(1,1'-Biphenyl)-4-butanamide, 2',4'-difluoro-alpha-methyl-gamma-oxo-N-(1-phenylethyl)-, (R-(R*,S*))- 161692-87-1 R-(+)-1-Phenylethylamide of 4-(2',4'-difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid