jo6b00670_si_004.cif (23.85 kB)
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
dataset
posted on 2016-05-12, 00:00 authored by Naoki Kise, Yusuke Hamada, Toshihiko SakuraiThe 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 1H NMR spectra.