A new method for the synthesis of pyran fused coumarins by 3-bromo-4-hydroxycoumarins as cyclic α-halo ketones based on an organocatalyst assisted three-component tandem reaction is investigated. To the best of our knowledge, cyclic α-halo ketones have not yet been used for the synthesis of pyran fused coumarins.

The chemical constituents of an acetone extract of the stems of Micromelum minutum Wight et Arn (Rutaceae), collected at Nakorn-Rachasima province in Thailand, were studied. Six new coumarins, named micromarin-A (1), -B (2), -C (3), -F (4), -G (5), and -H (6), were isolated along with six known coumarins, and their structures were elucidated by chemical and spectroscopic methods.

Cu-catalyzed A(3) coupling of ethoxyacetylene, pyrrolidine and salicylaldehydes led to a concomitant cycloisomerization followed by hydrolysis of the resultant vinyl ether to afford coumarins in a cascade process. The reaction proceeded through exclusive 6-endo-dig cyclization and is compatible with halo and keto groups giving coumarins in good to moderate yields.

A base-free process to access indole-fused polyheterocycles via a highly efficient and atom-economic palladium-catalyzed intramolecular cross dehydrogenetive coupling (CDC) reaction of 4-aniline substituted coumarins, quinolinones, and pyrones has been developed. A wide range of indolo[3,2-c]coumarins, indolo[3,2-c]quinolinones, and indolo[3,2-c]pyrones can be facilely afforded in good to excel...

Fusion of a pyrone ring with a benzene nucleus gives rise to a class of heterocyclic compounds called Benzopyrones, of which two distinct types are recognized: (1) benzo-α-pyrone commomly called coumarins and (2) benzo-Υ-pyrone called chromones or flavanoids, latter differing from former only in the position of the carbonyl group in heterocyclic system. Coumarins have attracted considerable att...

BACKGROUND The benefit and risk of oral anticoagulation in dialysis patients are debated controversially. METHODS We prospectively followed 235 dialysis patients of the INVOR Study (Study of Incident Dialysis Patients in Vorarlberg) for up to 7 years and analysed the prevalence and incidence of atrial fibrillation (AF) and the impact of coumarin therapy on survival. Oral anticoagulation was m...

The Authors have studied the capacity to photoreact with native DNA and r-RNA using six coumarins and four 4',5'-dihydro-furo-coumarins. Six of these substances have shown a definite photoreactivity both with DNA and r-RNA, even if in a very much lower extent in respect to that of skin-photosensitizing furocoumarins. The low capacity to photoreact with nucleic acids of these substances is discu...

The generation of a small and representative library of 3,5,8-trisubstituted coumarins (21 compounds, 7 families, 3 groups) is described. The library was built from the corresponding propargyl vinyl ethers and three different 1,3-dicarbonyl derivatives using a one-pot coupled domino strategy. These coumarins constitute a novel chemotype defined by the presence of a chemical handle in the pyrano...