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DOI: 10.1055/s-0033-1340457
Asymmetric Formal Insertion of Diazo Esters into Aryl–CHO Bonds
Publication History
Publication Date:
13 December 2013 (online)

Significance
The authors developed an oxazaborolidinium ion catalyzed asymmetric formal C–C bond insertion of diazo esters into aryl–CHO bonds to give functionalized acyclic all-carbon α-quaternary aldehydes in good yields (up to 83%) and excellent enantioselectivities (up to 99%). The products were transformed into synthetically useful α- and β-amino esters with ease.
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Comment
Contrary to the Roskamp reaction, the 1,2-aryl shift is preferred over the 1,2-hydride shift. It is the first catalytic asymmetric report of such a reaction. A variety of diazo esters and aldehydes were explored emphasizing synthetic flexibility. However, the regioselectivities are rather moderate (up to 88:12). Recently, Feng and co-workers reported a similar 1,2-aryl shift for the asymmetric homologation of α-keto esters (Angew. Chem. Int. Ed. 2013, 52, 10883).
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