The invention provides JAK kinase inhibitors of Formula Ia, enantiomers, diasteriomers or pharmaceutically acceptable salts thereof, wherein R1, R2, R7 and Z are defined herein, a pharmaceutical composition that includes a compound of Formula Ia and a pharmaceutically acceptable carrier, adjuvant or vehicle, and methods of treating or lessening the severity of a disease or condition responsive to the inhibition of a JAK kinase activity in a patient.