New efficient, flexible and regioselective synthesis of 2,4-Di- and 2,3,4-trialkylated and arylated 1H-pyrroles

Article abstract of DOI:10.1002/jlac.199619961011

Starting from easily available 2-acetoxy aldehyde dimethylhydrazones rac-2, we prepared various alkyl- and aryl-substituted 1H-pyrroles 6 in good overall yield. The titanium-mediated a²-umpolung reaction of rac-2 with different acyclic and cyclic silyl enol ethers 3 leads directly or via 4-oxo hydrazones rac,anti-4 to 1-(dimethylamino)-1H-pyrroles 5. A novel method for the reductive removal of the dimethylamino group affording 1H-pyrroles 6 is presented. VCH Verlagsgesellschaft mbH, 1996.