2-Amino-6-furan-2-yl-4-substituted nicotinonitriles as A2A adenosine receptor antagonists.

A2A adenosine receptor antagonists usually have bi- or tricyclic N aromatic systems with varying substitution patterns to achieve desired receptor affinity and selectivity. Using a pharmacophore model designed by overlap of nonxanthine type of previously known A2A antagonists, we synthesized a new class of compounds having a 2-amino nicotinonitrile core moiety. From our data, we conclude that the presence of at least one furan group rather than phenyl is beneficial for high affinity on the A2A adenosine receptor. Compounds 39 (LUF6050) and 44 (LUF6080) of the series had Ki values of 1.4 and 1.0 nM, respectively, with reasonable selectivity toward the other adenosine receptor subtypes, A1, A2B, and A3. The high affinity of 44 was corroborated in a cAMP second messenger assay, yielding subnanomolar potency for this compound.