Aprotic pyridinium ions incorporating electron-withdrawing substituents
on the aromatic ring are powerful catalysts for the acetalization of
aldehydes and the formation of dithianes, dithiolanes, dioxanes,
and dioxolanes. Under optimum conditions the best catalyst can be
used at a loading as low as 0.1 mol% and can outperform
a Brønsted acid catalyst with a pK
a of
2.2.
organocatalysis - catalysis - aldehydes - acetals - dithianes
