Microwave synthesis of Melatonin

[Rhodium]

Microwave Assisted Synthesis of Melatonin

Synthetic Communications Vol. 33, No. 5, pp. 741–747 (2003)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/melatonin.microwave.pdf)

Abstract

Melatonin was prepared from phthalimide by N- and C-alkylation, cyclization, hydrolytic, decarboxylation, and acetylation. The four-pot reactions were carried out on microwave irradiation in good yield with short time.

[Greensnake]

Ok, could anybody explain reaction step from 2 to 3, something rather fishy there. (I would believe in Japp-Klingeman reaction , but then it use diazonium salt, not arylhydrazine - yet another example of "not very accurate" research paper?)