A modified approach to C-14-labeled 2-(3,4-difluorophenoxy)-5- fluoronicotinic acid and other halogen-substituted analogs
A modified approach to a carbon-14-labeled pyridine ring system was developed based on the electrocyclic ring-closure of 1,4,4-trisubstituted butadiene. The new method was applied to prepare 2-(3,4-difluorophenoxy)-5- fluoro-[2-14C] nicotinic a