3- Hydroxycoumarin structure

The ultraviolet spectra provide further evidence for the predominance of the hydroxycoumarin structure. The spectra of 4-hydroxycoumarin (20, R = H) and 20 (R = Me) are very similar, indicating that the former exists in the hydroxy form, and this formulation is supported by more recent ultraviolet spectral data." Later, the ultraviolet spectra of 26 (R = H) and 26 (R = Me) were reported to differ, this difference being considered to indicate that 4-hydroxycoumarins exist in a keto form in ethanoP however, this... 

Chemical Name 4-hydroxy-3-(1-phenylpropyl)-2H-1-benzopyran-2-one Common Name 3-(1-phenylpropyl)-4-hydroxycoumarin Structural Formula ... 

Therapeutic Function Anticoagulant, Vitamin K antagonist Chemical Name 3-(Q -acetonyl-p-nitrobenzyl)-4-hydroxycoumarin Common Name Nicoumalone Structural Formula ... 

Hydroxycoumarin (67) was found to react with o-phenylenediamine on refluxing in toluene to give product 69 (Scheme 20). According to the elemental analysis, IR and NMR spectroscopy data, the structure of 4-(2-... 

We also investigated reaction of 4-hydroxycoumarin with an excess of Ar,Ar-dimethylformamide dimethyl acetal (DMFDMA) which afforded the corresponding 3-(dimethylaminomethylene)-chromane-2,4-dione derivative 72. The structure was again confirmed by IR, NMR, and MS analyses. 

Kirkiacharian S, Thuy DT, Sicsic S, Bakhchinian R, Kurkjian R, Tonnaire T (2002) Structure-activity relationships of some 3-substituted-4-hydroxycoumarins as HIV-1 protease inhibitors II. Farmaco 57 703-708... 

Another example of fluorescence intensity modulation in cou-marins is the 3-azido substitution that quenches the fluorescence completely. These compounds are used as starting material for the synthesis of fluorescent triazolocoumarins by click chemistry [31], Interestingly, the fluorescence of some coumarins depends strongly on the solvent. This is the case for 7-alkoxycoumarins that have been used as probes for microenvironments [32], 7-hydroxycoumarin that is pH sensitive, and 7-NR2 substituted coumarins such as coumarin 120 whose quantum yield is reduced in nonpolar solvents due to a change in the 3D structure [33],... 

Scheme 16 3-Alkylated 4-hydroxycoumarins the core structure for various warfarin derivatives...

Scheme 18 Structural similarities between acetylacetonate and 4-hydroxycoumarin...

Coumarinic Acid Compounds. These synthetic phylloquinone derivatives and congeners have been employed as anticoagulants since the isolation of 3,3,-methylenebis(4-hydroxy-2H-l-benzopyran-2-one) [66-76-2] (bis-4-hydroxycoumarin or dicoumarol) (1) from spoiled sweet clover in 1939. The ingestion of the latter was responsible for widespread and extensive death of bovine animals at that time. The parent compound for the synthesis of many congeners is 4-hydrocoumarin, which is synthesized from methyl salicylate by acetylation and internal cydization. The basic structures of these compounds are shown in Figure 2, and their properties listed in Table 6 (see Coumarin). 

The changes in the spectral parameters of hydroxycoumarins brought about by the addition of acids or bases are of value in structural elucidation (60JOC2183, 67JCS(C)2545). For example, both 5- and 7-hydroxycoumarins show red shifts and increases in intensity upon the addition of base, whereas for the 6- and 8-substituted compounds the bathochromic shift is accompanied by a reduction in intensity (69JCS(C)526). Several other additives have proved useful in structure elucidation, notably sodium acetate (66IJC120) and aluminum chloride (69MI22201). ... 

Both direct and heavy-atom methods have been used to determine structures of substituted coumarins. Examples include 4-hydroxycoumarin and its 3-bromo derivative (65AX927, 66AX646) and the 7,8- and 6,7-dihydroxycoumarins, daphnetin and esculetin, respectively <76AX(B)946, 77AX(B)283). In the last compounds, hydrogen bonds link the molecules in the crystal. The stacking distances are comparable to those for other substituted coumarins <75AX(B)1287). A study of the structure of 7-hydroxy-4-methylcoumarin contains... 

The structure of 3-arylazo-4-hydroxycoumarin (246) has been investigated (78IJC(B)295). The authors stated that IR and UV spectral data indicate (246) to exist as such in the solid state and in solution the presence of the other possible tautomers (247) and (248) was discounted. 

Treatment of the acid chloride (401) with sodium azide yields a 4-azidocoumarin (73CR(C)(276)1603) and acid hydrolysis of the carbamate (402) gives 4-hydroxycoumarin indicating that an amino group stabilizes a pyran-4-one structure better than does a hydroxy... 

Thus, with methyl and also ethyl cyanoacetate, the anilinomethylene chromonedione (220) (this form has been found94 to predominate in dimethylsulfoxide solution rather than the tautomeric structure of the formal SchifFs base from 3-formyl-4-hydroxycoumarin and aniline) yields, initially, with potassium hydroxide in DMF, following hydrolysis, the pyronocoumarin 221. 

Enol glycosides which are alkali-sensitive may be divided into three sub-groups (1) glycosides of 4-hydroxycoumarins, (2) glycosides of purines and pyrimidines, and (3) glycosides of simple enols (acetoacetic ester, acetoacetaldehyde). This division is made on the basis of structural differences and the type of alkaline degradation which the compounds undergo. 

Figure 16.2 Typical structures of fluorescent proton sensors (a) hydroxycoumarin, (b) pyra nine, (c) anthracene derivative, (d) perylenebisimide, and (e) fluorescein...

Lactone An organic compound that contains an ester group incorporated into a carbon ring structure. Lactones include the coumarins, e.g. umbelliferone or 7-hydroxycoumarin. Lactones and furocoumarins, e.g. bergaptene, exist in small quantities in essential oils and should be used with care. Lactones can be neurotoxic (poisonous to the nervous system) and cause skin allergies. Bergaptene is well known for its phototoxicity on the skin. 

Oral anticoagulants. Structurally related to vitamin K, 4-hydroxycoumarins act as false vitamin K and prevent regeneration of reduced (active) vitamin K from vitamin K epoxide, hence the synthesis of vitamin K-dependent clotting factors... 

The most frequently used probes for studying of protein structure seem to be ANS, TNS, NPN, 9-aminoacridine, umbelliferone (7-hydroxycoumarin), auramine 0 and dansylchloride and in membranology they are pyren, perylen, AS, AP, ANS and NPN. Among the main criteria for selecting an appropriate probe are the character of the interaction, its polarity and hydrophobicity (Table 10). For details see for example... 

Synonyms Courmadin Hydroxycoumarin Chemical/Pharmaceutical/Other Class A synthetic derivative of 4-hydroxycoumarin, the hemorrhagic component of sweet clover Chemical Formula C19H16O4 Chemical Structure ... 

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