Ammonium Bromides/KF Catalyzed Trifluoromethylation of Carbonyl Compounds with (Trifluoromethyl)trimethylsilane and Its Application in the Enantioselective Trifluoromethylation Reaction.

Abstract

Alcohols Q 0230 Ammonium Bromides/KF Catalyzed Trifluoromethylation of Carbonyl Compounds with (Trifluoromethyl)trimethylsilane and Its Application in the Enantioselective Trifluoromethylation Reaction. -(MIZUTA, S.; SHIBATA*, N.; HIBINO, M.; NAGANO, S.; NAKAMURA, S.; TORU, T.; Tetrahedron 63 (2007) 35, 8521-8528; Dep. Appl. Chem., Nagoya Inst. Technol., Showa, Nagoya 466, Japan; Eng.) -Nuesgen 51-087

Synthesis of Both Enantiomers of Chiral Phenylalanine Derivatives Catalyzed by Cinchona Alkaloid Quaternary Ammonium Salts as Asymmetric Phase Transfer Catalysts

“…Chiral unnatural α-phenylalanine derivatives were synthesized through the asymmetric α-alkylation reaction of N -(dibenzylidene)glycine tert -butyl ester ( 2 ) [ 23 , 24 ] with substituted benzyl bromides catalyzed by a phase transfer catalyst. Compounds 1a – 1h ( Figure 2 ) were chosen as phase transfer catalysts, and they were obtained from cinchonine according to the reported procedures [ 25 , 26 , 27 , 28 , 29 , 30 ].…”

Cs2CO3-Initiated Trifluoro-Methylation of Chalcones and Ketones for Practical Synthesis of Trifluoromethylated Tertiary Silyl Ethers

“…For this purpose, a direct trifluoromethylation of carbonyl compounds, such as ketones, could be easily completed by nucleophilic addition of TMSCF 3 to give trifluomethylated alcohols in the presence of a fluoride catalyst or other Lewis bases, including phosphines, amines, TBD, sodium or lithium acetates, etc., which mediate the silicon-carbon cleavage of TMSCF 3 [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]. Notably, since the first report of Prakash and Olah [ 23 ] concerning the trifluoromethylation of benzaldehyde to give organofluorine compounds bearing secondary hydroxyl groups in the presence of fluoride ion reagent there has been a lot of effort devoted to the development of this type of trifluoromethylation reaction, including asymmetric versions of such transformations [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. In this regard, despite the fact that there are several successful synthetic methods in the case of the trifluoromethlytion reactions with TMSCF 3 , the introduction of commercially available, simple and cheap bases as catalyst precursors for the establishment of a highly efficient ...…”