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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]

New Ir complexes bearing N-(methylsulfonyl)-2-pyridinecarboxamide (C1) and N-(phenylsulfonyl)-2-pyridinecarboxamide (C2) were employed as catalysts for aqueous formic acid dehydrogenation (FADH). The ligands were designed to maintain the picolinamide skeleton and introduce strong sigma sulfonamide moieties. C1 and C2 exhibited good stability towards air and concentrated formic acid (FA). During 20 continuous cycles, C1 and C2 could achieve the complete conversion of FA with TONs of 172 916 and 172 187, respectively. C1 achieved a high TOF of 19 500 h−1 at 90 °C and an air-stable Ir–H species was observed by 1H NMR spectroscopy. [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]