Showing papers on "Benzopyrans published in 1997"

A One-Pot Condensation of Pyrones and Enals. Synthesis of 1H,7H-5a,6,8,9-Tetrahydro-1-oxopyrano[4,3-b][1]benzopyrans

Abstract: Condensation of various 6-substituted 4-hydroxypyrones 1 with 1-cyclohexenecarboxaldehydes in the presence of l-proline in ethyl acetate gave high yields of substituted 1H,7H-5a,6,8,9-tetrahydro-1-oxopyrano[4,3-b][1]benzopyrans. The reaction presumably occurs via the 1,2-addition of the pyrone with the aldehyde followed by dehydration and then cyclization through a 6Π electrocyclic process. A remarkable asymmetric induction was obtained from a stereogenic center (C4) of the cyclohexenecarboxaldehyde [such as (S)-perillaldehyde] to provide only the C5a,7-trans tricyclic pyrone products. On the other hand, condensation of 3-(formyloxy)- or 3-hydroxy-2-methyl-1-cyclohexenecarboxaldehydes with pyrones 1 gave mixtures of C5a,6−cis and -trans products. Several of the tricyclic pyrones strongly inhibit acetylcholinesterase activity, DNA synthesis, and tumor cell growth in vitro.

Amberlyst 15 Catalyzed Prenylation of Phenols: One-Step Synthesis of Benzopyrans

Abstract: A convenient one-step synthesis of 2,2-dimethylchromans and chromenes using Amberlyst 15 as a catalyst is described.

Novel photochromic indeno-fused naphthopyrans

Abstract: Described are novel photochromic indeno-fused naphthopyran compounds, examples of which are naphthopyran compounds having a substituted or unsubstituted indeno group, the 2,1 positions of which are fused to the f side of the naphtho portion of the naphthopyran, and having certain substituents at the 3-position of the pyran ring. Certain substituents may also be present at the number 5, 6, 7, 8, 9, 10, 11, 12 or 13 carbon atoms of the compounds. These compounds may be represented by graphic formula (I). Also described are polymeric organic host materials that contain or that are coated with such compounds. Optically clear articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel naphthopyran compounds or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, benzopyrans and spiro(indoline)type compounds, are also described.

Antitumor activity of novel tricyclic pyrone analogs in murine leukemia cells in vitro.

Abstract: New tricyclic pyrone derivatives were synthesized and tested for their ability to prevent L1210 leukemic cells from synthesizing DNA and growing in vitro. At 50 microM, a pyripyropene analog has no effect, whereas four pentahydro-3-aryl-1-oxopyrano[4,3-b][1]benzopyrans all inhibit DNA synthesis by 79-91% and tumor cell growth by 93-100%. These inhibitory effects are concentration dependent with IC50 around 8.5 microM for DNA synthesis at 2 hours and 1.1 microM for tumor cell growth at 4 days. The aryl groups of these antitumor agents are either 3,4-dimethoxyphenyl or 3-pyridyl. Introduction of a methyl group at C5a and a formyloxy or hydroxy group at C6 does not alter the antitumor effects of the 3,4-dimethoxyphenyl benzopyrans but reduces those of the 3-pyridyl benzopyrans, which, at 50 microM, inhibit DNA synthesis by only 32-49% and fail to alter tumor cell growth. The 4-hydroxy-6-(3-pyridyl)-2-pyrone has no effect and the tricyclic pyrones lacking aryl groups have very little inhibitory effects on DNA synthesis, suggesting that a greater conjugation is required for the antitumor activity. These molecules have never been reported and might be valuable to develop a new class of anticancer drugs.

Benzofurans and benzopyrans as cytoprotective agents

Abstract: Methods for treating inflammnatory pathologies are disclosed. Particularly, the methods utilize pharmaceutical compositions containing certain compounds having an anti-inflanumatory and anti-oxidant moiety covalently linked by thiol or sulfoxide or sulfone bond. The compounds are useflil in preventing and treating inflammatory disorders through several mechanisms.

2-adamantyl benzopyrans, the compositions and (co)polymer matrices containing them

Abstract: The present invention has for subjects, novel benzopyran derivatives, substituted in position 2 with an adamantyl group as well as the compositions and (co)polymer matrices containing such derivatives. Said derivatives possess interesting photochromic properties.

Structure-Property Relationship of Heterofused Benzopyran

Abstract: A series of photochromic diaryl benzopyrans fused with benzofuran have been prepared and tested for photochromic performance The four isomeric hydroxydibenzofurans were coupled with (un)substituted 1,1-diphenyl propargyl alcohols The resulting photochromic products show bathochromic shifts in the UV and broad bands in the visible spectra compared to 2,2-diaryl benzopyrans (2,2-diarylchromenes) It has also been found that the position of the benzofuran fusion has a profound effect on the visible spectrum and fade rate In addition to structure-property relationships, the synthesis of these compounds is discussed

Benzofurans and benzopyrans as chronobiological agents

Abstract: Formula (Ⅰ) compound and pharmaceutically acceptable solvates thereof, in which may be the same or different R

Herbicidal compositions containing pyrido-anellated 4-oxo-4h-benzopyrans as antidotes, using them and process for preparing the compounds

Abstract: Pyrido-fused 4-oxo-4H-benzopyrans I I (m=0, 1 or 2; R1, R6 and R7 have the meanings stated in the description) and the salts of I, and herbicides which contain 2-(4-hetaryloxy)- and 2-(4-aryloxy)-phenoxyacetic acid derivatives or cyclohexenone derivatives as herbicidal active ingredients and pyrido-fused 4-oxo-4H-benzopyrans I' as antidotes.

A Convenient Synthesis of 6‐Substituted‐2,2‐dimethyl‐2H‐1‐benzopyrans.

Abstract: Various 2,2-dimethyl-6-functional-2H-1-benzopyrans were prepared via a halogen-metal exchange reaction followed by treatment with electrophiles. These 6-functionalized chromenes are important synthetic intermediates for preparation of benzopyran-based potassium channel openers.

A simple approach to the synthesis of 2H-1-benzopyrans and 3H-naphtho[2,1-b] pyran via intramolecular wittig reactiont

Abstract: In the presence of K2CO3, 2-hydroxyethyltripheny phosphonium bromide (1) reacts with substituted salicylaldehyde (2) and 2-hydroxy-1 naphthaldehyde (4) at 110 °C in a sealed tube. The title compounds were prepared in medium yield. The ratio of bromide (1) to aldehyde derivatives was also discussed in this paper.

A Facile Synthesis of Angularly‐Fused 3,4,4a,10b‐Tetrahydro‐2H,5H‐ pyrano(3,2‐c) (1)benzopyrans by the One‐Pot Condensation Between Salicylaldehydes and Unsaturated Alcohols.

Abstract: Salicylaldehydes reacted with 5-methyl-4-hexen-1-ol (4a) or 6-methyl-5-hepten-2-ol (4b) in benzene in the presence of trimethyl orthoformate and a catalytic amount of p-toluenesulfonic acid at rt to give angularly-fused trans-5,5-dimethyl-3,4,4a,10b-tetrahydro-2H,5H-pyrano[3,2-c][1]benzopyrans (6) in high yields with complete stereoselectivity.

Furo-Fused 2H-Chromenes: Synthesis and Photochromic Properties.

Abstract: New photochromic chromenes annulated with a furan ring have been synthesized. Thus, suitable heterocyclic phenols react with different propargylic alcohols in acidic medium to give the corresponding ethers, which cyclize into benzopyrans by thermal Claisen rearrangement. This synthetic approach was found to lead to a mixture of linear and angular chromenes that is strictly related to the nature of the phenol. However, regiospecificity could be obtained by reacting β-phenylcinnamaldehyde, in refluxing aprotic nonpolar solvents, with titanium(IV) salts of the former phenols. Electrocyclization of intermediately generated o-quinoid structures occurs on the α position towards the heterocyclic junction. All compounds exhibit photochromic behavior at room temperature. Furo-fused benzopyrans are particularly interesting with respect to naphthopyran parents in view of the bathochromically shifted and broadened absorption spectra of photoinduced forms. This trend is confirmed by the spectral data of several hetero...