Preheat oven to 350 degrees.
Lightly grease and flour 10 inch tube pan.
Mix flour, baking powder, and salt; set aside.
Mix sour cream and pineapple; set aside.
Beat butter and sugar in large bowl at medium speed until light and fluffy.
Add eggs, one at a time, beating well after each addition.
Beat in melted chocolate and vanilla.
Add flour mixture alternately with sour cream mixture.
Beat in coconut.
Pour into prepared pan.
Bake 70 - 75 minutes or 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 spatula.
Invert cake onto rack and gently remove pan.
Cool completely on wire rack.
Sprinkle with powdered sugar, if desired.