Patent ID: 7408059
Filing Date: 2008-08-05
Classification: C07D

Abstract:
1. A method for producing a 3,4-dihydro-1,2,3-oxathiazin-4-one-2,2-dioxide compound represented by the following formula (2): wherein R the method comprising the step of subjecting a beta-ketoainide-N-sulfonic acid represented by the following Formula (1): wherein R wherein the cyclization is continuously carried out using a continuous flow reactor selected from a tubular reactor or a motionless mixer having a tube in the tubular reactor or the motionless mixer having an inner diameter of from 0.2 to 30 millimeters, wherein the beta-ketoamide-N-sulfonic acid or the salt thereof and the acid anhydride are cooled to −100° C. to 10° C. before the cyclization, an amount of the acid anhydride for use in the cyclization is 1 to 20 moles per 1 mole of the beta-ketoamide-N-sulfonic acid or the salt thereof, and wherein a premixer selected from the group consisting of a stirred mixer, an ultrasonic mixer, a static mixer and a piping joint is optionally employed with the continuous flow reactor, and when a premixer is employed, a residence time in the premixer ranges from 0.1 to 10 second, and the residence time in the continuous flow reactor ranges from 0.001 to 60 seconds, and when the continuous flow reactor is used without a premixer, the residence time in the continuous flow reactor ranges from 0.1 to 10 seconds.