Chlorosulfonic acid → 4-Chloro-1-hydroxy-7-isoquinolinesulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

4-Chloro-1-(2H)-isoquinolone (20.62 g, 115 mmol) was added portionwise to stirred chlorosulphonic acid (61 mL, 918 mmol) at 0° C. The mixture was heated at 100° C. for 3.5 d and then cooled to room temperature. The reaction mixture was added in small portions onto ice-water [CAUTION] and the resulting precipitate was collected by filtration. The solid was washed with water, triturated with MeCN and then dried in vacuo to give 4-chloro-7-chlorosulphonyl-1-(2H)-isoquinolone (18.75 g, 67.4 mmol) as a cream solid.

Provenance & Evidence