Highly enantioselective carbene insertion into N–H bonds of aliphatic amines

A tag team approach to forming C–N bonds Many pharmaceutical compounds contain carbon-nitrogen (C–N) bonds in just one of two mirror-image orientations. Forging these bonds with electron-rich nitrogen reactants is challenging because the nitrogen groups can coordinate with, and thus interfere with, the catalyst. Li et al. report a cooperative approach to overcoming this obstacle (see the Perspective by Ovian and Jacobsen). They used a copper catalyst to activate the carbon reactant and then a hydrogen-bonding thiourea catalyst to set the product geometry with high selectivity. The reaction is compatible with a broad range of diazo ester and amine coupling partners. Science , this issue p. 990 ; see also p. 948