反应详情

cyclizing the acetoacetamide derivative; the process comprises using, as the sulfamic acid derivative in stage (a), a salt of sulfamic acid which is at least partly soluble in the inert organic solvent employed, cyclizing the acetoacetamide-N-sulfonate formed in this stage or the free acetoacetamide-N-sulfonic acid in stage (b) by the action of an at least approximately equimolar amount of SO3, if appropriate in an inert inorganic or organic solvent, to give 6-methyl-3,4-dihydro-1,2,3-oxa-thiazin-4-one 2,2-dioxide, and then, if desired, also neutralizing with a base, in a stage (c), the product obtained here in the acid form.

1. customformed in this stage