A series of 3, 5-disubstituted-1, 2, 4-oxadiazoles has been prepared and evaluated for phosphodiesterase inhibition (PDE4B2). Among the prepared 3, 5-disubstituted-1, 2, 4- oxadiazoles, compound 9a is the most potent inhibitor (PDE4B2 IC50= 5.28 lM). Structure– activity relationship studies of 3, 5-disubstituted-1, 2, 4-oxadiazoles revealed that substituents 3-cyclopentyloxy-4-methoxyphenyl group at 3-position and cyclic ring bearing ...