Preheat oven to 425°F. Line a baking sheet with parchment paper.
In a large bowl, sift together flour, sugar, baking powder, baking soda, salt and cinnamon. Cut in butter using a pastry blender or rubbing between fingers, until mixture resembles coarse meal. Stir in chocolate chips. Add buttermilk and vanilla, stirring just until moistened.
Turn dough onto a lightly floured surface and knead briefly, 5 or 6 times, to gather into a large ball. Do not overwork the ball or the result will be tough scones. Divide the ball of dough in half and gently pat each into 8-inch flat rounds. Brush the top of each with melted butter and sprinkle with sugar.
Using a sharp knife, cut each circle into 6 even triangles and place on prepared baking sheet, about 1 inch apart. Bake 16-18 minutes until tops are golden.