Asymmetric Copper-Carbenoid O-H Insertion with Water

Significance

Fu and co-worker have recently described the copper-catalyzed enantioselective O-H insertion of various alcohols to generate α-hydroxy carbonyl compounds (J. Am. Chem. Soc. 2006, 128, 4594). However, very few catalytic, asymmetric examples describing O-H insertions with water have been described. In the present study, the authors report that a chiral spiro bisoxazoline copper complex effectively catalyzes the insertion of various α-diazoesters in the O-H bond of water to afford the corresponding α-hydroxy esters in high yields and enantioselectivities. The results from a competitive reaction between H₂O and D₂O indicated a predominant (72%) H₂O insertion product, which agrees with Fu’s earlier mechanism.