Oxindole and spirooxindole

This chapter is a survey of recent works in the general area of oxindole and spirooxindole synthesis with specific attention on strategies for the installation of the C3 quaternary centers that characterize members of this unique family of indole alkaloids. As investigations that have resulted in modest observed selectivities represent important opportunities for further synthetic advancement, those studies will be described alongside illustrations of chemical technologies that represent the state of the art of the discipline. 

Additional examples of synthetic applications of hypervalent iodine-induced heterocyclizations include the following the metal-free one-pot synthesis of 2-acylbenzothiazoles by oxidative cyclization of multiform substrates [434], iodine(III)-mediated tandem oxidative cyclization for construction of 2-nitrobenzo[ ]furans [435], hypervalent iodine mediated oxidative cyclization of o-hydroxystilbenes into benzo- and naphthofu-rans [436], PhI(OCOCF3)2-mediated synthesis of 3-hydroxy-2-oxindoles and spirooxindoles from anilides [437], synthesis of isoxazoles by hypervalent iodine-induced cycloaddition of nitrile oxides to alkynes [438],... 

For important reviews abont 3,3 -disnbstitnted oxindole strnc-tural motif, see (a) F. Zhou, Y.-L. Liu, J. Zhou, Adv. Synth. Catal. 2010, 352, 1381-1407. Catalytic asymmetric synthesis of oxindoles bearing a tetrasubstituted stereocenter at the C-3 position, (b) J. J. BadiUo, N. V. Hanhan, A. K. Franz, Curr. Opin. Drug Discov. Dev. 2010, 13, 758-776. Enantioselective synthesis of substituted oxindoles and spirooxindoles with applications in drug discovery, (c) A. Kumar, S. S. Chimni, RSC Advances 2012, 2, 9748-9762. Catalytic asymmetric synthesis of hydroxyoxindole a potentially bioactive molecule, (d) S. Mohammadi, R. Heiran, R. P. Herrera, E. Marques-L6pez,... 

Scheme 8 PIFA-mediated synthesis of oxindoles and spirooxindoles...

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