Copper-catalysed enantioselective intramolecular C–H insertion reactions of α-diazo-β-keto esters and α-diazo-β-keto phosphonates

Copper-catalysed intramolecular C–H insertion reactions of α-diazo-β-keto esters and α-diazo-β-keto phosphonates are described, with moderate-to-good levels of enantioselectivity achieved for reactions employing the borate additive sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBARF). Notably, the first example of asymmetric induction reported to date for intramolecular C–H insertion of an α-diazo-β-keto phosphonate is also described.