Catalytic Asymmetric [4+1] Cyclization of ortho-Quinone Methides with 3-Chlorooxindoles

In this work, we established catalytic asymmetric [4+1] cyclization of ortho-quinone methides (o-QMs) with 3-chlorooxindoles and a catalytic asymmetric domino oxidation/[4+1] cyclization reaction of 2-alkylphenols with 3-chlorooxindoles, which constructed a spirooxindole-based 2,3-dihydrobenzofuran scaffold in good yield (up to 97%), with excellent diastereoselectivity (up to > 95: 5 dr) and high enantioselectivity (up to 99% ee). This work is not only the first highly enantioselective [4+1] cyclization of o-QMs but has also realized the first catalytic asymmetric domino [4+1] cyclization of o-QMs. In addition, both of the reactions provide efficient stereoselective methods for constructing spirooxindole-based 2,3-dihydrobenzofuran scaffolds with optical purity.