Highly potent aminopyridines as Syk kinase inhibitors

A novel class of potent Syk inhibitors has been developed from rational design. Highly potent aminopyridine derivatives bearing a 4-trifluoromethyl-2-pyridyl motif and represented by compound 13b IC50: 0.6 nM were identified. Substitution by a 2-pyrazinyl motif and SAR expansion in position 4 of the central core provided diverse potent non-cytotoxic Syk inhibitors showing nanomolar activity inhibiting human mast cell line LAD2 degranulation.