c 1 6 alkoxy c 1 6 perfluoroalkyl c 1 6 perfluoroalkoxy phenyl and benzyl wherein phenyl or benzyl is optionally substituted with one or two substituents each independently selected from c 1 6 alkyl c 1 6 perfluoroalkyl halogen hydroxy or c 1 6 perfluoroalkyl or c 1 6 perfluoroalkoxy z is n u2014 r or s wherein r is selected from the group consisting of hydrogen c 1 6 alkyl c 1 6 alkylcarbonyl c 1 6 alkoxycarbonylc 1 6 alkyl c 1 6 alkylcarbamoyl c 1 6 alkyl and c 1 6 dialkylcarbamoylc 1 6 alkyl r 1 is selected from the group consisting of hydrogen c 1 6 alkyl c 2 6 alkenyl c 2 6 alkynyl c 1 6 perfluoroalkyl c 3 8 scycloalkyl c 3 8 cycloalkylc 1 6 alkyl c 1 6 alkoxyc 1 6 alkyl hydroxyc 1 6 alkyl aminoc 1 6 alkyl mono or di c 1 6 alkyl aminoc 1 6 alkyl formyl c 1 6 alkylcarbonyl aminoc 1 6 alkylcarbonyl c 1 6 alkoxycarbonyl phenyl diphenylc 1 6 alkyl and phenylc 1 6 alkyl phenylcarbonylc 1 6 alkyl phenoxyc 1 6 alkyl wherein phenyl is optionally substituted with one or two substituents each independently selected from c 1 6 alkyl c 1 6 perfluoroalkyl halogen hydroxy or c 1 6 perfluoroalkyl or c 1 6 perfluoroalkoxy r 3 is r 4 is selected form the group consisting of hydrogen halogen nitro amino hydroxy c 1 6 alkyl c 1 6 alkoxy c 1 6 perfluoroalkyl c 1 6 perfluoroalkoxy n morpholinylcarbonyl phenyl and benzyl wherein phenyl or.