Thermal rearrangement is heating the epoxide to about ~260C and holding for a few minutes, cranking the heat, and distilling it... it comes over somewhere around 300C (I didn't have a thermometer that went above 260C). What distills over is not epoxide, it is ketone. The crude yield is about 80%, the flask is relatively hard to clean afterwards. It has not been verified to give a good purity, but I know it works, and I think the purity is decent.