Identification of 2,3-disubstituted pyridines as potent, non-emetic PDE4 inhibitors.

A series of 2,3-disubstituted pyridines were synthesized as potential non-emetic PDE4 inhibitors. To decrease brain exposure and minimize emesis, we modified the lipophilic moiety of a series of emetic PDE4 inhibitors and found that introduction of a hydroxy group into the pyridine moiety of the side chain led to non-emetic compounds with preserved PDE4 inhibitory activity. Following optimization at the phenoxy group, we identified compound 1 as a potent non-emetic PDE4 inhibitor.

Identification of 2,3-disubstituted pyridines as potent, orally active PDE4 inhibitors.

A series of 2,3-disubstituted pyridines were synthesized and evaluated for their PDE4 inhibitory activity. We successfully modified undesirable cyano group of initial lead compound 2 to 4-pyridyl group with improvement of in vitro efficacy and optimized the position of nitrogen atoms in pyridine moiety and alkylene linker. The most potent compound showed significant efficacy in animal models of asthma and inflammation.