The 5-(ethoxymethylene)-4-thioxothiazolidin-2-ones 2a-c were synthesized and reacted with acrylonitrile. ethyl acrylate. ß-nitrostyrene. N-phenylmaleimide and malononitrile under different conditions. to yield the cycloaddition products 3-14. The antibacterial and antifungal activities of the new products were tested.Reaktionen mit 5-Ethoxymethylenthiazolidin-2,4-dion-Derivaten und ihre biologische Wirksamkeit Die 5-Ethoxymethylen-4-thioxo-2-one 2a-c wurden synthetisiert und mit Acrylnitril, Ethylacrylat. ß-Nitrostyrol. N-Phenylmaleinsäureimid und Malonodinitril unter verschiedenen Bedingungen umgesetzt. Die Wirkungen der neuen Verbindungen gegen Bakterien und Pilze wurde geprüft.As apart of our studies directed towards the synthesis of new compounds of biological potentialities, comaining thiopyrano-thiazole ring system 1-)1, we report here the results of cycloaddition of some dienophiles with the ethoxymethylene derivatives of 4-thioxo-thiazolidine-2-ones.The 5-ethoxymethylene derivatives 2a-c were synthesized by the reaction of 2-thiazolidinone-4-thiones la-c with ethylorthoformate in acetic anhydride.Treatment of the coloured 2a-c with acrylonitrile in toluene at room tempo afforded the colourless 1: 1 adducts 3a-c. Structure 3 was established from elemental and IR data. Besides, the 1 H -NMR data of 3c can be interpreted in terms of 6-cyano-3-phenyl-7 -ethoxy-5,6-dihydrothiopyranoI2,3-dl-thiazolidin-2-one. The formation of the adduct 3c is a conclusive evidence for 2 + 4 cycloaddition rather than N-cyanoethylation re action represented by structure 4.On the other hand, when the above re action was carried out in refluxing acetic acid, 5a-c were obtained via ethoxy group elimination. Similar ethoxy group elimination has been reported by acid treatment 4l . Moreover. when 3a-c were refluxed in acetic acid, 5a-c were obtained.
We propose an alternative approach that does not rely on tensor models for characterizing diffusion anisotropy from diffusion-weighted magnetic resonance images. Information content inherent in the diffusion attenuation values are the only measures needed for our characterization. We explore the information content inherent in these values. We calculate Shannon's entropy on the diffusion attenuation values measured across the applied diffusion-sensitizing gradient directions. This method is evaluated with data generated with different diffusion gradient encoding schemes demonstrating the validity of our approach and its potential use to better differentiate between brain tissue types over tensor-based measures.
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