Phosgene → 3,4-Dihydro-2,2-dioxo-3-methyl-1,2-benzoxathiin-8-ylsulfonylisocyanate
Reaction equation
[CH3:1][CH:2]1[CH2:7][C:6]2[CH:8]=[CH:9][CH:10]=[C:11]([S:12]([NH:15][C:16](NC)=[O:17])(=[O:14])=[O:13])[C:5]=2[O:4][S:3]1(=[O:21])=[O:20].C(Cl)(Cl)=O>C1C(Cl)=CC=C(Cl)C=1>[CH3:1][CH:2]1[CH2:7][C:6]2[CH:8]=[CH:9][CH:10]=[C:11]([S:12]([N:15]=[C:16]=[O:17])(=[O:14])=[O:13])[C:5]=2[O:4][S:3]1(=[O:21])=[O:20]Participants
4
Procedure
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).