title: Interrogation of a Sonogashira cross-coupling of 8-bromoguanosine with phenylacetylene on amberlite: evidence for Pd/Cu ion binding and propagation of Pd/Cu nanoparticles.
abstract: The reactivity of Amberlite (IRA-67) base "heterogeneous" resin in Sonogashira cross-coupling of 8-bromoguanosine 1 with phenylacetylene 3 to give 2 has been examined. Both 1 and 2 coordinate to Pd and Cu ions, which explains why at equivalent catalyst loadings, the homogeneous reaction employing triethylamine base is poor yielding. X-ray photo-electron spectroscopy (XPS) has been used to probe and quantify the active nitrogen base sites of the Amberlite resin, and postreaction Pd and Cu species. The PdCl(2)(PPh(3))(2) precatalyst and CuI cocatalyst degrade to give Amberlite-supported metal nanoparticles (average size ∼2.7 nm). The guanosine product 2 formed using the Amberlite Pd/Cu catalyst system is of higher purity than reactions using a homogeneous Pd precatalyst, a prerequisite for use in biological applications.
authors.affiliation: Department of Chemistry, University of York, Heslington, York, United Kingdom.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Firth
authors.forename: Karen
authors.initials: K
authors.lastname: Wilson
authors.forename: Christoph G
authors.initials: CG
authors.lastname: Baumann
authors.forename: Ian J S
authors.initials: IJ
authors.lastname: Fairlamb
mesh_terms: D000114:Acetylene / Q000031:analogs & derivatives* / Q000737:chemistry; D001665:Binding Sites; D003300:Copper / Q000737:chemistry*; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D010316:Particle Size; D012117:Resins, Synthetic / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D009942:Organometallic Compounds; D012117:Resins, Synthetic; D006151:Guanosine; C044736:phenylacetylene; C035169:8-bromoguanosine; D010165:Palladium; D003300:Copper; C046797:amberlite; D000114:Acetylene