In a large mixing bowl, make the pancake batter by stirring together crushed pineapple, sugar, baking powder, baking soda, salt, eggs, and melted butter. Slowly add in flour until you have a nice batter. You want it to remain thin enough to spread slightly, without being runny.
Heat a heavy flat nonstick griddle or skillet over medium-high heat. Pour pancake batter in 1/4 cup scoops onto the griddle or skillet. When bubbles start to form on top, flip and cook on the other side until lightly browned. Keep warm until serving (a 200 degree oven and a cookie sheet works great for this).
Make the syrup by melting butter in a medium-size saucepan over medium heat. Stir in sugar, coconut milk, and vanilla. Bring to a boil over medium-high heat and simmer 4 minutes. Store in a heat-safe airtight container in the refrigerator.
Serve pineapple pancakes warm with warm coconut syrup.