Table 1. SAR of the Hinge Binding Group.

compd	X	Y	Z	CDK8 enzyme IC50 (nM)	CDK19 enzyme IC50 (nM)
3	NH	CH	CH	2	7
4	NH	N	CH	178	214
5	NH	CH	N	10	5
6	S	CH	CH	206	a

^aNot determined.