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, a related newly developed Cu(I)-mediated synthesis of 2,3-disubstituted pyrroles by the reaction of copper acetylides derived from unactivated terminal alkynes with substituted methyl isocyanides is described (11 examples, 5-88% yield).
Lygin
Alexander V
AV
Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany.
Larionov
Oleg V
OV
Korotkov
Vadim S
VS
de Meijere
Armin
A
D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D003486:Cyanides / Q000138:chemical synthesis* / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry
D000480:Alkynes; D003486:Cyanides; D011758:Pyrroles; D003300:Copper