Showing papers on "Pyran published in 1989"
TL;DR: In this article, a highly convergent synthesis of the macrolide natural product milbemycin β1 is reported, which includes the introduction of the C11-C15 side chain by selective ring opening of a symmetrical 1,4-pentane bis-epoxide, followed by reaction with the anion derived from the 2,3-trans-dimethyl-6-phenylsulphonyl pyran.
83 citations
Patent•
22 Feb 1989
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 article, where 1,6-heptadien-4-ol is converted in eight operations to the desired products.
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-heptadien-4-ol is converted in eight operations to the desired products, as well as an improved process for the preparation of (2R-trans) and trans-(U)-5-(4-fluoro-phenyl)-2-(1-methylethyl)-N,4-diphenyl-1-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-1H-pyrrole-3-carboxamide by a novel synthesis where 4-methyl-3-oxo-N-phenylpentanamide is converted in eight operations to the desired product or alternatively 4-fluoro-alpha-[2-methyl-1-oxopropyl]-gamma-oxo-N,beta-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]-1H-pyrrole-3-carboxamide from (R)-4-cyano-3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]butanoic acid, as well as other valuable intermediates used in the processes.
48 citations
TL;DR: In this article, the functionality of α- d -glucose is stereoselectively manipulated exploiting pyranose ⇋ furanoses ⇋ pyrinose interconversions and lactonization for selective masking to achieve a stereocontrolled synthesis of the densely substituted H-ring pyrans of halichondrins.
46 citations
TL;DR: In this paper, the authors showed that 6-amino-5-cyano-4-aryl-2-methyl-4H-pyran-3-carboxylates 4 could be converted into 1,6-diazanaphthalene, pyrano-[2,3-c]pyrazole, isoxazolo[3,4-b]pyridine, Pyrano[2, 3-b]-polycyclic pyridine derivatives on treatment with malononitrile, hydrazine hydrate,
39 citations
Journal Article•
TL;DR: In this article, the authors showed that 6-amino-5-cyano-4-aryl-2-methyl-4H-pyran-3-carboxylates 4 could be converted into 1,6-diazanaphthalene, pyrano-[2,3-c]pyrazole, isoxazolo[3,4-b]pyridine, Pyrano[2, 3-b]-polycyclic pyridine derivatives on treatment with malononitrile, hydrazine hydrate,
37 citations
36 citations
36 citations
TL;DR: In this article, the glycosidic bond of 6-alkoxy-2,3-dihydro-6H-pyran-3-ones is made advantageously in the presence of catalytic ZnCl2·etherate.
27 citations
TL;DR: In this article, an elegant one-step synthesis of two spiro ring systems viz: spiro[3H-indole-3,4′-(2′-amino-3-carbonitrile-[4′H]-pyrano[3,2-c]benzopyran)]-2,5′(1H)-dione8 and spiro
22 citations
TL;DR: The structure of a 9,10,dihydro-5H-phenanthro-(4,5-b, c, d )-pyran, amoenumin, from the orchid Dendrobium amoenum has been established on the basis of spectral data.
21 citations
TL;DR: The morpholino(het)arylacetonitriles (I) were deprotonated and then coupled with the bromo(methoxy)butenoate (II) to give the pentenoates (III) as mentioned in this paper.
Abstract: The morpholino(het)arylacetonitriles (I) are deprotonated and then coupled with the bromo(methoxy)butenoate (II) to give the pentenoates (III).
TL;DR: In this paper, the reaction of dimethyl diazomalonate with 2-alkoxy-6-methyl-3,4-dihydro-2H-pyran in hot fluorobenzene has been studied in the presence of some transition metal catalysts.
TL;DR: In this article, peracid oxidation and HF-catalyzed treatment of furfuryl alcohol derivatives affords lactone products arising from a highly stereoselective rearrangement process.
TL;DR: In this article, the synthesis of 8-ethenyl-1-hydroxy-4-(βD-ribo-furanosyl) benzo [d] naphtho [1,2-b] pyran-6-one, a C-glycoside analogue of ravidomycin and gilvocarcin V, has been achieved by a sequence of reactions involving Lewis acid catalysed coupling of the aglycon and carbohydrate followed by introduction of the vinyl group and unmasking of the carbohydrate and phenolic hydroxyls.
Abstract: Synthesis of 8-ethenyl-1-hydroxy-4-(βD-ribo-furanosyl) benzo [d] naphtho [1,2-b] pyran-6-one, a C-glycoside analogue of ravidomycin and gilvocarcin V, has been achieved by a sequence of reactions involving Lewis acid catalysed coupling of the aglycon and carbohydrate followed by introduction of the vinyl group and unmasking of the carbohydrate and phenolic hydroxyls.
Patent•
17 May 1989
TL;DR: Aldose reducing enzyme inhibitor capable of preventing and treating complication of diabetes mellitus is described in this paper, using 6H-Dibenzo[b,d]pyran-6-one derivative expressed by formula IV (X 1 to X 8 are H, Cl, lower alkyl, lower alkoxy or OH and at least one among X 1 to x 8 is OH) is subjected to sulfur esterification or glycolic acid etherification.
Abstract: NEW MATERIAL:A compound expressed by formula I [R 1 to R 8 are H, Cl, lower alkyl, lower alkoxy, formula II or formula III (M is H, alkali metal or ammonium) and at least one among R 1 to R 8 is formula II or formula III]. EXAMPLE: 6H-Dibenzo[b,d]pyran-6-one-3-sulfuric acid ester potassium salt. USE: An aldose reducing enzyme inhibitor capable of preventing and treating complication of diabetes mellitus. PREPARATION: A hydroxy-6H-dibenzo[b,d]pyran-6-one derivative expressed by formula IV (X 1 to X 8 are H, Cl, lower alkyl, lower alkoxy or OH and at least one among X 1 to X 8 is OH) is subjected to sulfur esterification or glycolic acid etherification, or a substance subjected to the abovementioned esterification or etherification is reacted with a substance capable of producing alkali metal ion or ammonium ion. COPYRIGHT: (C)1990,JPO&Japio
Patent•
05 Jun 1989
TL;DR: In this article, the authors defined a new class of compounds of formulae, in which a hydrogen atom can be substituted with a lower alkyl, a halogen, a trifluoromethyl, a methoxy, a methylthio or a nitro, or R3 and R4 together form a methylene dioxy group.
Abstract: The invention relates to new compounds of formulae: in which: - R1 and R2 represent a hydrogen atom, a lower alkyl, an aryl or aryl(lower alkyl) which may be substituted with a lower alkyl, a halogen, a trifluoromethyl, a methoxy, a methylthio, a methylenedioxy group or a nitro, or R1 and R2 together form a non-aromatic C3-C7 carbon ring, a nitrogenous heterocycle such as pyridine, pyrazine, pyrimidine, pyridazine, indole or pyrazole, a saturated or unsaturated oxygen-containing heterocycle such as pyran or furan or a saturated or unsaturated sulphur-containing heterocycle such as thiopyran or thiophene, it being possible for this heterocycle to be unsubstituted or substituted with a halogen or a lower alkyl; - R3 and R4 represent a hydrogen atom, a lower alkyl, a halogen, a trifluoromethyl, a methoxy, a methylthio or a nitro, or R3 and R4 together form a methylene dioxy group; - R5 represents hydrogen, a lower hydroxyalkyl, a (lower alkanoyl)oxy(lower alkyl) or a lower amino alkyl; - Z is a heterocycle such as pyridine, thiazole, benzothiazole, benzimidazole or quinoline, which may be unsubstituted or substituted with a halogen or a lower alkyl. Lower alkyl is understood to mean a linear or branched or cyclic chain of 1 to 5 carbon atoms. Aldose reductase inhibitors. Treatment of certain complications of diabetes.
TL;DR: In this paper, the structure-activity relationship in oximes of a series of sixteen 3-acyltetrahydro-2H-pyran-2,4-diones, exhibiting a variety of pre- and post-emergent herbicidal activities, have been studied by means of computer graphics methods.
Abstract: Structure-activity relationships in oximes of a series of sixteen 3-acyltetrahydro-2H-pyran-2,4-diones, exhibiting a variety of pre- and postemergent herbicidal activities, have been studied by means of computer graphics methods. The most active compounds are potent grass-killers. This graminicidal activity appears to depend strongly on the size and shape of the substituent at the 6-position of the pyran. The activity correlates with both molar refractivity and fit to a hypothetical ‘receptor’ probably the active site of acetyl coenzyme A carboxylase. The herbicide sethoxydim and the pyrandione herbicides appear to mimic the transition state of the reaction catalyzed by acetyl-CoA carboxylase.
The study has yielded a receptor model which defines clearly the three-dimensional binding reguirements of the pyran ring and the substituents at the 6 position. It is not capable of providing information on the structural requirements of the 3-acyl moiety. The model is capable of discriminating between active and inactive herbicidal compounds and provides a basis for the design of new herbicidal compounds with enhanced graminicidal activity.
TL;DR: In this paper, photolysis of 4-(t-Bu)-substituted [b]-fused bi- and tricyclic pyrandiones 5 affords title compounds 4 in good yields as well as small amounts of spiroalkanediones 8.
Abstract: Photolysis (λ = 254 nm) of 4-(t-Bu)-substituted [b]-fused bi- and tricyclic pyrandiones 5 affords title compounds 4 in good yields as well as small amounts of spiroalkanediones 8. The alkyl-substitution pattern at C(4) of the pyran ring in 5 determines the relative amount of α vs. β-cleavage products obtained from the primarily formed acyl-vinyloxy biradical.
TL;DR: In this paper, the [Co2 (CO)8]-catalyzed reaction between propyne and CO in acetone at 110° and 170 bar was re-investigated and five major products: (E)-3,4′-dimethyl-2,2′-bifurylidene-5,5′-dione (4), 3,5,8-trimethylcoumarin (8), 3a, 7a-dihydro-2.
Abstract: The [Co2 (CO)8]-catalyzed reaction between propyne and CO in acetone at 110° and 170 bar was re-investigated. There are five major products: (E)-3,4′-dimethyl-2,2′-bifurylidene-5,5′-dione (4), 3,5,8-trimethylcoumarin (8), 3a, 7a-dihydro-2,4,7,7a-tetramethyl-1H-inden-1-one (9), 2,6-dimethyl-5H-furo [3,2, -b]- pyran-5-one (11), and 2,7-dimethyl-5H-furo 3,2-b-pyran-5-one (12); of these, only one, 4. had previously been recognized. In parallel experiments were obtained 2,6-dipentyl-5 H-furo[3,2-b]pyran-5-one (13), 2,7-dipentyl–5H-furo[3,2-b]pyran-5-one (14), 3a, 7a-dihydro-2,4,7,7a-tetrapentyl-1H-inden-1-one (15). And 3a, 7a-dihydro-2,4,6,7a-tetrapentyl-1H-inden-1-one (16) from hept-1-yne, and two further types of products from two atypical 1-alkynes: 3,6,9-tri(tert-butyl)-1-oxaspiro[4.4]nona-3,6,8-trien-2-one (20) from (tert-butyl)acetylene and the exo-dimer 21 of 2,5-bis(trimethylsilyl)cyclopenta-2,4-dien-1-one (22) from (trimethylsilyl)acetylene. Compounds 11,12, and 20 were identified by X-ray analysis.
TL;DR: In this paper, the reaction of acetoacetanilide with the α-cyanocinnamonitrile derivatives yielded the Michael adducts which could be converted into the pyrano[2,3-c] pyrazole derivatives via their reaction with hydrazine hydrate.
Abstract: The reaction of acetoacetanilide (1) with the α-cyanocinnamonitrile derivatives2 yielded the Michael adducts4 which could be converted into the pyrano[2,3-c] pyrazole derivatives5 via their reaction with hydrazine hydrate. Cyclisation of4 afforded the cyanoaminopyrans9 which could in turn be converted into the corresponding pyridine derivatives10. The pyranopyrazoles9 reacted with different activated nitrile derivatives (3a-c) to give the pyrano[2,3-c]pyridine derivatives13, 16 and19 respectively. The biological activity of the synthesised heterocyclic derivatives was investigated and discussed.
TL;DR: In this paper, a series of novel trans-3-(octahydro-2H-pyrano[2,3-c]pyridin-4a-yl) phenols are described.
Abstract: The synthesis of a series of novel trans-3-(octahydro-2H-pyrano[2,3-c]pyridin-4a-yl)phenols (12a–g), (20a–c), (21), (22) and trans-3-(octahydro-1H-pyrano[3,4-c]pyridin-4a-yl) phenols (28a, b), (34) is described. Construction of the pyrano[2,3-c]pyridines is achieved via annulation of the pyran ring onto the arylpiperidin-3-ones (6) and (14)(R = CO2Ph). The pyrano[3,4-c]pyridines are synthesized by application of metallated enamine chemistry to 1-methyl-4-(3-methoxyphenyl)1,2,3,6-tetrahydropyridine (4) and proceeds via the novel 2-oxa-8-azabicyclo[3.3.1 ] nonane (23) and the bicyclic enamines (24) and (29). Manipulation of this general methodology has afforded a number of structural variants bearing strategic substitutions in the pyran ring as well as alternative N-groups. The antinociceptive activity and opioid receptor profile of these compounds has been determined and structure-activity relationships are discussed.
TL;DR: The photolysis of the 7-acetoxybenzopyran derivatives 1a-5a has been carried out as mentioned in this paper, where chromene 1a was found to undergo extensive photopolymerization.
TL;DR: A series of N-alkyl-O-(arylsulphonyl)hydroxylamines (NSA) was treated with 3,4-dihydro-2H-pyran (DHP) and acid-catalysed addition to the double bond followed by cationic rearrangement gave cyclic imidates from hydride migration (major) and ring expansion (minor) as mentioned in this paper.
Abstract: A series of N-alkyl-O-(arylsulphonyl)hydroxylamines (NSA) was treated with 3,4-dihydro-2H-pyran (DHP). Acid-catalysed addition to the double bond followed by cationic rearrangement gave cyclic imidates from hydride migration (major) and ring expansion (minor), which were reduced to amino alcohols for analysis. The results indicate that NSA function as nucleophiles which capture the oxonium ion produced by protonation of DHP, and give new NSA derivatives that rearrange to the observed products.
Journal Article•
Journal Article•
TL;DR: In this paper, the stereochemical aspects of the Bucherer-Bergs reaction and a modified Strecker reaction on tetrahydro-2H-pyran-3-one derivatives have been studied in details through the use of several nmr techniques.