Catalytic Asymmetric [3 + 2] Cyclization Reactions of 3‑Isothiocyanato Oxindoles and Alkynyl Ketones Via an in Situ Generated Magnesium Catalyst

A highly
enantioselective formal [3 + 2] cycloaddition reaction
between 3-isothiocyanato oxindoles and alkynyl ketones is reported
for the first time. An oxazoline–OH type chiral ligand derived
from o-hydroxy-phenylacetic acid is employed to generate
an effective magnesium catalyst in the current cyclization reaction
and give serials of chiral spirooxindoles with good chemical yields
and enantioselectivities.