Showing papers on "Benzopyrans published in 2009"
TL;DR: The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters is described and experimental evidence supports a mechanism proceeding via the generation of a stabilized carbocation from an allylic oxonium intermediate and subsequent trapping by a chiral allylgold(I) spieces.
Abstract: The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters is described. The (R)-MeO-DTBM-BIPHEP(AuCl)2-catalyzed reactions allow for the construction of benzopyrans containing quaternary stereocenters with excellent enantioselectivity. Experimental evidence supports a mechanism proceeding via the generation of a stabilized carbocation from an allylic oxonium intermediate and subsequent trapping by a chiral allylgold(I) spieces.
147 citations
TL;DR: A new recyclable temperature-dependant phase-separation system comprised of PEG-1000-based dicationic acidic ionic liquid and toluene was developed and used in one-pot three-component condensation to prepare benzopyrans in excellent yields.
102 citations
TL;DR: The results revealed that the reaction does not significantly depend on the electronic effects of substituents in the aromatic ring bonded to the chalcogen atom of the electrophilic chalCogen species, and the cyclization efficiency was significantly influenced by the steric effects of aromatic ring.
Abstract: We herein described the synthesis of various organochalcogen propargyl aryl ethers via reaction of lithium acetylide intermediate with electrophilic chalcogen (sulfur, selenium, tellurium) species....
56 citations
TL;DR: In this paper, the synthesis of free aldehyde functionalities of 2,3,5,7-tetrasubstituted benzofurans was investigated.
45 citations
TL;DR: A novel photoswitchable benzopyran-based ω-amino acid 6 for Fmoc-based solid-phase peptide synthesis is presented and the photochromic behaviour of the 3-cyano-substituted benzopyrs 5a was investigated by time-resolved absorption spectroscopy in the picosecond time domain.
Abstract: Photochromic pyrans for applications in material and life sciences were synthesized via palladium-mediated cyanation, carbonylation and Sonogashira cross-coupling starting from bromo-substituted naphthopyran 1 and benzopyrans 2a/b. A novel photoswitchable benzopyran-based ω-amino acid 6 for Fmoc-based solid-phase peptide synthesis is presented. The photochromic behaviour of the 3-cyano-substituted benzopyran 5a was investigated by time-resolved absorption spectroscopy in the picosecond time domain.
16 citations
14 citations
TL;DR: In this article, a carbanion-olefin intramolecular 6-endo-trig cyclization reaction was used to provide 2-aroyl-3,4-dihydro-2H-benzopyrans.
12 citations
TL;DR: In this paper, photochromic spiro[indoline-benzopyrans] containing 4,5-diphenyloxazolyl group at position 8 of the benzopyran fragment have been obtained.
Abstract: Photochromic spiro[indoline-benzopyrans] containing 4,5-diphenyloxazolyl group at position 8 of the benzopyran fragment have been obtained. New diphenyloxazolyl-substituted spiropyrans manifest considerably higher thermal stability of the merocyanine isomers than their naphthopyran analogs.
8 citations
TL;DR: Treatment of 2-C-hydroxymethyl-D-glycals with phenols in trifluoroacetic acid at ambient temperature leads to an extremely facile transformation affording chiral pyrano[2,3-b]benzopyrans in high yields.
8 citations
TL;DR: C3-Pyridyl-containing TPs may represent a novel synthetic class of microtubule de-stabilizing anti-cancer drugs that inhibit macromolecule synthesis, tubulin polymerization, and the proliferation of a spectrum of wild-type and multi-drug resistant tumor cell lines in vitro.
Abstract: A class of substituted 1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano[4,3-b][1]benzopyrans (tricyclic pyrones; TPs) was synthesized from a one-pot condensation reaction of 6-substituted 4-hydroxy-2-pyrones and cyclohexenecarboxaldehydes. The reaction involves a 6pi-electrocyclic ring closing process, and stereo- and regioselectivities were examined. C3-Pyridyl-containing TPs may represent a novel synthetic class of microtubule de-stabilizing anti-cancer drugs that inhibit macromolecule synthesis, tubulin polymerization, and the proliferation of a spectrum of wild-type and multi-drug resistant tumor cell lines in vitro. A linear skeleton with a N-containing aromatic ring attached at C3 of the top A-ring, a central pyran B-ring and a six-membered bottom C-ring with no alkylation at C7 are required for the antitumor activities of the lead compounds, a 3-pyridyl benzopyran (code name H10) and its 2-pyridyl regioisomer (code name H19). In addition to interacting with the colchicine-binding site to inhibit tubulin polymerization and increase the mitotic index, these TP analogs also block the cellular transport of nucleosides to inhibit DNA synthesis more effectively than other antimitotic agents. The anticancer potential of TPs in vivo is suggested by the fact that i.p. injections of H10 decrease the growth of solid tumors in mice inoculated with lung or ovarian carcinomas. A drug-delivery system involving nanogels was studied. We incorporated the anticancer compound, 6-hydroxymethyl-1,4-anthracenedione (code name AQ10) into PEG-PEI nanogel, and found that AQ10-encapsulated nanogel PEG-PEI is significantly more effective in altering the growth of Pan 02 (pancreatic cancer) cells compared to AQ10 or nanogel PEG-PEI alone. Since AQ10 is insoluble in water, PEG-PEI encapsulation represents a way to solubilize and deliver this as well as other poorly soluble compounds.
6 citations
TL;DR: The enantioselective synthesis of 2-isopropenyl-2,3-dihydrobenzofurans, 4-methylbut-3-en-2- ols, 2-hydroxymethylchromans, and 4-chroman was achieved using Sharpless asymmetric epoxida- tion-derived enantiomerically enriched epoxy alcohols as chiral building blocks.
Abstract: The enantioselective synthesis of 2-isopropenyl-2,3-dihydrobenzofurans, 4-(2,3-dihydrobenzofuran-2-yl)-2-methylbut-3-en-2- ols, 2-hydroxymethylchromans, and 4-chroman-2-yl-2-methyl-but-3-en-2-ols has been achieved using Sharpless asymmetric epoxida- tion-derived enantiomerically enriched epoxy alcohols as chiral building blocks. A phenolate ion-mediated intramolecular epoxide ring opening reaction was the key step for every cyclization reaction.
TL;DR: The Suzuki cross-coupling reaction of 3-iodo-4-chalcogen-2 H -benzopyran derivatives with a variety of organoboron compounds in the presence of catalytic amount of palladium salt is described in this paper.
TL;DR: In this article, a series of approaches for synthesis of 2-(coumarin-3-yl)-3H-quinazolin-4-thiones were evaluated.
Journal Article•
TL;DR: The phototransformations of 2-thienyl-3-cycloalkenyloxy benzopyrans in benzene lead to fused spirocyclic compounds bearing thiophene ring system as discussed by the authors.
Patent•
04 Mar 2009
TL;DR: In this paper, a pharmaceutical composition for inhibiting oxidative stress comprises a 2-methyl-2'-hydroxymethyl-6-amidobenzopyran derivative represented by the formula 1.
Abstract: A pharmaceutical composition for inhibiting oxidative stress is provided to treat Alzheimer's diseases and cerebral apoplexy by using a 2-methyl-2'-hydroxymethyl-6-amidobenzopyran derivative and its salts. A pharmaceutical composition for inhibiting oxidative stress comprises a 2-methyl-2'-hydroxymethyl-6-amidobenzopyran derivative represented by the formula 1. A method for manufacturing the 2-methyl-2'-hydroxymethyl-6-amidobenzopyran derivative consists of the following steps of manufacturing a 6-amino benzopyran derivative represented by the formula 3 by reducing a 6-nitrobenzopyran derivative represented by the formula 2 with 1.0-3.0 mole equivalent of reductant.
Journal Article•
TL;DR: The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters was described in this article, where the (R)-MeO-DTBM-BIPHEP(AuCl)2-catalyzed reactions allow for the construction of benzopyrans containing quaternary stereocenters with excellent enantioselectivity.
Abstract: The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters is described. The (R)-MeO-DTBM-BIPHEP(AuCl)2-catalyzed reactions allow for the construction of benzopyrans containing quaternary stereocenters with excellent enantioselectivity. Experimental evidence supports a mechanism proceeding via the generation of a stabilized carbocation from an allylic oxonium intermediate and subsequent trapping by a chiral allylgold(I) spieces.
TL;DR: In this article, the synthesis of various organochalcogen propargyl aryl ethers via reaction of lithium acetylide intermediate with electrophilic chalinogen (sulfur, selenium, tellurium) species was described.
Abstract: We herein described the synthesis of various organochalcogen propargyl aryl ethers via reaction of lithium acetylide intermediate with electrophilic chalcogen (sulfur, selenium, tellurium) species....