Preheat oven, lightly grease and flour 12-cup Bundt pan or 10-inch tube pan.

Mix flour, baking powder and salt; set aside.
Mix sour cream and pineapple; set aside.
Beat butter and granulated sugar in large bowl with electric mixer on medium speed until light and fluffy. Add eggs, 1 at a time, beating well after each addition. Blend in melted chocolate and vanilla.
Add flour mixture alternately with sour cream mixture, beating until well blended after each addition.
Add coconut; mix well.

Pour into prepared pan. Bake until toothpick inserted near center comes out clean.
Cool in pan 10 minutes on wire rack.
Loosen cake from side of pan with small knife or metal spatula.
Invert cake onto rack; gently remove cake.
Cool completely on wire rack.
Sprinkle with powdered sugar.