In this study, we report on pyrazin-2(1H)-ones as lead for the development of potent adenosine triphosphate (ATP) competitive protein kinase inhibitors with implications as anti-cancer drugs. Initially, we identified the pyrazin-2(1H)-one scaffold from hamacanthins (deep sea marine sponge alkaloids) by Molecular Modeling studies as core binding motif in the ATP pocket of receptor tyrosine kinases (RTK), which are validated drug targets for the treatment of various neoplastic diseases. Structure-based design studies on a human RTK member PDGFR (platelet-derived growth factor receptor) suggested a straight forward lead optimization strategy. Accordingly, we focused on a Medicinal Chemistry project to develop pyrazin-2(1H)-ones as optimized PDGFR binders. In order to reveal Structure-Activity-Relationships (SAR), we established a flexible synthetic route via microwave mediated ring closure to asymmetric 3,5-substituted pyrazin-2(1H)-ones and produced a set of novel compounds. Herein, we identified highly potent PDGFR binders with IC50 values in an enzymatic assay below µM range, and possessing significant activity against PDGFR dependent cancer cells. Thus, marine hamacanthin-derived pyrazin-2(1H)-ones showing interesting properties as lead for their further development towards potent PDGFR-inhibitors.
In this study we report on a flexible straight forward synthesis toward novel 3,5-diaryl-(1H)-pyrazin-2-ones. Our synthetic strategy involved an acyclic di-keto derivative as key intermediate. The final pyrazin-2-one ring closure reaction was yield-optimized by using a microwave mediated procedure and ammoniumacetate as nitrogen source. Our method is a suitable alternative to palladium-catalyzed coupling reactions for the 3,5-diaryl decoration of the (1H)-pyrazin-2-one scaffold. Since the (1H)-pyrazin-2-ones is present as scaffold in a number of biologically active compounds the reported synthetic platform is a useful approach to generate a set of highly diverse 3,5-diaryl-(1H)-pyrazin-2-one compounds. (C) 2013 Elsevier Ltd. All rights reserved.