Showing papers on "Benzopyrans published in 1998"

Photochromic 6-aryl substituted 3H-naphtho(2,1-b)pyrans

Abstract: Described are novel photochromic 6-aryl substituted 3H-naphtho[2m1-b]pyran compounds, examples of which are naphthopyran compounds having a substituted aryl group at the number 6 carbon atom and certain substituents at the 3-position of the pyran ring. Certain substituents may also be present at the number 7, 8, 9 or 10 carbon atoms of the compounds. These compounds may be represented by graphic formula (I). Also described are polymeric organic host materials that contain one or more of such compounds or combinations of such compound(s) with complementary photochromic compounds, e.g., other naphthopyrans, benzopyrans and spiro (oxazine) type compounds.

Effect of heteroaromatic annulation with five-membered rings on the photochromism of 2H- [1] -benzopyrans

Abstract: Photochromic properties (colorability, UV-VIS spectra of photo-merocyanines, rate constant of thermal bleaching) of chromenes annulated with different five-membered azaheterocycles or with furan cycles were investigated under flash photolysis. All the compounds, i.e., the 7H-pyrano[2,3-g]benzazoles 4–6, the 7H-pyrano[3,2-e]benzazoles 7–10, the 7H-pyrano[3,2-e]indoles 11–12, the 3H-pyrano[3,2-a]carbazole 13, the 8H-pyrano [2,3-e] indole 14 and the 3H-furano [ 3,2-f]chromenes 15–18 undergo reversible photochromic reaction at room temperature. They are compared with naphthopyranic parents 1–3. Whatever the structure of the heteroaromatic moiety, the annulation of the benzopyrans leads to the splitting into two bands of the electronic absorption spectra of the photoinduced forms with a significant bathochromic shift, a feature of interest for variable optical absorption systems. Unfortunately, diaryl-substituted azolo-fused chromenes exhibit decreased colorabilities. Furofused benzopyrans are particularly interesting with respect to naphthopyran parents owing to the bathochromically shifted and broadened absorption spectra of photoinduced forms and slightly enhanced colorabilities.

Photochromic indeno-fused naphtho [2,1-b] pyrans

Abstract: Described are novel photochromic indeno-fused naphthopyran compounds having certain substituents at the 2-position of the pyran ring and an alkoxy group at the number 6 carbon atom. Certain other substituents may also optionally be present at the number 5, 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 certain novel indeno-fused naphthols which are used to make the novel naphthopyran compounds. Further described are polymeric organic host materials that contain or that are coated with the novel naphthopyran compounds, or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, benzopyrans, and spiro(indoline)type compounds.

A diastereoselective cobalt-mediated synthesis of benzopyrans using a novel variation of an intramolecular Nicholas reaction in the key cyclisation step: optimisation and biological evaluation1

Abstract: A range of novel intramolecular cyclisation reactions between an organocobalt stabilised cation and a trisubstituted alkene have been accomplished that provide a concise route for the diastereoselective synthesis of a range of functionalised benzopyrans. In addition to the usual Lewis acids employed in the Nicholas reaction our studies have identified several other reagents for effecting the cyclisation reaction. In some examples sub-stoichiometric quantities of Lewis acid were successfully employed. These studies were concluded with a biological evaluation of specific derivatives, conducted by comparing their activity with the antihypertensive agent cromakalim 2, a drug whose mode of action is known to occur via the modulation of potassium channel activity.

Recyclization of 2-imino-2H-1-benzopyrans using nucleophilic reagents 3. Reaction of 2-iminocoumarin-3-carboxamides with o-phenylenediamines and o-amino(thio)phenols

Abstract: Using o-phenylenediamines, o-aminophenol or o-aminothiophenol, 2-iminocoumarin-3-carboxamide can be recyclized to the corresponding 3-(1H-benzimidazol-2-yl), 3-(benzoxazol-2-yl), or 3-(benzothiazol-2-yl) coumarins. An alternative synthesis has been carried out and an analytical comparison of the synthetic routes made.

Recyclization of 2-imino-2H-1-benzopyrans under the influence of nucleophilic reagents. 2. Reaction of 2-iminocoumarin-3-carboxamides witho-aminobenzenesulfonamide

Abstract: 2-Iminocoumarin-3-carboxamides recyclized into 3-(1,1-dioxo-2H-benzo-1,2,4-thiadiazinyl-3)coumarins under the Influence ofo-aminobenzenesulfonamide. An alternative method of synthesis is discussed. Proposed mechanisms for the recyclization are discussed.

On the Formation and Reactivity of 2-Alkylidene-benzopyrans and their 2-amino-5,6-benzo-2H-pyran precursors

Abstract: A series of 2-amino-substituted 5,6-benzo-2H-pyrans 14, 2-alkylidene-5,6-benzo-2H-pyrans 15, and their dimers 17 are obtained, depending on the condition used, by the reaction of 2-hydroxy-benzaldehydes 1 with enamines 9 derived of (cyclo)aliphatic ketones. Compounds 14, 15, and 17 can be transformed into 2-alkyl-benzopyrylium salts 16 or 2-[1-(2-hydroxyphenyl)-alken-2-yl]-benzopyrylium salts 23 by treatment with mineral acids. With aromatic aldehydes or the Vilsmeier reagent the compounds 14, 15, or 17 are transformed into deeply colored 2-(aryl-alkenyl)-benzopyrylium perchlorates 25 or 2-(2-dialkylamino)-alkenyl-benzopyrylium salts 26, respectively.

Photochromic pyrano-fused naphthopyrans

Abstract: Described are novel photochromic pyrano-fused naphthopyran compounds, examples of which are naphthopyran compounds having a substituted or unsubstituted 'S' pyran ring, the 3,4 positions of which are fused to the f side of the naphtho portion of the naphthopyran, and certain substituents at the 2-position of the 'T' pyran ring. Certain substituents may also be present at the number 5, 7, 8, 9, 10, 11 or 12 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 or combinations thereof with complementary photochromic compounds, e.g., certain other naphthopyrans, benzopyrans, and spiro(indoline) type compounds.

Benzopyrans. Part 38.1 Reactions of 4-Oxo-4H-1-benzopyran-3-carbaldehyde, -3-carbonitrile and -3-carboxylate with Chloroacetone and a Note on the Stereochemistry of Benzo[b]cyclopropa[e]pyrans

Abstract: The title benzopyranones 1–3 give the benzo[b]furan 7 and the benzo[b]cyclopropa[e]pyrans 8 and 9 with chloroacetone in acetone containing anhydrous potassium carbonate and a catalytic amount of potassium iodide but give the 1-benzopyranones 10, 11 and 14 in dichloromethane in the presence of Brockman neutral alumina, respectively.

Preparation of diaryl-benzopyrans

Abstract: The present invention relates to a process for the preparation of optically active 2,3-diaryl-2H-1-benzopyrans. The compouds are useful in the prevention or treatment of estrogen related diseases or syndromes.

2H-1-Benzopyrans. III. 4-Hydroxy-3-methoxycarbonyl-2-dimethoxyphosphoryl-2H-1-benzopyran

Abstract: The title compound, C 13 H 15 O 7 P, consists of two condensed rings, namely, a pyranoid ring with an axially attached partially disordered dimethoxyphosphoryl group and a benzene ring. The conformation of the pyranoid ring is halfway between half-boat and half-chair, and the fusion of the rings does not exert significant influence on the planarity of the benzene ring.

2-Imino-2H-1-benzopyrans as Versatile Synthons in Heterocyclic Synthesis: Studies on Novel Rearrangements of 3-Substituted 2-Imino-2H-1- benzopyrans Under Action of N-Nucleophiles

Abstract: A new chemoselective approach to synthesis of a series of 3-substituted coumarin derivatives and 6- substituted benzo[4,5]imidazo[1,2-a]quinolines was developed. It was based on novel rearrangements of different 3-substituted 2-imino-2H-1-benzopyrans 1 (2-imino-2H-1-benzopyran-3-carboxamide and 2-imino-3-(1Hbenzoimidazol- 2-yl)-2H-1-benzopyran) under action of N-nucleophiles. By using this methodology, two series of heterocyclic systems were synthesized, namely: i) containing coumarin (2-oxo-2H-1-benzopyran) moiety substituted at C-3 position with different heterocycles such as 4H-1,2,4-triazole (7 and 10), 1,3,4-oxadiazole (8), 1,3,4-thiadiazole (9), 5-oxo-1,4- dihydro-benzo[e][1,2,4]triazepine (12), 1,1-dioxo-2H-benzo[e][1,2,4]thiadiazine (13), 4-oxo-3H-quinazoline (17), 4-oxo-5,6,7,8-tetrahydro-3H-benzo[4,5]thieno[2,3-d]pyrimidine (19), 1H-benzoimidazole (20), benzooxazole (21), benzothiazole (22), and ii) comprising benzo[4,5]imidazo[1,2-a]quinoline backbone substituted at C-6 position with 1Hbenzoimidazole (23) and benzooxazole (24) units. Possible mechanisms of the revealed rearrangements were discussed and this approach is considered to be a new and efficient alternative route to a variety of heterocyclic compounds.

Adventures in Search of New Dyes Absorbing in the Red or Near Infrared Region

Abstract: Unexpected results were obtained when trying to synthesize new long wavelength absorbing methine dyes starting from bridged benzopyrans or bridged aniline derivatives. Thus, by reaction of mineral acids with bridged 2-amino-substituted benzopyrans 21 instead of corresponding bridged benzopyrylium salts 15 dimers of the intermediate bridged 2-alkylidene benzopyrans 22 are formed. Analogously, reaction of the bridged aniline and 1-naphthylamine derivatives 62, 65, 68, and 72 with nitrous acid yields 4-aminophenyl substituted quinolines or quinolinium salts 64, 70, or 74, respectively. Unexpected results also have been obtained in course of the synthesis of 2,4-diamino-thiazoles 36 and 2-amino-selanzoles 41 which, by analogy to the 2-aminosubstituted heterocyclic compound of the general structure 48, are versatile educts for the synthesis of the new methine dyes 50-53 and the azamethine dyes 57 and 58. Their spectral properties are recorded for some representative examples.