Showing papers on "Pyran published in 1992"
Patent•
01 Jun 1992
TL;DR: An improved process for the preparation of trans-6-[2-(substituted-pyrrol-1-yl)alkyl]pyran-2-ones by a novel synthesis is described in this paper, where 1,6-heptadien4-ol is converted in eight operations to the desired products, as well as a process for (2R-trans) and trans-(±)-5-(4-fluorophenyl)-2-(1-methylethyl)-N,4-diphenyl-1]-
Abstract: An improved process for the preparation of trans-6-[2-(substituted-pyrrol-1-yl)alkyl]pyran-2-ones by a novel synthesis is described where 1,6-heptadien4-ol is converted in eight operations to the desired products, as well as an improved process for the preparation of (2R-trans) and trans-(±)-5-(4-fluorophenyl)-2-(1-methylethyl)-N,4-diphenyl-1-[2-(tetrahydro4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-1H-pyrrole-3carboxamide by a novel synthesis where 4-methyl-3-oxoN-phenylpentanamide is converted in eight operations to the desired product or alternatively 4-fluoro-α-[2methyl-1-oxopropyl]-γ-oxo-N,β-diphenylbenzenebutaneamide is converted in one step to the desired product, and additionally, a process for preparing (2R-trans)-5-(4-fluorophenyl)-2-(1-methylethyl)-N,4-diphenyl-1-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-1Hpyrrole-3-carboxamide from (R)-4-cyano-3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]butanoic acid, as well as other valuable intermediates used in the processes.
89 citations
TL;DR: In this article, a complete assignment of the 1H and 13C NMR spectra of 1-oxide and 1-1-dioxide analogues of 4(1, X = SO and SO2) as well as of compounds 3c, j, I, m, 4a-m, 6(the pyran analogue of 7) and 7 has been carried out.
Abstract: 1,3,3,5-Tetraarylpentane-1,5-diones 2 and 5 react with tetraphosphodecasulfide in xylene at elevated temperature to give the corresponding 2,4,4,6-tetraaryl-4H-thiopyrans 4 and 7. The mechanism of this transformation involves a fast initial step of dehydration of 2 and 5 to 2,4,4,6-tetraaryl-4H-pyrans 3, followed by a slower transformation to the 4H-thiopyran analogues 4. Using 2D NMR techniques, a complete assignment of the 1H and 13C NMR spectra of the 1-oxide and 1,1-dioxide analogues of 4(1, X = SO and SO2) as well as of compounds 3c, j, I, m, 4a–m, 6(the pyran analogue of 7) and 7 has been carried out. Compounds 4 and 7 undergo a reversible photochemical colour change after UV illumination. The maxima of the new absorption bands are situated at 540–660 nm. The non-exponential time dependence of the photodecolouration of 4a in the solid state is analysed in terms of dispersive first-order reaction kinetics. Dioxygen accelerates the decolouration process; the half-life at 299 K lies between 6600 s in air and several days in a vacuum (10–3 Pa). The trapping of photoproducts 10a, 10e and 11a enables us to postulate the whole photolysis sequence.
33 citations
TL;DR: In this paper, the authors present a rearrangement of Furylabelinol to 6-HYDROXY-2H-PYRAN-3(6H)-ONES, a useful synthon for the preparation of a VARIETY OF HETEROCYCLIC COMPOUNDS, a review.
31 citations
Abstract: Syntheses of 8-ethenyl-1-hydrory-4-β-D-ribofuranosylbenzo[d]naphtho[1,2-b]pyran-6-one (1) and 8-ethenyl- 1-hydrory-4-(2'-deoxy-β-ribofuranosyl)benzo[d]naphtho[1,2-b]pyran-6-one (2) have been accomplished. These two compounds are the first synthetic C-glycosides structurally related to the gilvocarcin, ravidomycin, and chrysomycin antibiotic class which possess the aglycon substituents (hydroxyl at C-1 and ethenyl at C-8) considered critical for the photolytic nicking of DNA.Anthracycline C-glycoside 1 was prepared by a route involving Lewis acid-catalyzed C-glycosyl bond formation between the tetracyclic aglycon and 1,2,3,5-tetra-O-acetyl-D-ribose followed by construction of the aglycon 8-ethenyl substituent from the corresponding ethyl group by radical bromination-dehydrobromination.Synthesis of C-glycoside 2 utilized a different, complementary procedure for C-glycosyl bond formation by palladium-mediated coupling of an iodoaglycon derivative with 1,4-anhydro-2-deoxy-3-O-(tert-butyldiphenylsilyl)-D-erythro-pent-1-enitol,a furanoid glycal designed to form only β C-glycosyl bonds in this reaction
31 citations
TL;DR: The alpha,beta-enone system is essential for the activity of 6-hydroxy-2H-pyran-3(6H)-ones, and the size and nature of substituents at C-2 are associated with antimicrobial activity.
28 citations
TL;DR: In this paper, an approach to the synthesis of C-aryl glycosides is described, where β-lactam is treated with N-bromosuccinimide (NBS) or N-iodosucinimides (NIS) to obtain trans-2,6-disubstituted pyrans.
Abstract: An approach to the synthesis of C-aryl glycosides is described. Treatment of β-lactam 9 with N-bromosuccinimide (NBS) or N-iodosuccinimide (NIS) afforded trans-2,6-disubstituted pyrans 11a and 11b. Treatment of 9 with phenylselenenyl chloride (PhSeCl) or N-(phenylselenenyl)phthalimide (N-PSP) gave 11c and cis-2,6-disubstituted pyran 12c in different ratios depending on the reaction conditions. Treatment of β-lactam 10 with NBS, NIS, PhSeCl, or N-PSP gave mixtures of pyrans 16 and 17
26 citations
24 citations
TL;DR: Surprisingly, the elimination of water to give the enamides 50-52, thiophene isosteres of bimakalim, diminishes activity significantly, and the antihypertensive activity determined to reside primarily in the (6S,7S)-(-)-enantiomer 41.
Abstract: The synthesis and antihypertensive activity of novel 7-(cyclic amido)-6-hydroxy-5,5-dimethylthieno[3,2-b]pyrans and related compounds are described. The compounds were tested for oral antihypertensive activity in spontaneously hypertensive rats (SHR) and selected compounds were evaluated in vitro for increases in 86Rb efflux in rabbit isolated mesenteric arteries. The effects on activity in SHR of lactam ring size, the presence of heteroatoms in the lactam ring, the relative stereochemistry at C-6 and C-7, and the substituents on the thiophene ring are examined. The best racemic compound in this series is 32, trans-5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(2-oxopiperidin -1-yl)-5H- thieno[3,2-b]pyran, which is 10-fold more potent than cromakalim with an ED30 = 0.015 mg/kg in SHR. Compound 32 could be resolved and the antihypertensive activity determined to reside primarily in the (6S,7S)-(-)-enantiomer 41. Surprisingly, the elimination of water to give the enamides 50-52, thiophene isosteres of bimakalim, diminishes activity significantly.
22 citations
TL;DR: In this paper, a one-pot synthesis from dimethyl 1,3-acetonedicarboxylate, diethoxymethyl acetate, hippuric acid and acetic anhydride was presented.
Abstract: Treatment of 4-ethoxymethylene-2-phenyl-5(4H)-oxazolone with activated methylene compounds under acidic or basic conditions leads to 2H-pyran-2-ones and fused pyran-2-ones. On the other hand, methyl (3-benzoylamino-5-methoxycarbonyl-2-oxo-2H-pyran-6-yl)-acetate (4) has also been prepared by a one-pot synthesis from dimethyl 1,3-acetonedicarboxylate, diethoxymethyl acetate, hippuric acid and acetic anhydride
22 citations
Patent•
12 Mar 1992TL;DR: In this article, a process for the preparation of a tautomeric mixture of compounds of the formulas is described, where a low valent metal is used to synthesize tetrahydrolipstatin.
Abstract: A process for the preparation of a tautomeric mixture of compounds of the formulas ##STR1## wherein W is hydrogen or C6 H13, which comprises treating a compound of the formula ##STR2## wherein R is unsubstituted or substituted alkoxy, arylalkoxy, aryloxy or amine and R1 is hydrogen or when R is alkoxy, substituted alkoxy, substituted amine, unsubstituted or substituted arylalkoxy R1 can also be metal, with a compound of the formula ##STR3## wherein W is as described above, both X and Y are reducible groups or X is hydrogen and Y is a reducible group or Y is hydrogen and X is a reducible group and, Z is hydroxy or a leaving group to form the compound of formula IV ##STR4## wherein W, X, Y and R are as defined above, the compound of formula IV is treated with a low valent metal to form a tautomeric mixture of compounds of formulas I and Ia, which are useful in the synthesis of tetrahydrolipstatin.
20 citations
Patent•
25 Feb 1992TL;DR: In this paper, the authors describe compounds of Formula I (STR1) which are useful as antiatherosclerotic agents and inhibitors of cell proliferation for the treatment of proliferative diseases.
Abstract: This invention relates to compounds of Formula I ##STR1## which are useful as antiatherosclerotic agents and inhibitors of cell proliferation for the treatment of proliferative diseases. In addition, various compounds of Formula I are useful inhibitors of platelet aggregation.
TL;DR: In this article, a series of spiro[2,5-cyclohexadiene]-1,1′(3′ H )-isobenzofuran]-3′-ones were prepared from metalled benzamides and 4,4-dimethoxy cyclohexadienone.
TL;DR: In this article, the introduction of allyl and 2-oxo-2H-pyran-6-yl carbonyl groups into the isoquinoline system can be effectively accomplished by reaction of allyltributyltin with 3,4-dihydro-β-carboline activated by 2 -oxo 2H-Pyran 6-ylcarbonyl chloride to give the corresponding 1,2-adduct.
Abstract: 1,2-Introduction of allyl and 2-oxo-2H-pyran-6-ylcarbonyl groups into isoquinoline system can be effectively accomplished by reaction of allyltributyltin with 3,4-dihydroisoquinoline activated by 2-oxo-2H-pyran-6-ylcarbonyl chloride. Allyltributyltin reacts similarly with 3,4-dihydro-β-carboline activated by 2-oxo-2H-pyran-6-ylcarbonyl chloride to gave the corresponding 1,2-adduct. Intramolecular Diels–Alder reactions of the 1,2-adducts followed by DDQ oxidations afford 8-oxoprotoberberine and norketoyobirine.
TL;DR: The furan-fused chlorocyclobutanone 6 undergoes reaction with O, N, S, C nucleophiles at a much slower rate than its pyran homolog, which is attributed to a reluctance to enolization as mentioned in this paper.
Abstract: The furan-fused chlorocyclobutanone 6 undergoes reaction with O, N, S, C nucleophiles at a much slower rate than its pyran homolog, which is attributed to a reluctance to enolization. Instead of subsititution products, rearranged products were formed.Enolization of 6 (6=chlorooxabicyclo[3.2.0]heptanone)toward the ring jonction in the oxabicycloheptanone is greatly retarded compared to the oxabicyclooctanone and proceeds only with strong nucleophiles(MeO - , - CH(COOEt) 2 at 20°C or with N 3 - on heating).The cine substitution products were not isolated but underwent further transformations;with oxygen nucleophiles such as AcO - or HO - ,when heating was required, the products were seven- or five- membered-ring lactones.These were formed either via vinylketenes or by opening of the cyclobutanone and/or the tetrahydrofuran ring.PhS - gave an ipso substitution product (presumably via electron transfer) that underwent acid-catalysed rearrangement to a naphtofuran
TL;DR: The reaction of 3-aroyl-6-aryl-4-hydroxy-2H-pyran-2-ones with aniline and substitutedo-phenylenediamine (R=H, CH3 or Cl) yields a series of new Schiff bases2a-f in 51-72% yield as discussed by the authors.
Abstract: The reaction of 3-aroyl-6-aryl-4-hydroxy-2H-pyran-2-ones (Ar=p-tolyl, 1,1′-biphenyl-4-yl or thienyl) with aniline and substitutedo-phenylenediamine (R=H, CH3 or Cl) yields a series of new Schiff bases2a–f in 51–72% yield. Bromination of1a gave the 5-bromo derivative1c, while the compounds1a,1b,2b,2e, and2f were converted into 2,6-diaryl-4H-pyran-4-ones3a–c. All products have been fully characterized.
TL;DR: Two novel antifungal agents, Lanomycin and glucolanomycin, as well as a biologically inactive degradation product, lanomycinol, were isolated from liquid fermentations of Pycnidiophora dispersa by spectroscopic analysis and partial chemical degradation.
Abstract: Two novel antifungal agents, lanomycin and glucolanomycin, as well as a biologically inactive degradation product, lanomycinol, were isolated from liquid fermentations of Pycnidiophora dispersa. All three compounds share an E,E,E-triene appended to a pyran ring. Lanomycin contains a glycine ester and glucolanomycin possesses a glucose unit attached to the glycine nitrogen. The structures, including absolute stereochemistry, were determined by spectroscopic analysis and partial chemical degradation. Both of the glycine containing compounds show activity against several pathogenic fungi in vitro.
TL;DR: Some compounds showed a platelet antiaggregating activity in vitro superior or comparable to that of acetylsalicylic acid, as well as a weak local anesthetic activity in mice and antiinflammatory activity in rats.
TL;DR: In this article, the reaction of 4-ethoxymethylene-5(4H)-oxazolone (2 a) with ethyl 3-oxo-4-(triphenylphosphoranylidene)butyrate (1) affords the corresponding 4-chloromethylene compound 2b and 1, besides 3, besides 4, 3-benzoylamino-6-[2-(4,5-dihydro-5-oxO-2-phenyl-4-oxazolylidene)-1
Abstract: The reaction of 4-ethoxymethylene-5(4H)-oxazolone (2 a) with ethyl 3-oxo-4-(triphenylphosphoranylidene)butyrate (1) affords ethyl 3-benzoylamino-2-oxo-6-triphenylphosphoranylidenemethyl-2H-pyran-5-carboxylate (3). Starting from the corresponding 4-chloromethylene compound 2b and 1, besides 3, ethyl 3-benzoylamino-6-[2-(4,5-dihydro-5-oxo-2-phenyl-4-oxazolylidene)-1- (triphenylphosphoranylidene)ethyl]-2-oxo-2H-pyran-5-carboxylate (5) is formed
TL;DR: The title biaryl was prepared by Pd-catalyzed intramolecular aryl coupling as discussed by the authors, and it crystallizes monoclinically in the space group P2i with a = 1064.9(2), b = 1850.6(5), c = 742.5(1) pm and β = 106.06(2)°.
Abstract: The title biaryl was prepared by Pd-catalyzed intramolecular aryl coupling. It crystallizes monoclinically in the space group P2i with a = 1064.9(2), b = 1850.6(5), c = 742.5(1) pm and β = 106.06(2)°. The asymmetric unit contains two molecules together with one phenol.
TL;DR: The reaction of dibromine with the heterocycles I-IV gives corresponding 3,5-dibromo derivatives, while the less selective reactions with dichlorine afforded 3, 5-dichloro derivative XII only in the case of 4 H -thiopyran IV and trichloronitriropyridine II as discussed by the authors.
Abstract: The reaction of dibromine with the heterocycles I-IV gives corresponding 3,5-dibromo derivatives, while the less selective reactions with dichlorine afforded 3,5-dichloro derivative XII only in the case of 4 H -thiopyran IV and trichloro derivative of the probable formula XIII in the case of 1,4-dihydropyridine II . Dichloro derivative IX was obtained on reaction of phosphorus pentachloride with substrate I . Nitration of compounds I-IV gives 3,5-dinitroderivatives XV-XVIII , but mononitro derivatives XIX and XX were also obtained. Iodination of compounds II-IV with di-iodine was unsuccessful.
TL;DR: In this paper, a base-induced cyclisation of the diketones 10(X = H or F), prepared in a two-step sequence from thiochroman-3-one, affords 6H,12H-[1]benzothiopyrano[3,4-b][1]-benzopyran-12-ones 11.
Abstract: Base-induced cyclisation of the diketones 10(X = H or F), prepared in a two-step sequence from thiochroman-3-one, affords 6H,12H-[1]benzothiopyrano[3,4-b][1]benzopyran-12-ones 11. Reduction with diisobutylaluminium hydride affords a separable mixture of the cis- and trans-5-thiorotenoids. Dieckmann cyclisation of ethyl 2-(ethoxycarbonylmethylthio)phenylethanoate affords a mixture of 4-ethoxycarbonyl- and 2-ethoxycarbonyl-thiochroman-3-ones. Attempts to prepare a thiorotenoid by condensation of these β-keto esters with 4-methoxyphenol resulted in formation of the novel bis[1]benzothiopyrano[3,2-b:4′,3′-e]pyran ring system.
TL;DR: 3-Nitro-5,6-dihydro-4H-pyran reacts with organoaluminum compounds and, after hydrolysis with 3 N HCl;, gives aldehydes arising from a formal carbonylation of the alane.
TL;DR: The Diels-Alder adducts from the reaction of 3-amino-2H-1,4-oxazin-2-ones 1b-d with olefins in toluene at reflux, undergo ring transformation yielding previously unknown 5,6-dihydro-2,2-oxo-2h-pyran-6-carbonitriles.
TL;DR: In this article, the α,β unsaturated monophosphonate heterocycles were obtained from tetraethyl ethylidene gem-bisphosphonates and 2-hydrocydohexanone, substituted salicylaldehydes or 2hydroxy-1-naphthaldehyde.
Abstract: The preparation of α,β unsaturated monophosphonate heterocycles is reported. 9-diethylphosphono-7-oxabicyclo[4.3.0]non-1(9)-ene, some 3-diethylphosphono-2H-1-benzopyrans and 2-diethylphosphono-3H-naphtol[2,1-b]pyran have been prepared from tetraethyl ethylidene gem-bisphosphonate and 2-hydrocydohexanone, substituted salicylaldehydes or 2-hydroxy-1-naphthaldehyde respectively.
Patent•
23 Jun 1992TL;DR: In this paper, a process of making an anticholesterolemic compound of the formula "STR1" and corresponding ring-opened hydroxy acids derived therefrom and pharmaceutically acceptable salts thereof is described.
Abstract: Disclosed are intermediates and a process of making an anticholesterolemic compound of the formula ##STR1## the corresponding ring-opened hydroxy acids derived therefrom and pharmaceutically acceptable salts thereof.
TL;DR: The title biaryl was prepared by Pd-catalysed intramolecular aryl coupling and crystallized monoclinically in the space group P2 1 /n with a = 1479.6(3), b = 1052.4(2), c = 1371.4 (2) pm, β = 104.85(2)° and Z = 4 as mentioned in this paper.
Abstract: The title biaryl was prepared by Pd-catalysed intramolecular aryl coupling. It crystallizes monoclinically in the space group P2 1 /n with a = 1479.6(3), b = 1052.4(2), c = 1371.4(2) pm, β = 104.85(2)° and Z = 4
TL;DR: In this article, a path to synthesize germacranolides with ether bridges between C 1 and C 5 or C 3 and C 10 was described, and a joint precursor was prepared using a readily available and inexpensive compound as starting material.
TL;DR: Stereoselective reductions of compound 5, by means of(+)-B-chlorodiisopinocampheylboraned led to 6 with a good selectivity.
Abstract: Stereoselective reductions of compound 5, by means of(+)-B-chlorodiisopinocampheylboraned led to 6 with a good selectivity. Intramolecular hetero-Michael cyclization of 13 with NaH in HMPA gave 14 with an excellent selectevity.