“…In 2016, Mohammadi and co-workers have synthesized 1 H -imidazol[1,2- a ]indeno[2,1- e ]pyridine-6(5 H )-one derivatives via a one-pot four-component condensation of aldehydes, 1,3-indandione, diamine, and nitro ketene dithioacetal using KAl(SO 4 ) 2 .12H 2 O (alum) in good to excellent yields 31 . In 2017, Mohammadi et al have described a one-pot four-component, and efficient method by reaction of isatins, 1,3-indandione, diamine, and nitro ketene dithioacetal in the presence of Alum as a green catalyst for the synthesis of 4-nitro-2,3-dihydrospiro[imidazo[1,2- a ]indeno[2,1- e ]pyridine-5,3 ' -indoline]-2 ' ,6(1 H )-dione derivatives in good yields 32 .…”