Chemistry of 4-Oxo-4H-1-benzopyran-3-carbonitrile

Rearrangements of N-alkyl-/aryl-nitrones derived from 4-oxo-4H-1-benzopyran-3-carboxaldehyde––a solvent-dependent process

Synthesis of 3-alkenyl-2-arylchromones and 2,3-dialkenylchromones via acid-catalysed retro-Michael ring opening of 3-acylchroman-4-ones

Seagrass meadows perform essential ecosystem functions and services. Though the meadows are globally deteriorating, numerous regressions remain unreported as a result of data fragmentation. Cymodocea nodosa is the most important seagrass in shallow coastal waters of the Canary Islands. No study has so far investigated temporal population trends at the entire archipelago scale. Using data collected in the past 23 years by local companies, public authorities and research groups, the population trends of Cymodocea nodosa were analysed over the past two decades at the scales of islands, island sectors and meadows. During this period, a prevalence of negative trends was revealed for three seagrass demographic descriptors (seagrass shoot density, coverage and leaf length) at the three scales, evidencing an overall deterioration in seagrass meadow integrity. These results suggest the need to develop correct management strategies to guarantee the conservation of this seagrass and the meadows it creates.

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Trends of the seagrass Cymodocea nodosa (Magnoliophyta) in the Canary Islands: population changes in the last two decades

We report here the synthesis of newly coumarinic derivatives by using 4-hydroxy coumarine as starting material. These newly compounds were screened in vitro for their antimicrobial and antifungal activities. The structures of the synthesized compounds were proved by IR, 1 H NMR, 13 C NMR and mass-spectral.

4-Hydroxy Coumarine: a Versatile Reagent for the Synthesis of Heterocyclic and Vanillin Ether Coumarins with Biological Activities

The enamine (2), prepared from the title benzopyranone (1; R2= H, Me, and Ph) and dimethylformamide dimethyl acetal, on treatment with ammonia and hydroxylamine gives the fused pyridine (5) and pyridine 2-oxide (10), respectively. Hydrazine, phenylhydrazine, and guanidine undergo initial 1,6-addition to the enamine (2) ultimately giving the pyrazoles (14) and (15), and the pyrimidine (17), respectively. The pyridinioacetamidate (11), prepared from the enamine (2; R2= Me and Ph) and acetohydrazide, thermolyses to the fused pyridine (5). A refluxing ethanolic solution of the enamine (2; R2= Me and Ph) with ethyl glycinate forms the ester (18) which on treatment with ethanolic sodium ethoxide produces the azepine (20).

Benzopyrans. Part 23. Nitrogen heterocycles fused with or linked to 1-benzopyran from 3-acyl-2-methyl-1-benzopyran-4-one

Article de synthese couvrant la litterature correspondant au volume 103 des Chemical Abstracts

J. Maiti

Papers

Benzopyrans. Part 23. Nitrogen heterocycles fused with or linked to 1-benzopyran from 3-acyl-2-methyl-1-benzopyran-4-one

Heterocycles fused with the 2,3-bond of [1]benzopyran

Benzopyrans. Part 23. Nitrogen Heterocycles Fused with or Linked to 1-Benzopyran from 3-Acyl-2-methyl-1-benzopyran-4-one.

Heterocycles Fused with the 2,3-Bond of (1)Benzopyran