The present invention is directed to compounds of formula I-V and tautomers thereof or pharmaceutically acceptable salts, esters, and prodrugs thereof which are inhibitors of syk kinase. The present invention is also directed to intermediates used in making such compounds, the preparation of such a compound, pharmaceutical compositions containing such a compound, methods of inhibition syk kinase activity, methods of inhibition the platelet aggregation, and methods to prevent or treat a number of conditions mediated at least in part by syk kinase activity, such as undesired thrombosis and Non Hodgkin's Lymphoma.