studied electrocyclic reaction is the conrotatory thermal ring-opening of benzocyclobutene. The reaction product is a very unstable ortho-quinodimethane but this molecule can be trapped in an endo addition with a strong dienophile such as maleic anhydride to the Diels-Alder adduct. The chemical yield for the ring opening of the benzocyclobutane depicted in scheme 2 is found to depend on the nature of the substituent R. With a reaction solvent such as toluene and a reaction temperature of 110 °C, the yield increases going from methyl to isobutylmethyl to (trimethylsilyl)methyl. The increased reaction rate for the trimethylsilyl compound can be explained by silicon hyperconjugation as the βC-Si bond weakens the cyclobutane C-C bond by donating electrons. A biomimetic electrocyclic cascade reaction was discovered in relation to the isolation and synthesis of certain endiandric acids: Asymmetric electrocyclic reactions are an emerging field in contemporary organic synthesis. The most commonly studied reactions in this field are the 4π Staudinger β-lactam synthesis and the 4π Nazarov reaction; asymmetric catalysis of both reactions have been controlled by use of a chiral auxiliary, and the Nazarov reaction has been performed catalytically using chiral Lewis acids, Brønsted acids and chiral amines. References Rearrangement reactions Pericyclic reactions Reaction mechanisms