Preparation of carbon-14 labeled N-(2,6-dichloro-3-methylphenyl)-5,7-dimethoxy[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide

Abstract

A new 6-step process was developed for the synthesis of radiolabeled metosulam, a broadleaf post emergent herbicide being commercialized by DowElanco for use in small grains. Each step of the process can be accomplished in >80% yield thereby making the process a convenient and efficient route for the preparation of both radiolabeled and unlabeled samples of metosulam. A significant improvement was made in the coupling of the silylaniline with the sulfonyl chloride over the previously reported procedure which represents a key step in the process. © 1997 John Wiley & Sons, Ltd.