111170-67-3Relevant academic research and scientific papers
Asymmetric Alkylation of β-Keto Esters with Optically Active Sulfonium Salts
Umemura, Kazuyuki,Matsuyama,Haruo,Watanabe, Nobuko,Kobayashi, Michio,Kamigata, Nobumasa
, p. 2374 - 2383 (2007/10/02)
Alkylation of the cyclic β-keto ester2-(methoxycarbonyl)-1-indanone (2) with racemic alkylsulfonium salts 1a-h gave 2-alkylindanones 3 and 4 in 60-96percent yields.The relative reactivities of the alkyl substituents of aryldialkylsulfonium salts 1e and 1f were quite different from those in SN2 alkylations.Asymmetric induction occured upon alkylation of 2 with optically active sulfonium salts. (R)-2-Ethyl-2-(methoxycarbonyl)cyclohexanone (11) was obtained in up to 16percent ee by alkylation of the enolate ion of 2-(methoxycarbonyl)cyclohexanone (9) with optically active (R)-(+)-(p-chlorophenyl)ethylmethylsulfonium d-10-camphorsulfonate (1k).Alkylation of the enolate ion of 2 with sulfonium salts containing optically active alkyl groups afforded C-alkylated products with inversion of configuration at the asymmetric alkyl carbon atom.These alkylations appear to proceed via an S-O sulfurane intermediate or a tight ion pair with subsequent stereoselective alkyl migration to the enolate.
Studies on the Stereochemistry in the Alkylation of Enolate Ion of Cyclic β-Keto Ester with Sulfonium Salts Containing Optically Active Alkyl Groups
Kobayashi, Michio,Umemura, Kazuyuki,Matsuyama, Haruo
, p. 327 - 328 (2007/10/02)
Alkylation of cyclic β-keto ester with racemic sulfonium salts containing optically active alkyl groups such as (S)-2-octyl and (S)-2-butyl was found to afford C-alkylated products with inversion of configuration at asymmetric alkyl carbon atom.Stereochemical reaction course via formation of S-O sulfurane intermediate and succesive stereoselective intramolecular alkyl migration to enolate is described.
