SYNTHESIS OF N-ARYL SUBSTITUTED 4H-1,4-BENZOTHIAZINE 1,1-DIOXIDE 2-CARBOXYLIC ACID-ESTERS

Abstract

A group of N-aryl substituted 1,4-benzothiazine-1,1-dioxide-2 carboxylic acid esters is reported. This is the first example of N-aryl-derivatives of the 4H-1,4-benzothiazine nucleus; the key step is the cyclization of N-aryl-phenylsulfonyl-acrylates 4–8 using potassium carbonate in acetonitrile/18-crown-6-ether to the corresponding title compounds in moderate yields.

Key Words:

• 4H-1,4-Benzothiazine-1
• 1-dioxide
• N-aryl-phenylsulfonylacrylates
• cyclization reaction