and pyrrolyl groups each optionally substituted by from 1 to 3 preferably 1 to 2 substituents independently selected from halogen u2014 cn u2014 cho u2014 cf 3 u2014 ocf 3 u2014 oh c 1 c 6 alkyl c 1 c 6 alkoxy u2014 nh 2 u2014 n c 1 c 6 alkyl 2 u2014 nh c 1 c 6 alkyl u2014 nh u2014 c o u2014 c 1 c 6 alkyl u2014 no 2 u2014 so 2 c 1 c 3 alkyl u2014 so 2 nh 2 u2014 so 2 nh c 1 c 3 alkyl u2014 so 2 n c 1 c 3 alkyl 2 u2014 cooh u2014 ch 2 u2014 cooh u2014 ch 2 u2014 nh c 1 c 6 alkyl u2014 ch 2 u2014 n c 1 c 6 alkyl 2 u2014 ch 2 u2014 nh 2 pyridinyl 2 methyl thiazolyl morpholino 1 chloro 2 methyl propyl c 1 c 6 thioalkyl phenyl further optionally substituted with one or more e g 1 5 1 4 1 3 or 1 2 halogens dialkylamino u2014 cn or u2014 ocf 3 benzyloxy u2014 c 1 c 3 alkyl c o ch 3 u2014 c 1 c 3 alkyl och 3 u2014 c o nh 2 or x 2 is selected from u2014 o u2014 u2014 ch 2 u2014 u2014 s u2014 u2014 so u2014 u2014 so 2 u2014 u2014 nh u2014 u2014 c o u2014 r 2 is a ring moiety selected from phenyl pyridinyl pyrimidinyl furyl thienyl.