Palladium-Catalyzed Atom-Economical Synthesis of Pyrroles

Significance

Reported is the synthesis of substituted pyrroles from propargyl amines 1 and terminal acetylenes 2 under palladium-catalyzed conditions. The intermediate enynes 3 may be isolated in good yield and further converted into pyrroles 4. Alternatively, a two-stage, one-pot process delivers the pyrroles 4 in a single step. Functionalization of isopyrrole intermediates 5 and 7 was also reported using ene-type additions (5 → 6) or further palladium-catalyzed cross-coupling reactions (7 → 8).