反应详情

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).

1. concentrationWith the exclusion of moisture, the solution is concentrated by evaporation at 90° C./20 mbar