Fig. 5. Key intermediates and products detected (and characterised) by ESI(+)-MS: (A) C₇H₁₃CuN₂O₂ ⁺; (B) C₁₄H₁₈N₂O₃ ⁺; (C) C₂H₇CuN₄O₂ ⁺; (D) C₁₂H₁₉CuO₆ ⁺; (E) iminium intermediate C₈H₉N₂O⁺; and (F) C₁₄H₁₇N₂O₃ ⁺. Reprinted with permission from ref. 112. Copyright (2012) American Chemical Society.