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Six new compounds including four tyrosine derivatives ( 1 – 4 ), and two hydantoin derivatives ( 5 – 6 ) were obtained from the investigation of the endophytic fungus Phoma herbarum PSU-H256, which was isolated from a leaf of Hevea brasiliensis . Their structures were determined by analysis of spectroscopic data, especially 1D and 2D NMR. The relative configurations were assigned using NOEDIFF data while the absolute configurations were established by comparison of the optical rotations and circular dichroism data with those of structurally related compounds. [ABSTRACT FROM AUTHOR]

An unexpected reaction between 4-phenylurazole and fumaric esters which led to the formation of 5-alkylidene derivatives of hydantoin is described in this paper. The reaction takes place in the presence of tetrabutylammonium bromide (TBAB), and 1,4-diaza-bicyclo[2,2,2]octane (DABCO) at 70 °C under solvent-free conditions. [ABSTRACT FROM AUTHOR]

Abstract: The potential of α-amino nitrile-derived ureas for the synthesis of imidazolidin-2-one derivatives has been studied in the context of a medicinal chemistry project focused on the search of antagonists of the thrombin receptor PAR1. In this study α-amino nitrile-derived ureas have shown chameleonic reactivity. Thus, under neutral, basic or mild acid media they cyclize to 4-iminoimidazolidin-2-one derivatives, which tautomerize to 4-amino-2,3-dihydro-1H-imidazol-2-ones. This tautomerism triggers epimerization at the C5 of the imidazolidine ring, as well as its oxidation. However, they give stable highly functionalized hydantoin derivatives under strong acid media, by a no-epimerizing two-step hydrolysis. [Copyright &y& Elsevier]