Barton-Zard Pyrrole Synthesis is the process of preparing substituted pyrrole by condensing substituted nitroalkenes with an isocyanoester.

  1. One alpha hydrogen is removed by the base to form a conjugate base.
  2. The conjugate base then add with the double bond opposite to the nitro site.
  3. The negative charge of the carbanion thus produced, combine with the Carbon atom of -CN group.
  4. After the ring closure, the negatively charged double bond accept proton to become neutral.
  5. From the other side of the nitrogen, one alpha hydrogen is removed by the base.
  6. This negative charge now gets delocalised, and ultimately leaves the nitro group from the molecule.
  7. Finally rearrangement of double bonds occur.
Barton-Zard Pyrrole Synthesis