 Preferably, R is phenyl optionally substituted by 0 to 0 halo substituents. More preferably, R is phenyl substituted by 0 or 0 substituents each independently selected from fluoro and chloro. Yet more preferably, R is phenyl substituted by 0 or 0 fluoro substituents. Most preferably, R is 0,0-difluorophenyl. 