Asymmetric copper-catalysed intramolecular C-H insertion reactions of α-diazo-β-keto sulfones.

Asymmetric copper-catalysed intramolecular C-H insertion reactions of a series of α-diazo-β-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.