The synthesis of [U-14C phenyl] LS 840606, an agricultural fungicide

2,2',4'-Trichloro-[ring U- 14 C]acetophenone 3 was the key intermediate of this synthesis patterned after the industrial route. An unexpected poor yield was observed during the preparation of 3 by the Friedel-Crafts reaction of chloroacetyl chloride with 1,3-dichloro-[U- 14 C]benzene 10, possibly the result of an isotope effect although this poor yield might be explained by other factors. Two routes were checked for the preparation of 1,3-dichloro-[U- 14 C]benzene 10. The action of CCl 4 with 1,3-dinitro-[U- 14 C]benzene at 280°C was entailed with explosions. A safer route started from [U- 14 C]aniline via 2,4-dichloro-[ring U- 14 C]acetanilide. Friedel-Crafts reaction of 10 with acetyl chloride gave rise in 52% yield to 2',4'-dichloro-[ring U- 14 C]acetophenone 16 which was brominated to 2-bromo-2',4'-dichloro-[ring U- 14 C]acetophenone 17 ; 17 was condensed with 2,2-(ethylenedioxy)ethylmagnesium bromide to compound 18 ; 18 was condensed with 1,2,4-triazole to 5 then successively treated with HCl :water :dioxane and 2,2,2-trifluoroethanol/HCl. Separation of the two diastereomers by medium pressure liquid chromatography. 7% overall radioactive yield from [U- 14 C]aniline. Radiochemical purity 99%