title: Electroreductive Intermolecular Coupling of Uracils with Aromatic Ketones: Synthesis of 6-Substituted and cis-5,6-Disubstituted 5,6-Dihydro-1,3-dimethyluracils and Their Transformation to 6-Substituted 1,3-Dimethyluracils, trans-5,6-Disubstituted 5,6-Dihydro-1,3-dimethyluracils, and 4,5,5-Trisubstituted 3-Methyloxazolizin-2-ones.
abstract: The electroreductive coupling of 1,3-dimethyluracil, thymine, and 5-fluorouracil with aromatic ketones in the presence of TMSCl gave 6-substituted and cis-5,6-disubstituted 5,6-dihydro-1,3-dimethyluracils. The dehydrotrimethylsiloxylation of the adducts afforded 6-substituted and 5,6-fused 1,3-dimethyluracils. The detrimethylsilylation of the adducts with TBAF or 1 M HCl-MeOH gave 4,5,5-trisubstituted 3-methyloxazolizin-2-ones or 3-methyloxazolizin-2-imines in addition to simply desilylated alcohols. The cis-5,6-disubstituted 5,6-dihydro-1,3-dimethyluracils were isomerized to the corresponding trans-isomers by heating in the presence of cat. DMAP. The cis- and trans-5,6-disubstituted 5,6-dihydro-1,3-dimethyluracils were assigned by the coupling constants J5,6 of their (1)H NMR spectra.
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University , 4-101, Koyama-cho Minami, Tottori 680-8552, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Kise
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University , 4-101, Koyama-cho Minami, Tottori 680-8552, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hamada
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University , 4-101, Koyama-cho Minami, Tottori 680-8552, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Sakurai