• The first stage of this reaction, to start the formation of the reagent for the second half, goes by an E1 mechanism.
• The reagent for the conjugate addition step which has been formed in the first part of the reaction is called acrolein.
• In the second half of the reaction a conjugate addition begins the mechanism. The first half simply forms the reagent.
• Ring closure comes from an electrophilic aromatic substitution reaction. This is followed by an E2 elimination.
• The reagent for the loss of H₂ at the end of the reaction is PhNO₂.
• Isoquinoline can be formed by the Bischler-Napieralski reaction.
• An alternative reaction mechanism for the Skraup process is called the Doebner-Von Miller reagaction. It goes via an intermolecular [2+2] cycloaddition.
  
  
  References:
• Theoclitou M-E.; Robinson L.A.; Tetrahedron Letters, 2002, Volume 43, Issue 21, 3907-3910
• O'Neill P.M.; Storr R.C.; Park B.K.; Tetrahedron, 1998, Volume 54, Issue 18, 4615-4622