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Cherkupally Sanjeeva Reddy Adki Nagaraj 《中国化学快报》2007,18(12):1431-1435
An efficient route for the synthesis of 5-(arylpropenylidine)-2,4,6-pyrimidinetrione 3 from an appropriateα,β-unsaturated aromatic aldehydes 1 and barbituric acid 2 under both non-catalytic and solvent-free microwave irradiation conditions was described.In this way,a range of biologically important compounds 3 was obtained in good to excellent yields (86-98%) in a very short reaction time (30-80s). 相似文献
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Norbornene-constrained cyclic peptides with hairpin architecture: design, synthesis, conformation, and membrane ion transport 总被引:1,自引:0,他引:1
Ranganathan D Haridas V Kurur S Nagaraj R Bikshapathy E Kunwar AC Sarma AV Vairamani M 《The Journal of organic chemistry》2000,65(2):365-374
A novel family of hairpin cyclic peptides has been designed on the basis of the use of norbornene units as the bridging ligands. The design is flexible with respect to the choice of an amino acid, the ring size, and the nature of the second bridging ligand as illustrated here with the preparation of a large number of norborneno cyclic peptides containing a variety of amino acids in ring sizes varying from 12- to 29-membered, with the choice of the second bridging ligand being a rigid norbornene (11, 13a,b), an adamantane unit (7a,b and 8), or a flexible cystine residue (4a,b and 10). The presence of built-in handles (as protected COOH groups) permits the attachment of a variety of subunits as shown here with the ligation of Leu-Leu, Val-Val, or Aib-Aib pendants in 4b, 7b, and 13b, respectively. This novel class of constrained cyclic peptides are demonstrated to adopt beta-sheet- or hairpin-like conformation as shown by (1)H NMR and CD spectra. Membrane ion-transport studies have shown that the norborneno cyclic peptides 4b and 7b containing Leu-Leu or Val-Val pendants symmetrically placed on the exterior of the ring show high efficiency and selectivity in the transport of specifically monovalent cations. This property can be attributed to the hairpin-like architecture induced by the norbornene unit since the bis-adamantano peptide 15 containing two pairs of Leu-Leu pendants on the exterior is able to transport both monovalent (Na(+), K(+)) and divalent (Mg(2+)/Ca(2+)) cations. 相似文献
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Haruvegowda Kiran Kumar Hemmige S. Yathirajan Nagaraj Manju Balakrishna Kalluraya Ravindranath S. Rathore Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(6):768-776
The reaction of 5‐chloro‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde with phenols under basic conditions yields the corresponding 5‐aryloxy derivatives; the subsequent reaction of these carbaldehydes with substituted acetophenones yields the corresponding chalcones, which in turn undergo cyclocondensation reactions with hydrazine in the presence of acetic acid to form N‐acetylated reduced bipyrazoles. Structures are reported for three 5‐aryloxycarbaldehydes and the 5‐piperidino analogue, and for two reduced bipyrazole products. 5‐(2‐Chlorophenoxy)‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde, C17H13ClN2O2, (II), which crystallizes with Z′ = 2 in the space group P, exhibits orientational disorder of the carbaldehyde group in each of the two independent molecules. Each of 3‐methyl‐5‐(4‐nitrophenoxy)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde, C17H13N3O4, (IV), 3‐methyl‐5‐(naphthalen‐2‐yloxy)‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde, C21H16N2O2, (V), and 3‐methyl‐1‐phenyl‐5‐(piperidin‐1‐yl)‐1H‐pyrazole‐4‐carbaldehyde, C16H19N3O, (VI), (3RS)‐2‐acetyl‐5‐(4‐azidophenyl)‐5′‐(2‐chlorophenoxy)‐3′‐methyl‐1′‐phenyl‐3,4‐dihydro‐1′H,2H‐[3,4′‐bipyrazole] C27H22ClN7O2, (IX) and (3RS)‐2‐acetyl‐5‐(4‐azidophenyl)‐3′‐methyl‐5′‐(naphthalen‐2‐yloxy)‐1′‐phenyl‐3,4‐dihydro‐1′H,2H‐[3,4′‐bipyrazole] C31H25N7O2, (X), has Z′ = 1, and each is fully ordered. The new compounds have all been fully characterized by analysis, namely IR spectroscopy, 1H and 13C NMR spectroscopy, and mass spectrometry. In each of (II), (V) and (IX), the molecules are linked into ribbons, generated respectively by combinations of C—H…N, C—H…π and C—Cl…π interactions in (II), C—H…O and C—H…π hydrogen bonds in (V), and C—H…N and C—H…O hydrogen bonds in (IX). The molecules of compounds (IV) and (IX) are both linked into sheets, by multiple C—H…O and C—H…π hydrogen bonds in (IV), and by two C—H…π hydrogen bonds in (IX). A single C—H…N hydrogen bond links the molecules of (X) into centrosymmetric dimers. Comparisons are made with the structures of some related compounds. 相似文献
77.
Biochemical properties of ricin in immature castor seed 总被引:1,自引:0,他引:1
The biochemical properties of ricin at different stages of seed i.e. from immature to mature seed were studied. Hemagglutination, SDS-PAGE and UV-spectrometry studies showed total absence of RCA protein in the immature seed. Interestingly, ricin extract on SDS-PAGE showed only one protein band with a molecular weight of 29,000 dalton corresponding to the molecular weight of A chain of ricin. Our results have shown that at immature seed level only the toxic moiety of ricin (A chain) is being synthesized first and gradually the RCA and B chain of ricin. 相似文献
78.
A series of novel bis-chalcones 3 were prepared by the reaction of 5,5′-methylene-bis-salicylaldehyde 2 with various acetophenones, subsequent treatment of 3 with thiourea or guanidine resulted to the corresponding bis-thiazines or bispyrimidines in good yields. All the new compounds have been characterized by IR, 1H NMR, MS and elemental analysis. The antibacterial, antifungal and anti-inflammatory activities of the compounds have also been evaluated. 相似文献
79.
We get an upper bound of on the number of Carmichael numbers with exactly three prime factors.
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