4.5- Dihydro benzothiazepine-6,6-dioxide

The 4,5-dihydro-3,2-benzothiazepine (380) has been prepared by the thermally induced ring expansion of 1-azidoisothiochroman (74LA734). The product reacted with acetyl chloride and then with alcohols to give the l-alkoxy-2-acyl derivatives, and was oxidized to the 3,3-dioxide. 

By the reaction of 4-amino-2,3-dihydro-l,5-benzothiazepine (79) with triethyl orthoacetate at 150°C followed by treatment with ammonia at room temperature, an acetamidine intermediate was obtained which, by oxidative cyclization with sodium hypochlorite, was converted to 4,5-dihydrol[ 1,2,4]triazolo[5, -d [ 1,5]benzothiazepine 6,6-dioxide (98) (Scheme 29) (92M1023). 

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