Catalyst-Controlled Straightforward Synthesis of Highly Substituted Pyrroles/Furans via Propargylation/Cycloisomerization of α-Oxoketene-N,S-acetals.

A facile and efficient InCl3 catalyzed one-pot synthesis of highly substituted pyrroles has been developed via a tandem propargylation/cycloisomerization reaction of α-oxoketene-N,S-acetals with propargyl alcohols. Notably, in the presence of Bronsted acid p-TSA·H2O, the reaction afforded the hydrolyzed product propargylated-1,3-dicarbonyl compounds, which upon treatment with Cs2CO3 underwent regioselective intramolecular cyclization furnishing tetrasubstituted furan derivatives.