title: Cocyclotrimerization of 6-alkynylpurines with alpha,omega-diynes as a novel approach to biologically active 6-arylpurines.
abstract: Transition metal complex catalyzed cocyclotrimerization of 6-alkynylpurines 1 with various diynes enables the preparation of a plethora of substituted 6-arylpurines 3 in good yields. The most general catalyst for the reaction is a user-friendly system based on a nickel-phosphine complex and reductant (NiBr(2)(dppe)/Zn) in MeCN. The reaction conditions are compatible with various protective groups on the purine moiety (Bn, THP). As far as other potential catalysts were concerned, only CoBr(PPh(3))(3) showed reasonable activity in cocyclotrimerization of alkynylpurines with dipropargyl ether. A comparison of catalytic with stoichiometric approaches and the ligand effect in the catalyst is also given. Cytostatic activity screening of title 6-arylpurines was performed and several moderately active compounds were found.
authors.affiliation: Department of Organic and Nuclear Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 43 Prague 2, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Turek
authors.forename: Martin
authors.initials: M
authors.lastname: Kotora
authors.forename: Iva
authors.initials: I
authors.lastname: Tislerová
authors.forename: Michal
authors.initials: M
authors.lastname: Hocek
authors.forename: Ivan
authors.initials: I
authors.lastname: Votruba
authors.forename: Ivana
authors.initials: I
authors.lastname: Císarová
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D011108:Polymers / Q000737:chemistry*; D011687:Purines / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D011108:Polymers; D011687:Purines