TRICYCLIC COMPOUNDS AND THEIR USE AS PHOSPHODIESTERASE INHIBITORS

摘要

The present invention is directed to compounds of Formula I: or a pharmaceutically acceptable salt thereof, wherein the substituents A, R1, R2, R3a, R3b, R4a, R4b and n are as defined herein. The inventions also directed to pharmaceutical compositions comprising the compounds, methods of treatment using the compounds and methods of preparing the compounds.