“…Shaabani's research group in 2012 developed the synthesis of structurally diverse 1H-pyrazolo[1,2-b]phthalazine-1,2dicarboxylates ( 257) via a four-component reaction of PA (1), hydrazine hydrate (56), dialkyl acetylenedicarboxylates (17), and isocyanides (196) in ethanol/acetone (1 : 1) at room temperature in good to moderate yields (Scheme 97). 228 Kumar's research group in 2013 presented one-pot fourcomponent protocol for the synthesis of structurally diverse spirooxindoles, spiroannulated with chromenopyrazolophthalazines/pyranopyrazolophthalazines/ indazolophthalazine (262,263,264) from the reaction of PA (1), hydrazine hydrate (56), isatins (258), and cyclic ketones [4hydroxy-2H-chromen-2-one (259), 4-hydroxy-6-methylpyran-2one (260), dimedone (261)] in aqueous alcoholic medium (H 2 O/C 2 H 5 OH, 5 : 1) using catalytic amounts of sulphamic acid (SA) (Scheme 98). 229 The reaction mechanism is considered to involve acid-catalyzed Knoevenagel condensation, Michael-type addition reaction, and consequent intramolecular dehydrative cyclization to obtain the pure products via recrystallization from ethanol.…”