title: Sequential intermediates in the base-catalyzed conversion of bis(pi-conjugated propargyl) sulfones to 1,3-dihydrobenzo- and naphtho[c]thiophene-2,2-dioxides.
abstract: [reaction: see text] In a recent article, we reported on the base-catalyzed rearrangements of dipropargyl selenides, -sulfides, -sulfoxides, and -sulfones that eventually lead to polycyclic aromatic products. In the present work, we report on the first isolation and characterization of the thiophene dioxide intermediates 5b,c from a mild tandem isomerization/cyclization/aromatization of bis(pi-conjugated propargyl) sulfones. Monoallene 2b,c and diallene 3b intermediates were also identified by NMR. A kinetic study of the rearrangement of 1a-c revealed that the unusual facile tandem process is highly dependent on the nature of gamma-substitution.
authors.affiliation: Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel.
authors.forename: Yossi
authors.initials: Y
authors.lastname: Zafrani
authors.forename: Hugo E
authors.initials: HE
authors.lastname: Gottlieb
authors.forename: Milon
authors.initials: M
authors.lastname: Sprecher
authors.forename: Samuel
authors.initials: S
authors.lastname: Braverman