Obradors C,
List B.
*
Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
Azine Activation via Silylium Catalysis.
J. Am. Chem. Soc. 2021;
DOI:
10.1021/jacs.1c03257
Key words
silylium catalysis - C–C bond formation - Lewis acid catalysis
Significance
Obradors and List report a nucleophilic addition to nitrogen-based heterocycles through
silylium activation for C−C bond formation. The silylated catalyst, formed in situ
by deprotosilylation of a Brønsted acid with a silylated nucleophile, coordinates
to the heterocyclic substrates, activating them toward nucleophilic attack to produce
the corresponding dihydropyridine derivatives. In situ oxidation with an oxidant gives
the functionalized azines in moderate to excellent yield for a variety of functionalized
and, notably, unfunctionalized substrates.
Comment
N-Heteroaromatics are motifs widely present in many natural products, agrochemicals,
and pharmacophores. However, direct functionalization of these molecules typically
requires transition-metal catalysis, preactivation of the substrates, strong bases,
and harsh reaction conditions. The present method involving the use of a highly reactive
silylated catalyst permits the use of N-heteroaromatics for selective C-4 functionalization
under mild reaction conditions.
