Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line with parchment paper, leaving overhang for easy lifting.
Drain crushed pineapple in a fine-mesh strainer, pressing to remove excess liquid. Reserve ½ cup of the juice. Pat pineapple rings and cherries dry with paper towels.
In a large bowl, whisk together flour, baking powder, baking soda, and salt.
In a separate bowl, whisk sugar, oil, eggs, and sour cream until smooth. Stir in drained crushed pineapple.
Pour wet ingredients into dry ingredients and fold gently with a spatula until just combined. Do not overmix.
Scrape batter into prepared pan and smooth the top. Arrange pineapple rings on top, then place a cherry in the center of each ring.
Bake for 55-65 minutes, until a toothpick inserted in the center comes out clean. If browning too quickly, tent with foil after 40 minutes.
While bread bakes, combine reserved pineapple juice and ¼ cup sugar in a small saucepan. Bring to a simmer, stirring until sugar dissolves. Remove from heat.
Let bread cool in pan for 10 minutes. Brush warm syrup over the top. Lift out using parchment and transfer to a wire rack to cool completely.