title: Uncommon regioselectivity in thiacalix[4]arene formylation.
abstract: To reveal the alternative ways for upper-rim thiacalixarene derivatization, the formylation reactions (Gross and/or Duff conditions) of the corresponding tetrapropoxythiacalix[4]arene immobilized in the 1,3-alternate conformation were systematically studied. Surprisingly, albeit using an excess of the formylation agent, only two formyl groups were introduced exclusively into the meta positions of thiacalixarene skeleton. Unexpected regioselectivity of these reactions opens the door for a unique substitution pattern in thiacalixarene chemistry. The formation of meta-substituted aldehydes is another illustration showing remarkably different reactivity of the thiacalix[4]arene system compared with that of a classical calyx[4]arene analogue.
authors.affiliation: Department of Organic Chemistry, Prague Institute of Chemical Technology, Technicka 6, 166 28 Prague 6, Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Kundrat
authors.forename: Ivana
authors.initials: I
authors.lastname: Cisarova
authors.forename: Stanislav
authors.initials: S
authors.lastname: Böhm
authors.forename: Michaela
authors.initials: M
authors.lastname: Pojarova
authors.forename: Pavel
authors.initials: P
authors.lastname: Lhotak