title: Synthesis and application of monodisperse oligo(oxyethylene)-grafted polystyrene resins for solid-phase organic synthesis.
abstract: In a preliminary investigation by our group, we found that poly(styrene-oxyethylene) graft copolymers (PS-PEG), for example, TentaGel resins, are advantageous for gel-phase (13)C NMR spectroscopy. Because of the solution-like environment provided by the PS-PEG resins, good spectral quality of the attached moiety can be achieved, which is useful for nondestructive on-resin analysis. The general drawbacks of such resins are low loading capacities and the intense signal in the spectra resulting from the PEG linker (>50 units). Here, we describe the characterization of solvent-dependent swelling and reaction kinetics on a new type of resin for solid-phase organic synthesis (SPOS) that allows an accurate monitoring by gel-phase NMR without the above disadvantages. A series of polystyrene-oligo(oxyethylene) graft copolymers containing monodisperse PEG units (n = 2-12) was synthesized. A strong correlation between the linker (PEG) length and the line widths in the (13)C gel-phase spectra was observed, with a grafted PEG chain of 8 units giving similar results in terms of reactivity and gel-phase NMR monitoring to TentaGel resin. Multistep on-resin reaction sequences were performed to prove the applicability of the resins in solid-phase organic synthesis.
authors.affiliation: Institute of Applied Synthetic Chemistry, Vienna University of Technology , Getreidemarkt 9/163, 1060 Vienna, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lumpi
authors.forename: Christian
authors.initials: C
authors.lastname: Braunshier
authors.forename: Ernst
authors.initials: E
authors.lastname: Horkel
authors.forename: Christian
authors.initials: C
authors.lastname: Hametner
authors.forename: Johannes
authors.initials: J
authors.lastname: Fröhlich
mesh_terms: D002247:Carbon Isotopes; D060326:Chemistry Techniques, Synthetic; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010316:Particle Size; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry; D011137:Polystyrenes / Q000138:chemical synthesis* / Q000737:chemistry; D013499:Surface Properties
chemical_list: D002247:Carbon Isotopes; D011137:Polystyrenes; C103390:polyethylene glycol-polystyrene; C101297:Tentagel resin; D011092:Polyethylene Glycols