The present invention relates to a compound formula [I]: ##STR1##

wherein ##STR2##

Y is bond, —O—(CH₂)_n— (in which n is 1, 2, 3 or 4), etc.,

Z is cyano, tetrazolyl, etc.,

R¹ is hydrogen, lower alkyl, etc.,

R² is hydrogen or an amino protective group,

R³ is hydrogen or lower alkyl,

R⁴ is hydrogen or lower alkyl,

R⁵ and R⁸ are each independently hydrogen, halogen, hydroxy, lower alkyl, etc.,

R⁶ is hydrogen, lower alkyl, etc.,

R⁹ is hydrogen or lower alkyl, and

i is 1 or 2,

or a salt thereof. The compound [I] of the present invention and pharmaceutically acceptable salts thereof are useful for the prophylactic and/or the therapeutic treatment of pollakiurea or urinary incontinence.