Frontier-Controlled Pericyclic Reactions of Powerful Electron-Attracting Cyclic Dienones and Diazadienones with 1H-Azepine: Molecular Structures of Cycloadducts and Some Comments

Article abstract of DOI:10.1021/jo01310a037

Pericyclic reactions of 2,5-bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone (1a) and 2,5-diphenyl-3,4-diazacyclopentadienone (1d) with N-(ethoxycarbonyl)azepine (2a) were investigated. For 1a, novel exo<4+6>? and anti endo <2+4>? cycloadducts were obtained, whereas for 1d, only the anti endo <2+4>? cycloadduct was obtained. These structures were verified by X-ray crystallography. The anti endo <2+4>? cycloadduct was found to be formed via Cope rearrangement of the endo <4+2>? cycloadduct by UV spectrometry. Compounds 1 are found to have high reactivities toward 2a, and the selectivities were discussed in terms of frontier molecular orbital theory, indicating that 1 is a useful 4? component with inverse electron demand.