Synthesis of Spiro[indole-3,5'-isoxazoles] with Anticancer Activity via a Formal (4+1)-Spirocyclization of Nitroalkenes to Indoles

An acid-assisted (4+1)-cycloaddition of indoles with nitrostyrenes affords 4'H-spiro[indole-3,5'-isoxazoles] in a diastereomerically pure form. Several of these spirocyclic molecules exhibit promising anti-cancer activity by reducing viability and inducing differentiation of neuroblastoma cells.