Heterocycles via SiCl4-Promoted Isocyanide Additions to Oxonitriles.

ABSTRACT

SiCl4 promotes isocyanide additions to oxoalkenenitriles to selectively generate 3-acylpyrroles, 2-aminofurans, or pyrrolidinones. Cyclic oxoalkenenitriles add 2 equiv of an isocyanide that installs the two core atoms of an acylpyrrole and a nitrile substituent, whereas acyclic oxoalkenenitriles add 1 equiv of an isocyanide to afford 2-aminofurans; subsequent air oxidation generates pyrrolidinones via a furan oxygenation-cleavage-cyclization sequence. The syntheses proceed under mild conditions to rapidly access three richly decorated heterocycles.