Synthesis and Selected Transformations of New 2-Aminopyridine Derivatives Based on Furan-2(5H)-ones

Compounds with gamma-lactone fragments, as well as derivatives of 2-aminopyridines and 2-aminopyridons, are biologically active, and some of them are used as drugs. The condensed combination of gamma-lactones with 2-aminopyridones, such as the natural alkaloid cerpegin, has a wider spectrum of biological activities. Here we combined gamma-lactone and 2-aminopyridine derivatives into one molecule via a single bond. A series of such compounds were synthesized in high yields through the transformations of unsaturated furan-2(5H)-ones. Interestingly, only two of the obtained compounds underwent intermolecular cyclization and led to new isoquinoline derivatives with skeletons similar to the "proton sponges".