The rhodium(III)-catalyzed redox-neutral coupling reaction of N-acyl ketimines generated in situ from 3-hydroxyisoindolinones with various activated olefins is described. This approach leads to the synthesis of bioactive spiroisoindolinone derivatives in moderate to high yields. In the case of internal olefins such as maleimides, maleates, fumarates, and cinnamates, spiroindanes were obtained by the [3 + 2] annulations reaction. In sharp contrast, acrylates and quinones displayed the β-H elimination followed by Prins-type cyclization furnishing spiroindenes. The synthetic compounds were evaluated for in vitro anticancer activity against androgen-sensitive human prostate adenocarcinoma cells (LNCaP), human prostate adenocarcinoma cells (DU145), human endometrial adenocarcinoma cells (Ishikawa), human breast cancer cell (MCF-7), and triple negative human breast cancer cells (MDA-MB-231). Notably, quinone-containing spiroindenes displayed potent anticancer activity about 2- to 3-fold stronger than that of anticancer agent doxorubicin.

The site‐selective C−H amination reaction of 7‐azaindoles with various benzisoxazoles as amination surrogates under cationic rhodium(III) catalysis is described. This transformation efficiently provides a range of ortho‐aminated N‐aryl‐7‐azaindoles with excellent site‐selectivity and functional group compatibility. The formed ortho‐aminated 7‐azaindoles were readily transformed into biologically relevant heterocycles such as azaindoloacridine, azaindoloacridone, and bis‐indole compounds. Moreover, the synthetic derivatives were tested for in vitro anticancer activity against human breast adenocarcinoma cells (MCF‐7), human renal carcinoma cells (786‐O), and human prostate adenocarcinoma cells (DU145). Notably, some synthetic compounds were found to display most potent anticancer activity, compared to that of anticancer doxorubicin as a positive control.

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The rhodium(III)-catalyzed site-selective CÀH alkylation of azobenzenes and internal olefins, such as maleimides, maleates and fumarates, followed by reductive intramolecular cyclization is described. A cationic rhodium catalyst in the presence of acetic acid additive in dichloroethane solvent was found to be the optimal catalytic system for the construction of ortho-alkylated azobenzenes, which smoothly underwent the intramolecular cyclization leading to the formation of C3-functionalized oxindoles in the presence of zinc powder and acetic acid. The formed oxindole scaffold could be an important asset towards the development of novel bioactive compounds.

The rhodium­(III)-catalyzed direct C–H functionalization of various indolines with 1,4,2-dioxazol-5-ones as new amidating agents is described. This transformation provides efficient preparation of C7-amidated indolines known to display potent anticancer activity. The synthetic compounds were evaluated for in vitro anticancer activity against human prostate adenocarcinoma cells (LNCaP), human endometrial adenocarcinoma cells (Ishikawa), and human ovarian carcinoma cells (SKOV3). Compound 4f was found to be highly cytotoxic, with activity competitive with that of anticancer agent doxorubicin.