21462-02-2Relevant academic research and scientific papers
Cyclosophoraose as a catalytic carbohydrate for methanolysis
Lee, Sanghoo,Jung, Seunho
, p. 461 - 468 (2004)
A novel catalytic methanolysis can be induced by a natural cyclooligosaccharide, a cyclosophoraose (cyclic-(1→2)-β-D-glucan, Cys), which is a member of a family of unbranched cyclooligosaccharides produced as intra- or extraoligosaccharides by soil microorganisms of the genus, Rhizobium. Cys catalyzed the methanolysis for 5(4H)-oxazolones and various phospholipids. Cys enhanced the methanolysis reaction about 9200-fold for a benzylidene oxazolone or 250-fold for dipalmitoylphosphatidylcholine comparing with control. In this study, we describe that natural cyclosophoraoses isolated from the Rhizobium species function as catalytic carbohydrates for the methanolysis.
Ni(ii)-Catalyzed vinylic C-H functionalization of 2-acetamido-3-arylacrylates to access isotetronic acids
Das, Eshani,Mal, Dipakranjan,Roy, Avijit,Roy, Biswajit
supporting information, p. 3697 - 3706 (2020/06/03)
A ligand-free Ni(ii)-catalyzed cascade annulation reaction for the synthesis of 4-aryl-substituted isotetronic acids from 2-acetamido-3-arylacrylatesviavinylic C-H functionalization is reported. The reaction proceeds through heteroatom guided electrophilic insertion of nickel to the vinylic double bond followed by annulation with dibromomethane. This unconventional route features cascade steps, sole product formation, multiple functional group tolerance, low cost of catalysts and reagents, and readily available starting materials. Using this method, various aryl-substituted isotetronic acids have been synthesized which are biologically relevant. The annulation of 2-acetamido-3-arylacrylates has also been assessed with 1,2-dichloroethane, which resulted in the rearranged annulated products of 5-methyl substituted isotetronic acids.
Nickel-Catalyzed Asymmetric Hydrogenation of 2-Amidoacrylates
Chen, Jianzhong,Gridnev, Ilya D.,Hu, Yawen,Li, Bowen,Zhang, Wanbin,Zhang, Zhenfeng
supporting information, p. 5371 - 5375 (2020/02/15)
Earth-abundant nickel, coordinated with a suitable chiral bisphosphine ligand, was found to be an efficient catalyst for the asymmetric hydrogenation of 2-amidoacrylates, affording the chiral α-amino acid esters in quantitative yields and excellent enantioselectivity (up to 96 % ee). The active catalyst component was studied by NMR and HRMS, which helped us to realize high catalytic efficiency on a gram scale with a low catalyst loading (S/C=2000). The hydrogenated products could be simply converted into chiral α-amino acids, β-amino alcohols, and their bioactive derivatives. Furthermore, the catalytic mechanism was investigated using deuterium-labeling experiments and computational calculations.
Synthesis of 4-benzylidene-oxazol-5(4H)-imines, structural analogs of PK11195, under Bischler-Napieralski conditions
Almaraz-Girón, Marco A.,Vázquez, Alfredo
, p. 785 - 788 (2017/03/31)
A simple and convenient one-pot procedure to prepare 4-benzylidene-2-aryl-1,3-oxazol-5(4H)-imines from phenyl pyruvic acid and a series of arylamides, under classical Bischler-Napieralski (B-N) conditions and microwave heating (MW) has been developed. The
Synthesis of oxazoles from enamides via phenyliodine diacetate-mediated intramolecular oxidative cyclization
Zheng, Yunhui,Li, Xuming,Ren, Chengfeng,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
, p. 10353 - 10361 (2013/01/15)
A group of functionalized oxazoles were synthesized in moderate to good yields from enamides via phenyliodine diacetate (PIDA)-mediated intramolecular cyclization. The main advantageous features of the present method include its broad substrate scope and the heavy-metal-free characteristic of the oxidative carbon-oxygen bond formation process.
Reactivity of unsaturated 5(4H)-oxazolones with Hg(II) acetate: Synthesis of methyl N-benzoylamino-3-arylacrylates
Roiban, Gheorghe-Doru,Soler, Tatiana,Contel, Maria,Grosu, Ion,Cativiela, Carlos,Urriolabeitia, Esteban P.
experimental part, p. 195 - 203 (2011/10/31)
An efficient and high-yield procedure to prepare methyl N-benzoylamino-3-arylacrylates from unsaturated (Z)-2-aryl-4-arylidene-5-(4H)- oxazolones and Hg(OAc)2 in methanol is described herein. The observed reactivity of mercury(II) acetate here
Synthesis and electrochemical behaviour of β-halodehydroamino acid derivatives
Ferreira, Paula M. T.,Monteiro,Pereira
experimental part, p. 499 - 513 (2010/11/04)
Several new β,β-dihalo and β-halo-β-substituted dehydroalanines and dehydrodipeptides were synthesized by reacting the corresponding dehydroamino acid derivative with a N-halosuccinimide or in the case of β,β-di-iododehydroalanines with iodine. The results obtained confirmed that the stereochemical outcome of the halogenation reaction with β-substituted dehydroamino acids depends on the substrate. Thus, an increase Z-stereoselectivity was found when the β-phenyldehydroalanines were used as substrates and when these compounds were N-protected with 4-tolylsulfonyl or with carbamates. From this study, it is also possible to conclude that when N-iodosuccinimide was used as reagent a much higher Z-stereoselectivity is found. The electrochemical behaviour of the halogenated dehydroamino acids was studied by cyclic voltammetry. The results show a shift in the reduction peak to higher potentials of the β-halogenated dehydroamino acids when compared with the corresponding non-halogenated derivatives. As expected, the β,β-dihalodehydroalanines exhibit higher peak potentials than β-halo-β-substituted dehydroalanines and the bromo derivatives have lower peak potentials when compared with the corresponding iododehydroamino acids. Controlled potential electrolysis of several β-halo-β-substituted dehydroamino acids afforded the corresponding dehalogenated dehydroamino acids as mixtures of their E and Z-isomers. In all cases, the major isomer isolated results from dehalogenation without isomerization. These new results show that electrochemical reduction constitutes a valuable method for the synthesis of the E-isomer of β-substituted dehydroalanines. Springer-Verlag 2010.
Synthesis of substituted oxazoles from N-acyl-β-hydroxyamino acid derivatives
Ferreira, Paula M. T.,Monteiro, Luis S.,Pereira, Goreti
experimental part, p. 4676 - 4683 (2009/05/27)
Several N-acyl-β-hydroxyamino acids were prepared and treated with di-tert-butyl dicarbonate in the presence of 4-(dimethylamino)pyridine, followed by treatment with N,N,N′,N′-tetramethylguanidine to give the corresponding N-acyldehydroamino acids in good
Practical preparation of Z-α-(N-acetylamino)- and Z-α-(N-benzoylamino)-α,β-unsaturated acids
Jursic, Branko S.,Sagiraju, Sarada,Ancalade, Dustin K.,Clark, Traneil,Stevens, Edwin D.
, p. 1709 - 1714 (2008/02/01)
An efficient two-step synthetic procedure for the preparation of numerous variations of N-protected α,β-unsaturated α-amino acids and their corresponding esters from N-protected glycine and either aliphatic or aromatic aldehydes was developed. The reaction involved cyclization of the N-protected glycine into oxazolone, condensation with the aldehyde, and ring opening with a base. Copyright Taylor & Francis Group, LLC.
Preferential formation of cis-4,5-dihydrooxazole derivatives via photoinduced electron transfer-initiated cyclization of N-acyl-α-dehydroarylalanine alkyl esters
Maekawa, Kei,Hishikawa, Norikazu,Kubo, Kanji,Igarashi, Tetsutaro,Sakurai, Tadamitsu
, p. 11267 - 11281 (2008/03/12)
The alkyl, aryl, and acyl substituent effects on the photoinduced electron transfer-initiated cyclization reaction of the title compounds (1) were investigated in polar solvents from mechanistic and synthetic points of view. The irradiation of (Z)-1 in me
