$$\hbox {FeCl}_{3}$$ FeCl 3 -catalyzed $$[3{+}3]$$ [ 3 + 3 ] annulation between 3-oxirane-indolin-2-ones and nitrones to construct spiro[1,4,2-dioxazinan]oxindoles

Syntheses and reactivity of spiro-epoxy/aziridine oxindole cores: developments in the past decade

This review highlights various reactions to afford spiro-epoxy/aziridine oxindoles and their potential synthetic transformations.

Synthesis of CF3-containing spiro-epoxyoxindoles via the Corey–Chaykovsky reaction of N-alkyl isatins with Ph2S+CH2CF3OTf−

CF₃-containing spiro-epoxyoxindoles were successfully prepared via Corey–Chaykovsky reaction of N-alkyl isatins with the ylide generated from Ph₂S⁺CH₂CF₃OTf⁻ with almost exclusive diastereoselectivity.

Total Syntheses of (±)-Rhodonoids C, D, E, F, and G and Ranhuadujuanine B

Here we describe the divergent, biosynthetically inspired syntheses of (±)-rhodonoids C-G and (±)-ranhuadujuanine B. The key steps of the syntheses include the construction of the chromene unit through a formal oxa-[3 + 3] annulation and a biomimetic acid-catalyzed ring cyclization. Cationic [2 + 2] cycloaddition is accomplished to form the cyclobutane core of (±)-rhodonoids E and F.