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Showing papers on "Pyran published in 2010"


Journal ArticleDOI
TL;DR: The straightforward and efficient synthesis of naphtho[1,8-bc]pyran derivatives and related polycyclic compounds is achieved by the rhodium-catalyzed oxidative coupling of 1-naphthols or other phenolic and alcoholic substrates with alkynes.
Abstract: The straightforward and efficient synthesis of naphtho[1,8-bc]pyran derivatives and related polycyclic compounds is achieved by the rhodium-catalyzed oxidative coupling of 1-naphthols or other phenolic and alcoholic substrates with alkynes. In these annulation reactions, the hydroxy groups effectively act as the key function for the regioselective CH bond cleavage.

142 citations


Journal ArticleDOI
TL;DR: A series of pyrimidine nucleoside-pyrano[3,2-c]pyridone or pyrano(4,3-b)pyran hybrids were efficiently obtained and showed encouraging biological activities.

119 citations


Journal ArticleDOI
TL;DR: The Nazarov cyclization, a stereospecific 4p electrocyclization that converts divinyl ketones into cyclopentenones through a conrotatory cyclizing, has distinguished itself as a powerful tool for the synthesis of such compounds.
Abstract: Alkoxy divinyl β-ketoesters (I) undergo the title reaction to give cyclopenta[b]pyran derivatives (II) with high regio-, diastereo- and enantioselectivities.

110 citations


Journal ArticleDOI
TL;DR: A simple and efficient method for the one-pot three-component synthesis of new spirooxindoles in room temperature is described and the results are good on comparison with of standard antibacterial compounds.

105 citations


Journal ArticleDOI
TL;DR: Structural comparison of these compounds suggests the differences in function may be due to the structure of the xanthene heterocycle which adopts a nonplanar conformation about the pyran ring.

87 citations


Journal Article
TL;DR: Tetrabutylammonium bromide (TBAB) was used as a green catalyst for the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-d]pyrimidinone derivatives in water as a solvent.
Abstract: Tetrabutylammonium bromide (TBAB) was used as a green catalyst for the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-d]pyrimidinone derivatives in water as a solvent. Use of nontoxic reaction components, short reaction times, easy work-up and high yields are some important advantages of this method.

66 citations


Journal ArticleDOI
TL;DR: This MCR followed by a postcondensation cyclization via an intramolecular S(N)Ar in the presence of K(2)CO(3) led to an unprecedented novel chromeno[2,3-b]quinoline framework containing an important chromene moiety in good yields.
Abstract: Regioselective synthesis of functionalized tetrahydrobenzo[b]pyrans has been developed by multicomponent reactions (MCRs) and tandem [3 + 3] annulations of β-benzoylthioacetanilides or β-(2-haloaroyl)thioacetanilides as valuable sources with aromatic aldehydes and 5,5-dimethyl-1,3-cyclohexanedione catalyzed by triethylamine. This MCR followed by a postcondensation cyclization via an intramolecular SNAr in the presence of K2CO3 led to an unprecedented novel chromeno[2,3-b]quinoline framework containing an important chromene moiety in good yields. The reactions were very mild, convenient, and o-selective to form new fused tetracyclic target molecules.

46 citations


Journal ArticleDOI
TL;DR: Tetrahydrobenzo[b]pyran and pyrano[2,3-d]pyrimidinone derivatives were synthesized efficiently in the presence of KAl(SO4)2.12H2O (alum) in water.
Abstract: Tetrahydrobenzo[b]pyran and pyrano[2,3-d]pyrimidinone derivatives were synthesized efficiently in the presence of KAl(SO4)2.12H2O (alum) in water. Green media, lack of toxicity, short reaction times, easy work-up and high yields are some advantages of this method.

46 citations


Journal ArticleDOI
TL;DR: In this article, a series of Ce1MgxZr1-xO2 mixed metal oxides with different molar ratios were prepared by simple co-precipitation and were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive spectrograph, temperature-programmed desorption of CO2, and N2 adsorption techniques.

42 citations


Journal ArticleDOI
TL;DR: Some naphthoquinones exhibited inhibition with MIC values of 1.25 μg/mL, similar to that of pharmaceutical concentrations currently used in tuberculosis treatment, justifying further research into the value of these quinones as part of an original treatment for tuberculosis.
Abstract: A series of alpha- and beta-pyran naphthoquinones (lapachones) have been synthesized and evaluated for their in-vitro antibacterial activity against Mycobacterium tuberculosis strain H37Rv (ATCC 27294) using the Alamar-Blue susceptibility test; the activity was expressed as the minimum inhibitory concentration (MIC) in microg/mL. The synthetic methodology consisted of the formation of methylene and aryl o-quinone methides (o-QMs) generated by Knoevenagel condensation of 2-hydroxy-1,4-naphthoquinone with formaldehyde and arylaldehydes. These o-QMs then undergo facile hetero Diels-Alder reactions with dienophiles in aqueous ethanol media. Some naphthoquinones exhibited inhibition with MIC values of 1.25 microg/mL, similar to that of pharmaceutical concentrations currently used in tuberculosis treatment. These results justify further research into the value of these quinones as part of an original treatment for tuberculosis.

40 citations


Journal ArticleDOI
TL;DR: A number of new 2,6-didisubstituted pyrimidine, pyrazoline, and pyran derivatives were synthesized starting from their chalcone derivative and displayed different degrees of antimicrobial activity against Bscillus subtilis, Pseudomonas aeruginosa, and Streptomyces species.
Abstract: A number of new 2,6-didisubstituted pyrimidine, pyrazoline, and pyran derivatives were synthesized starting from their chalcone derivative. The synthesized compounds displayed different degrees of antimicrobial activity against Bscillus subtilis (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Streptomyces species (Actinomycetes).

Journal ArticleDOI
TL;DR: This review intends to explore the synthetic methodologies for preparing pyran naphthoquinones and their applications in searching for new pharmacologically promising molecules against different therapeutic targets.
Abstract: Taking into account the numerous reports in the literature related to pyran naphthoquinones in searching for new pharmacologically promising molecules against different therapeutic targets, this review intends to explore the synthetic methodologies for preparing these bioactive compounds.

Journal ArticleDOI
TL;DR: One-pot synthesis of multi-substituted 6-aryl-6H-dibenzo[b,d]pyran derivatives was achieved via vinylogous Michael addition as the key step and domino reactions under mild reaction conditions, employing readily available α,α-dicyanoolefins and 3-nitro-2H-chromenes as substrates as mentioned in this paper.

Journal ArticleDOI
TL;DR: Compared with the conventional thermal methods, the remarkable advantages of this method are the simple experimental procedure, shorter reaction time and high yield of product.

Journal ArticleDOI
TL;DR: The total synthesis of (+)-demethoxycardinalin 3 is described, which features the synthesis of dimeric Fischer carbene and its use in a bidirectional Dötz benzannulation reaction to set the dimeric structure of the cardinalins.
Abstract: The total synthesis of (+)-demethoxycardinalin 3 is described. The synthetic strategy features the synthesis of dimeric Fischer carbene and its use in a bidirectional Dotz benzannulation reaction to set the dimeric structure of the cardinalins. The oxa-Pictet−Spengler reaction was used to construct the pyran rings. The synthesis is completed in seven steps and an overall yield of 7%.

Journal ArticleDOI
TL;DR: The trail pheromone of the pharaoh ant, Monomorium pharaonis, was obtained via transformation of methyl 3-bromomethyl-3-butenoate (1 ) into allylstannane 2 and subsequent allylation of (benzyloxy)acetaldehyde (6 ) in accordance with the Keck procedure as the key steps.

Journal ArticleDOI
TL;DR: An efficient method for synthesis of 2H-pyran-3,4-dicarboxylates using the three-component reaction of dithiocarbamates, dialkyl acetylenedicarboxesylates, and isocyanides in solvent-free conditions is described in this paper.

Journal ArticleDOI
TL;DR: The linear 9-methoxy-2,2-dimethyl-2H-benzofuro[2,3-g][1]benzopyran exhibiting a good antimycobacterial activity and devoid of cytotoxicity appeared to be the most promising compound.

Journal ArticleDOI
TL;DR: This present protocol provides an efficient synthetic route to the target compounds with the characteristics of short reaction time, high yield, and easy separation of the products.

Journal ArticleDOI
TL;DR: The first total synthesis of hirtellanines A was described in this paper, where the key transformations include base-mediated regioselective pyran ring formation, one-pot sequential boronation and Suzuki-Miyaura cross-coupling.

Journal ArticleDOI
01 Jun 2010-Synlett
TL;DR: The salient feature of this synthesis is the extension of carbon chains using alkynols followed by the use of an alkyne system to generate the desired functionalities, in particular formation of the embedded pyran via an intramolecular oxa-Michael addition of a β-hydroxyynone.
Abstract: The asymmetric synthesis of the tetrahydropyran con taining C8-C20 fragment, a common key subunit of both (-)-dactylolide and (-)-zampanolide, is described. The salient feature of this synthesis is the extension of carbon chains using alkynols followed by the use of an alkyne system to generate the desired functionalities, in particular formation of the embedded pyran via an intramolecular oxa-Michael addition of a β-hydroxyynone.

Journal ArticleDOI
TL;DR: A series of 4H-5,6,7,8-tetrahydrobenzo[b]pyran derivatives has been synthesised in excellent yield in a single pot using trioctylmethylammonium chloride (Aliquat®336) as phase-transfer catalyst in this article.
Abstract: A series of 4H-5,6,7,8-tetrahydrobenzo[b]pyran derivatives has been synthesised in excellent yield in a single pot using trioctylmethylammonium chloride (Aliquat®336) as phase-transfer catalyst in ...

Journal ArticleDOI
TL;DR: The first enantioselective syntheses of sulfur flavan-3-ol analogues 1–8 have been accomplished, whereby the oxygen atom of the pyran ring has been replaced by a sulfur atom.
Abstract: The first enantioselective syntheses of sulfur flavan-3-ol analogues 1–8 have been accomplished, whereby the oxygen atom of the pyran ring has been replaced by a sulfur atom. The key steps were: (a) Pd(0) catalyzed introduction of –S t-butyl group, (b) Sharpless enantioselective dihydroxylation of the alkene, (c) acid catalyzed ring closure to produce the thiopyran ring, and (d) removal of benzyl groups using N,N-dimethylaniline and AlCl3. The compounds were isolated in high chemical and optical purity.

Journal ArticleDOI
TL;DR: A maleimide derivative, where the central quinone between the pendant hydroxyquinones was replaced, was successfully synthesised and although it exhibited comparable enzyme inhibitory activity it had negligible HIV inhibitory cellular activity.

Journal ArticleDOI
TL;DR: Ferrocenyl and pyridyl methylenepyrans were obtained from a Wittig reaction between a pyran phosphorane and ferroceneyl or pyrin-aldehydes.

Journal ArticleDOI
TL;DR: The 4CC coupling of sugar hydroxyaldehyde, Meldrum's acid, isocyanide, and a secondary alcohol in dichloromethane has been accomplished at room temperature in a highly stereoselective manner to produce a novel class of carbohydrate derivatives, 5-oxo-perhydrofuro[3,2-b]pyrans in good yields with transselectivity as mentioned in this paper.

Journal ArticleDOI
TL;DR: This work reportscise and efficient asymmetric total syntheses of (+)-strictifolione 1 and (6R)-6-[(4R, 6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5, 6- dihydro-2H-pyran-2-one 2 based on the strategic application of one-pot double allylboration and ring-closing metathesis reactions.
Abstract: Concise and efficient asymmetric total syntheses of (+)-strictifolione 1 and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one 2 have been achieved based on the strategic application of one-pot double allylboration and ring-closing metathesis reactions. The total syntheses proceeded in only five and seven steps, respectively, from readily available 3-butenal and represent the shortest syntheses of 1 and 2 reported to date.

Journal ArticleDOI
TL;DR: InCl3 catalyzed reactions of 2-C-acetoxymethylglycal derivatives with different phenolic compounds resulted in the formation of sugar-based pyrano-arenopyrans in good yields and moderate to excellent diastereoselectivity as discussed by the authors.

Journal ArticleDOI
TL;DR: A series of merocyanines containing isophorone or pyran rings in the spacer have been synthesized as discussed by the authors, which show higher second-order optical nonlinearities, but lower thermal stabilities.

Journal ArticleDOI
TL;DR: Pyridine-functionalized MCM-41 catalyzed reactions between tetracyanoethylene and various activated CH-acid compounds are described, which afford the corresponding pyran annulated heterocyclic ring systems in high yields at room temperature within a few minutes.
Abstract: Pyridine-functionalized MCM-41 catalyzed reactions between tetracyanoethylene and various activated CH-acid compounds are described. These reactions afford the corresponding pyran annulated heterocyclic ring systems in high yields at room temperature within a few minutes. The work-up procedure is very simple and the products do not require further purification. The catalyst can be recycled and reused for several times without observable loss of performance.