Compounds of Formula (00A) and salts thereof, wherein R1, R2R3, R4andnare defined herein, are useful as inhibitors of one or more Janus kinases. Also provided are pharmaceutical compositions that include a compound of Formula (00A) 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 Janus kinase activity in a patient.本發明揭示式(00A)之化合物及其鹽,其中R1、R2、R3、R4及n在本文中定義,適用作一或多種傑納斯激酶(Janus kinase)之抑制劑。亦提供包括式(00A)之化合物及醫藥學上可接受之載劑、佐劑或媒劑之醫藥組合物以及治療或減輕患者中對抑制傑納斯激酶活性起反應之疾病或病況之嚴重性的方法。