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11.
Adriana Tudose 《Tetrahedron letters》2006,47(48):8529-8533
Simple catalysts formed in situ from palladium acetate and a variety of imidazolium and imidazolinium carboxylates and dithiocarboxylates have been screened in the coupling of aryl halides with trans-2-phenylvinylboronic acid. Imidazol(in)ium carboxylates show an excellent activity, which compares to that displayed by the parent imidazol(in)ium chlorides, whereas imidazol(in)ium dithiocarboxylates are poorly efficient. Interestingly, the base employed exerts a profound influence on the trans/cis stereochemistry of the coupling product. 相似文献
12.
Ana M. Piloto 《Tetrahedron》2006,62(39):9258-9267
Four carboxylic fused furans are presented as new fluorescent labels for the amino and hydroxyl functions of organic molecules. Various representative l-amino acids were chosen as models, labelled at their N-terminus and also at their side-chain. Fluorescent derivatives were obtained in high yields, and their absorption and emission properties were studied. 相似文献
13.
14.
Three four-step enantiospecific syntheses of different diastereomers of AES, a new biodegradable chelating agent, are described. The stereocenters in each of the isomers are accessible from l- and d-malic and aspartic acids. 相似文献
15.
《Magnetic resonance in chemistry : MRC》2003,41(12):975-982
The reaction of 2,4‐pentanedione ( 1 ) with (R)‐(—)‐2‐phenylglycine methyl ester ( 2 ), (R)‐(—)‐2‐phenylglycinol ( 3 ) and the proteinogenic amino acids (2S,3R)‐(—)‐2‐amino‐3‐hydroxybutyric acid (L ‐threonine) ( 4 ) and (R)‐(—)‐2‐amino‐3‐mercaptopropionic acid (L ‐cysteine) ( 5 ) methyl esters was investigated. The corresponding enamines 6 , 7 and 8 were isolated and characterized spectroscopically whereas 9 , which is unstable, was transformed in situ into 13 . Treatment of 7 , 8 and 9 with boron trifluoride etherate afforded the new [1,4]oxazepines 10 , 11 and [1,4]thiazepine ( 12 ) as their BF3O? salts. The structures of the enamines and their corresponding seven‐membered heterocycles were assessed by 1D and 2D NMR spectroscopy. Variable‐temperature experiments revealed different molecular mobility behavior among these heterocycles. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
16.
Valérie Michaut Jean-Marc Paris Jean-Christophe Plaquevent 《Journal of fluorine chemistry》2007,128(8):889-895
Herein are studied new transformations of ethyl-4,4,4-trifluoroacetoacetate (ETFAA), giving access to a series of enantiopure chirons bearing both a trifluoromethyl group and an amino moiety. The key intermediate is obtained optically pure by a resolution procedure. 相似文献
17.
Inés CarrancoJosé Luis D?&#x;az Oscar JiménezRodolfo Lavilla 《Tetrahedron letters》2003,44(46):8449-8452
The Lewis acid-catalyzed interaction of dihydropyridines with ethyl glyoxalate and primary aliphatic amines yields, depending on the reaction conditions, bicyclic aminals or rearranged tetrahydropyridines in one-pot multicomponent reactions. 相似文献
18.
G. I. Nikishin L. L. Sokova V. D. Makhaev N. I. Kapustina 《Russian Chemical Bulletin》2008,57(1):118-123
The solid-phase oxidation of cinnamic, 4-methoxy- and 3,4-dimethoxycinnamic acids with Ce(NH4)2(NO3)6—MHal system leads to β-halostyrenes. Similar procedure in the absence of a metal halide results in a cleavage of the C=C
bond giving the corresponding benzaldehydes.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 114–118, January, 2008. 相似文献
19.
采用固定化单宁对酒中可能存在的营养成分蛋白质、氨基酸、糖类、有机酸、乙醇和铁离子等进行吸咐试验。结果表明:固定化单宁对不同营养成分的吸附率差别明显,它通过氢键和疏水作用对蛋白质有较大的吸附率,通过多个酚羟基与中心铁离子形成螯合物而对其有较大的吸附率,对氨基酸、糖、有机酸和乙醇等营养成分或风味物质吸附率不大,固定化单宁可以作为一种较为理想的酒类处理剂。 相似文献
20.
L. G. Mezhlumyan Sh. Kh. Rakhimova P. Kh. Yuldashev N. K. Aikhodzhaeva M. A. Saidkhodzhaeva A. I. Massino S. Makhmudova 《Chemistry of Natural Compounds》2004,40(1):59-62
The glutelin fraction was used as the food value index of local corn. The base-soluble fraction was used as a test of the glassiness of local strains of rice grain. The content of gliadins and glutelins did not change over 24 h after wheat grain cultivated in Uzbekistan was moistened. 相似文献