Compounds of formula (I):
wherein A is S or O; R is H; Ar is an optionally substituted phenyl group; X is an optionally substituted phenyl group, a C
1
-C
4
alkyl, a C
3
-C
6
cycloalkyl group or a CH
2
(C
3
-C
6
cycloalkyl) group; R′ is H or C
1
-C
4
alkyl; and each R
1
is independently H or C
1
-C
4
alkyl; and pharmaceutically acceptable salts thereof are selective inhibitors of norepinephrine reuptake.