Stereoselective Synthesis of 1-Methyl-3',4',5',6'-tetrahydrospiro[indoline-3,2'-pyran]-2-one Derivatives via Prins Cyclization.

A novel spirocyclization has been developed for the construction of functionalized spirooxindole pyran via Lewis acid promoted Prins cyclization. The reaction proceeds through formation of a single diastereoisomer with high stereoselectivity. This approach can be used to construct biologically important substituted spirooxindole as well as fluorinated pyran scaffolds.