“…Due to the constrained structure of spiro compounds, the existence of the chiral central spiro carbon and the indole core represents an interesting pharmacophore, and these compounds show a wide range of biological and pharmacological activities. 9 Furthermore, a broad range of natural alkaloids contain well-known spirooxindole moieties, such as formosanine, 4 pteropodine, 5 coerulescine, 6 strychnofoline, 7 rychnophyilline, 4 and alstonisine, 8 with highly pronounced proved pharmacological properties ( Fig. 1 ).…”