Asymmetric oxidation of chiral enolates in the preparation of acyclic tertiary .alpha.-hydroxy amides in high optical purity

Asymmetric hydroxylation of enolates with N-sulfonyloxaziridines

“…In studies directed toward the asymmetric synthesis of 58, the AB ring of the antitumor antibiotic aklavinone (57), Meyers and Higashiyama isolated 60 as a single diastereomer in 54% yield on oxidation of the sodium enolate of 59 with (±)-la.59 57 58…”

Synthesis of Derivatives of (1R)-(-)- and (1S)-(+)-10-Camphorsulfonic Acid

“…The use of camphorylsulfonyloxaziridine, a Davis reagent, for synthesis of chiral compounds is of current interest (3). The oxaziridines are known to be excellent hydroxylating agents and have been shown to be effective with ketones (4 ), esters (5), amides (6 ), phosphonates (7), and other activated methylene positions (8). Enantioselective syntheses of αhydroxy carbonyl compounds have been reported that are based on oxidations with enantiomerically pure oxaziridines.…”

Addition–Rearrangement of Ketenes with Lithium N-tert-Butanesulfinamides: Enantioselective Synthesis of α,α-Disubstituted α-Hydroxycarboxylic Acid Derivatives

“…In contrast, asymmetric α-oxygen–functionalization of common acyclic α,α-disubstituted carbonyls is challenging. This reflects the difficulty with which these compounds form the corresponding stereodefined enolates as well as the sometimes poor enantio-discrimination between the re and si faces of these enolates . Nevertheless, Davis and co-workers achieved some success in such functionalizations using double-asymmetric induction involving diastereoselective oxidation of chiral acyclic, polysubstituted enolates with chirality-matched camphorylsulfonyl oxaziridines.…”

“…This reflects the difficulty with which these compounds form the corresponding stereodefined enolates as well as the sometimes poor enantio-discrimination between the re and si faces of these enolates . Nevertheless, Davis and co-workers achieved some success in such functionalizations using double-asymmetric induction involving diastereoselective oxidation of chiral acyclic, polysubstituted enolates with chirality-matched camphorylsulfonyl oxaziridines. Subsequently, several examples of enantioselective construction of tertiary α-hydroxy carbonyls via oxidation of stereodefined acyclic enolates or their analogues have been reported. − …”