Catalytic Asymmetric [3+2] Cyclization Reactions of 3-lsothiocyanato 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-hydroxyphenylacetic acid is employed to generate an effective magnesium catalyst in the current cyclization reaction and give serials of chiral spirocodndoles with good chemical yields and enantioselectivities.