Design, synthesis and structure–activity relationships of a series of 9-substituted adenine derivatives as selective phosphodiesterase type-4 inhibitors
Adenine derivatives substituted in position 9 have been demonstrated to have potent cyclic nucleotide phosphodiesterase (PDE) inhibition properties with high selectivity toward PDE-4. Starting from our initial lead compound 9-(2-fluorobenzyl)-N(6)-methyl-2-trifluoromethyladenine (4, NCS613), we designed and synthesized a new series of 9-substituted derivatives for developing structure-activity relationship