Melt butter and brown sugar in the pan before putting in the pineapples.
Pineapple Upside down cake is my son's favorite cake, I make it when we go camping a lot. I turn the cake upside down within a minute of removing it from the oven and never have any problem with pineapples sticking to the pan. I usually have to scoop up a small amount of brown sugar left in the pan. I don't use any special pan, glass 9x11 pan.