title: λ-Orthogonal pericyclic macromolecular photoligation.
abstract: A photochemical strategy enabling λ-orthogonal reactions is introduced to construct macromolecular architectures and to encode variable functional groups with site-selective precision into a single molecule by the choice of wavelength. λ-Orthogonal pericyclic reactions proceed independently of one another by the selection of functional groups that absorb light of specific wavelengths. The power of the new concept is shown by a one-pot reaction of equimolar quantities of maleimide with two polymers carrying different maleimide-reactive endgroups, that is, a photoactive diene (photoenol) and a nitrile imine (tetrazole). Under selective irradiation at λ=310-350 nm, any maleimide (or activated ene) end-capped compound reacts exclusively with the photoenol functional polymer. After complete conversion of the photoenol, subsequent irradiation at λ=270-310 nm activates the reaction of the tetrazole group with functional enes. The versatility of the approach is shown by λ-orthogonal click reactions of complex maleimides, functional enes, and polymers to the central polymer scaffold.
authors.affiliation: Preparative Macromolecular Chemistry, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstrasse 18, 76128 Karlsruhe (Germany); Institut für Biologische Grenzflächen (IBG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany).
authors.forename: Kai
authors.initials: K
authors.lastname: Hiltebrandt
authors.forename: Thomas
authors.initials: T
authors.lastname: Pauloehrl
authors.forename: James P
authors.initials: JP
authors.lastname: Blinco
authors.forename: Katharina
authors.initials: K
authors.lastname: Linkert
authors.forename: Hans G
authors.initials: HG
authors.lastname: Börner
authors.forename: Christopher
authors.initials: C
authors.lastname: Barner-Kowollik
keywords: click reactions; orthogonal reactivity; photochemistry; photoenol; tetrazole