(Phys.org)—The Diels-Alder reaction is a mainstay in organic chemistry. The reaction traditionally involves a diene and a dienophile. The diene has four carbons that are sp2 hybridized to form pi bonds. The dienophile has two sp2 hybridized carbons. The diene and dienophile undergo a cycloaddition reaction to form a cyclohexene. This reaction can be tweaked to originate six-membered rings with a higher oxidation state by removing hydrogens from the reactants to originate sp hybridized carbons. For example,rather than an alkene and a diene reacting, the reactants could be an alkyne and an allenyne.
Source: phys.org