An Efficient and Environmentally Benign Four-component Domino Protocol for Synthesis of Spirooxindoles Spiroannulated with Fused Heterosystems of Privileged Heterocycles

An efficient and environmentally benign one- pot four-component domino protocol has been presented for the synthesis of structurally diverse spirooxindoles spiroannulated with chromenopyrazolophthalazines, indazolophthalazines and pyranopyrazolophthalazines involving the reaction of phthalic anhydride, hydrazine hydrate, isatins and cyclic ketones in aqueous alcoholic medium (H2O-C2H5OH: v 5:1) using catalytic amount of sulphamic acid.