Showing papers on "Pyran published in 2012"
TL;DR: The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho[1,8-bc]pyran products, which exhibit intense fluorescence in the solid state.
Abstract: The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho[1,8-bc]pyrans by sequential cleavage of C(sp2)–H/C(sp3)–H and C(sp2)–H/O–H bonds. These cascade reactions are highly regioselective with unsymmetrical alkynes. Experiments reveal that the first-step reaction proceeds by sequential cleavage of C(sp2)–H/C(sp3)–H bonds and annulation with alkynes, leading to 1-naphthols as the intermediate products. Subsequently, 1-naphthols react with alkynes by cleavage of C(sp2)–H/O–H bonds, affording the 1:2 coupling products. Moreover, some of the naphtho[1,8-bc]pyran products exhibit intense fluorescence in the solid state.
236 citations
TL;DR: In this article, a three-component regioselective synthesis of 2-amino-3-cyano-4 H -chromene and tetrahydrobenzo[b ]pyran derivatives has been developed by annulation of aldehydes, malononitrile, and resorcinol or dimedone under reflux conditions in 2,2,2-trifluoroethanol without the use of a catalyst or any other additive.
104 citations
TL;DR: Catalytic asymmetric [4+2] cycloadditions of β,γ-unsaturated α-ketophosphonates with allenic esters catalyzed by organocatalysts derived from different cinchona alkaloids have been developed, affording phosphonate-substituted functionalized pyran and dihydropyran derivatives in excellent yields with high enantioselectivities under mild conditions.
Abstract: Tell me which you want: catalytic asymmetric [4+2] cycloadditions of β,γ-unsaturated α-ketophosphonates with allenic esters catalyzed by organocatalysts derived from different cinchona alkaloids have been developed, affording phosphonate-substituted functionalized pyran and dihydropyran derivatives in excellent yields with high enantioselectivities under mild conditions. The choice of product is controlled by the hydrogen bonding characteristics of the chosen catalyst.
75 citations
TL;DR: A novel and convenient organocatalytic tandem reaction has been developed for the asymmetric assembly of saturated aldehydes, nitroolefins and isatins to produce six-membered oxa-spirooxindole backbones bearing four contiguous stereogenic centers and multiple functional groups with high stereoselectivity.
72 citations
TL;DR: The multicomponent reaction of aromatic aldehydes 1 and malononitrile with active methylenes 5a–h in the presence of L-proline produced pyrans and thiopyran stereospecifically and in good yields.
Abstract: The multicomponent reaction (MCR) of aromatic aldehydes 1 and malononitrile (2) with active methylenes 5a-h in the presence of L-proline produced pyrans and thiopyrans 6a-h stereospecifically and in good yields. Moreover a novel MCR of ethyl propiolate (8) with 1 and 2 in the presence of L-proline to afford (R)-polysubstituted pyran is also reported. X-ray structures, e.e. and optical activity of the synthesized compounds indicated that L-proline as a catalyst is responsible for the observed enantioselectivity in the studied reactions.
67 citations
TL;DR: In this paper, a review focused on the application of nano-materials in heterocyclic chemistry is presented, where the main part of review is constituted by sections in which the reactions catalyzed by nanomaterials.
Abstract: Recent achievements in the construction of heterocycles by the reaction of arynes with carbon-heteroatom double bonds are reviewed. Use of the Diels-Alder type, ionic, and radical mechanisms resulted in the formation of novel heterocycles containing oxygen, nitrogen, sulfur, and selenium atoms. Abstract This review focused on the application of nano-materials in heterocyclic chemistry. The main part of review is constituted by sections in which the reactions catalyzed by nanomaterials. In the last part of this review, emphasis is given to the heterocyclic supported nanomaterials and their importance in the catalysis. Abstract Aspergillides A, B, and C are cytotoxic macrolides produced by the marine-derived fungus Aspergillus ostianus strain TUF 01F313. The unique molecular architectures of the aspergillides featuring 14-membered marocyclic structures embedded with a tetrahydro- or dihydropyran unit have attracted significant attention from the synthetic chemistry community, and thereby various synthetic approaches to these structurally as well as pharmacologically intriguing molecules have been reported by as many as 12 research groups in the past 3 years. This review describes all of the syntheses disclosed to date, focusing mainly on the methodologies employed for the diastereoselective installation of the pyran ring systems.
63 citations
TL;DR: Among these, compounds 4a, 4b and 4j displayed the most potent anti-proliferative activity against human lung cancer A549 cell lines, while 4a and 4b displayed against neuroblastoma SK-N-SH cancer cell lines when compared to the standard doxorubicin.
Abstract: A new series of chromeno-annulated cis-fused pyrano[3,4-c]pyran derivatives have been synthesized by intramolecular [4 + 2] domino Knoevenagel–hetero-Diels–Alder reactions of 1-oxa-1,3-butadienes derived in situ from 1,3-dicarbonyls/active methylenes and 7-O-prenyl derivatives of 8-formyl-2,3-disubstituted chromenones in the presence of 20 mol% ethylenediamine diacetate (EDDA) in acetonitrile under reflux conditions in good to excellent yields. The structures were established based on spectroscopic data, and were further confirmed by X-ray diffraction analysis. These compounds were evaluated for their anti-proliferative activity using an in vitro MTT cytotoxicity assay. The results clearly demonstrated that compounds 4a, 4b, 4c, 4j, 4k, 4l, 4m and 4n exhibited significant anti-proliferative activity against human A549 lung cancer and non-cancer MRC-5 cell lines along with potent inhibitory activity against human neuroblastoma SK-N-SH cancer cell lines. Among these, compounds 4a, 4b and 4j displayed the most potent anti-proliferative activity against human lung cancer A549 cell lines, while 4a and 4b displayed against neuroblastoma SK-N-SH cancer cell lines when compared to the standard doxorubicin.
60 citations
TL;DR: A series of four new promising D-π-A conjugated organic sensitizers with a proaromatic 4H-pyran-4-ylidene as a donor, a thiophene ring in the bridge, and 2-cyanoacrilic acid as acceptor are synthesized.
58 citations
TL;DR: Chromenes and isochromenes react quickly with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) to form persistent aromatic oxocarbenium ions through oxidative carbon-hydrogen cleavage.
Abstract: Chromenes and isochromenes react quickly with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) to form persistent aromatic oxocarbenium ions through oxidative carbon–hydrogen cleavage. This process is tolerant of electron-donating and electron-withdrawing groups on the benzene ring and additional substitution on the pyran ring. A variety of nucleophiles can be added to these cations to generate a diverse set of structures.
58 citations
TL;DR: In this paper, a number of ruthenium complexes were prepared and their catalytic activities in three-component one-pot condensation of aldehydes, malononitrile and 4-hydroxycoumarin or dimedone was considered to afford dihydropyrano[3,2-c]chromenes and tetrahydrobenzo[b]pyran derivatives under optimum reaction conditions.
Abstract: A number of ruthenium complexes were prepared and their catalytic activities in three-component one-pot condensation of aldehydes, malononitrile and 4-hydroxycoumarin or dimedone was considered to afford dihydropyrano[3,2-c]chromenes and tetrahydrobenzo[b]pyran derivatives under optimum reaction conditions. We found that a catalytic amount of RuBr2(PPh3)4 efficiently promotes the reaction in a short time (3–15 min) and with high yield (75–88%). Copyright © 2012 John Wiley & Sons, Ltd.
57 citations
TL;DR: The majority of the compounds synthesized were found to be active against Bacillus subtilis, Clostridium tetani and Candida albicans as compared to standard drugs.
Abstract: A new series of pyrano[4,3-b]pyran 4a-i and pyrano[3,2-c]chromene 6a-r derivatives bearing a 2-thiophenoxyquinoline nucleus were synthesized by reaction of 2-(4-(un)-substituted thiophenoxy)quinoline-3-carbaldehydes 2a-i with 6-methyl-4-hydroxypyran-2-one 3 and 4-hydroxy-6-(un)-substituted-2H-chromen-2-one 5a-b respectively and malononitrile at room temperature in the presence of KOH as a basic catalyst. All the compounds were screened against three Gram-positive bacteria (Streptococcus pneumoniae, Bacillus subtilis, Clostridium tetani), three Gram-negative bacteria (Salmonella typhi, Escherichia coli, Vibrio cholerae) and two fungi (Candida albicans, Aspergillus fumigatus) using the broth microdilution MIC (minimum inhibitory concentration) method. Upon antimicrobial screening, it was observed that the majority of the compounds were found to be active against Bacillus subtilis, Clostridium tetani and Candida albicans as compared to standard drugs.
TL;DR: A new approach to synthesize a homologous series of 14, 15, and 16-membered drug-like, macrocyclic glycoconjugates involving TBAHS promoted azide-propenone intramolecular cycloaddition in designed C-glycopyranosyl butenones from a simple sugar d-glucose and d-mannose is reported.
Patent•
15 Aug 2012TL;DR: Novel quinoline compounds pharmaceutical compositions containing such compounds and their use in therapy were described in detail in this paper, where the authors proposed a method for synthesizing new quinelline compounds.
Abstract: Novel quinoline compounds pharmaceutical compositions containing such compounds and their use in therapy.
TL;DR: Iodo-substituted compounds generated by the electrophilic iodocyclization were further diversified via Pd-catalyzed cross-coupling reactions and structure of the products were confirmed by the X-ray crystallographic studies.
Abstract: An efficient strategy for the synthesis of pyrrolo[1,2-a]quinolines and indolizines from pyranoquinolines via site-selective electrophilic cyclization and subsequent opening of pyran ring using silver/iodine under mild reaction conditions is described. This approach involves the preferential attack of the pyridyl nitrogen over aryl ring and leads to the formation of 5-endo-dig cyclized products. Quantum chemical calculations between C–N (ΔEa = 9.01 kcal/mol) and C–C (ΔEa = 31.31 kcal/mol) bond formation were performed in order to rationalize the observed site selectivity. Structure of the products were confirmed by the X-ray crystallographic studies. Iodo-substituted compounds generated by the electrophilic iodocyclization were further diversified via Pd-catalyzed cross-coupling reactions.
TL;DR: In this article, a new and efficient method was developed for the synthesis of highly functionalized 2-amino-4H-pyran derivatives through one-pot, three component tandem reactions of structurally diverse 1,3-diketones, dialkyl acetylenedicarboxylates, and malononitrile or ethyl cyanoacetate in the presence of a catalytic amount of Na2CO3 in ethanol.
TL;DR: Results provide experimental evidence that the pyranopterin dithiolene ligand in molybdenum and tungsten enzymes could participate in catalysis through dynamic processes modulated by the protein.
Abstract: The syntheses and X-ray structures of two molybdenum pyranopterin dithiolene complexes in biologically relevant Mo(4+) and Mo(5+) states are reported. Crystallography reveals that these complexes possess a pyran ring formed through a spontaneous cyclization reaction of a dithiolene side-chain hydroxyl group at a C═N bond of the pterin. NMR data on the Mo(4+) complex suggest that a reversible pyran ring cyclization occurs in solution. These results provide experimental evidence that the pyranopterin dithiolene ligand in molybdenum and tungsten enzymes could participate in catalysis through dynamic processes modulated by the protein.
TL;DR: An efficient method for the construction of enantiomerically enriched spiro[2H-pyran-3,4′-indoline] derivatives by a systematic Michael/reduction/cyclization sequence is reported.
TL;DR: The antitumor activity of the newly synthesized compounds was evaluated against three human tumor cells lines, namely breast adenocarcinoma, non-small cell lung cancer and CNS cancer and some of these compounds were found to exhibit much higher inhibitory effects towards the three tumor cell lines than the Gram positive control doxorubicin.
Abstract: The reaction of cyanoacetylhydrazine with chloroacetyl chloride gave N'-(2-chloroacetyl)-2-cyanoacetohydrazide. The latter underwent cyclization to afford 1-(5 amino-3-hydroxy-1H-pyrazol-1-yl)-2-chloroethanone, which underwent nucleophilic substitution to give 3-(5-amino-3-hydroxy-1H-pyrazol-1-yl)-3-oxopropanenitrile. The latter two compounds were used as key synthons to synthesize new thiophene, pyran, thiazole and some fused heterocyclic derivatives. The antitumor activity of the newly synthesized compounds was evaluated against three human tumor cells lines, namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) and some of these compounds were found to exhibit much higher inhibitory effects towards the three tumor cell lines than the Gram positive control doxorubicin.
TL;DR: A series of naphthopyran derivatives 3a-f were prepared as mentioned in this paper, and the structures of the newly synthesized compounds were confirmed by spectral data, and they were also screened for their antimicrobial activity.
Abstract: A series of naphthopyran derivatives 3a–f were prepared. Reaction of 2-amino-4-(p-chlorophenyl)-7-methoxy-4H-naphtho[2,1-b]pyran-3-carbonitrile (3b) with Ac2O afforded two products, 2-acetylamino-7-methoxy-4-(p-chlorophenyl)-4H-naphtho-[2,1-b]pyran-3-carbonitrile (4) and 10,11-dihydro-3-methoxy-9-methyl-12-(p-chloro-phenyl)-12H-naphtho[2,1-b]pyran[2,3-d]pyrimidine-11-one (5) and treatment of 3b with benzoyl chloride gave the pyranopyrimidin-11-one derivative 6. While treatment of 3b with formamide afforded 11-amino-3-methoxy-12-(p-chlorophenyl)-12H-naphtho[2,1-b]pyrano[2,3-d]pyrimidine (7). Reaction of 3b with triethyl orthoformate gave the corresponding 2-ethoxymethyleneamino-7-methoxy-4-(p-chlorophenyl)-4H-naphtho-[2,1-b]pyran-3-carbonitrile (8). Hydrazinolysis of 8 in EtOH at room temperature yielded 10-amino-10,11-dihydro-11-imino-3-methoxy-12-(p-chlorophenyl)-12H-naphtho[2,1-b]pyrano-[2,3-d]pyrimidine (9), while aminolysis of 8 with methylamine or dimethylamine gave the corresponding pyranopyrimidine and N,N-dimethylaminomethylene derivatives 10 and 11. Condensation of 9 with some carboxylic acid derivatives afforded triazolopyrimidine derivatives 12–16, while reaction of 9 with benzaldehyde gave 10-benzalamino-10,11-dihydro-11-imino-3-methoxy-12-(p-chlorophenyl)12H-naphtho[2,1-b]pyrano[2,3-d]pyrimidine (17). The structures of the newly synthesized compounds were confirmed by spectral data. The synthesized compounds were also screened for their antimicrobial activity.
TL;DR: A variety of pyrano[2,3-d]pyrimidine-5-one derivatives have been synthesized from 6-amino-4-(substituted phenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano [2, 3-c]pyrazole derivatives via cyclization using formic acid and acetic acid as discussed by the authors.
TL;DR: In this paper, two green protocols have been developed for the synthesis of 3,4-dihydropyridin-2-one derivatives from different starting materials exploring two reaction specific catalysts, vitamin B 1 (VB 1 ), and PEG-SO 3 H.
TL;DR: A series of new 4H-pyran-4-ylidene donor-based chromophores with a thiophene ring in the spacer has been synthesized, with the best results obtained when the heterocyclic system was closer to the donor moiety.
Abstract: A series of new 4H-pyran-4-ylidene donor-based chromophores with a thiophene ring in the spacer has been synthesized The linear and nonlinear optical (NLO) properties of these compounds have been determined and compared with the results of computational calculations The position of the thiophene ring proved essential to optimize the figure of merit μβ, with the best results obtained when the heterocyclic system was closer to the donor moiety
TL;DR: In this paper, a series of trifluoromethylated cyclopenta[b]pyran derivatives were synthesized efficiently from 1,3-cyclopentanedione, arylaldehydes, and ethyl 4,4,4-trifluoro-3-oxobutanoate via one-pot multi-component reaction catalyzed by NH4OAc.
TL;DR: In this article, a simple and facile synthesis of 12-aryl-12 H -indeno[1,2- b ]naphtho[3, 2- e ]pyran-5,11,13-trione derivatives was accomplished via the one-pot condensation of 2-hydroxynaphthalene-1,4-dione, aldehydes, and 2 H-indene- 1,3dione at 100°C under solvent-free conditions in the presence of the solid acid catalyst, poly(4-
TL;DR: In this paper, an organocatalytic cascade reaction of malononitrile and α-substituted chalcones was developed for the synthesis of chiral multisubstitized 2-amino-4 H -pyran derivatives.
Abstract: An organocatalytic cascade reaction of malononitrile and α-substituted chalcones has been developed for the synthesis of chiral multisubstituted 2-amino-4 H -pyran derivatives. A series of chiral primary/tertiary amines and cinchona alkaloids were examined as the catalysts. Quinine was found to be the most efficient catalyst in the absence of any additive. The α-substitutents of the chalcones had a siginificant effect on the yield and the enantioselectivity. A number of multisubstituted 2-amino-4 H -pyrans were obtained in excellent yields and enantioselectivities.
TL;DR: The crystal structure analysis of an active compound along with hydrogen bonding patterns and molecular arrangement present within the molecule is described and some of the compounds synthesized showed selective growth inhibition of cancer cells in vitro.
TL;DR: An organocatalytic construction of optically enriched substituted pyran derivatives via amine-catalyzed Michael addition and subsequent enolization/cyclisation has been described starting from electronically poor alkenes.
TL;DR: Concise synthesis of (-)-epicatechin and its 3-O-gallate is described, illustrating efficacy of the new strategy for catechin-class polyphenols based on assembly of lithiated fluorobenzene and epoxy alcohol followed by a pyran cyclization.
TL;DR: This Pd-catalyzed cross-coupling reaction presents a facile access to alkynyl C-glycosides and sets the stage for a reductive/oxidative refunctionalization of the enyne moiety to regenerate either C- Glycosidic structures or pyran derivatives with a substituent in position 2.
Abstract: Herein, we report on our findings of the Sonogashira–Hagihara reaction with 1-iodinated and 2-brominated glycals using several aromatic and aliphatic alkynes. This Pd-catalyzed cross-coupling reaction presents a facile access to alkynyl C-glycosides and sets the stage for a reductive/oxidative refunctionalization of the enyne moiety to regenerate either C-glycosidic structures or pyran derivatives with a substituent in position 2.