title: Synthesis, characterization, and reactivity of [Li(N6,N9-Me2Ade(-H))]: a structurally characterized lithiated adenine.
abstract: The reaction of N6,N9-dimethyladenine (N6,N9-Me2Ade, 1) with methyllithium in aprotic solvents such as tetrahydrofuran and pyridine resulted in the formation of the lithiated adenine [Li(N6,N9-Me2Ade-H)] (2) that was isolated as highly air and moisture sensitive tetrahydrofuran (2.(1/4)THF) and pyridine (2.py) adducts in excellent yields (>90%). The identities of 2.(1/4)THF and 2.py were confirmed by 1H and 13C NMR spectroscopy. In crystals of 2.(3/2)py, the dimethyladeninato ligand exhibited a chelating and bridging coordination mode (kappa2N6,N7:kappaN3) resulting in a 1-D polymeric chain-like structure in which the tetrahedral coordination sphere of the lithium atoms was completed by a pyridine molecule. Reactions of 2.(1/4)THF with electrophiles such as MeI, Me3SiCl, and Me3SnCl resulted in high yields (88-98%) of the formation of the adenine deriatives N6,N6,N9-Me3Ade-H (3), N6-(SiMe3)-N6,N9-Me2Ade(-H) (4), and N6-(SnMe3)-N6,N9-Me2Ade-H (5), respectively. Compounds 3-5 were characterized by 1H, 13C, 29Si (4), and 119Sn (5) NMR spectroscopy and MS investigations, and the stannylated derivative 5 also was characterized by single-crystal diffraction analysis exhibiting a mononuclear structure. The reaction of the stannylated adenine 5 with n-BuLi in n-hexane proceeded in the sense of a tin-lithium transmetalation reaction yielding the solvent-free lithium adeninate [Li(N6,N9-Me2Ade-H)] (2) in 90% yield.
authors.affiliation: Institut für Chemie-Anorganische Chemie, Martin-Luther-Universität Halle-Wittenberg, D-06120 Halle, Kurt-Mothes-Strasse 2, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Krüger
authors.forename: Tobias
authors.initials: T
authors.lastname: Rüffer
authors.forename: Heinrich
authors.initials: H
authors.lastname: Lang
authors.forename: Christoph
authors.initials: C
authors.lastname: Wagner
authors.forename: Dirk
authors.initials: D
authors.lastname: Steinborn
mesh_terms: D000225:Adenine / Q000737:chemistry*; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008094:Lithium / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction
chemical_list: D008094:Lithium; D000225:Adenine