INTRAMOLECULAR AND BIMOLECULAR NUCLEOPHILIC SUBSTITUTIONS OF RIMSULFURON SULFONYLUREA

The sulfonylurea herbicide rimsulfuron 1 oxypyrimidin-2-yl)aminocarbon yl)-3-(ethylsulfonyl) -2-pyridinesulfonamide) in aqueous solutions of KOH, NaOH, NH4OH, or dilute HCl, and thermally (rimsulfuron or monomet hylated rimsulfuron at the sulfonamide hydrogen) was transformed by SO 2 extrusion and intramolecular nucleophilic substitution into 2-(N-(4, 6-dimethoxy)pyrimidin-2-yl)amino 3. In mild methanol + HCl conditions, the intermediate rearranged urea midin-2-yl)-N-((3-(ethylsulfonyl)-2- pyridinyl)urea 2 was isolated. In concentrated hydrochloric acid, rims ulfuron 1 was transformed by bimolecular nucleophilic substitution suc cessively into 2-chloro-3-ethylsulfonylpyridine 6 and 2-hydroxy-3-ethy lsulfonylpyridine 4. Sodium sulfite transformed rimsulfuron 1 into a m ixture of 2-sodiumsulfonate-3-ethylsulfonylpyridine 7 and amine 3.