Coumarin 4-hydroxy-3-phenyl

It is known that certain coumarins are transformed into 5-(2-hydroxy-phenyl)-3H-pyrazol-3-ones by reaction with hydrazines [10]. Upon appUca-tion of this method, the expected pyrazolones 25 were synthesized starting from 3-nitrocoumarins [11] as known in (Scheme 6). 

Fig. 1. A generalized scheme showing the kinds of secondary products that arise from the aromatic amino acids in higher plants. Several similarities are found in fungi and bacteria some fungi produce alkaloids ftom tryptophan and lignin-like materials from phenylalanine. Plant pathogenic fungi produce cinnamate and para and meta hydroxy phenyl-acetate from phenylalanine. Certain bacteria produce antibiotics and fluorescent pigments from metabolites in the shikimate pathway. Microorganisms are not known to produce coumarin, substituted coumarins, flavonoids and isoflavonoids.

The experiments are performed on polycarbonate films with high optical quality that are prepared as follows. Commercially available 2,2-bis(4-hydroxy phenyl)propane-polycar-bonate granulate (Bayer, m=. S g) and coumarin 6 (m = 120 mg) are dissolved in tri-chloromethane V = 10 ml). The solution is carefully spread over a cellulose acetate sheet with a thickness of 200 pm. After drying a film of about 3 pm results with a dye concentration of 0.3 M. The thin film is detached from the cellulose acetate substrate and used as a free standing film. 

Coumarin, 7-amino-7-(diethylamino)-, I, 333 Coumarin, 7-amino-4-methyl-fluorescence spectra, 3, 601 Coumarin, 7-amino-3-phenyl-brightening agents, I, 339 Coumarin, 4-aryl-occurrence, 3, 677 synthesis, 3, 810 Coumarin, 3-arylazo-4-hydroxy-structure, 3, 643 Coumarin, 3-bromo-reactions... 

It is notable that flavone and its derivatives are substituted predominantly in the phenyl group at positions 3 and 4 whereas reaction with Fenton s reagent gives mainly the S-hydroxy isomer." " Similarly, comparison of the distribution of products from coumarin obtained with Udenfriend s system with that given by Fenton s reagent re-... 

Hydroxyphenol, see Hydroquinone p-Hydroxyphenol, see Hydroquinone 4-Hydroxy-3-(l-phenyl-3-oxobutyl)coumarin, see Warfarin 1 -Hydroxypropane, see 1 -Propanol 3 Hydroxypropene, see Allyl alcohol 3 Hydroxypropionic acid lactone, see p-Propiolactone... 

Deacetylation of 4-[(o-acetoxy)benzylidene]-2-phenyl-5(47/)-oxazolone also immediately affords 602. The starting oxazolone was obtained by cyclodehydration of the corresponding cinnamic acid precursor or by condensation of hippuric acid with 2-acetoxybenzaldehyde in the absence of base. In examples using 2-hydroxy-acetophenone, 4-methyl-3-(acylamino)coumarins are obtained. ... 

A very simple synthesis of coumestrol (228) has been described by Kappe and coworkers (Scheme 46) (74ZN(B)292). It is based upon dehydrogenation of 4-hydroxy-3-phenyl-coumarins to coumestans (720PP233). A number of 2 -hydroxy 3-phenylcoumarins were oxidized with lead tetraacetate to the corresponding coumestans 3-(l-acetoxy-4-methoxy-2-oxo-3,5-cyclohexadienyl)coumarins were obtained as by-products (76BCJ1955). Coumes-tan itself (226) has been obtained by photolysis of the phenol ether (232), which is in turn available from 4-hydroxycoumarin (229) and (diacetoxyiodo)benzene (Scheme 47) (78CB3857) via an iodonium ylide (231). 

The reaction is somewhat less involved for 4-hydroxy-3-phenyl-coumarin tetra-0-acetyl-/3-D-glucopyranoside (LII).20 Since one of the products of methanolysis is methyl a-D-glucopyranoside (XLVIII), it is obvious that inversion of configuration has occurred, and that the oxygen-glucosyl bond was cleaved. These facts are rationalized if the controlling... 

A tellurium-triggered cyclization of methyl 2-(2-bromoacetoxy)benzoates 671 affords 4-hydroxy coumarins in good yield (Scheme 160) <2005JOC4682>. Similarly, the tellurium-triggered cyclization of 2-formyl and 2-acetyl-phenyl 2-bromoacetates 672 provides coumarins (Equation 271) <2005JOC4682>. 

In the presence of acetic acid and pyridine, 5-phenyl- or 5- eri-butyl-3-methylthio-l,2-dithiolium ions have been reacted with cyanoacetone to give, in the usual way, an a-(l,2-dithiol-3-ylidene) ketone. A similar reaction has been observed with 4-hydroxy-6-methylpyran-2-one and with 4-hydroxy-coumarin (Eq. 23). In the same way, 4-hydroxy-6-methylchromene-2-thione and 3-methylthio-5-phenyl-l,2-dithiolium cation gave the fused trithiapentalene 59. ... 

PHENYL-l-ACETYL-2 ETHYD-3-HYDROXY-4 COUMARINE (French) (81-81-2)... 

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