being optionally substituted with 1 3 groups independently selected from halogen ch 3 cf 3 u2014 och 3 and u2014 ocf 3 in some embodiments r 7 is selected from h and c 1 c 3 alkyl optionally substituted with 1 3 f in some embodiments x is selected from u2014 sc 1 c 3 alkyl and u2014 oz in some embodiments x is selected from u2014 sc 1 c 2 alkyl and u2014 oz in some embodiments x is u2014 sc 1 c 2 alkyl in some embodiments x is u2014 oz a u2014 ch 2 ch 2 o u2014 n c 1 c 3 alkyl where n is 0 or 1 and wherein c 1 c 3 alkyl is optionally substituted with 1 2 substituent groups independently selected from phenyl u2014 c u2550 o or 6 u2014 op u2550 o or 7 2 and p u2550 o or 7 2 wherein phenyl is optionally substituted with one group u2014 c u2550 o or 7 and b phenyl which is optionally substituted with 1 3 substituents independently selected from c 1 c 4 alkyl u2014 oc 1 c 3 alkyl u2014 c u2550 o or 7 and cyclohexyl wherein c 1 c 4 alkyl and u2014 oc 1 c 3 alkyl are optionally substituted with 1.