Biomedical subjects
Publications and source records attributed to J H van Maarseveen.
[reaction: see text] The first examples of ring-closing metathesis reactions of olefin-containing enamides using ruthenium-based catalysts have been demonstrated. A preliminary investigation into the scope and limitations, leading to protected five- and six-membered cyclic enamides, will be presented.
The design and synthesis of an orally active LMW non-peptide GPIIb/IIIa antagonist, based on a N,N'-bisphenylpiperazine scaffold, is described. The optimal compound showed a high in vitro binding potency (pIC50 = 8.7) in combination with potent oral antithrombotic activity (30-40% inhibition of thrombus growth at 0.3-3 mg/kg) with a duration of action of > 90 min. in a hamster cheek pouch model.
For the solid phase preparation of various (pharmacologically important) heterocycles, cyclization/cleavage (C/C) or cyclorelease strategies proved to be superior. CC approaches take utmost advantage of the benefits of solid phase synthesis. Besides the practical benefits of solid phase reactions, cyclative release approaches are distinguished especially because of the generally found high purity of the final detached products, since only the anticipated structures cleave off the resin. Also cyclization/cleavage strategies are "traceless", as the obtained moiety after cyclization is part of the formed heterocycle. Over the last thirty years numerous approaches towards important heterocycle classes have been published. Among the successfully applied strategies are carbon-nitrogen (sulfur) bond, carbon-oxygen bond, sulfur-sulfur bond and carbon-carbon forming reactions in the final cyclorelease step.
In a search for the minimum pharmacophore of the naturally occurring tetracyclic eudistomins, five structural analogues (4-8) were evaluated for their in vitro antiviral and tumor cell antiproliferative activities. For the synthesis of these derivatives both intra- and intermolecular Pictet-Spengler reactions have been used. Opening of the beta-carboline annulated 7-membered D-ring in 6 and 7 resulted in a complete loss of activity. On the other hand, replacement of either the oxygen atom or the sulfur atom in the 7-membered ring by a methylene group in 5 and 8, respectively, is allowed. These results combined with previous SAR data underline the crucial importance of the D-ring in eudistomins as a scaffold for the correct positioning of both basic nitrogen atoms. Also bioisosteric replacement of the bicyclic indole system with a dimethoxyphenyl group, to give the isoquinoline skeleton, is allowed. The tricyclic isoquinoline derivative 4 is, so far, the most promising antiviral analogue; it combines a high potency (MIC at 100 ng/ mL (340 nM)) with high MCC/MIC ratios (ranging from 1000 to 5000 against HSV-1, HSV-2, vaccinia virus, and vesicular stomatitis virus.