Preheat oven to 350℉.
In a large frying pan, add 2 cups water, 2 cups sugar, and 1½ sticks butter. Heat until sugar is dissolved and butter is melted.
In a small container, add ¼ cup water and 1 tablespoon flour. Mix well and add to sugar mixture.
Open crescent rolls, roll each sweetpotato half in the crescent rolls and place into glass baking dish.
Pour liquid mixture over crescent rolls and sprinkle with cinnamon.
Bake for approximately 35 minutes.