O-Hydroxycinnamic acid

Coumarin, the lactone of o-hydroxycinnamic acid, and some of its derivatives have been isolated from many plant species 31). Thimann and Bonner 141) attributed the growth-inhibiting effects of coumarin to its action on enzyme sulfhydryl groups. Inhibitory effects of coumarin on Avena coleoptiles and pea stem sections could be overcome by 2,3-dimercaptopropanol (BAL). Coumarin has also been reported to disrupt mitosis 29,30). 

The course of the reaction has not been fully clarified. Hydrolytic and aromatization processes are probably responsible for the formation of colored or fluorescent deriva4 tives (cf. Potassium Hydroxide Reagent). For instance, sevin is converted to a-naphthalkali metal salt of the o-hydroxycinnamic acid pro- duced by hydrolytic cleavage of the pyrone ring is converted from the non-fluorescent cis- to the fluorescent trans-form by the action of long-wavelength UV light (X = 365 nm) [2]. 

Figure 2. Linear regression plot of root growth inhibition of tomato and radish seedlings by o and -hydroxyphenyl) acids. o-Hydroxycinnamic acid, (o-hydroxyphenyl) acetic acid ( ) melilotic acid, 2-(o-hydroxyphenyl) butanoic acid ( ) o-hydroxy-benzoic acid, ( -hydroxypheny 1 )acetic acid (0) -hydroxycinnamic acid, =hydroxybenzoic acid, 3-( -hydroxyphenyl) propanoic acid (X) o-coumaryl glucoside, water control (----) (1 ). ...

Coumarins are lactones of o-hydroxycinnamic acids in which side chains often are isoprenoid (78). Coumarin, esculin, and psoralen (a furanocoumarin) all strongly inhibit seed germination. Such inhibitors are produced by a variety of legumes and cereal grains. 

Roll, R. Bar, F. (1967) [Effect of coumarin (o-hydroxycinnamic acid-lactone) on pregnant female mice.] Arzneim.-Forsch., 17, 97-100 (in German)... 

The excited states (108a-108c) have been proposed as the species responsible for the fluorescence of 7-hydroxy-4-methylcoumarin at various acidities (74JA4699). In strongly alkaline solution, the coumarin is hydrolyzed to an o-hydroxycinnamic acid which emits at 500 nm (70MI22201). However, a detailed study of several 7-hydroxycoumarin derivatives indicated that complex fluorescence spectra were obtained when aqueous solvents were used (77JCS(P2)262). 

Coumarin is formed from acetic anhydride and salicylaldehyde in the presence of triethylamine as the base catalyst. It is the lactone of the (Z)-form of o-hydroxycinnamic acid some of the ( )-isomer in the form of its acetyl derivative (o-acetoxycinnamic acid) is also obtained (Expt 6.138). 

The reaction involves a spontaneous cyclisation of o-hydroxycinnamic acid obtained by a Perkin reaction using triethylamine as the base catalyst (Expt 6.138). 

Major simple phenylpropanoids include cinnamic acid (Phe-CH=CH-COOH), j6-coumaric. acid (jfr-hydroxycinnamic acid), o-coumaric acid (o-hydroxycinnamic acid), caffeic... 

SYNS 2H-1-BENZOPYRAN-2-ONE 1,2-BENZO-PYRONE cis-o-COUiMARINIC ACID LACTONE COUMARINIC ANHYDRIDE o-HYDROXYCINNAMIC ACID LACTONE o-HYDROXYZIMTSAEURE-LACTON (GERMAN) NCI-C60297 2-OXO-l,2-BENZOPYRAN RATTEX TONKA BE.YN CAMPHOR... 

C9H7N04 m-nitrocinnamic acid, predominantly trans 555-68-(T 25.00 1.3674 2 16225 C9H803 o-hydroxycinnamic acid, predominantly trans 614-60-8 25.00 1.2467 2... 

Coumarins are 1,2-benzopyrones that are derived from the phenylpropanoid pathway however, major details of their biosynthesis are still largely unknown.187 Coumarins can also be produced, through the cleavage of meliotoside (the /3-glucopyranoside of o-hydroxycinnamic acid) in dead plant material, or hay, where in the... 

H.83) 2-Propenoic acid, 3-(2-hydroxyphenyl)-, 3-( 2-hydroxyphenyl)prop-2-enoic acid, o-hydroxycinnamic acid, o-coumaric acid 583-17-5] ( )- 614-60-8] (Z)- [495-79-4]... 

Derivatives of benzo-a-pyrone such as coumarin, Fig. (48) (the lactone of o-hydroxycinnamic acid) are common in plants both in the free state and as glycosides. Not all are phenolic but they are included here with the phenolic derivatives for convenience. Some 1000 natural coumarins have been isolated. Coumarin Fig. (48) itself has been found in about 150 species belonging to over 30 different families, although it is probably present in the undamaged plant as mmv-o-glucosylcinnamic acid. 

Ring-compounds are also readily formed from ortho derivatives of benzene. Thus, o-hydroxycinnamic acid loses water and passes into coumarin, a constituent of tonka beans, which is used in the preparation of perfumery and as an adulterant in vanilla extract —... 

Hydroxide ions open the lactone ring of coumarin forming the dianion of the (Z)-o-hydroxycinnamic acid 3 (coumarinic acid) which recylizes to coumarin when acid is added. The dianion 3 can be stabilized as the (2)-methoxy ester 5 by methylation with dimethyl sulfate. However, in prolonged reaction, it changes into the -compound 4 ... 

Cottonseed oil, winterized. See Cottonseed (Gossypium) oil Coumadin. See Warfarin 2-Coumarate. See o-Hydroxycinnamic acid Coumaric acid. See Coumarin 2-Coumaric acid o-Coumaric acid. See o-Hydroxycinnamic acid cis-o-Coumaric acid lactone. See Coumarin Coumarin... 

Synonyms 1-Benzopyran-2-one 2H-1-Benzopyran-2-one 2H-1-Benzopyran, 2-oxo- Benzopyrone 1,2-Benzopyrone Benzo-a-pyrone Chromen-2-one Cinnamic acid, o-hydroxy-, 5-lactone Coumaric acid cis-o-Coumaric acid lactone cis-o-Coumarinic acid lactone Coumarinic anhydride Cumarin o-Hydroxycinnamic acid lactone o-Hydroxycinnamic acid 5-lactone o-Hydroxycinnamic lactone 2-Oxo-1,2-benzopyran 2-Propenoic acid, 3-(2-hydroxyphenyl)-5-lactone Tonka bean camphor... 

See o-Hydroxycinnamic acid 2-Propenoic acid, 3-(2-hydroxyphenyl)-5-lactone. SeeCoumarin... 

Diethyl maleate Formaldehyde o-Hydroxycinnamic acid 1-(2-Hydroxy-3-sulfopropyl) pyridinium betaine Levulinic acid... 

Two mechanisms can be envisioned for the Pechmann condensation (1) acid-catalyzed transesterification of the P-keto ester followed by acid-catalyzed cyclodehydration of the resulting aryl acetoacetate (4), or (2) acid-catalyzed Friedel-Crafts-like phenol alkylation ortho to the phenolic hydroxyl group) followed by intramolecular transesterification/cyclization of the resulting o-hydroxycinnamic acid ester (5). 

The intermediacy of o-hydroxycinnamic acid esters (5) in the Pechmann condensation was first proposed by Pechmann in 1884. In 1932, Robertson and co-workers provided support for this proposal through their examination of the reactions of w-methylanisole and dimethylresorcinol with ethyl acetoacetate under the conditions of the Pechmann condensation. Allowing these anisoles to stand with ethyl acetoacetate in sulfuric acid resulted in the formation of 4,7-dimethylcoumarin and 7-methoxy-4-methylcoumarin, respectively. 3 -(2-Methoxy-4-methylphenyl)-2-butenoic acid could likewise be converted to 4,7-dimethylcoumarin under similar conditions. These observations revealed cinnamate intermediates such as 5 to be viable intermediates in the Pechmann condensation and demonstrated that the formation of aryl acetoacetate intermediates such as 4 is not required for coumarin formation. 

Other Names Coumarin 1,2-Benzopyrone 2-Propenoic acid, 3-(2-hydroxyphenyl)-, 8-lactone 5,6-Benzo-2-pyrone Benzo-a-pyrone Coumarinic anhydride NSC 8774 Rattex Tonka bean camphor cis-o-Coumarinic acid lactone o-Hydroxycinnamic acid lactone CA Index Name 2H-l-Benzopyran-2-one CAS Registry Number 91-64-5 Merck Index Number 2562 Chemical Structure... 

Coumarins are lactones that are formally derived from o-hydroxycinnamic acids by ring closure between the phenol and carboxyl groups. The chemistry of natu-... 

Coumarin, together with o-hydroxycinnamic acid and other compounds, has been reported in wood and barks of infected stems of Prunus yedoensis (60). The simple coumarins (Table 7.1.3.A) vary in their substitution of the aromatic ring. Prenylation (i.e., dimethylallyl substitution) also contributes to the great diversity. Umbelliferone (26), aesculetin (27), and scopoletin (28) corresponding in structure to j9-coumaric, caffeic, and ferulic acid - and various types of derivatives, are the three most common hydroxycoumarins in plants, including many species... 

Another group of related phenylpropanoids are the coumarins. These compounds are believed to result from the lactonisation of cw-o-hydroxycinnamic acid derivatives. Coumarin itself is widely distributed in plants and is the lactone of cw-o-hydroxycinnamic acid. 

---