Chlorosulfonylation of the starting quinoline/isoquinoline was effected by chlorosulfonic acid. Isolation of the sulfonyl chloride was achieved either in a one-step procedure (Method B) or in two-steps via initial isolation of the sulfonic acid (Method A). The isolation of the sulfonic acid was identified by the characteristic stretch in the infrared (ν max 2800–2000 cm −1 ). These were then converted to the sulfonyl chloride in a subsequent step using thionyl chloride ( ...
