1/2 cup (1 stick) unsalted butter, room temperature, plus more for pan
1 1/2 cups all-purpose flour, (spooned and leveled), plus more for pan
1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup sugar
3 large eggs
1 cup sour cream
1 can (20 ounces) pineapple chunks in juice, drained well
Preheat oven to 350 degrees. Spread coconut on a rimmed baking sheet. Bake until lightly toasted, tossing occasionally, 6 to 10 minutes; set aside. Butter and flour a 9-by-5-inch (8-cup) loaf pan; set aside. In a medium bowl, whisk together flour, baking soda, and salt; set aside.
Using an electric mixer on high speed, beat butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Reduce speed to low, and alternately add flour mixture in three parts and sour cream in two, beginning and ending with flour mixture. Mix just until combined (do not overmix).
Using a rubber spatula, fold pineapple and 1 cup coconut into batter. Spoon into prepared pan, and smooth top; sprinkle with remaining 1/2 cup coconut. Bake until a toothpick inserted in center comes out clean, 65 to 70 minutes (cover pan with foil halfway through). Let cake cool in pan 15 minutes. Remove from pan, and transfer to a wire rack to cool completely.