Asymmetric generation of fluorine-containing quaternary carbons adjacent to tertiary stereocenters: uses of fluorinated methines as nucleophiles
作者:Xiao Han、Jie Luo、Chen Liu、Yixin Lu
DOI:10.1039/b823184b
日期:——
Organocatalytic asymmetric Michael reactions of fluorinatednucleophiles with nitroolefins catalyzed by Cinchona alkaloid-derived thiourea catalysts generated the desired Michael products containing vicinal fluorinated quaternary and tertiary chiral centers with exceptional enantioselectivity.
Organocatalytic synthesis of quaternary stereocenter bearing a fluorine atom: enantioselective conjugate addition of α-fluoro-β-ketoesters to nitroalkenes
作者:Yeonock Oh、Sun Mi Kim、Dae Young Kim
DOI:10.1016/j.tetlet.2009.06.003
日期:2009.8
The catalytic enantioselective conjugateaddition reaction of α-fluoro-β-ketoesters to nitroalkenespromoted by chiral bifunctional organocatalysts is described. The treatment of α-fluoro-β-ketoesters with nitroalkenes under mild reaction conditions afforded the corresponding Michael adducts containing a fluorinated quaternary stereogenic center with excellent enantioselectivity (up to >99% ee).
Enantioselective Alkylation of α-Fluoro-β-Keto Esters by Asymmetric Phase-Transfer Catalysis
作者:Keiji Maruoka、Changhua Ding
DOI:10.1055/s-0028-1087813
日期:2009.3
Highly enantioselective alkylation of tert-butyl α-fluoro-β-keto esters can be effected by the use of N-spiro chiral quaternary ammonium salt as chiral phase-transfer catalyst, as a complementary approach to the asymmetric fluorination of α-alkyl-β-keto esters.
Primary−secondarydiaminecatalysts were used to catalyze the asymmetric Robinson annulation to synthesize multiply substituted fluorinated chiral cyclohexenones with two contiguous stereogenic centers, one of which is a fluorinated quaternary chiral center, with excellent enantioselectivities and diastereoselectivities in moderate to good yields.
Binaphthyl-Modified Quaternary Phosphonium Salts as Chiral Phase Transfer Catalysts: Application to Asymmetric Amination of β-Keto Esters
作者:Keiji Maruoka、Rongjun He
DOI:10.1055/s-0029-1216848
日期:2009.7
A chiral quaternary tetraalkylphosphonium salt has been successfully utilized for the first time as a phase-transfer catalyst for asymmetric amination of β-keto esters in high yield with high ee. Asymmetric amination of a cyclic five-membered β-keto ester is a valuable method for preparing a key intermediate for asymmetric synthesis of aldose reductase inhibitor AS-3201 (Ranirestat). amination - asymmetric