## str1 ## fused benzo compounds of formula , wherein a is a 2 to 6 membered hydrocarbon spacer group , b is a polar divalent group selected from so , so 2 , and a group ; u is c , n or ch ; x is a divalent 3 - 4 membered chain optionally comprising one or more heteroatoms ; r 1 is an aliphatic hydrocarbon group , arylalkyl or diphenylalkyl ; r 2 and r 3 are hydrogen or alkyl or together form an ethylene or propylene bridge ; r 4 , r 5 and r 6 are hydrogen or substituents ; r 7 and r 8 are hydrogen or substituents including , a group -- coor 9 and a group -- conr 10 r 11 ; are 5 - ht 1a receptor ligands useful in the treatment of cns disorders . pharmaceutical compositions comprising the compounds and their use for the manufacture of a pharmaceutical preparation are also disclosed .