Catalytic Enantioselective Intramolecular C(sp3 )-H Amination of 2-Azidoacetamides.

An enantioselective ring-closing C(sp3 )-H amination of 2-azidoacetamides is catalyzed by a chiral-at-metal ruthenium complex and provides chiral imidazolidin-4-ones in 31-95 % yield, with enantioselectivities of up to 95 % ee, and at catalyst loadings down to 0.1 mol % (turnover number (TON)=740). To our knowledge, this is the first example of a highly enantioselective C(sp3 )-H amination with aliphatic azides. Mechanistic experiments reveal the importance of the amide group, which presumably enables initial bidentate coordination of the 2-azidoacetamides to the catalyst. DFT calculations show that the transition state leading to the major enantiomer features a better steric fit and favorable π-π stacking between the substrate and the catalyst framework.