1,4-Naphthoquinone acts as strong dienophile in Diels-Alder reaction. Its adduct with 1,3-butadiene can be prepared by two methods: 1) long (45 days) exposure of naphthoquinone in neat liquid butadiene taken in huge excess at room temperature in a thick-wall glass tube or 2) fast catalyzed cycloaddition at low temperature in the presence of 1 equivalent of tin(IV) chloride:[5]