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Displaying article 1-16
M127
Received: 26 November 1999 / Accepted: 15 December 1999 / Published: 24 January 2000
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M128
Received: 26 November 1999 / Accepted: 15 December 1999 / Published: 24 January 2000
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M129
Received: 25 November 1999 / Accepted: 15 December 1999 / Published: 24 January 2000
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M130
Received: 21 December 1999 / Accepted: 14 January 2000 / Published: 24 January 2000
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M131
Received: 16 December 1999 / Accepted: 17 January 2000 / Published: 24 January 2000
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M132
Received: 10 January 2000 / Accepted: 14 January 2000 / Published: 24 January 2000
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M133
Short Note:
Copper 1,14:7,8-Diethenotetrapyrido-[2,1,6-de:2',1',6'-gh:2'',1'',6'''-na][1,3,5,8,10,12]hexaazacyclotetradecine Trifluoroacetate
Received: 29 December 1999 / Accepted: 17 January 2000 / Published: 24 January 2000
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p. 1-3
Received: 18 January 2000 / Published: 31 January 2000
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p. 4-18
Received: 14 September 2000 / Accepted: 15 November 2000 / Published: 21 January 2001
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| Download PDF Full-text (88 KB) Abstract: The use of an enantiomerically pure amino alcohol, coupled to a transfer hydrogenation process, in the asymmetric catalysis of the reduction of ketones to alcohols, is described. The process works well for unfunctionalised ketones, affording e.e.s of up to 98%, and excellent conversions. We have recently extended, for the first time in this application, the scope of the methodology to the reductions of a-heteroatom substituted substrates, through the use of the appropriate protecting groups on each atom.
p. 19-32
Received: 7 December 1999 / Accepted: 31 December 1999 / Published: 21 January 2000
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| Download PDF Full-text (65 KB) Abstract: Reaction of 4-hydroxy-6-methyl-2-pyrone (1a) as well as 4-hydroxy-6-methyl-2(1H)-pyridones (1b-d) with arylmethylene malononitriles or arylmethylene methyl cyanoacetates (2a-h) leads to the formation of the very stable 5,6-fused bicyclic 2-amino-4Hpyran derivatives 3a-3af.
p. 33-36
Received: 14 January 2000 / Accepted: 14 January 2000 / Published: 21 January 2000
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| Download PDF Full-text (18 KB) Abstract: Cambridge University Department of Chemistry has a list of University Chemistry Departments and Chemistry-related journals around the world: ChemSites (http://www.ch.cam.ac.uk/ChemSitesIndex.html). This article describes what makes it distinct from other lists, and justifies the existence of more than one such list.
p. 37-50
Received: 27 May 1999 / Accepted: 29 November 1999 / Published: 21 January 2000
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| Download PDF Full-text (86 KB) Abstract: Acid and base initiated cyclization and retrocyclization reactions of the selenoureas 1-6 and isoselenoureas 7-12 to fused 4H-1,3-selenazine and 1,2,3,4-tetrahydropyrimidine-4-one skeletons are reported. Fused 2-acylamino-4H-1,3-selenazine-4-ones 13-18 were formed by the action of concentrated sulfuric acid on acylselenoureas 1-6 or on 2,2-dimethylpropanoylisoselenoureas 10-12 at room temperature. On the other hand, benzoylisoselenoureas 7-9 were not obtained in this cyclocondensation under the same conditions. The reaction of potassium ethoxide on selenazines 13-18 in the ethanol solution evoked retrocyclization to the starting acylselenoureas 1-6. Both types of the title compounds, i.e. selenoureas 1-6 and isoselenoureas 7-12, were deprotonated in a methanol solution of potassium hydroxide used in an equimolar amount, giving rise to potassium salts 19-24, which were isolated only for the thiophene series. By heating the separated potassium salts 20, 21, 23 and 24 in the methanol solution provided, deacylation and isoselenoureas 26, 27 were formed. The in situ prepared salts 19, 22 cyclized under the same conditions with deacylation to 4-selanyl-3,4-dihydroquinazoline-4-one 28. The title compounds 1-6, 7-12 and products of their deacylation 26, 27 on boiling in methanolic potassium hydroxide cyclized to the corresponding fused 2-selenoxo-1,2,3,4-tetrahydropyrimidine-4-one potassium salts. These compounds provided pyrimidine-4-ones 28-30 on acidification. Acid initiated retrocyclization 28-30 to the corresponding 2-amino-4H-1,3-selenazine-4-ones was unsuccessful. C, H, N, Se elemental analyses, FTIR, 1H-NMR, and 13C-NMR spectroscopies supported the structure of synthesized compounds.A short review on cardiotonic steroids and their analogues is presented. The natural, semisynthetic and synthetic derivatives, as well as their mechanism of action and structure-activity relationships are shown, with a special reference to aminoguanidine derivatives.
p. 51-81
Received: 14 November 1999 / Accepted: 9 December 1999 / Published: 21 January 2000
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| Download PDF Full-text (181 KB) Abstract: A short review on cardiotonic steroids and their analogues is presented. The natural, semisynthetic and synthetic derivatives, as well as their mechanism of action and structure-activity relationships are shown, with a special reference to aminoguanidine derivatives.
p. 82-88
Received: 2 November 1999 / Accepted: 12 January 2000 / Published: 18 January 2000
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| Download PDF Full-text (37 KB) Abstract: A short, high-yielding synthesis of the antitumour agent irisquinone (1) is described. The key steps are the palladium catalysed coupling reaction of dec-9-yn-1-ol with iodide (2) to form alkyne (3) and the Fremy’s salt oxidation of phenol (7).
p. 89-92
Received: 14 December 1999 / Accepted: 22 January 2000 / Published: 26 January 2000
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| Download PDF Full-text (15 KB) Abstract: A stepwise synthesis of a-unsubstituted pyrroles with desired substituents in the b-positions of the ring has been devised.
p. 93-98
Received: 26 January 2000 / Accepted: 27 January 2000 / Published: 28 January 2000
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| Download PDF Full-text (186 KB) Abstract: The open source program for drawing 2D chemical structures JChemPaint, its current features, its envisioned further development and the principles enabling researchers and students at places all over the world to collaboratively develop such a program are described.
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