One-pot four-component domino reaction for the synthesis of bifunctionalized spiro[indazolo[3,2-b]quinazoline-7,3′-indoline hybrids: A green approach

An efficient tandem route to obtain novel spiro[indazolo[3,2-b]quinazoline-7,3′-indolines has been explored. The one-step domino reaction proceeds via in situ generation of the 1H-indazol-3-amines followed by its reaction with the cyclic 1,3-dicarbonyls and isatin derivatives to furnish complex N-fused spiro-polyheterocyclic frameworks. This protocol describes a valuable route to concisely and feasibly obtain spiro[indazolo[3,2-b]quinazoline-7,3′-indolines from isatin derivatives. The present protocol is particularly attractive because of the following features: group-assisted-purification (GAP) chemistry process, low-cost solvent, convenience of operation, excellent atom economy, and high yields.