Compounds of Formula I: are HIV reverse transcriptase inhibitors, wherein R1, R2, RE, L, M and Z are defined herein. The compounds of Formula I and their pharmaceutically acceptable salts are useful in the inhibition of HIV reverse transcriptase, the prophylaxis and treatment of infection by HIV and in the prophylaxis, delay in the onset or progression, and treatment of AIDS. The compounds and their salts can be employed as ingredients in pharmaceutical compositions, optionally in combination with other antivirals, immunomodulators, antibiotics or vaccines.本發明係關於式I化合物:其為HIV反轉錄酶抑制劑,其中R1、R2、RE、L、M及Z如本文所定義。式I化合物及其醫藥學上可接受之鹽適用於抑制HIV反轉錄酶,預防及治療HIV感染,及預防、延遲AIDS發作或發展,及治療AIDS。該等化合物及其鹽可視情況與其他抗病毒劑、免疫調節劑、抗生素或疫苗組合用作醫藥組合物中之成分。