Enantioselective Synthesis of Spiro Heterocycles

This chapter reviews catalytic synthetic methods allowing enantioselective construction of spiro heterocyclic compounds, excluding oxindole motif. It discusses the enantioselective methods for the construction of spirocycles with one heteroatom, such as nitrogen-containing heterocycles (pyrrolidine, indolizine, and piperidine), oxygen- and sulfur-containing heterocycles (furanone, benzofuranone, and pyrane). N-Heterocyclic carbene catalysis can be used for the enantioselective synthesis of spiroindolenines. Among catalytic approaches, asymmetric organocatalysis predominates in the preparation of chiral sulfur-containing spiro compounds. The organic chemists have studied catalytic approaches to synthesize chiral spirocyclic compounds containing more than one spiro atom; some of them led to structurally valuable substances. The chapter presents synthetic strategies for the preparation of chiral spirocycles containing more than one heteroatom, including pyrazolones, azlactones, barbituric acid derivatives, sultams. It also presents catalytic methods for enantioselective preparation of other types of spiro heterocycles and bispiro compounds.