Synthesis and Mutagenesis of the Butadiene-Derived N3 2‘-Deoxyuridine Adducts
摘要:
1,3-Butadiene is a known carcinogen and mutagen that acts through a variety of metabolic intermediates that react with DNA, forming stable and unstable lesions on dG, dA, dC, and dT. The N3 2'-deoxyuridine adducts are a highly stable, stereoisomeric mixture of adducts derived from the reaction of cytosine with the monoepoxide metabolite of butadiene, followed by spontaneous deamination. In this study, the phosphoramidites and subsequent oligodeoxynucleotides containing the N3 2'-deoxyuridine adducts have been constructed and characterized. Using a single-stranded shuttle vector DNA, the mutagenic potential of these adducts has been tested following replication in mammalian cells. Replication past the N3 2'-deoxyuridine adducts was found to be highly mutagenic with an overall mutation yield of similar to 97%. The major mutations that were observed were C to T transitions and C to A transversions. In vitro, these adducts posed a complete block to both the Klenow fragment of Escherichia coli polymerase I and polymerase epsilon, while these lesions significantly blocked polymerase delta. These data suggested a possible involvement of bypass polymerases in the in vivo replication of these lesions. Overall, these findings indicate that the N3 2'-deoxyuridine adducts are highly mutagenic lesions that may contribute to butadiene-mediated carcinogenesis.
Enantioselective Synthesis of Cyclic, Quaternary Oxonitriles
作者:Yakup Güneş、M. Fatih Polat、Ertan Sahin、Fraser F. Fleming、Ramazan Altundas
DOI:10.1021/jo1011202
日期:2010.11.5
Quaternaryoxonitriles are stereoselectively generated from the union of five-, six-, and seven-membered 2-chloroalkenecarbonitriles with chiral alcohols via a Claisen rearrangement. The strategy rests on a new conjugate addition−elimination of allylic alkoxides to 2-chlorocycloalkenecarbonitriles to afford substituted 2-alkoxyalkenenitriles. Subsequent thermolysis unmasks a cyclicoxonitrile while
Iron(III)-Catalyzed Consecutive Aza-Cope−Mannich Cyclization: Synthesis of <i>trans</i>-3,5-Dialkyl Pyrrolidines and 3,5-Dialkyl-2,5-dihydro-1<i>H</i>-pyrroles
作者:Rubén M. Carballo、Martín Purino、Miguel A. Ramírez、Víctor S. Martín、Juan I. Padrón
DOI:10.1021/ol102372c
日期:2010.11.19
efficient alkene aza-Cope−Mannich cyclization between 2-hydroxy homoallyl tosylamine and aldehydes in the presence of iron(III) salts to obtain 3-alkyl-1-tosyl pyrrolidines in good yields is described. The process is based on the consecutive generation of a γ-unsaturated iminium ion, 2-azonia-[3,3]-sigmatropic rearrangement, and further intramolecular Mannich reaction. Iron(III) salts are also shown to be
Synthesis of methyl 2-oxo-5-vinyl-2,5-tetrahydrofuran-3-carboxylate
作者:Maximilian A. Silvestri、Chang He、Anita Khoram、Salvatore D. Lepore
DOI:10.1016/j.tetlet.2005.12.114
日期:2006.3
A synthesis of methyl 2-oxo-5-vinyl-tetrahydrofuran-3-carboxylate involving five synthetic steps from commercially available 3,4-dihydroxybutene is reported. (c) 2006 Elsevier Ltd. All rights reserved.