In a food processor, pulse brown sugar and pistachios until coarsely ground. Sprinkle 3 tablespoons sugar mixture into an 8-inch round baking pan (2 inches deep) and drizzle with 2 tablespoons butter.
On a lightly floured work surface, roll and stretch dough into a 12-by-18-inch rectangle. Spread with marmalade, leaving a 1-inch border. Top with remaining sugar mixture, sprinkle with salt, and drizzle with 3 tablespoons butter. Starting at a long edge, roll up dough like a jelly roll. Cut crosswise into 8 pieces and place in pan. Cover with plastic wrap and let rise in a warm, draft-free place until buns are puffed and begin to touch, about 1 hour.
Preheat oven to 350 degrees. Place pan on a rimmed baking sheet and bake until buns are golden brown, about 35 minutes. Immediately run a knife around edge of pan and invert buns onto a serving platter. Serve warm.