A New Organocatalytic Domino Sequence

Significance

The authors report the highly selective, secondary amine catalyzed domino reaction of aldehydes 1 and iodo-nitropentenes 2 affording cyclic γ-nitroaldehydes 3. The multistep sequence starts with a Michael addition of enamine 4 to the iodo-nitropentene 2. The resulting iminium ion 5 can undergo isomerization to furnish enamine 6. This species is prone to intramolecular alkylation to form iminium ion 7, which liberates the catalyst and the product upon hydrolysis.