3- Methoxy-5-phenylsulfonyl-1,2,4-triazine

The reaction of 3-methoxy-1,2,4-triazine 1-oxide 20 with the carbanion generated from chloromethyl phenyl sulfone proceeds as the vicarious nucleophilic substitution (VNS) of hydrogen (Scheme 1, path B) via addition of the carbanion at position 5 of the heterocycle. Following base-induced elimination of HCl and protonation, 3-methoxy-5-phenylsulfonyl-1,2,4-triazine 4-oxides 65 result (88LA627). 

Microsomes isolated from shoot tissues of etiolated wheat seedlings (Tritkum aestivum L. var. Olaf) oxidized the sulfonylurea herbicide prosulfuron (CGA 152005). Identification of the major oxidation product as l-(4-methoxy-6-methyl-l,3,5-triazin-2-yl)-3-[2-(3,3,3-trifluoropropyl)-5-hydroxyphenylsulfonyl]-urea 28 was confirmed by proton NMR spectroscopy (Figure 15). Proton NMR spectra of isolated minor oxidation products were not obtained because of insufficient sample size for analysis. However, these products were identified tentatively as l-[4-(hydroxymethyl)-6-methoxy-l,3,5-triazin-2-yl]-3-[2-(3,3,3-trifluoropropyl)phenylsulfonyl] urea 29 and an intermediate oxidation product l-[4-[(hydroxymethyl)oxy]-6-methyl]-l,3,5-triazin-2-yl]-3-[2-(3,3,3-trifluoropropyl)phenylsulfonyl]urea 30, that degraded to l-(4-hydroxy-6-methyl-l,3,5-triazin-2-yl)-3-[2-(3,3,3-trifluoropropyl)phenylsulfonyl]urea 31 <19%JFA3658>. 

---