Studies on the structure-enantioselectivity relationships in the catalytic asymmetric intramolecular cyclopropanation reaction of α-diazo-β-keto sulfones possessing a methyl-substituted phenyl group

This manuscript describes studies on structure-enantioselectivity relationships in the catalytic asymmetric intramolecular cyclopropanation (IMCP) reaction of α-diazo-β-keto sulfones possessing a methyl-substituted phenyl group. Enantioselectivity of the IMCP reaction of the α-diazo-β-keto sulfones was varied by the position of a methyl group on the phenyl group in the substrate, and the 2,3-dimethylphenyl sulfone 11h provided the product 12h in 95% yield with 93% ee. This yield is superior to that of the substrate with a mesityl sulfone 11b, and the product 12h is useful because alkylation of its cyclopropane-opened β-keto sulfone derivative 15h provides the C-alkylated product as a major product.