7-Methoxy 4-methyl coumarin

Abbreviations CEC 3-cyano-7-ethoxycoumarin EEC 7-ethoxy-4-trifluoro-methyl-coumarin DBE Dibenzylfluorescein 7-MEC 7-methoxy-4-trifluoro-methyl-coumarin AMMC 3-[2-(N,N-diethyl-N-methylamino)ethyl]-7-methoxy-4-methyl-coumarin 7-BQ 7-Benzyloxoquinone. 

Methyl radical loss from [3-methylbenzofuran]t gives a minor peak at m/e 77. In contrast, expulsion of a methyl radical from the [M-CO]t ion derived from 7-methoxy-4-methyl-coumarin is facile. Deuterium labelling experiments confirmed that the methoxy methyl group is preferentially eliminated (66JCS(C)1712). 

The compounds chosen for the transformation studies, namely 7-methoxy 4-methyl coumarin(III), 7-ethoxy 4-methyl coumarin(IV), 7-butoxy 4-methyl coumarin(V), 7-o-benzyloxy 4-methyl coumarin(VI) and 7-acetoxy 4-methyl coumarin(VII) (Fig. 2), were synthesized following classical chemical methods. Their purity was tested using TLC and their identity was confirmed by comparing their melting points and UV data, as shown in Table I, with literature cited values. 

Cinnamic acids can be created from the methylation of coumarins. Methoxy substituted coumarins produce lower yields than do non-substituted and hydroxy substituted coumarins. 

In general, the a SCS are similar to those of corresponding 1- and 2-substituted naphthalenes (20, 49, 70-72). There are only a few exceptions. For example, the a-methyl effect in 7-methyl-coumarin is considerably larger than for all other isomers (11.2 vs. 8.3-9.7 ppm) (20). Despite the similarity of the a-hydroxy effects in 4-hydroxycoumarin and 1-naphthol (22.4 and 23.4 ppm, respectively), the corresponding methoxy effects are quite different (22.6 and 27.6 ppm, respectively). In 6-cyano- and 7-nitrocoumarin the a SCS are smaller by ca. 3 ppm than in 2 cyano- and 2-nitro-naphthalene. Again, there is no satisfactory explanation. 

Esculetin, umbeUiferone (7-hydroxycoumarin) and 7-hydroxy-4-methyl coumarin are strong xanthine oxidase inhibitors (Chang and Chiang 1995). The structure of 7-hydroxy coumarin plays a very important role in xanthine oxidase inhibition, the 6-hydroxy group present in the molecule of 7-hydroxy coumarin, e.g. esculetin enhanced the activity, whereas substitution by the 6-methoxy group, e.g. scopoletin (formula [47]), reduced the inhibitory effect. (Chang and Chiang 1995). 

Coumarin, 4-methyl-7-methoxy-mass spectra, 3, 608 Coumarin, 4-methylsulfonylmethyl-synthesis, 3, 805 Coumarin, nitro-reduction, 3, 691 Coumarin, 3-nitro methylation, 3, 682 Coumarin, 3-phenoxy-synthesis, 3, 807... 

The nOe difference measurements not only help in stereochemical assignments but also provide connectivity information. A large nOe at 8 6.91 (G-8H), resulting from the irradiation of the methyl singlet of the methoxy group (8 3.94), confirms their proximity in space. This nOe result is consistent with structure A for the coumarin. 

The vanillin ethers 36 and 39 exhibited the IR band of the lactone carbonyl group at 1710-1720 cm whereas the aldehydic carbonyl stretching was observed in the range of 1680-1690 cm In the NMR spectra all the protons resonated at expected fields. The aldehydic proton appeared downfield around 9-10 aromatic protons in the range of 7-8 and the C3 - H of coumarin around 6.5. The methylene, methoxy, and methyl protons resonated around 5, 3.8, and 2.2, S respectively. 

Formation of mixtures of the above type, which is common with internal olefins, do not occur with many functionalized alkenes. Thus, tertiary cinnamates and cinnamides undergo cycloadditions with benzonitrile oxides to give the 5-Ph and 4-Ph regioisomers in a 25-30 75-70 ratio. This result is in contrast to that obtained when methyl cinnamate was used as the dipolarophile (177). 1,3-Dipolar cycloaddition of nitrile oxides to ethyl o -hydroxycinnamate proceeds regiose-lectively to afford the corresponding ethyl fra s-3-aryl-4,5-dihydro-5-(2-hydro-xyphenyl)-4-isoxazolecarboxylates 36 (178). Reaction of 4-[( )-(2-ethoxycarbo-nylvinyl)] coumarin with acetonitrile oxide gives 37 (R = Me) and 38 in 73% and 3% yields, respectively, while reaction of the same dipolarophile with 4-methoxy-benzonitrile oxide affords only 37 (R = 4-MeOCr>H4) (85%) (179). 

Dihydro- 7 -methoxy-2S, 3 R -dimethyl-2-[4-methyl-5-(4-methyl-2-furyl)-3(E)-pentenyl]-furo[3,2-C]coumarin Rt AOSO... 

To design a supercritical fluid extraction process for the separation of bioactive substances from natural products, a quantitative knowledge of phase equilibria between target biosolutes and solvent is necessary. The solubility of bioactive coumarin and its various derivatives (i.e., hydroxy-, methyl-, and methoxy-derivatives) in SCCO2 were measured at 308.15-328.15 K and 10-30 MPa. Also, the pure physical properties such as normal boiling point, critical constants, acentric factor, molar volume, and standard vapor pressure for coumarin and its derivatives were estimated. By this estimated information, the measured solubilities were quantitatively correlated by an approximate lattice equation of state (Yoo et al., 1997). 

Bromination of a methyl group in a pyran-2-one is a useful first step to a number of derivatives, for example 4-methoxy-6-(l-propenyl)pyran-2-one (329) (74JOC3615). NBS monobrominates methyl groups only on the benzene ring of coumarins and nuclear bromination has not been observed (47CR937). 

Wittig reagents, which are formed in situ from ethyl 2-chloroacetate and triphenylphosphine, react with salicylal-dehydes under solvent-free conditions to afford coumarins in high yield (Equation 278) <2003PS501>. Methyl 2-hydroxybenzoate reacts with keteneylidene(triphenyl)phosphorane 685 to yield 4-methoxy coumarin, via formation of the ylide intermediate 686 (Scheme 166) <1996J(P1)2799>. 

The high diastereoselective synthesis of multifunctionalized 3,4-dihydro-coumarins bearing a quaternary stereocenter was developed through tandem Michael additions of indole and its derivatives (1-methyl, 2-methyl, 4-methoxy, 5-methoxy, 5-bromo, 6-benzyloxy) to 3-nitrocoumarines (3-nitro-chromen-2-one, 6- and 7-methyl-3-nitro-chromen-2-one) followed by methyl vinyl ketone in a one-pot step. For the tandem Michael additions, after the first Michael reaction of indole (2) with 3-nitrocoumarine (51) catalyzed... 

The direct irradiation of the parent coumarin in the presence of alkenes results only in an inefficient photodimerization and [2 + 2]-photocycloaddition. Lewis acid coordination appears to increase the singlet state lifetime, and leads to improved yields in the stereospecific [2 + 2]-photocycloaddition [95]. Alternatively, triplet sensitization can be employed to facilitate a [2 + 2]-photocycloaddition. Yields of intramolecular [2 + 2]-photocycloadditions remain, however, even with electron-rich alkenes in the medium range at best. The preference for HT addition and for formation of the exo-product is in line with mechanistic considerations discussed earlier for other triplet [2 + 2]-photocycloadditions [96, 97]. Substituted coumarins were found to react more efficiently than the parent compound, even under conditions of direct irradiation. 3-Substituted coumarins, for example, 3-methoxy-carbonylcoumarin [98], are most useful and have been exploited extensively. The reaction of 3-ethoxycarbonylcoumarin (100) with 3-methyl-l-butene yielded cleanly the cyclobutane 101 (Scheme 6.36) with a pronounced preference for the exo-product (d.r. = 91/9). Product 101 underwent a ring-opening/ring-closure sequence upon treatment with dimethylsulfoxonium methylide to generate a tetrahydrodibenzofur-an, which was further converted into the natural product ( )-linderol A (102) [99]. 

A comparison of the solid state photochemistry of two crystals, 7-methoxycoumarin and methyl m-bromo-cinnamate, further exemplifies the importance of the existence of free volume near the reaction site (Sch. 15) [127-129], In spite of the fact that the reactive double bonds are rotated by 65° with respect to each other and a center-to-center double-bond distance of 3.83 A (Fig. 16), photodimerization occurs in crystals of 7-methoxy-coumarin to give the syn head-to-tail isomer (Sch. 15). On the other hand, methyl m-bromo-cinnamate, which also has a nonideal arrangement of the... 

Evaluation for chemical constituents in open-pollinated seedling progenies of C. cassia accessions from Calicut (India) showed that these contained 1.20. 95% bark oil, 6.0-10.5% bark oleoresin and 0.40-1.65% leaf oil. The principal component of both the oils, namely, cinnamaldehyde, varied from 40.7-86.0 and61.9-91.5%, respectively, in leaf and bark oils (Krishnamoorthy et al., 1999). The bark oil of C. cassia from the Yunnan province was dominated by cinnamaldehyde (80.40-88.50%) (Li et al., 1998). The bark oil from China recorded 65.5% E-cinnamalde-hyde, 8.7% coumarin, 3.6% cinnamyl acetate and 2.7% 2-methoxy cinnamaldehyde as chief components, whereas in the Australian oil, cinnamaldehyde (87%), benzaldehyde (4.7%), 2-phenyl ethanol (2.5%) and 3-phenyl pro-panal (2%) predominated (Vernin et al., 1990). Li and Yuan (1999) reported cassia oil from China containing 67.12% E-cinnamaldohydo, 6.17% methyl salicylate, E-2-melhoxy cinnamaldehyde (7.40%) and -cinnamyl acetate (3.47%) as major components. 

The substitution pattern of TfOH-mediated electrophilic aminomethylation of psoralens (furo-coumarins) by V-(hydroxymethyl)phthalimide has been elucidated <85JHC73>. Multiple phthal-imidoylated adducts were obtained when a B-ring hydroxy or methoxy activating group was present, and these resisted simple cleavage with NH2NH2. However, this two-step procedure to aminomethyl group introduction worked well when the psoralens contained only methyl substituents. 

Monosubstituted Analogs Xie et al. synthesized a series of monosub-stituted derivatives at the coumarin 3,4, 5, and 6 positions. The data in Table 9-2 show that mono-methyl substitution at the 3, 4, or 5 position (51, 53, and 59) greatly increased potency in comparison with 2. 3- and 4-Methoxy DCK analogs (52 and 54) showed slightly less potency whereas 5-methoxy DCK (60) retained activity. However, although methylation or methoxylation at the 3, 4, and 5 positions did not affect the antiviral activity of DCK analogs, these same substitutions at... 

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