Showing papers on "Benzopyran published in 2000"
TL;DR: Heber et al. as discussed by the authors showed that 4-hydroxycoumarin cyclized through Michael addition to ben-zylidene malononitrile in pyridine as solvent to give a derivative of 2-aminopyrano[3,2-c]benzopyran(A) (Figure 1).
Abstract: Pharmaceutical Institute, Christian-Albrechts University of Kiel, Gutenbergstr. 76, D-24118 Kiel,GermanyTel.: (+49-431) 880-1118, Fax: (+49-431) 880-1352, E-mail: dheber@pharmazie.uni-kiel.de*Author to whom correspondence should be addressed.Received: 7 December 1999 / Accepted: 31 December 1999 / Published: 21 January 2000Abstract: 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 cyano-acetates (2a-h) leads to the formation of the very stable 5,6-fused bicyclic 2-amino-4H-pyran derivatives 3a-3af.Keywords: pyrano[4,3-b]pyran, pyrano[3,2-c]pyridine, arylmethylene malononitrile, aryl-methylene cyanoacetate, Michael addition.IntroductionWiener et al. first published [1] that 4-hydroxycoumarin cyclized through Michael addition to ben-zylidene malononitrile in pyridine as solvent to give a derivative of 2-aminopyrano[3,2-c]benzopyran(A) (Figure 1). Later, Junek and Aigner [2] found a second case of this heterocyclization via additionof 4-hydroxy-6-methyl-2-pyrone (1a, “triacetic acid lactone”, Scheme 1) to tetracyanoethylene, thuspreparing a substituted 2-amino-4H,5H-pyrano[4,3-b]pyran (B). Many years thereafter, Shaker [3] re-
57 citations
TL;DR: As part of a search for a new potassium channel opener, the 1,4-benzoxazine skeleton derived from the benzopyran skeleton of cromakalim, was transformed into other fused rings such as 1,2,3, 4-tetrahydroquinoline, indoline, and 1,5-benZoxazepine.
45 citations
TL;DR: K-10 Montmorillonite mediated condensation of aldehyde 1 with arylamine 2 affords chroman-2,4-dione 5 which gives tricoumarol 8 by acid hydrolysis, 4-arylamino-3-formylcoumarin 11 and 1-benzopyrano[4,3-b]quinoline 12 on heating with POCl3 as discussed by the authors.
41 citations
TL;DR: In this article, a traceless diisopropylsilyloxy linker was used to synthesize a small library of target benzopyranones in generally high yield and purity.
28 citations
TL;DR: In this article, trans,trans-isomer 6a and cis,cis-isome 6d were synthesized as major products from (E)-5 and (Z)-5, respectively.
23 citations
TL;DR: In this article, the preparation of 2H-benzopyrans from bromophenols and tertiary allylic alcohols is described, characterised by its mildness, good yields and ease of work-up.
Abstract: The preparation of 2H-benzopyrans from bromophenols and tertiary allylic alcohols is described. The reaction is characterised by its mildness, good yields and ease of work-up. Kinetic resolution of the latter up to 95% ee was obtained by using enzyme-catalysed enantioselective hydrolysis. # 2000 Elsevier Science Ltd. All rights reserved.
21 citations
TL;DR: The structure was determined by spectroscopic analyses, which included 1D and 2D (1)H and (13)C NMR experiments, as well as MS, IR, and UV spectroscopy, and the reverse reaction was also observed.
Abstract: (Z)-2,2-Dimethyl-8-(3-methyl-2-butenyl)-benzopyran-6-propenoic acid (1) was isolated from Brazilian propolis, together with the known benzopyran derivative, (E)-2, 2-dimethyl-8-(3-methyl-2-butenyl)-benzopyran-6-propenoic acid (2). The structure was determined by spectroscopic analyses, which included 1D and 2D (1)H and (13)C NMR experiments, as well as MS, IR, and UV spectroscopy. Compound 2 rapidly changed to 1 under UV irradiation conditions (365 nm), and the reverse reaction was also observed. The ratio of 1 to 2 reached 2.3 when the reaction began from either 1 or 2, indicating a photostationary state. Compound 1 displayed an approximate 7-fold stronger cytotoxicity against human lung carcinoma cells (HLC-2) compared with 2.
19 citations
TL;DR: The piperidine catalyzed Knoevenagel condensation of 2′-aryl/alkyl-2-hydroxyacetophenones 7 and aryl-alkylaldehydes 8 in refluxing isopropyl alcohol with azeotropic removal of water affords, in high yield, equilibrium mixtures of E - and Z -chalcones 9 and cis - and trans -chroman-4-ones 10 which are effectively isomerized in situ to the trans -2,3-diaryl/kylchroman 4-
18 citations
TL;DR: A general stereoselective method for the synthesis of 4-deoxynovobiocin-related glycosides is described and the corresponding deprotected 3-benzoylamino-2-oxo-2H-1-benZopyran-7-yl beta-D-glycopyranosides are synthesised.
12 citations
TL;DR: Triarylmethane dyes containing a 2,2-dimethyl-2H-1-benzopyran unit have been synthesized in this article and the visible spectral parameters of these novel dyes are akin to those of the 1-and 2-naphthyl analogues of Malachite Green with the effects of a methoxy group superimposed to represent the influence of the oxygen heteroatom.
Abstract: Triarylmethane dyes containing a 2,2-dimethyl-2H-1-benzopyran unit have been synthesised. The visible spectral parameters of these novel dyes are akin to those of the 1- and 2-naphthyl analogues of Malachite Green with the effects of a methoxy group superimposed to represent the influence of the oxygen heteroatom. Steric constraints are accommodated by an increased departure from molecular coplanarity along the y-axis.
11 citations
Patent•
13 Nov 2000TL;DR: In this article, a general formula for spiro[2H-1-benzopyran-2,4′-piperidine derivatives having general formula (I), wherein the substituents R 1, R 2, X and Y are defined in the claims or a pharmaceutically acceptable salt thereof.
Abstract: The present invention relates to spiro[2H-1-benzopyran-2,4′-piperidine] derivatives having general formula (I), wherein the substituents R 1 , R 2 , X and Y are ase defined in the claims or a pharmaceutically acceptable salt thereof. The invention also relates to pharmaceutical compositions comprising said derivatives, as well as to the use of these spiro[2H-1-benzopyran-2,4′-piperidine] derivatives in therapy, more specifically for the treatment of CNS disorders.
TL;DR: In this article, it was shown that with tricarbonyl(trispyridine)chromium as complexing agent, in the presence of Lewis acid, complexation of naphthopyrans can be achieved and is totally regioselective.
Abstract: Although in the 2H-chromene (benzopyran) series complexation with tricarbonylchromium, under thermal conditions, is totally regioselective, in the naphthopyran series the same reaction cannot be observed. We show here that with tricarbonyl(trispyridine)chromium as complexing agent, in the presence of Lewis acid, complexation of naphthopyrans can be achieved and is totally regioselective. The complexes formed are photochromic compounds, and their thermal bleaching kinetic constants are reduced as compared with the non-complexed homologous compound.
Patent•
02 Feb 2000TL;DR: In this paper, a class of benzopyran derivatives is described for use in treating cyclooxygenase-2 mediated disorders, where compounds of particular interest are defined by Formula I′ wherein X, A1, A2, A3, A4, R, R″, R1 and R2 are as described in the specification.
Abstract: A class of benzopyran, derivatives is described for use in treating cyclooxygenase-2 mediated disorders. Compounds of particular interest are defined by Formula I′ wherein X, A1, A2, A3, A4, R, R″, R1 and R2 are as described in the specification.
Patent•
13 Nov 2000TL;DR: In this paper, a general formula for spiro[2H-1-benzopyran-2,4'-piperidine derivatives having general formula (I), wherein the substituents R1, R2, X and Y are defined in the claims or a pharmaceutically acceptable salt thereof.
Abstract: The present invention relates to spiro[2H-1-benzopyran-2,4'-piperidine] derivatives having general formula (I), wherein the substituents R1, R2, X and Y are ase defined in the claims or a pharmaceutically acceptable salt thereof. The invention also relates to pharmaceutical compositions comprising said derivatives, as well as to the use of these spiro[2H-1-benzopyran-2,4'-piperidine] derivatives in therapy, more specifically for the treatment of CNS disorders.
TL;DR: In this article, 3-Methoxycarbonylchromenone 4 reacts with sodium naphthalenide to afford 4-hydroxy-3-salicyloylxanthone 7 via the dimer 5.
Abstract: 3-Methoxycarbonylchromenone 4 reacts with sodium naphthalenide to afford 4-hydroxy-3-salicyloylxanthone 7, via the dimer 5.
Dissertation•
01 Jan 2000
TL;DR: In this paper, the novel potassium channel openers benzopyran-4-amides have been synthesized via palladium-catalyzed amidation of 4-bromobenzopyrans under an atmoshere in the presence of an equivalent of potassium iodide.
01 Jan 2000
TL;DR: K-10 Montmorillonite mediated condensation of aldehyde 1 with arylamine 2 affords chroman-2,4-dione 5 which gives tricoumarol 8 by acid hydrolysis, 4-arylamino-3-formylcoumarin 11 and 1-benzopyrano[4,3-b]quinoline 12 on heating with POCl3 as mentioned in this paper.
Abstract: K-10 Montmorillonite mediated condensation of aldehyde 1 with arylamine 2 affords chroman-2,4-dione 5 which gives tricoumarol 8 by acid hydrolysis, 4-arylamino-3-formylcoumarin 11 and 1-benzopyrano[4,3-b]quinoline 12 on heating with POCl3.
Patent•
22 Mar 2000
01 Mar 2000
TL;DR: In this paper, the intramolecular cycl isation potenti al of halomethyleniminium salts formed under Vilsmeier condition was exploited for exploring new and simple synthetic strategies in organic synthesis.
Abstract: Vilsmeier Haack reaction is primarily an ad hoc procedure for the facile synthesis of aldehydes.I.2 A number of heterocycles have also been synthesised using thi s reaction.3-5 We have been focussing attention on exploiting the intramolecular cycl isation potenti al of halomethyleniminium salts formed under Vilsmeier condition for exploring new and simple synthetic strategies in organic synthesis. Recently, synthesis of many heterocyclic compounds and biological activities of some of them have been reported by our group.6-IO The skeleton of benzopyran widely occurs in plants" -'3 and is associated with diverse physiological appl ications. 14. 15 Benzopyrano[ 4,3-c ]pyrazoles are found to exhibi t many pharmacological activities such
Patent•
23 Feb 2000
TL;DR: In this paper, the photochromic behavior of 2-phenyl-2-(thien-2-yl)-2H-benzo [b]furano[3,2-f]benzopyran (1) and 2, 2-diphenyl -2H -benzo[b] furano[1,2]-benzo (2) was examined by the nanosecond laser photolysis and normal time scale analysis.
Abstract: ABATRACT The photochromic behavior of 2-phenyl-2-(thien-2-yl)-2H-benzo [b]furano[3,2-f]benzopyran (1) and 2,2-diphenyl-2H-benzo[b] furano[3,2-f]benzopyran (2) was examined by the nanosecond laser photolysis and normal time scale analysis. The results showed that the thienyl group could stabilize the colored forms as compared with the phenyl group and both singlet and triplet states were involved in the formation of the colored forms.
TL;DR: In this paper, the 3-cyclopent-2-enyl-4-hydroxy[1]benzopyran-2]-one was cycled with cold cone and mercuric acid.
TL;DR: The extent of diastereotopy depends upon their nature and the separation of methylene groups from the chiral centre; the effect is greatly influenced by the pi-electron system of the substituent.
Patent•
06 Apr 2000
TL;DR: A process for the preparation of 4-substituted benzopyran derivatives is described in this article, which comprises preparing N-(2-cyanoethyl)-5-fluoro-4-fluoromethyl-4-(4-trifluoromethsylphenoxy)-2-pentynamide from 1.
Abstract: A process for the preparation of 4-substituted benzopyran derivatives which comprises preparing N-(2-cyanoethyl)-5-fluoro-4-fluoromethyl-4-(4-trifluoromethylphenoxy)-2-pentynamide from 1-fluoro-2-fluoromethyl-3-butyn-2-yl 4-trifluoromethylphenyl ether and cyclizing this pentynamide derivative into 2,2-bis(fluoromethyl)-N-(2-cyanoethyl)-6-trifluoromethyl-2H-1-benzopyran-4-carboxamide; and other processes therefor. The processes make it possible to prepare the benzopyran derivatives in a shortened process time as compared with those of the prior art with high safety through easy purification.