- Effect of Transition Metals on Chemodivergent Cross-Coupling of Acrylamides with Vinyl Acetate via C-H Activation
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A novel chemodivergent cross-coupling of acrylamides and vinyl acetates has been realized via metal-catalyzed vinylic C-H activation. The selective olefinic C-H vinylation and alkenylation reaction was examined with a variety of differently functionalized acrylamides. The reaction efficiently generates a range of highly synthetically valuable butadienes with good functional group tolerance in good to moderate yields. A possible catalytic reaction mechanism involving the chelation-assisted olefinic C-H activation via an acetate-assisted deprotonation pathway is proposed.
- Logeswaran, Ravichandran,Jeganmohan, Masilamani
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supporting information
p. 5679 - 5683
(2021/08/03)
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- One-pot lipase-catalyzed enantioselective synthesis of (r)-(?)-n-benzyl-3-(benzylamino)butanamide: The effect of solvent polarity on enantioselectivity
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The use of the solvent engineering has been applied for controlling the resolution of lipase-catalyzed synthesis of β-aminoacids via Michael addition reactions. The strategy consisted of the thermodynamic control of products at equilibrium using the lipase CalB as a catalyst. The enzymatic chemo- and enantioselective synthesis of (R)-(?)-N-benzyl-3-(benzylamino)butanamide is reported, showing the influence of the solvent on the chemoselectivity of the aza-Michael addition and the subsequent kinetic resolution of the Michael adduct; both processes are catalyzed by CalB and both are influenced by the nature of the solvent medium. This approach allowed us to propose a novel one-pot strategy for the enzymatic synthesis of enantiomerically enriched β-aminoesters and β-aminoacids.
- Ortega-Rojas, Marina A.,Rivera-Ramírez, José Domingo,ávila-Ortiz, C. Gabriela,Juaristi, Eusebio,González-Mu oz, Fernando,Castillo, Edmundo,Escalante, Jaime
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- Direct amidation of carboxylic acids with amines under microwave irradiation using silica gel as a solid support
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A highly improved and green methodology for the direct amidation of carboxylic acids with amines using silica gel as a solid support and catalyst is described. The scope of this method is exemplified by the use of several aliphatic, aromatic, unsaturated and fatty acids. The reaction is also applied to different primary and secondary amines. Typically, the amines should be aliphatic, but aromatic amines can be used as well, though with lower yields. Several experiments to illustrate the selectivity of this methodology were also carried out with several more functionalized acids and amines. This approach is a substantial improvement over other previously described methods in amide synthesis.
- Ojeda-Porras, Andrea,Hernández-Santana, Alejandra,Gamba-Sánchez, Diego
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supporting information
p. 3157 - 3163
(2015/05/27)
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- Lipase-catalyzed aza-michael reaction on acrylate derivatives
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A methodology has been developed for an efficient and selective lipase-catalyzed aza-Michael reaction of various amines (primary and secondary) with a series of acrylates and alkylacrylates. Reaction parameters were tuned, and under the optimal conditions it was found that Pseudomonas stutzeri lipase and Chromobacterium viscosum lipase showed the highest selectivity for the aza-Michael addition to substituted alkyl acrylates. For the first time also, some CLEAs were examined that showed a comparable or higher selectivity and yield than the free enzymes and other formulations.
- Steunenberg, Peter,Sijm, Maarten,Zuilhof, Han,Sanders, Johan P. M.,Scott, Elinor L.,Franssen, Maurice C. R.
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p. 3802 - 3813
(2013/06/05)
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- Convenient synthesis of various substituted homotaurines from alk-2-enamides
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Various substituted homotaurines (=3-aminopropane-1-sulfonic acids) 6 were readily synthesized in satisfactory to good yields via the Michael addition of thioacetic acid to alk-2-enamides 3 (→4), followed by LiAlH4 reduction (→5) and performic acid oxidation (Scheme 1). The configuration of 'anti'-disubstituted homotaurine 'anti'-6h was deduced from the 3-(acetylthio)alkanamide (=S-(3-amino-1,2-dimethyl-3-oxopropyl) ethanethioate)'anti'-4h formed in the Michael addition, which was identified via the Karplus equation analysis, and confirmed by X-ray diffraction analysis. The current route is an efficient method to synthesize diverse substituted homotaurines, including 1-, 2-, and N-monosubstituted, as well as 1,2-, 1,N-, 2,N-, and N,N-disubstituted homotaurines (Table). Copyright
- Nai, Youfeng,Xu, Jiaxi
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p. 1355 - 1365
(2013/08/23)
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- Ruthenium- and rhodium-catalyzed cross-coupling reaction of acrylamides with alkenes: Efficient access to (Z,E)-dienamides
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Ruthenium- and rhodium-catalyzed direct oxidative cross-coupling reactions of acrylamides with alkenes were developed. These methods provide an efficient route for the synthesis of (Z,E)-dienamides in excellent yields with good stereoselectivity. The catalytic systems allowed oxidative olefination of a wide range of alkenes bearing different functional groups, such as CO2R, COMe, SO2Ph, aryl, CONHBn, CN, PO(OEt)2, as well as Weinreb amide.
- Zhang, Jian,Loh, Teck-Peng
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supporting information
p. 11232 - 11234
(2013/01/15)
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- Synthesis of β,γ-unsaturated primary amides from α,β-unsaturated acids and investigation of the mechanism
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α,β-Unsaturated acids, through their acid chlorides, react with tritylamine in the presence of triethylamine under mild conditions, to afford in high yield and high regioselectivity the corresponding β,γ- unsaturated tritylamides. Detritylation with TFA generates quantitatively β,γ-unsaturated primary amides. An investigation of this deconjugative isomerization was performed.
- Theodorou, Vassiliki,Gogou, Marina,Philippidou, Maria,Ragoussis, Valentine,Paraskevopoulos, Georgios,Skobridis, Konstantinos
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experimental part
p. 5630 - 5634
(2011/08/22)
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- Diastereoselective Michael addition of magnesium amide to O-(2-Alkenoyl)TEMPOs and comparison of reactivity with acyl substituent-modified carboxylic analogues
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O-(2-Alkenoyl)TEMPOs bearing an ON bond in the acyl substituent are highly reactive in Michael addition of magnesium amide compared with their acyl substituent-modified analogs. Highly diastereoselective addition is achieved to the AlMe3-treated O-(2-alkenoyl)TEMPO as an acceptor with the Mg amide generated from optically active secondary amine.
- Ma, Li-Jian,Mei, Zhen-Wu,Toyohara, Keisuke,Kawafuchi, Hiroyuki,Nokami, Junzo,Inokuchi, Tsutomu
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supporting information; experimental part
p. 1545 - 1547
(2011/03/16)
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- Practical, highly enantioselective chemoenzymatic one-pot synthesis of short-chain aliphatic β-amino acid esters
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A practical, highly enantioselective method for the synthesis of short-chain aliphatic β-amino acid esters was developed starting from prochiral and easily accessible substrates. This chemoenzymatic approach is based on a nonenzymatic aza-Michael addition
- Wei?, Markus,Gr?ger, Harald
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scheme or table
p. 1251 - 1254
(2009/09/06)
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- Solvent engineering: an effective tool to direct chemoselectivity in a lipase-catalyzed Michael addition
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A solvent engineering strategy was implemented in order to control the chemoselectivity in a lipase-catalyzed Michael addition reaction. This strategy was revealed as a high-effective tool for the selective synthesis of Michael adduct 3 or aminolysis product 4 from benzylamine 1 and methyl crotonate 2. Chemoselectivity of the enzymatic process was elucidated in terms of polarity of the medium, hence, adduct 3 was preferentially accumulated in hydrophobic medium, whereas in polar solvents the amide 4 was preferentially formed.
- Priego, Jaime,Ortíz-Nava, Claudia,Carrillo-Morales, Manuel,López-Munguía, Agustín,Escalante, Jaime,Castillo, Edmundo
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experimental part
p. 536 - 539
(2009/04/07)
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- Solid-supported chloro[1,3,5]triazine. A versatile new synthetic auxiliary for the synthesis of amide libraries
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(equation presented) 2,4,6-Trichloro[1,3,5]triazine was loaded on different types of NH2-functionalized resins to give a new supported reagent. The best results, in term of yields products, were obtained using the chlorotriazine linked to a polystyrene-poly(ethylene glycol) resin. This reagent was employed for the solution-phase synthesis of different amides and dipeptides.
- Masala, Simonetta,Taddei, Maurizio
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p. 1355 - 1357
(2008/02/09)
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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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- ONE-POT SELECTIVE ACYLATION OF AMINES USING 3,6-DIETHYL-2-HYDROXYPYRAZINE AS ACYL CARRIER
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Introduction of 3,6-diethyl-2-hydroxypyrazine into a system of amide syntheses using acyl diethylphosphates resulted in the performance of selective acylation in satisfactory yields.
- Ohta, Akihiro,Inagawa, Yukiko,Okuwaki, Yukari,Shimazaki, Makoto
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p. 2369 - 2373
(2007/10/02)
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