Phosgene → 3,4-Dihydro-2,2-dioxo-3-methyl-1,2-benzoxathiin-8-ylsulfonylisocyanate

Participants

Reaction Steps

14.3 g of N-(3,4-dihydro-3-methyl-2,2-dioxo-1,2-benzoxathiin-8-ylsulfonyl)-N'-methylurea are suspended in 143 ml of dry dichlorobenzene. 9.5 g of phosgene are introduced into the mixture over 75 minutes at 140° C. Dry nitrogen is subsequently blown through the reaction mixture for 20 minutes. With the exclusion of moisture, the solution is concentrated by evaporation at 90° C./20 mbar, affording 15.1 g of 3,4-dihydro-3-methyl-2,2-dioxo-1,2-benzoxathiin-8-ylsulfonyl isocyanate in the form of an oil which is dissolved in warm absolute dioxane and, without further storage, is reacted in the subsequent step (c).

Provenance & Evidence