Dissolve the yeast in warm water and set aside.
Sift together the flour and other dry ingredients in large bowl. Cut in the shortening with a pastry blender. Add buttermilk and yeast mixture, stir to make a soft dough.
Place dough on floured surface and knead until smooth. Roll dough out 1/2″ thick (no rising is necessary) and cut with a biscuit cutter.
Bake in preheated 400° oven until golden brown, about 12 minutes.