Enantioselective electrophilic trifluoromethylation of beta-keto esters with Umemoto reagents induced by chiral nonracemic guanidines.
Chiral nonracemic guanidines act as Brønsted bases to generate guanidinium enolates for the enantioselective electrophilic trifluoromethylation of beta-keto esters by means of S-(trifluoromethyl)dibenzothiophenium tetrafluoroborate (Umemoto reagent) with good enantioselectivity of 60-70% range. Despite the fact that the ees are still improvable, the model reported in this work could spark the imagination of chemists to design new chiral bases to improve the stereochemical outcome.
Noritake
Shun
S
Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya 466-8555, Japan.
Shibata
Norio
N
Nomura
Yoshinori
Y
Huang
Yiyong
Y
Matsnev
Andrej
A
Nakamura
Shuichi
S
Toru
Takeshi
T
Cahard
Dominique
D
D005617:Chlorofluorocarbons, Methane / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D006146:Guanidines / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry; D008745:Methylation; D013237:Stereoisomerism
D005617:Chlorofluorocarbons, Methane; D004952:Esters; D006146:Guanidines; D007202:Indicators and Reagents; C009554:fluoroform