Nitrene‐Mediated C−H Oxygenation: Catalytic Enantioselective Formation of Five‐Membered Cyclic Organic Carbonates

The synthesis of non‐racemic 5‐membered cyclic carbonates from abundant alcohols is reported. Conversion of the alcohol into an azanyl carbonate is followed by a chiral‐at‐ruthenium catalyzed cyclization to provide chiral cyclic carbonates in yields of up to 95 % and with up to 99 % ee. This new synthetic method is proposed to proceed through a nitrene‐mediated intramolecular C(sp(3))−H oxygenation which includes an unusual 1,7‐hydrogen atom transfer within a ruthenium nitrene intermediate. The method is applicable to the synthesis of non‐racemic chiral mono‐, di‐ and trisubstituted cyclic alkylene carbonates.