Dimethyl Sulfate → 2-Methyl-1,2-benzoisothiazolin-3-one

Participants

Reaction Steps

To a stirred suspension of 1,2-benzisothiazolin-3-one lithium salt (10.0 g, 63.7 mmol) in butanone (30 ml) was added dropwise dimethyl sulfate (8.4 g, 6.4 ml, 66.9 mmol). The resulting slurry was stirred at room temperature for 90 hours. HPLC analysis showed greater than 96% alkylation of 1,2-benzisothiazolin-3-one lithium salt. The solvent was evaporated and the crude product distilled under reduced pressure to give a combined 77% yield of N-methyl-1,2-benzisothiazolin-3-one and 3-methoxy-1,2-benzisothiazole, with N-methyl-1,2-benzisothiazolin-3-one isolated in 94% purity. The ratio of N-alkylated material to O-alkylated material was 90:10.

Provenance & Evidence