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

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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 a very unusual 1,7-hydrogen atom transfer within a ruthenium nitrenoid intermediate. The method is applicable to the synthesis of non-racemic chiral mono-, di- and trisubstituted cyclic alkylene carbonates.