title: Generation and Trapping Reactions of 1-tert-Butoxycarbonyl-3,4-didehydro-1H-pyrrole.
abstract: 3,4-Bis(trimethylsilyl)-1H-pyrrole (5) was employed as a key precursor to generate a highly strained and reactive five-membered cyclic cumulene, namely 1-tert-butoxycarbonyl-3,4-didehydro-1H-pyrrole (4). The transient existence of 4 at room temperature was confirmed by trapping reactions with furan, acrylonitrile, and benzene, affording cycloadducts 13-15. The choice of the electron-withdrawing tert-butoxycarbonyl group as the N-substituent was essential because it was able to adjust the electron density of 11a and 11b. As a result, monoiodonium triflates 12a and 12b were obtained, respectively. On the contrary, N-tert-butyl-3,4-bis(trimethylsilyl)-1H-pyrrole (9) led instead to the bisiodonium triflate 10 upon treatment with the Zefirov reagent.
authors.affiliation: Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Liu
authors.forename: Ho-Wai
authors.initials: HW
authors.lastname: Chan
authors.forename: Feng
authors.initials: F
authors.lastname: Xue
authors.forename: Qi-Guang
authors.initials: QG
authors.lastname: Wang
authors.forename: Thomas C. W.
authors.initials: TC
authors.lastname: Mak
authors.forename: Henry N. C.
authors.initials: HN
authors.lastname: Wong