Showing papers on "Pyran published in 1998"
TL;DR: Some new pyran 3,8, pyrano[2,3-b]pyridine 4, 5, 6, 7, 8, 9, 10 and 14 derivatives have been developed.
Abstract: Some new pyran 3,8; pyrano[2,3-b]pyridine 4; pyrano[2,3-d] pyrimidine 5,6,7 and 9; pyridine 10–14 derivatives have been prepared. The structure of all the new compounds have been established on the basis of elemental analyses and spectroscopic data. All the synthesized compounds have been screened for their antibacterial activity. Pyranopyrimidinethione 7 and pyridinethione 10 exhibited a good antibacterial activity compared with the standard antibiotic Gentamycin.
80 citations
TL;DR: In this article, the tetrahydropyranyl ethers were obtained in the presence of 5 M lithium perchlorate in diethyl ether (5 M LPDE), which is essentially a neutral medium.
50 citations
Patent•
07 Dec 1998
TL;DR: In this paper, photochromic 6-aryl substituted 3H-naphtho[2m1-b]pyran compounds are described, examples of which are naphthopyran compound having a substituted aryl group at the number 6 carbon atom and certain substituents at the 3position of the pyran ring.
Abstract: Described are novel photochromic 6-aryl substituted 3H-naphtho[2m1-b]pyran compounds, examples of which are naphthopyran compounds having a substituted aryl group at the number 6 carbon atom and certain substituents at the 3-position of the pyran ring. Certain substituents may also be present at the number 7, 8, 9 or 10 carbon atoms of the compounds. These compounds may be represented by graphic formula (I). Also described are polymeric organic host materials that contain one or more of such compounds or combinations of such compound(s) with complementary photochromic compounds, e.g., other naphthopyrans, benzopyrans and spiro (oxazine) type compounds.
41 citations
TL;DR: In this paper, the synthesis of 5-(indol-2′-yl)pyridin-2-ones and 5-indol 2′-lzinc halides by Pd-catalyzed reactions is described.
41 citations
TL;DR: The synthesis of the highly substituted E and F pyran fragment 23 of altohyrtin A 1 from tri-O-benzyl-d-glucal 5 is described in this article.
Abstract: The synthesis of the highly substituted E and F pyran fragment 23 of altohyrtin A 1 from tri-O-benzyl-d-glucal 5 is described. The synthesis of a model compound 31 containing the altohyrtin A triene side-chain outlines the proposed strategy for the elaboration of the F pyran.
38 citations
TL;DR: In this article, a 5-substituted 2-perfluoroalkyl-4H-pyran-4-ones by dehydration of 2,3-dihydro-3-hydroxy-6-per-fluorochemically-constrained 2.
30 citations
Patent•
07 Dec 1998TL;DR: In this article, the photochromic indeno-fused naphthopyran compounds have been described and represented by graphic formula (I) and polymeric organic host materials that contain or are coated with these compounds are described.
Abstract: Described are novel photochromic indeno-fused naphthopyran compounds having certain substituents at the 2-position of the pyran ring and an alkoxy group at the number 6 carbon atom. Certain other substituents may also optionally be present at the number 5, 7, 8, 9, 10, 11, 12 or 13 carbon atoms of the compounds. These compounds may be represented by graphic formula (I). Also described are certain novel indeno-fused naphthols which are used to make the novel naphthopyran compounds. Further described are polymeric organic host materials that contain or that are coated with the novel naphthopyran compounds, or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, benzopyrans, and spiro(indoline)type compounds.
27 citations
TL;DR: In this paper, the perhydro-furo[2,3- b ]pyran (and furan)-3-yl methanols in one step were successfully applied to carbohydrate derived substrates.
27 citations
TL;DR: In this paper, Suzuki cross-coupling of corresponding 3-iodo and 5-bromo derivatives with arylboronic acids was used to obtain 3-Arylpyrones and 5aryl pyrones.
26 citations
23 citations
TL;DR: Chiral non-racemic 6-(furan-3-yl)-pyran-2-one derivatives, key intermediates in the preparation of compactin, manoalide and cacospongionolide subunits, are easily accessible through a rapid and convenient six-step sequence as mentioned in this paper.
Abstract: Chiral non-racemic 6-(furan-3-yl)-pyran-2-one derivatives, key-intermediates in the preparation of compactin, manoalide and cacospongionolide subunits, are easily accessible through a rapid and convenient six-step sequence.
TL;DR: The intensely coloured (1 R,8a R )- and (1 S, 8a R ), 4-(2-furyl)-7-[(2-furl)methylidene]-2-hydroxy-2 H,7 H,8 H, 8 H -pyrano[2,3-b ]pyran-3-one (1a / 1b ) have recently been identified among the main coloured compounds formed in the presence of pentoses.
TL;DR: In this paper, pyrazolo[1,5-a]pyridines were synthesized from the reaction of pyran-2-one and 5-aryl-3-cyanomethyl-1H-pyrazole (2) through carbanion-induced ring transformation reactions.
TL;DR: The utility of the tandem conjugate addition-cyclization sequence was demonstrated in the synthesis of pyranonaphthoquinone antibiotics, (±)-eleutherin and (±-isoeleutherin.
Patent•
13 Oct 1998
TL;DR: In this paper, a 7-methylidene-5-oxo-furo fused naphthopyran compounds having certain substitutents at the 2 position of the pyran ring were described.
Abstract: Described are novel 7-methylidene-5-oxo-furo fused naphthopyran compounds having certain substitutents at the 2 position of the pyran ring. Also described are polymeric organic host materials that contain or that are coated with such compounds.
TL;DR: The linear 2-amino-10-methyl-4H-naphtho[2,3-b]pyran-4-ones 4a and 4b significantly inhibited the clonal growth in HeLa cells and T2 bacteriophage infectivity, respectively.
Abstract: The N-substituted 2-aminochromones 1 and their benzo-fused derivatives 2–4 described herein were mostly prepared by treating the corresponding (methylthio) derivatives 10–13 with an excess of the proper amines. Only the morpholino derivatives 3d and 4c were obtained from the reaction of the ethyl 3-morphohno-3-oxopropanoate/POCl3 reagent with 1-naphthol or 1-methyl-2-naphthol, respectively. The amino derivatives 1–4, as well as their methylthio analogues 10–13, were tested in vitro for their inhibitory activity on the infectivity of T2 bacteriophage, on the macromolecular synthesis in Ehrlich cells and on the clonal growth capacity of HeLa cells. Several of the angular or linear aminonaphthopyranones 2 and 3 or 4, respectively, and the (methylthio) derivatives 10, 11 and 13 induced a significant inhibition of DNA synthesis, but usually a clearly lower inhibition of clonal growth. Only the linear 2-amino- 10-methyl-4H-naphtho[2,3-b]pyran-4-ones 4a and 4b significantly inhibited the clonal growth in HeLa cells and T2 bacteriophage infectivity, respectively.
TL;DR: In this paper, three methods for the synthesis of deoxy sugar amicetose (2,3,6-trideoxy-d - erythro -hexopyranoside) are described.
Abstract: Three methods for the synthesis of the deoxy sugar amicetose (2,3,6-trideoxy- d - erythro -hexopyranoside) are described. All three utilize the known dihydropyran 2-isobutoxy-6-methyl-2,3-dihydro-4 H -pyran as an intermediate. Asymmetric hydroboration of the dihydropyran with IpcBH 2 gave enantiomerically enriched isobutyl α and β-amicetosides. Hydroboration with borane–tetrahydrofuran followed by derivatization of the major product (β-anomer) with R -(−)-1-(1-naphthyl)ethylisocyanate gave diastereomeric carbamates which were separated and converted to isobutyl β- d and β- l -amicetosides having high optical purity. Racemic isobutyl β-amicetosides were also resolved by enzymatic transesterification using lipase and an acyl transfer reagent. Porcine pancreatic lipase and lipases from Candida rugosa and Pseudomonas sp. were evaluated in the presence of either vinyl acetate, vinyl butyrate, or trifluoroethyl butyrate as acylating agents. A GC-based method for determining enantiomeric purity of amicetose derivatives was developed.
TL;DR: In this paper, a simple synthetic approach to α,β-unsaturated δ-lactones has been devised from the hydrozirconation of O-protected homopropargyl alcohols followed by carbonylation and quenching with iodine.
Abstract: A simple synthetic approach to α,β-unsaturated δ-lactones has been devised from the hydrozirconation of O-protected homopropargyl alcohols followed by carbonylation and quenching with iodine. The synthesis of ( S )-(+)-5,6-2 H -pyran-2-one (parasorbic acid) from easily available O-benzylated ( S )-(−)-4-pentyn-2-ol was chosen to exemplify the approach.
TL;DR: In this paper, 2-acetyl (3H)naphtho[2,l-6]pyran-3-one I with ylides 2aJ) led to the formation of the corresponding [2, l i]-fused substituted substituted benzene 6a.b and Wittig products 3a,b.d. with Ylides Zc.
Abstract: Treatment of 2-acetyl (3H)naphtho[2,l-6] pyran-3-one I with ylides 2aJ) led to the formation of the corresponding [2, l i]-fused substituted benzene 6a.b and the Wittig products 3a,b. with ylides Zc.d afforded, again the corresponding [2,l-o]-fused cyclopentadienes 9a,b and the olefination products 7a,b. Conversely, compound 1 undergoes conjugated addition reaction with both ylides 10 and 12 to give 1_1 and 13, respectively. Introduction Polyfunctionally substituted heteroaromatics are of immense importance in biochemistry (1-3). Thus, despite coumann itself, has very little physiological action upon human being, it has long been recognized the versatile applications of naturally occurring-and synthesized coumaran derivatives (4,5). Previously mentioned fact has encouraged us to synthesize and study the reactions of some novel pyrans by making use of 2-acetyl (3H)naphtho[2,l-6]pyran-3-one 1. (also known as 3-acetyl 5,6-benzocoumarin) and some methylenetriphenylphosphoranes (Wittig reagents) 2a-d, 10 and 12.
TL;DR: The methanol extract of Brazilian propolis was fractionated by HPLC, based on human hepatocellular carcinoma (HuH 13) cell cytotoxicity assay, and a new benzo-y-pyran derivative (PM-3) with a molecular formula of C19H22O3 was isolated.
Abstract: The methanol extract of Brazilian propolis was fractionated by HPLC, based on human hepatocellular carcinoma (HuH 13) cell cytotoxicity assay. A new benzo-γ-pyran derivative (PM-3) with a molecular formula of C19H22O3 (MW: 298.38) was isolated. The structure of this colorless compound was determined as 3-[2-dimethyl-8-(3-methyl-2-butenyl) benzopyran]-6-propenoic acid. This compound was chemically synthesized by cyclisation of artepillin C (3-[4-hydroxy-3,5-bis (3-methyl-2-butenyl) phenyl]-2-propenoic acid).
Patent•
22 Apr 1998
TL;DR: In this article, the carboxylate and/or counter ion provided on one side of an open pyran ring is preferably capable of complexing with functionality on the other side of the open ring, greatly stabilizing the open configuration.
Abstract: The present invention provides water-soluble, pyran-based photochromic compounds characterized by improved stability when in an open, excited configuration. The advantages of the present invention are provided, at least in part, by functionalizing a pyran-based photochromic compound with carboxylate functionality in such a way that the carboxylate and/or its counter ion have sufficient mobility to engage in intermolecular and intramolecular interactions. In preferred embodiments, such a mobile carboxylate and/or counter ion provided on one side of an open pyran ring is preferably capable of complexing with functionality on the other side of the open pyran ring, greatly stabilizing the open configuration.
TL;DR: The efficacy of a novel tetradentate iron(III) ligand for the in vitro mobilisation of ferritin-bound iron is measured in direct comparison to the clinically approved agents, 1,2-dimethyl-3-hydroxypyridin-4-one and desferrioxamine.
TL;DR: In this paper, the Wittig reaction was used to produce dialkyl 5-formyl-2H-pyran-2,3-dicarboxylates in fairly high yields.
Abstract: Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by triformylmethane leads to vinyltriphenylphosphonium salts which undergo an intramolecular Wittig reaction to produce dialkyl 5-formyl-2H-pyran-2,3-dicarboxylates in fairly high yields.
TL;DR: As spiro sugars is an apt way of considering perhydroxylated 1,7-dioxaspiro[5.5]undecanes-a class of compounds which has not been found in nature up to now, the crystal structure of a spiroacetal, in which the two pyran rings show the β-D-manno configuration, is depicted.
Abstract: As spiro sugars is an apt way of considering perhydroxylated 1,7-dioxaspiro[5.5]undecanes-a class of compounds which has not been found in nature up to now. The crystal structure of such a spiroacetal, in which the two pyran rings show the β-D-manno configuration, is depicted. Note that the all-trans arrangement of C-6, C,-5, Opyr , Cspiro , Opyr' , C-5', and C-6' does not allow any of the stereoelectronic effects that are typical of carbohydrates.
TL;DR: In this paper, a series of 2-amino-substituted 5,6-benzo-2H-pyrans and their dimers were obtained by the reaction of 2hydroxy-benzaldehydes with enamines derived of (cyclo)aliphatic ketones.
Abstract: A series of 2-amino-substituted 5,6-benzo-2H-pyrans 14, 2-alkylidene-5,6-benzo-2H-pyrans 15, and their dimers 17 are obtained, depending on the condition used, by the reaction of 2-hydroxy-benzaldehydes 1 with enamines 9 derived of (cyclo)aliphatic ketones. Compounds 14, 15, and 17 can be transformed into 2-alkyl-benzopyrylium salts 16 or 2-[1-(2-hydroxyphenyl)-alken-2-yl]-benzopyrylium salts 23 by treatment with mineral acids. With aromatic aldehydes or the Vilsmeier reagent the compounds 14, 15, or 17 are transformed into deeply colored 2-(aryl-alkenyl)-benzopyrylium perchlorates 25 or 2-(2-dialkylamino)-alkenyl-benzopyrylium salts 26, respectively.
TL;DR: In this article, the synthesis of novel aryl spiroketals, which contain a similar substitution pattern to that present in the antifungal agents the papulacandins, is described.
Abstract: The synthesis of novel aryl spiroketals, which contain a similar substitution pattern to that present in the antifungal agents the papulacandins, is described. Thus, spiroketal (7) was obtained from acid-catalysed cyclization of the keto alcohol (13), and spiroketal (8) was obtained from acid-catalysed cyclization of keto alcohols (12) and (19). Keto alcohols (12), (13) and (19) in turn were prepared by ortho-directed lithiation of amides (10), (11) and oxazoline (17) respectively, followed by reaction with δ-valerolactone. Substitution of the aromatic ring occurred at the sterically hindered position ortho to both the methoxy and ortho-directing metalation group. In an alternative approach to the synthesis of the desired spiroketals, two palladium(0)-catalysed coupling strategies were examined. The Stille coupling between the aryl stannane (24) and iodoglucal (25) resulted in a low yield of the aryl C-glycoside (21). Likewise, a low yield for the same coupled product (21) was achieved by a Suzuki coupling between the arylboronic acid (26) and iodoglucal (25).
TL;DR: In this article, a three-step sequence including acid-catalysed cycloaddition of cyclopentadiene to 6-oxo-6H-1,3,4-oxadiazines, dehydrogenation with DDQ of the dihydro-α-pyrones formed and reduction of the resulting α pyrones with DIBAL-H, 1,4disubstituted cyclopenta[c]pyrans are shown to undergo electrophilic substitution; the molecular structures of 1-(4-anisyl)-4
Patent•
30 Nov 1998
TL;DR: In this paper, the photochromic pyrano-fused naphthopyran compounds are described, examples of which are NPHO compounds having a substituted or unsubstituted 'S' pyran ring.
Abstract: Described are novel photochromic pyrano-fused naphthopyran compounds, examples of which are naphthopyran compounds having a substituted or unsubstituted 'S' pyran ring, the 3,4 positions of which are fused to the f side of the naphtho portion of the naphthopyran, and certain substituents at the 2-position of the 'T' pyran ring. Certain substituents may also be present at the number 5, 7, 8, 9, 10, 11 or 12 carbon atoms of the compounds. These compounds may be represented by graphic formula (I). Also described are polymeric organic host materials that contain or that are coated with such compounds or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, benzopyrans, and spiro(indoline) type compounds.