title: Synthesis, structure, and chemistry of new, mixed group 14 and 16 heterocycles: nucleophile-induced ring contraction of mesocyclic dications.
abstract: More than 40 new 4- to 12-membered ring heterocycles containing various combinations of Group 14 and 16 elements Si, Sn, S, Se, and Te have been synthesized and fully characterized. Synthesis of these small-ring as well as medium-ring (mesocyclic) heterocycles from alpha,omega-dihalides is facilitated by the presence of gem-dialkylsilyl and gem-dialkylstannyl groups in the precursors. Conformations of several of the new ring systems in the solid state have been determined by X-ray crystal structure analysis. Oxidation of mixed S(Se, Te)/Si eight-membered ring mesocycles with NOPF6 or Br2 gives dications or a bicyclic dibromide, respectively, which can be characterized by NMR methods. On treatment with nucleophiles, mesocyclic dications, or the corresponding radical cations undergo ring contraction, giving five- or six-membered ring heterocycles. Photolysis of a S/Se four-membered ring heterocycle gives selenoformaldehyde, trapped in 80% yield with 2,3-dimethyl-1,3-butadiene.
authors.affiliation: Departments of Chemistry, University at Albany, SUNY, Albany, NY 12222, USA. eb801@albany.edu
authors.forename: Eric
authors.initials: E
authors.lastname: Block
authors.forename: Evgeny V
authors.initials: EV
authors.lastname: Dikarev
authors.forename: Richard S
authors.initials: RS
authors.lastname: Glass
authors.forename: Jin
authors.initials: J
authors.lastname: Jin
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Li
authors.forename: Shao-Zhong
authors.initials: SZ
authors.lastname: Zhang