEDOT), where PEDOT mediates a Ritter reaction between alcohols and acetonitrile. The yields were variable and in most cases competitive with results obtained using sulfuric acid. Attempts at a stoichiometric reaction between benzonitrile and diphenylmethanol are also reported herein. Finally, described here are preliminary mechanistic studies that suggest PEDOT is behaving as an alcohol-selective or specific Lewis acid. Taylor & Francis Group, LLC.
- D-Angelo, John G.,Cody, Jeremy A.,Larrabee, Christian,Ostrander, Danica J.,Rugg, Kyle W.,Mamangun, Donna
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supporting information
p. 3224 - 3232
(2014/01/06)
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- Immobilization of Candida cylindracea lipase on poly lactic acid, polyvinyl alcohol and chitosan based ternary blend film: Characterization, activity, stability and its application for N-a
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The ecofriendly ternary blend polymer film was prepared from the chitosan (CH), polylactic acid (PLA) and polyvinyl alcohol (PVA). Immobilization of Candida cylindracea lipase (CCL) was carried out on ternary blend polymer via entrapment methodology. The ternary blend polymer and immobilized biocatalyst were characterized by using N2 adsorption-desorption isotherm, SEM, FTIR, DSC, and (%) water content analysis through Karl Fischer technique. Biocatalyst was then subjected for the determination of practical immobilization yield, protein loading and specific activity. Immobilized biocatalyst was further applied for the determination of biocatalytic activity for N-acylation reactions. Various reaction parameters were studied such as effect of immobilization support (ratio of PLA:PVA:CH), molar ratio (dibutylamine:vinyl acetate), solvent, biocatalyst loading, time, temperature, and orbital speed rotation. The developed protocol was then applied for the N-acylation reactions to synthesize several industrially important acetamides with excellent yields. Interestingly, immobilized lipase showed fivefold higher catalytic activity and better thermal stability than the crude extract lipase CCL. Furthermore various kinetic and thermodynamic parameters were studied and the biocatalyst was efficiently recycled for four successive reuses. It is noteworthy to mention that immobilized biocatalyst was stable for period of 300 days.
- Badgujar, Kirtikumar C.,Dhake, Kishor P.,Bhanage, Bhalchandra M.
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p. 1335 - 1347
(2013/09/12)
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- Isopropenyl acetate, a remarkable, cheap and acylating agent of amines under solvent- and catalyst-free conditions: A systematic investigation
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Isopropenyl acetate was proved to be an efficient reagent for acetylation of amine in the absence of solvent and catalyst. The corresponding acetamides were obtained in very high yields without any purification.
- Pelagalli, Romina,Chiarotto, Isabella,Feroci, Marta,Vecchio, Stefano
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supporting information; experimental part
p. 2251 - 2255
(2012/09/08)
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- Chemoselective amide formation using O-(4-nitrophenyl)hydroxylamines and pyruvic acid derivatives
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A series of O-(4-nitrophenyl)hydroxylamines were synthesized from their respective oximes using a pulsed addition of excess NaBH3CN at pH 3 in 65a-75% yield. Steric hindrance near the oxime functional group played a key role in both the ease by which the oxime could be reduced and the subsequent reactivity of the respective hydroxylamine. Reaction of the respective hydroxylamines with pyruvic acid derivatives generated the desired amides in good yields. A comparison of phenethylamine systems bearing different leaving groups revealed significant differences in the rates of these systems and suggested that the leaving group ability of the Na-OR substituent plays an important role in determining their reactivity with pyruvic acid. Competition experiments (in 68% DMSO/phosphate buffered saline) using 1 equiv of N-phenethyl-O-(4-nitrophenyl)hydroxylamine and 2 equiv of pyruvic acid in the presence of other nucleophiles such as glycine, cysteine, phenol, hexanoic acid, and lysine demonstrated that significant chemoselectivity is present in this reaction. The results suggest that this chemoselective reaction can occur in the presence of excess α-amino acids, phenols, acids, thiols, and amines.
- Kumar, Sonali,Sharma, Rashi,Garcia, Megan,Kamel, Joseph,McCarthy, Caroline,Muth, Aaron,Phanstiel, Otto
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p. 10835 - 10845
(2013/02/23)
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- Synthesis of amide libraries with immobilized HOBt
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Highly reactive N-acylating solid-phase reagents based on macroporous polystyrene-bound 1-hydroxybenzotriazole (P-HOBt) and silica-bound 1-hydroxybenzotriazole (Si-HOBt) were prepared and compared for reactivity by synthesis of small combinatorial libraries of acetamides and benzamides.
- Vokkaliga, Smitha,Jeong, Jeannie,Lacourse, William R.,Kalivretenos, Aristotle
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supporting information; experimental part
p. 2722 - 2724
(2011/06/19)
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- Microwave-assisted efficient one-step synthesis of amides from ketones and benzoxazoles from (2-hydroxyaryl) ketones with acetohydroxamic acid using sulfuric acid as the catalyst
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Efficient one-step method for the synthesis of amides directly from ketones and benzoxazoles from (2-hydroxyaryl) ketones by the reaction of acetohydroxamic acid using sulfuric acid as catalyst was described.
- Madabhushi, Sridhar,Chinthala, Narsaiah,Vangipuram, Venkata Sairam,Godala, Kondal Reddy,Jillella, Raveendra,Mallu, Kishore Kumar Reddy,Beeram, China Ramanaiah
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experimental part
p. 6103 - 6107
(2011/11/30)
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- THERMALLY STABLE VOLATILE FILM PRECURSORS
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A precursor for the deposition of a thin film by atomic layer deposition is provided. The compound has the formula MxLy where M is a metal and L is an amidrazone-derived ligand or an amidate-derived ligand. A process of forming a thin film using the precursors is also provided.
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Page/Page column 19
(2010/12/17)
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- PROTEIN KINASE INHIBITORS
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The present invention provides a compound of formula (I): or a pharmaceutically acceptable salt thereof which is useful in the treatment of cell proliferative diseases.
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Page/Page column 20-21
(2010/07/04)
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- Acyl transfer catalysis with 1,2,4-Triazole anion
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1,2,4-Triazole anion has been identified as an active acyl transfer catalyst suitable for the aminolysis and transesterification of esters.
- Yang, Xing,Birman, Vladimir B.
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supporting information; experimental part
p. 1499 - 1502
(2009/09/06)
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- Lawesson's reagent for direct thionation of hydroxamic acids: Substituent effects on LR reactivity
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To explore the generality and scope of direct thionation of hydroxamic acids (HAs), the reaction of various structurally diverse HAs with Lawesson's reagent was investigated. The yield of thiohydroxamic acid (THAs) is poor when HAs possess bulky acyl and/or N-substituents, acidic α-hydrogen atoms, or an N-phenyl ring. THAs yields were correlated with Brown sigma parameter. The relative rates of two subsequent processes kT2 and kR2 were also measured. Correlation was also found for methine proton chemical shifts of N-isopropyl benzothiohydroxamic acids.
- Przychodzen, Witold
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p. 676 - 684
(2007/10/03)
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- Transacylation of α-Aryl-β-keto Esters
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The acyl group of an α-aryl-β-keto ester was readily transferred to N-, O-, and S-nucleophiles. The transacylation from arylated diethyl 3-oxoglutarate to amines led to unsymmetrical malonic acid amide esters in high yields. The present reaction proceeded under mild conditions without formation of detectable byproducts. Only simple experimental manipulations were required. This reaction was also found to be sensitive to steric factors, which enabled the chemoselective monoacylation of diamines and amino alcohols without any modifications such as protection.
- Nishiwaki, Nagatoshi,Nishida, Daisei,Ohnishi, Tetsuya,Hidaka, Fumie,Shimizu, Satoru,Tamura, Mina,Hori, Kazushige,Tohda, Yasuo,Ariga, Masahiro
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p. 8650 - 8656
(2007/10/03)
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- DIBAL-H-H2NR and DIBAL-H-HNR1R2·HCl complexes for efficient conversion of lactones and esters to amides
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The reaction of a lactone or an ester with organoaluminum species generated from DIBAL-H-H2NR or DIBAL-H-HNR1R2·HCl complexes provided efficient methods for preparation of amides. Conditions were defined for the preparation of both secondary and tertiary amides, including Weinreb amides in excellent yields.
- Huang, Pei-Qiang,Zheng, Xiao,Deng, Xian-Ming
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p. 9039 - 9041
(2007/10/03)
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- Unusually facile dealkylation of alkyl 2-(methylthiomethyl)phenyl sulfoxides with triflic anhydride via dithia dications: Stereochemical and kinetic studies
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Alkyl 2-(methylthiomethyl)phenyl sulfoxides undergo facile monodealkylation on treatment with triflic anhydride in CH3CN to afford the corresponding thiasulfonium salts and alkyl iminium salts quantitatively. The dealkylation proceeds by an S(N)1 process which gives thiasulfonium salt and alkyl cation via an initial formation of the corresponding dithia dication species.
- Naka, Hiroyuki,Maruyama, Tetsushi,Sato, Soichi,Furukawa, Naomichi
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p. 345 - 348
(2007/10/03)
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- HOBT immobilized on macroporous polystyrene beads: A useful reagent for the synthesis of amides
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Polymer-supported 1-hydroxybenzotriazole (P-HOBT), prepared from macroporous polystyrene beads, was used to synthesize amides from primary and secondary amines.
- Dendrinos, Kleanthis,Jeong, Jeannie,Huang, Wei,Kalivretenos, Aristotle G.
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p. 499 - 500
(2007/10/03)
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- Stereodynamics of 2-(diethylamino)propane and 2-(dibenzylamino)propane. 1H and 13C{1H} DNMR studies. Molecular mechanics calculations
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2-(Diethylamino)propane (DEAP) and 2-(dibenzylamino)propane (DBAP) possess similar molecular symmetries. Interconversion among the stable equilibrium conformations occurs by inversion-rotation at the pyramidal nitrogen and by isolated rotation about carbon-nitrogen bonds. In DEAP and DBAP, the fact that stable equilibrium conformations cannot have destabilizing syn-1,5 interactions between methyl or phenyl groups limits the number of equilibrium conformations that will be present at concentrations high enough to be NMR detectable. The 1H and 13C{1H} NMR spectra of DEAP at 100 K show two diastereomeric pairs of enantiomeric conformations. One pair of enantiomers has the isopropyl methine proton and both ethyl methyl groups gauche to the lone pair (75%). The other pair has the methine proton anti to the lone pair with the ethyl methyl groups respectively gauche and anti to the lone pair (25%). The barrier to inversion-rotation in DEAP (ΔG? = 6.4 kcal/mol) is higher than barriers to isolated rotation about carbon-nitrogen bonds (ΔG? = 5.3-5.7 kcal/mol). The 1H and 13C{1H} NMR spectra of DBAP at 100 K show just one pair of enantiomeric conformations that have the isopropyl methine proton and both phenyl groups gauche to the lone pair. There is no evidence in the NMR spectrum at 100 K for those conformations of DBAP that have a phenyl group anti to the lone pair. The barrier to inversion-rotation in DBAP (ΔG? = 6.4 kcal/mol) is higher than the barrier to racemization via isolated rotation about carbon-nitrogen bonds (ΔG? = 5.5 kcal/mol). Molecular mechanics calculations of conformational energies are in good agreement with the observed conformational preferences.
- Brown, Jay H.,Bushweller, C. Hackett
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p. 12567 - 12577
(2007/10/03)
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- Aminolysis of N-Acylpyrazoles
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1-Acylpyrazoles reacted with amines having a tiny substituted to afford the corresponding amides.The aminolysis with bulky amines was controlled to be retarded by the steric factors.Due to this steric interaction, the stereoselective aminolysis was observed.This selectivity of aminolysis should increase the utility of pyrazoles as auxiliary compounds in the synthetic loop.
- Kashima, Choji,Fukuchi, Iwao,Takahashi, Katsumi,Hosomi, Akira
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p. 1407 - 1412
(2007/10/02)
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- A novel and versatile route to mixed p-toluenesulphonic carboxylic anhydrides
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A versatile route to the mixed p-toluenesulphonic carboxylic anhydrides (1) via the reaction of tetra-n-butylammonium carboxylate (2) with p-toluenesulphonyl chloride in a neutral medium is described.Some of the synthetic applications of the proposed method are described.
- Kumar, Arvind,Srivastava, Nivedita,Mital, Alka
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p. 606 - 607
(2007/10/02)
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- 1,1,1-TRICHLOROPROPANONE: A MILD, SELECTIVE ACETYLATING AGENT
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The use of the title compound in the acetylation of primary and secondary amines is described.
- Salim, Jose Roberto,Nome, Faruk,Rezende, Marcos Caroli
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p. 1181 - 1188
(2007/10/02)
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- ANODIC PHENYLSELENYLATION OF ASYMMETRIC OLEFINS
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The anodic phenylselenylation of asymmetric olefins is accompanied by vicinal addition of the active nucleophilic components (water, acetonitrile) at most substituted carbon atoms of the multiple bond.
- Latypova, V. Z.,Zhuikov, V. V.,Berestovitskaya, V. M.,Kargin, Yu. M.
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p. 1517 - 1519
(2007/10/02)
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- Hydrolysis of Unsymmetrical Acetamidines: Leaving Abilities and Stereoelectronic Effects
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Unsymmetrical acetamidines hydrolyze in alkaline D2O to a mixture of two acetamides and two amines.Product ratios from three N-methylated acetamidines and five N-alkyl-N'-methylacetamidines were determined by NMR.The direction of cleavage is determined largely by the relative basicities of the two amines, rather than by the relative basicities of the two nitrogens in the tetrahedral intermediate.Steric repulsion in the product amides can also affect the product ratio, but only slightly.There is also a novel configurational effect, which favors cleavage of the nitrogen whose alkyl group is (Z) in the amidinium ion.This arises from a stereoelectronic preference for cleavage of a leaving group that is antiperiplanar to two lone pairs in the tetrahedral intermediate.However, it is concluded that this preference is weak.These results have guided the design of a test of this stereoelectronic preference in the hydrolysis of a set of cyclic amidinium ions where product stabilities and leaving abilities can be closely matched.
- Perrin, Charles L.,Nunez, Oswaldo
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p. 522 - 527
(2007/10/02)
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- Phosphoryl to carbonyl migration of amino groups in mixed anhydrides
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Mixed anhydrides derived from carboxylic and aminophosphoric acids, (RO)(R'2N)P(O)OC(O)R'' (1), undergo unimolecular fragmentation yielding carboxyamides, R''C(O)NR'2, and metaphosphate esters, ROPO2.The mechanism of the amino group transfer was studied for substrate 1a (1, R = R' = Me; R'' = Ph); solvent as well as substituent effects indicate little (if any) charge development in the transition state.The effects of solvents and Lewis acids on the reaction rate and the activation parameters determined for 1a can be explained best in terms of stabilizing interactions with either carboxyamide or metaphosphate being formed in the course of reaction.The transfer of a functional group from one acyl center to another was investigated for other anhydride systems and the relative contributions of the fragmentation vs. disproportionation of substrates are discussed.
- Symes, Jill,Modro, Tomasz A.
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p. 1702 - 1708
(2007/10/02)
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- Applications of 1-Alkoxycarbonyl- and 1-Acyl-v-triazolopyridines as Acylating Reagents
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Selective N-protection of hydroxyamino esters has been readily achieved using 1-alkoxycarbonyl- or 1-acyl-v-triazolopyridines.The amide-type triazolides reacted with alcohols in the presence of DBU at room temperature to afford in high yields the corresponding esters.The different reactivity of 1- and 3-alkoxycarbonyl derivatives of the title bicyclic system toward primary amines has been further investigated.
- Torrini, Ines,Zecchini, Giampiero Pagani,Agrosi, Francesco,Paradisi, Mario Paglialunga
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p. 1459 - 1463
(2007/10/02)
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- Electro-organic Reactions. Part 24. Preparative and Mechanistic Aspects of the Anodic Oxidation of Dithioacetals and 1,3-Dithianes
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Anodic oxidation of the title compounds is a convenient and efficient method for deprotection, i.e. for the regeneration of carbonyl compounds. A detailed investigation of sulphur-containing products confirmed that the initial, 2 F mol-1, products are disulphides which, in aqueous acetonitrile, are oxidised further to alkyl alkane thiosulphinates and the corresponding thiosulphonates.In some cases alkyl polysulphides and N-alkylacetamides are important products.Unsymmetrical dithioacetals are oxidised anodically to the three possible disulphides, i.e. cross-coupling occurs.Unsymmetrical disulphides are similarly oxidised to a complex mixture of symmetrical and unsymmetrical thiosulphinates and thiosulphonates. These results, combined with those of cyclic voltammetric and coulometric experiments, suggest a mechanism in which the key step in carbon-sulphur bond cleavage in the initially formed radical cation.The direction of the cleavage is determined by understandable substituent effects.
- Porter, Quentin N.,Utley, James H. P.,Machion, Pedro D.,Pardini, Vera L.,Schumacher, Paolo R.,Viertler, Hans
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p. 973 - 979
(2007/10/02)
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- Acylation of Amines and Alcohols by Anodic Oxidation of N-Phenyl-hydroxamic Acids
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The electrochemical acylation of amines and alcohols is described.The yield of products from the electrochemical reaction is markedly improved by the use of N-phenyl derivatives of hydroxamic acids in place of the N-hydrogen counterparts.Keywords - anodic oxidation; acylation of amine and alcohol; N-phenylhydroxamic acid; acetonitrile; glassy-carbon electrode
- Masui, Masaichiro,Ueshima, Takahiro,Yamazaki, Tomoko,Ozaki, Shigeko
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p. 2130 - 2133
(2007/10/02)
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- Ester Aminolysis: New Reaction Series for the Quantitative Measurement of Steric Effects
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Further development of theoretical methods for computing steric effects on chemical reactivity requires a large body of new reliable quantitative data for calibration and for testing.We report here on design criteria for reaction series suitable for obtaining these data and on a successful implementation that shows promise of providing access to a particularly broad range of steric hindrance and which additionally has shown a new form of steric hindrance.The series examined in the present study is ester aminolysis in the form RCOOC6H4NO2-p + R'NH2 in acetonitrile solution.A primary purpose of the examination has been to ascertain whether aminolysis may be a useful general series or whether known or unexpected complications might render it unsuitable.We have measured rate constants for a matrix of reactions using five different R groups and four different R' groups, each reaction at a series of concentrations of amine.This is the first systematic study of the sumultaneous action of steric hindrance effects in both the acylating agent and the entering nucleophile.The reactions showed both a second-order term k2 and a relatively less important third-order term k32.The Taft equation was applied to subsets of the rate constants.For each amine there were data for a set of esters for which the R group was the variable.The slopes ρs for these sets were nearly unity.For each ester there were corresponding data for a series of amine reactions in which R' was the variable.These sets also gave good correlations, but the slopes ρs' were considerably larger, about 2.3.This unusually large difference in response to structural effects in the acylating agent and in the nucleophile is unexpected and appears to arise from a new type of steric hindrance.An obvious explanation based on bond lengths proves to be quantitatively insufficient; that explanation postulates that there is greater hindrance for the amine because the C-N bond is short in comparison with the C-C bond.The difference may be due instead to a requirement for special orientation within the transition state, a matter currently under theoretical investigation.The k2 and the k3 sets gave similar correlations, an important finding in at least two respects.It means that steric effects are well-defined in this example of ester aminolysis, and it means also that the extra molecule of amine is far enough from the reaction center so that no additional steric hindrance results.The reactions observed in the present study cover a range of 5 powers of 10 in relative rate constants.Preliminary studies with other examples of aminolysis suggest that a range of relative rate constants covering well in excess of 12 powers of 10 should be observable.
- DeTar, DeLos F.,Delahunty, Claire
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p. 2734 - 2739
(2007/10/02)
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- Alkylation of Nitriles with Gaseous Carbenium Ions. The Ritter Reaction in the Dilute Gas State
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Radiolytically formed carbenium ions, such as sec-C3H7+, sec-C4H9+, and t-C4H9+, react in the gas phase with model aliphatic and aromatic nitriles yielding the corresponding nitrilium ions.The latter undergo efficient condensation with water that eventually leads to the formation of the corresponding N-alkylamides.The mechanism is analogous to the Ritter reaction in solution.The reactivity and selectivity of the gas-phase electrophilic attack on nitriles has been deduced from competition experiments under conditions that largely exclude the effects of solvation, ion pairing, etc., which complicate the interpretation of solution-chemistry measurements.
- Cacace, Fulvio,Ciranni, Giovanna,Giacomello, Pierluigi
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p. 2258 - 2261
(2007/10/02)
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- OXIDATION-REDUCTION MECHANISMS - INNER-SPHERE AND OUTER-SPHERE ELECTRON TRANSFER IN THE REDUCTION OF IRON(III), RUTHENIUM(III), AND OSMIUM(III) COMPLEXES BY ALKYL RADICALS. MECHANISMS -
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Alkyl radicals are readily oxidized by the tris(phenanthroline) and tris(bipyridine) complexes ML//3**3** plus of iron(III), ruthenium(III), and osmium(III) in acetonitrile solution, the second-order rate constants easily exceeding 10**6 M** minus **1s** minus **1 at 25 degree C. Two oxidative processes are identified as (a) ligand substitution on the coordinated 1,10-phenanthroline to yield various alkylphenanthrolines and (b) cation formation to afford alkenes and N-alkylacetamides (after hydrolysis). Cation formation is characterized by extensive skeletal rearrangement of neopentyl, isobutyl, and n-propyl groups, whereas ligand substitution by the same alkyl radicals occurs without any rearrangement.
- Rollick,Kochi
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p. 1319 - 1330
(2007/10/02)
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- The Effect of Electrochemically Generated Positive Bromine Species in Acetonitrile on the Cleavage of C-Br and C-Cl Bonds.
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The fate of bromine formed from C-Br cleavage during the course of anodic oxidation of alkyl bromides in acetonitrile on platinum has been investigated potentiostatically.It is suggested that positive bromine species are formed and they are potentially reactive towards alkyl bromides, yielding similar products to those obtained by direct anodic oxidation of the same bromides.Furthermore, whereas alkyl chlorides do not undergo C-Cl fission by direct anodic oxidation it is shown that positive bromine species are energetically sufficient to break C-Cl bonds, although not very efficiently.We suggest that a possible structure for the complex between acetonitrile and positive bromine species is mainly +Br3- and the mechanism for its formation is discussed.The spectrum of this species found identical to that of Br3- (269 nm) in acetonitrile.
- Becker, James Y.,Zemach, Dvora
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p. 336 - 340
(2007/10/02)
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