Preheat oven to 450 degrees. Line a baking sheet with parchment; set aside. Dissolve yeast in warm water and let stand until foamy, 5 to 10 minutes.
Whisk together flour, baking powder, baking soda, sugar, and salt in a large bowl. Transfer half of mixture to a food processor and add butter. Pulse until mixture resembles coarse meal with some blueberry-size clumps. Return to remaining flour mixture in bowl and mix to combine. Make a well in center of bowl and add yeast mixture and buttermilk. Stir until a dough forms, then turn out onto a floured work surface. Knead until dough is smooth and no longer sticky, about 5 minutes.
Roll out dough to 1/2-inch thick and cut out 1 1/2-inch rounds with a biscuit cutter. Set rounds 1 inch apart on baking sheet, brush tops with melted butter, and bake until lightly golden (do not let brown), 10 to 12 minutes. Serve warm or at room temperature.