Mono, di, tri and tetra spiro heterocyclic compounds: Recent advances

Isatins and its C-3 functionalized derivatives occupy a conspicuous place in organic synthesis and medicinal chemistry. N-substituted isatins, and isatins with different substituents on a phenyl ring have been employed in two, three or four-component reactions leading to the formation of five and six membered spiro-heterocyclic frameworks bearing a 2-oxindole moiety. The development of diastereo and enantioselective methodologies containing two to four stereocenters for the synthesis of spiro-f ...