A base mediated aerobic oxidation of alkyl benzimidazoles for the preparation of carboxylic acid. A number of aliphatic carboxylic acids have been prepared in good to excellent yields via C–C bond rupture processes. Preliminary mechanistic studies suggested the reaction underwent a radical pathway initiated by strong bases such as potassium amide. This type of transformation provides an alternative strategy for the access of important carboxylic acid moieties.
Chiral ligands are the footstones for asymmetric synthesis constructing the enantio-enriched molecules that are widely used in material and medicinal sciences. Nature occurring compounds, such as proline analogues and cinchona alkaloids, were widely used as privileged ligands in asymmetric synthesis. Sparteine, a natural alkaloid firstly reported in 1968, was also employed in asymmetric synthesis albeit with less satisfactory results. In this perspective, transition metal-involved asymmetric transformations using sparteine or the family members as ligands are overviewed and discussed. The design and perspective on ligands with similar skeleton are also proposed.
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