Asymmetric copper-catalysed intramolecular C-H insertion reactions of alpha-diazo-beta-keto sulfones

Asymmetric copper-catalysed intramolecular C-H insertion reactions of a series of alpha-diazo-beta-keto sulfones are reported. Enantioselectivities of up to 82% ee were achieved in moderate to good yield. These results represent the highest level of enantiocontrol achieved to date for a copper-catalysed cyclopentanone synthesis via C-H insertion.