- 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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Read Online
- Double Reversible Networks: Improvement of Self-Healing in Hybrid Materials via Combination of Diels-Alder Cross-Linking and Hydrogen Bonds
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Intrinsic self-healing materials rely on a reversible bond formation after failure. In this study we report hybrid materials that contain two intrinsic self-healing forces: The reversible covalent bond formation of Diels-Alder groups is supported by intrinsic hydrogen bonds, which form supramolecular interactions and contribute to the mobility and proximity of the DA groups. This concept was realized by a combination of urea group containing spherosilicates with butyl methacrylate based polymers bearing both DA moieties and self-assembling hydrogen bonds. Multifunctional one-component polymers were synthesized and studied regarding their application in self-healing hybrid materials. The self-healing behavior was investigated following the signals for bond release and formation of DA groups in the material using IR, UV-vis, and CP-MAS NMR spectroscopy. Furthermore, DSC and rheological measurements were performed and revealed that the materials are superior compared to previously studied systems concerning their healing capacity. The self-healing behavior of the formed hybrid materials was proven by a cut healing test of several millimeters using microscope images. We can conclude that it is advantageous to combine several reversible functions in one material to promote the self-healing capacity particularly in nanocomposites where the flexibility of the network is restricted.
- Sch?fer, Sandra,Kickelbick, Guido
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Read Online
- Metal-Free O-Selective Direct Acylation of Amino Alcohols Through Pseudo-Intramolecular Process
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Efficient α-aryl-β-keto ester acylation of amine accompanied by the elimination of ethyl phenylacetate was achieved owing to the pseudo-intramolecular process. The eliminated ethyl phenylacetate could be recycled by conversion into an α-aryl-β-keto ester upon treatment with an acyl chloride in the presence of lithium bis(trimethylsilyl)amide, by which the atom economy considerably increased. Acylation using an α-aryl-β-keto ester is highly sensitive to the bulkiness of the nucleophile, which facilitated the regioselective-acylation of the less hindered amino group in diamine without protecting the other. The transacylation of α-aryl-β-keto ester with N-alkylamino alcohol resulted in chemoselective O-acylation without protecting the amino group because the hydroxy group was attracted to the reaction site of the keto ester by forming an ammonium salt. Transacylation was demonstrated to be a practically useful tool for organic synthesis because this protocol can be conducted under mild conditions with simple manipulations in the absence of any additives such as metal catalyst and base.
- Yokoyama, Soichi,Shibauchi, Hiroshi,Asahara, Haruyasu,Nishiwaki, Nagatoshi
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supporting information
p. 1125 - 1133
(2019/02/01)
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- METHOD FOR PREPARING SITE-SPECIFICALLY MODIFIED PROTEIN BASED ON NOVEL CARBON-CARBON BOND FORMATION
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A method for producing a site-specifically modified protein based on new carbon-carbon bond formation is disclosed, including the following three steps (marking, activation, and coupling steps): (a) marking of the modification site by incorporating a spec
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Paragraph 0099-0101
(2018/03/25)
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- Chemoselective N-acetylation of primary aliphatic amines promoted by pivalic or acetic acid using ethyl acetate as an acetyl donor
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The combination of pivalic or acetic acid as a promoter and EtOAc as a solvent and acetyl donor proved to be efficient for the chemoselective N-acetylation of primary aliphatic amines to afford the corresponding acetamides. We developed a simple and convenient approach, which requires mild reaction conditions. Competitive inter- and intramolecular reactions between aliphatic amines, alcohols, and aromatic amines were examined, and chemoselectivity was achieved by adjusting the conditions of the reaction.
- Yoshida, Tomoki,Kawamura, Shimpei,Nakata, Kenya
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supporting information
p. 1181 - 1184
(2017/03/02)
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- Acetic acid as a catalyst for the N-acylation of amines using esters as the acyl source
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We report a cheap and simple method for the acetylation of a variety of amines using catalytic acetic acid and either ethyl acetate or butyl acetate as the acyl source. Catalyst loadings as low as 10 mol% afforded acetamide products in excellent yields at temperatures ranging from 80-120 °C. The methodology can also be successfully applied for the synthesis of a broad range of other amides, including the formation of formamides at 20 °C.
- Sanz Sharley, Daniel D.,Williams, Jonathan M. J.
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supporting information
p. 2020 - 2023
(2017/02/15)
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- Efficient acylation and transesterification catalyzed by dilithium tetra-tert-butylzincate at low temperatures
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The acylation and transesterification of alcohols with vinyl acetate and carboxylic esters were investigated in the presence of a catalytic amount (1-10 mol %) of dilithium tetra-tert-butylzincate (TBZL) as a catalyst. The acylation proceeded quantitatively at 0 °C within 1 h. The transesterification occurred for a wide range of combinations of esters and alcohols at 0 to -40 °C. To the best of our knowledge, this is the first successful transesterification at such low temperatures. The time-conversion plots for the transesterification show that the reaction reached equilibrium within 5 min at 0 °C. The reaction proceeded quantitatively by addition of molecular sieves 4A. In addition, the transesterification proceeded even in the presence of H2O and amines.
- Oshimura, Miyuki,Oda, Yuki,Kondoh, Keita,Hirano, Tomohiro,Ute, Koichi
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p. 2070 - 2073
(2016/04/26)
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- Synthesis of oxazolidin-2-ones and imidazolidin-2-ones directly from 1,3-diols or 3-amino alcohols using iodobenzene dichloride and sodium azide
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A general and efficient method for the synthesis of oxazolidin-2-ones and imidazolidin-2-ones directly from 1,3-diols and 3-amino alcohols has been developed using the same reagent combination of iodobenzene dichloride (PhICl2) and sodium azide (NaN3).
- He, Tian,Gao, Wen-Chao,Wang, Wei-Kun,Zhang, Chi
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supporting information
p. 1113 - 1118
(2014/04/03)
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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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- SYNTHESIS OF HYDROXYALKYL AMIDES FROM ESTERS
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Hydroxyamides are synthesized from esters. A process of making hydroxyalkyl amides comprises: reacting an ester with a hydroxyalkyl amine having the formula H2N—R3—OH wherein R3 is a substituted or unsubstituted C2 to C5 alkyl, in the presence of a catalyst in an anhydrous solution to form the hydroxyalkyl amides. Monomers suitable for formation of polymeric articles can utilize these hydroxyamides.
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Page/Page column 3
(2012/11/08)
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- Polymer-mounted N3=P(MeNCH2CH2) 3N: A green, efficient and recyclable catalyst for room-temperature transesterifications and amidations of unactivated esters
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Merrifield resin-supported N3P(MeNCH2CH 2)3N shows excellent activity in the transesterification of higher esters such as glyceryl tribenzoate to methyl esters. The catalyst was successfully cycled 20 times (albeit with an increase in reaction time) without compromising yield up to the 20th cycle. The catalyst also showed good performance in amidation reactions of unactivated esters with amino alcohols.
- Chintareddy, Venkat Reddy,Ho, Hung-An,Sadow, Aaron D.,Verkade, John G.
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experimental part
p. 6523 - 6529
(2011/12/21)
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- A green approach to chemoselective N-acetylation of amines using catalytic amount of zinc acetate in acetic acid under microwave irradiation
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It has been found for the first time that zinc acetate alone can act as a selective A'-acetylating agent without any solvent under closed vessel microwave irradiation. It is also observed that the use of a catalytic amount of this reagent in acetic acid is sufficient enough for smooth running of A'-acetylation of a number of structurally diverse amines, and the reaction is chemoselective with respect to phenols, thiols, acids and alcohols. Herein is reported a simple, efficient, cost-effective and environmentally benign alternative method for chemoselective A'-acetylation of amines using catalytic amount of zinc acetate in acetic acid under microwave irradiation. The reaction procedure requires no other solvent, and is rapid with good to excellent yields.
- Brahmachari,Laskar,Sarkar
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experimental part
p. 1274 - 1281
(2010/12/24)
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- Discovery of novel spiro-piperidine derivatives as highly potent and selective melanin-concentrating hormone 1 receptor antagonists
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Optimization of high-throughput screening hit 1a led to the identification of a novel spiro-piperidine class of melanin-concentrating hormone 1 receptor (MCH-1R) antagonists. Compound 3c was identified as a highly potent and selective MCH-1R antagonist, which has an IC50 value of 0.09 nM at hMCH-1R. The synthesis and structure-activity relationships of the novel spiro-piperidine MCH-1R antagonists are described.
- Suzuki, Takao,Moriya, Minoru,Sakamoto, Toshihiro,Suga, Takuya,Kishino, Hiroyuki,Takahashi, Hidekazu,Ishikawa, Makoto,Nagai, Keita,Imai, Yumiko,Sekino, Etsuko,Ito, Masahiko,Iwaasa, Hisashi,Ishihara, Akane,Tokita, Shigeru,Kanatani, Akio,Sato, Nagaaki,Fukami, Takehiro
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scheme or table
p. 3072 - 3077
(2010/02/28)
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- Reactions on a Solid Surface. A Simple, Economical, and Efficient Acylation of Alcohols, Amines over Al2O3
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Al2O3 brings about a rapid acylation of a range of alcohols and amines with acid chlorides and acid anhydrides, respectively. Amines are easily Boc- and Cbz-protected on reaction with Boc-anhydride and Cbz-Cl, respectively. The acylation of phenols is slow enough to allow chemoselective acylation of alcohols and amines in the presence of phenols.
- Yadav, Veejendra K.,Babu, K. Ganesh
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p. 577 - 580
(2007/10/03)
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- Substituted tetrahydro-pyrimidine-2(1H)-thione HDL-C elevators useful as antiatherosclerotic agents
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Antiatherosclerotic agents are provided having the following structure: wherein: R1is hydrogen, alkyl of 1-6 carbon atoms, cycloalkyl of 3-8 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, or phenylalkyl of 7-10 carbon atoms; and R2, R3, R4, R5, and R6are each, independently, hydrogen, halogen, alkyl of 1-6 carbon atoms, cycloalkyl of 3-8 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, aralkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, aryloxy of 6-12 carbon atoms, aralkyloxy of 7-12 carbon atoms, fluoroalkoxy of 1-6 carbon atoms, trifluoromethyl, alkylthio of 1-3 carbon atoms, alkylsulfonyl of 1-3 carbon atoms, —SCF3, nitro, alkylamino in which the alkylamino moiety has 1-6 carbon atoms, or dialkylamino in which each alkyl group has 1-6 carbon atoms; or a pharmaceutically acceptable salt thereof.
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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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- N-Acetyl-N-acyl-3-aminoquinazolinones as chemoselective acetylating agents
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The title compounds, e.g. 3, are highly selective acetylating agents for primary amines in the presence of secondary amines and, in particular, for the less sterically hindered of two different secondary amines.
- Atkinson, Robert S.,Barker, Emma,Sutcliffe, Michael J.
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p. 1051 - 1052
(2007/10/03)
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- Carboxamido (meth) acrylic acid esters for treatment of collagen
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For bonding dental fillings to dentine, carboxamide group-containing (meth)acrylic acid ester of the formula STR1 in which R1 denotes hydrogen or methyl, R2 denotes alkyl (C1 -C4) or alkenyl (C2 -C4), optionally substituted by hydroxyl, carboxyl, halogen or amino of the formula STR2 in which R4 and R5 are identical or different and denote hydrogen or lower alkyl, R3 denotes hydrogen or has one of the abovementioned meanings of R2 and X is a divalent aliphatic (C1 -C6) or cycloaliphatic radical (C3 -C6), which can optionally contain one or more oxygen, sulphur and/or --NR4 -bridges, where R4 has the abovementioned meaning.
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- Oxime esters as acylating agents in the aminolysis reaction. A simple and chemoselective method for the preparation of amides from amino alcohols
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Oxime esters, such as acetone O-alkanoyl-, O-alkenoyl- or O-benzyloxycarbonyloximes, react with amines under extremely mild conditions to give the corresponding amides in very good yield. When amino alcohols are used a total chemoselectivity is observed.
- Fernandez,Menendez,Gotor
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p. 713 - 716
(2007/10/02)
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- Alkylation and Sulfenylation of Amino Thioethers. Tetrahydro-1,3-thiazine and Related Compounds
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Reactions of electrophiles with several amino thioethers of varying chain length and ring structure are described.The reactants include N,N-dimethylmethanesulfenamide, thio>methane, 1-(N,N-dimethylamino)-2-(methylthio)ethane, tetrahydro-1,3-thiazine, tetrahydro-2-methyl-1,3-thiazine, and the corresponding N-methyl and N-acetyl derivatives.Electrophiles include methyl iodide, ethyl iodide, 3-chloro- and 3-bromopropene, trimethyloxonium fluoroborate, methanesulfenyl chloride, and dimethyl(methylthio)sulfonium fluoroborate.The objective was to assess the influence of one heteroatom on the other in competition for an electrophile.The conditions of S-N, S-C, and N-C cleavage, and attack at sulfur as opposed to nitrogen, are described.
- Kim, Jhong K.,Souma, Yoshie,Beutow, Norman,Ibbeson, Chris,Caserio, Marjorie C.
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p. 1714 - 1720
(2007/10/02)
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- Research on radioprotective agents: Δ-2 Thiazolines and homologous derivatives
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Compounds derived from Δ-2 thiazoline, Δ-2 thiazolinium iodoalkylate and 4,5-dihydro-1,3 thiazine have been prepared and evaluated as potential antiradiation agents in mice. They generally have a low toxicity and significant radioprotective activity.
- Robbe,Fernandez,Chapat,et al.
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- A NEW REAGENT FOR ACTIVATING CARBOXYL GROUPS: DIPHENYL 2-OXO-3-OXAZOLINYLPHOSPHONATE
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Diphenyl 2-oxo-3-oxazolinylphosphonate serves as a carboxyl-activating reagent to permit a direct preparation of versatile intermediate, 3-acyl-2-oxazolones or a one-step formation of amides from carboxylic acids.
- Kunieda, Takehisa,Abe, Yoshihiro,Higuchi, Tsunehiko,Hirobe, Masaaki
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p. 1257 - 1258
(2007/10/02)
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