In the present work, we report a convenient synthesis of 5- and 7-substituted-4-phenyl coumarins. contrast to previous results obtained with 4-alkylcoumarins, nicotinoylation 5,7-dihydroxy-4-phenylcoumarin nicotinoyl benzotriazole or azide selectively provides 5-O protected ester. The combination reaction followed by tosylation-denicotinoylation yields 5-hydroxy-7-tosyloxy-coumarin derivative, ...

Silica sodium carbonate (SSC) has been used as a valuable silica-supported catalyst for the preparation of a range of known and novel pyrano coumarins via the three-component reactions of aryl aldehydes, active methylene compound (malononitrile or ethyl cyanoacetate), and hydroxycoumarin (5,7-dihydroxy-4-substituted coumarins or 4-hydroxycoumarin). The heterogeneous catalyst showed much the sam...

Fractionation of geopropolis from Melipona scutellaris, guided by antiproliferative activity against two colon cancer cell lines (COLO205 and KM12), led to the isolation of two new cinnamic acid esters, mammea-type coumarins 5,7-dihydroxy-6-(3-methyl-2-butenyl)-8-(4-cinnamoyl-3-methyl-1-oxobutyl)-4-propyl-coumarin (1) and 5,7-dihydroxy-6-(4-cinnamoyl-3-methyl-1-oxobutyl)-4-phenylcoumarin (2), a...

Abstract Many coumarin derivatives have good biological activity and application value in fluorescent probes. Therefore, synthetic routes to also attracted the attention of many research groups. In this work, based on Pechmann synthesis method, influence various Lewis acids reaction was discussed, optimal conditions 7-hydroxy-4-substituted coumarins were explored. Based experimental results, a ...

In this article we describe a new methodology for the total synthesis of 3,4-unsubstituted coumarins from commercially available starting materials. Six examples were prepared, including five naturally occurring coumarins--7-hydroxy-6,8-dimethoxy-coumarin (isofraxidin), 7-hydroxy-6-methoxycoumarin (scopoletin), 6,7,8-trimethoxy-coumarin, 6,7-dimethoxycoumarin (scoparone), and 7,8-dihydroxycouma...

Coumarins are secondary metabolites that are widely distributed within the plant kingdom, some of which have been extensively studied for their antioxidant properties. The antioxidant activity of coumarins assayed in the present study was measured by different methods, namely the 1,1-diphenyl-2-picryl-hydrazyl (DPPH(•)) method, cyclic voltammetry and the antioxidant capacity against peroxyl rad...

A number of novel 3-bromo-4-methyl-7-methoxy-8-amino substituted coumarins and 2-substituted 7-bromo-6-methyl-8H-pyrano-benzimidazoles, benzoxazoles and/or benzoxazine-8-ones were synthesized for the purpose of pharmacological evaluation. Some representative compounds showed antitumor activity in vitro on Ehrlich ascites carcinoma in the preliminary testing.

Z. Naturforsch. 55c, 5 2 8 -5 3 3 (2000); received April 5/April 20. 2000 Pelargonium Species, Umckaloabo, Coumarins, Oxygenation Pattern The coumarin patterns of Pelargonium sidoides DC. and Pelargonium reniforme CURT., forming the origin of the herbal medicine “umckaloabo”, were analysed and compared for therapeutic equivalence. For both species, members of triand tetraoxygenated coumarins al...