Oligosubstituted Pyrroles Directly from Substituted Methyl Isocyanides and Acetylenes

The formal cycloaddition of alpha-metallated methyl isocyanides 1 onto the triple bond of electron-deficient acetylenes 2 represents a direct and convenient approach to oligosubstituted pyrroles 3. The scope and limitations of this reaction (24 examples, 25-97% yield) are reported along with an optimization of the reaction conditions and a rationalization of the mechanism. in addition, it related newly developed Cu-1-mediated synthesis of 2.3-disubstituted pyrrole by the reaction of copper acetylides derived from unactivated terminal alkynes with Substituted methyl isocyanides is described (11 examples, 5-88% yield).