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A chiral N,N′-dioxide/Co(BF4)2·6H2O complex catalytic system has been developed to efficiently catalyze the asymmetric 1,3-dipolar cycloaddition of nitrones with methyleneindolinones. The corresponding chiral multisubstituted spiroisoxazolidines with three contiguous quaternary–tertiary stereocenters were obtained in moderate to high yields with excellent dr and ee values (up to 97% yield, ＞19 : 1 dr and 98% ee). [ABSTRACT FROM AUTHOR]

The highly efficient catalytic asymmetric inverse-electron-demand hetero-Diels–Alder reaction of methyleneindolinones with hetero-substituted alkenes has been accomplished under mild reaction conditions. In the presence of chiral N,N′-dioxide/Ni(ii) complexes, a wide range of optically active dihydropyran-fused indoles were obtained in up to 99% yield, ＞95 : 5 dr and 99% ee. [ABSTRACT FROM AUTHOR]