Dioxopyrrolines. LXI. Cycloaddition Reaction of 4-Benzoyl-5-ethoxycarbonyl-1-phenyl-1H-pyrrole-2, 3-dione with 1, 3-Dienes : Competitive Occurrence of Normal and Hetero Diels-Alder Reaction and Claisen Rearrangement of the Hetero Diels-Alder Product