Synthesis and Consecutive Double Diels–Alder Cycloadditions of 3-Methylene-5-phenylsulfinyl-1-pentene as a Synthetic Equivalent of Parent Cross-conjugated Triene, 3-Methylene-1,4-pentadiene
3-Methylene-5-phenylsulfinyl-1-pentene undergoes stepwise double Diels–Alder cycloadditions with two different dienophiles to afford hydronaphthalene skeletons. This sequence corresponds to cross type of diene-transmissive Diels-Alder cycloaddition of parent 3-methylene-1,4-pentadiene.