Compounds of formula I in which R1 is methoxy, R2 is methoxy, ethoxy, difluoromethoxy or 2,2-difluoroethoxy, R3 is hydrogen, R31 is hydrogen, R4 is -O-R41, in which R41 is hydrogen, R5 is hydrogen, Har is substituted by R6 and R7, and is pyridinyl, in which R6 is oxo, and R7 is methyl, or an enantiomer, a salt, a N-oxide or a salt of an enantiomer or N-oxide thereof are novel effective PDE4 inhibitors.本發明係有關一種式I化合物，其中R1、R2、R3、R31、R4、R5與Har如本說明書中定義，其係一種新穎有效之PDE4抑制劑。
