Pyran 4//-benzo

Chemical Name 4-Hydroxy-a-(4-hydroxy-2-oxo-2H-1-benzopyran-3-yl)-2-oxo-2H-1-benzo-pyran-3-acetic acid ethyl ester... 

The same substrate (451) and 4-phenylhydrazono-3,4-dihydro-2//-l-benzo-pyran-2,3-dione (454) [prepared from the dione (452) with benzenediazo-nium chloride] gave 3-(o-hydroxy-a-phenyUiydrazonobenzyl)-2(l//)-quinox-alinone (455) (EtOH-AcOH, reflux, 90 min 80%). ... 

New rearrangements of 2-imino-2//-l-benzopyran-3-carboxamides under the action of anthranilic acid as an N-nucleophile have been revealed. Depending on the conditions 2-(2-oxo-2//-l-benzopyran-2-yl)-3//-quinazolin-4-ones or 2-oxo-2//-l-benzo-pyran-3-((V-2-carboxyphenyl)carboxamides were found to be the products. 

Dihydro-5,7-dihydroxy-4-oxo-4H-l-benzo- pyran-2-yl)-2,3-dihydroxyphenyl]-5,7-dihydroxy- 2-(4-hydroxyphenyl)-4//-l-benzopyran-4-one 2,3-Dihydro-5 -hydroxyamentoflavone... 

Almost every class of natural phenolic compounds contains examples of substances with a 2,2-dialkylchromene ring, and the number of those that are discovered increases every year. It would be difficult to give an exhaustive list of these compounds. Their chemistry will be discussed here only when it is related to some particular behavior of the benzo-pyran ring. Examples include simple chromenes substituted in the aromatic ring,3,4,35-44 benzodipyrans,3,39 dimers of chromenes,45 naphthopyrans,46,47 quinones,48 flavones,49 flavonols,49 chalcones,49 flavanones,49 isoflavonoids,50 rotenoids,50 pterocarpans,50 couma-rins,17,51-53 3-arvl-4-hydroxycouniarins,50 4-phenylcoumarins,54 chroma-... 

The aromaticity obtained by means of the DE values and their differences in the single pseudoazulene systems are also the result of calculations of the bond orders (Fig. 1). The calculated bond alternations46 57-77-79-82-117118-129 are in line with the heteroaromaticity of the systems. Similar relationships were calculated for azulene.219 The extent of the bond alternation, however, differs from one system to the other (see Fig. 1). In indeno[2.1-f>]-l-benzo-pyran (44a) the bond lengths of the central cyclo[fo]pyran system indicate pronounced bond alternation, and in the opinion of the authors, the systems have little aromatic character.129 Calculations with 1 //-pyrindines (26) and 2//-pyrindines (29) show that 26 is more stable than 29, but both are less aromatic than indole.63 A comparison of SCF calculations for pseudoazulenes 26 and 29 with their aza analogs 68 and 69-73, which contain a pyrrole-type nitrogen, shows only minor perturbations of carbon-carbon bond lengths on replacing a =CH— moiety by =N—.66... 

Fig. 5 Smart UV-responsive coating on silica nanoparticles with PNIPAM brushes functionalized with FRET donors, 4-(2-acryloyloxyethylamino)-7-nitro-2,l,3-benzoxadiazole (NBDAE), and photoswitchable acceptors, l -(2-methacryloxyethyl)-3, 3 -dimethyl-6-nitro-spiro(2//-l-benzo-pyran-2,2 -indoline) (SPMA). The UV radiation induces the change from colorless spiropyran derivatives in the outer part of the coating (7) to the fluorescent merocyanine form (2). Thus, FRET with the benzoxadiazole moieties in the inner part of the coating is enabled and the fluorescence color changes from green to red. By variation of the temperature and induction of a collapse of the PNIPAM chains (3), the FRET efficiency can be tuned (4). Reprinted, with permission, from [70], Copyright (2009) American Chemical Society...

The synthesis of 2,4-diarylchromen-2-ols through the reaction of phenols with an excess of a chalcone in TFA involves sequential Friedel-Crafts alkylation, cyclisation to a 4/7-1-benzo-pyran, an intermolecular hydrogen transfer generates the 4-arylflavylium ion which is hydrated to give the final product (Scheme 12) <07JOC9383>. 

H-2,3-Benzodiazepin 1,4-Dihydr-oxy-8-nitro- E9d, 358 (1,3-Dioxo - 3,4-H2 — 1 H-2-benzo-pyran/N2H4)... 

The a-methyl derivative is produced from the acetate of o-allylphenol, HOC4H6CHjCH= CHj, by the addition of hydrogen bromide in the absence of peroxides followed by dehydrohalogenation of the free phenol with potassium hydroxide. In the presence of air or peroxides the mode of addition of hydrogen bromide is reversed and cyclization gives benzo-pyran. /3-Keto derivatives ate prepared by a similar ring closure. ... 

Synonyms 3-[3-(4 -Bromo[l,l -biphenyl]-4-yl)-3-hydroxy-1 -phenylpropyl] -4-hydroxy-2i4-1 -benzo-pyran-2-one... 

K. Matsui and S. Yoshida, Photochromic film of 6-nitro-l, 3, 3 -trimethylspiro-[2/f-l-benzo-pyran-2,2 -indoline] prepared by plasma polymerization, J. Appl. Phys. 64, 2607-2610 (1988). 

S. M. Aldoshin and L. O. Atovmyan, Crystal and molecular structure of the photochemical product of transformation of T-pentyl-3, 3 -dimethyl-6-nitro-8-bromospiro(indoline-2,2 -[2//-l]-benzo-pyran), Izv. Akad. NaukSSSR, Ser. Khim. 1985, 2016-2023. 

Following their first experiments devoted to 6-nitro-BIPS,17 Takahashi and co-workers conducted a series of nanosecond TR3 studies24-28 on a limited number of photochromic compounds, namely r,3, 3-trimethylspiro[2ff-l-benzo-pyran-2,2 -indoline] (BIPS), 6-nitro-BIPS, and spirobibenzopyran (SBP) (Scheme 4). This work was undertaken to elucidate the electronic distribution of the metastable photomerocyanines (ort/jo-quinoidal or zwitterionic) and the number of stereoisomers involved in the photochromic process. Therefore, the effects of temperature, solvent, laser excitation wavelengths, and isotopic substitutions (I3C and, 5N) on the resonance Raman spectra were intensively studied to clarify the photochromic mechanism in the compounds investigated. 

Hydroxyaryl)-3-phenylcyclopropenones underwent thermal transformation to give benzo-pyrans 1 and benzofurans 2. ... 

So far, the occurrence of seven polycyclic musks has been reported. Their chemical names, chemical structures and molecular formulae are described elsewhere (Rimkus, 1999). The structural feature of all polycyclic musks is an indane or tetraline skeleton, which is highly substituted mainly by methyl groups (Fig. 1). 7-Acetyl-l,l,3,4,4,6-hexamethyl-l,2,3,4-tetrahydronaphthalene (AHTN, trade name Tonalide) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzo-pyrane (HHCB, trade name Galaxolide) are the most abundant ones. In this study, also 4-acetyl-1,1 -dimethyl-6-fert-butylindane (ADBI, trade name Celestolide) and 6-acetyl-l,l,2,3,3,5-hexamethylindane (AHMI, AHDI, trade name Phantolide) are investigated (Fig. 1). Important physicochemical properties of these compounds, which determine their environmental distribution and transport (e.g. solubility), are presented in chapter 4.1.1, in Ricking et al. (2003) as well as in Simonich et al. (2000). 

Coumarin-3 carboxylic Acid 2-Oxo-2H-I benzo-pyran-3-carbojeytic acid, mol wt 190.15. C... 

Hexahydro4,6,6,7,8,8-hexamethylcyclopenta-y-2-benzo-pyran. Cyclopenta(g)-2-benzopyran, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl- EINECS 214-946-9 Galaxolide Hexahydrohexamethyl cyclopentabenzopyran. 

Methylbut-2-enyl)oxy]-7H-furo[3,2-g][1]benzo-pyran-7-one. AI3-61725 Ammidin 5-Benzofuranacryllc acid, 6-hydroxy-7-((3-methyl-2-butenyl)oxy)-, 8-lactone CCRIS 4346 EINECS 207-581-1 7H-Furo(3,2-g)(1)benzopyran-7-one, 9-((3-methyl-2-butenyl)oxy)- HSDB 3497 6-Hydroxy-7-(3-methyl-2-butenyioxy)-5-benzofuranacrylic acid ro-lactone 8-lsoamylenoxypsoralen 8-Isopentenyl-oxypsoralene Imperatorin Marmelosin 9-((3-methyl-2-butenyl)oxy)-9-(3-Methylbut-2-enyloxy)-7H-furo(3,2-g)-chromen-7-one 9-((3-Methyl-2-butenyl)oxy)-7H-furo(3,2-g)(1)benzopyran-7-... 

Interestingly, no regioselectivity is observed in the irradiation of 2H,SH-thiopyrano[3,2-g]benzo-pyran-2,8-dione in the presence of 2,3-dimethylbut-2-ene, as 50% of a 4 1 mixture of cis- and fra/is-fused monocycloadducts at the... 

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