72610-89-0Relevant articles and documents
Benzocyclobutenylidene-Cycloadditions, Reactivity, and Multiplicity
Duerr, Heinz,Nickels, Helmut,Pacala, Luba A.,Jones, Maitland
, p. 973 - 980 (2007/10/02)
EHT and CNDO/2 calculations on benzocyclobutenylidene (6) are described.Flash pyrolysis of the tosylhydrazone salt 7 affords benzocyclobutene and o-xylene in low yield, along with the formal syn and anti carbene dimers 13 and 14.Condensed-phase reactions were achieved by photolysis of the salt 15.Benzocyclobutenylidene (6) gave rise to the formal carbene dimers 17 and 18.Insertion of carbene 6 into the carbon-hydrogen bonds of 2,3-dimethylbutane produced the benzocyclobutenes 20 and 21 (insertion ratio tertiary:primary = 9:1).Cycloaddition of 6 to olefins gave only spirohexene derivatives 22.Multiplicity studies of 6 with cis or trans olefins indicated that 6 undergoes cycloaddition in a stereospecific manner.Competition experiments using dienes and monoolefins implicate an equilibrium between singlet and triplet 6.Further competition experiments with styrene/para-substituted styrene pairs demonstrated that 6 reacts faster with electron-poor styrenes.Possible explanations for this apparent anomaly are discussed.
