Sift together flour, sugar replacement, fructose, baking soda, salt, and cinnamon.
Combine margarine, water, and baking cocoa in a saucepan.
Cook over low heat until margarine is melted.
Beat cocoa mixture into dry flour mixture.
Add buttermilk, eggs, and vanilla extract.
Beat for 2 minutes.
Grease a 15 x 10 in. (39 x 25 cm) jelly-roll pan.
Pour brownie mixture into pan, spreading evenly.
Bake at 350°F (175°C) for 25 minutes, or until top springs back when lightly touched.
Cool slightly in pan before cutting into 50 brownies.