122977-71-3Relevant academic research and scientific papers
Efficient Asymmetric Biomimetic Aldol Reaction of Glycinates and Trifluoromethyl Ketones by Carbonyl Catalysis
Cao, Jing,Cheng, Aolin,Liu, Tao,Song, Guanshui,Zhang, Kun,Zhang, Liangliang,Zhao, Baoguo,Zhao, Guoqing,Zhou, Qinghai
supporting information, p. 20166 - 20172 (2021/07/20)
The direct asymmetric aldol reaction of glycinates represents an intriguing and straightforward strategy to make biologically significant chiral β-hydroxy-α-amino-acid derivatives. But it is not easy to realize the transformation due to the disruption of the reactive NH2 group of glycinates. Inspired by the enzymatic aldol reaction of glycine, we successfully developed an asymmetric aldol reaction of glycinate 5 and trifluoromethyl ketones 4 with 0.1–0.0033 mol % of chiral N-methyl pyridoxal 7 a as the catalyst, producing chiral β-trifluoromethyl-β-hydroxy-α-amino-acid esters 6 in 55–82 % yields (for the syn-diastereomers) with up to >20:1 dr and 99 % ee under very mild conditions. The reaction proceeds via a catalytic cycle similar to the enzymatic aldol reaction of glycine. Pyridoxal catalyst 7 a activates both reactants at the same time and brings them together in a specific spatial orientation, accounting for the high efficiency as well as excellent diastereo- and enantioselectivities.
Highly efficient synthesis of chiral α-CF3 amines via Rh-catalyzed asymmetric hydrogenation
Jiang, Jun,Lu, Wenxin,Lv, Hui,Zhang, Xumu
supporting information, p. 1154 - 1156 (2015/03/14)
Highly enantioselective catalytic asymmetric hydrogenation of α-CF3-enamides has been achieved by employing rhodium-DuanPhos as the catalyst, which provides a readily accessible method for the synthesis of chiral trifluoromethylated amines. The reaction has a broad substrate scope; both aryl- and alkyl-substituted α-CF3-enamides worked smoothly and afford the corresponding chiral amines in high yields and excellent enantioselectivities (up to 99% ee).
Dehydrogenation of perfluoroalkyl ketones by using a recyclable oxoammonium salt
Hamlin, Trevor A.,Kelly, Christopher B.,Leadbeater, Nicholas E.
supporting information, p. 3658 - 3661 (2013/07/19)
A novel dehydrogenation reaction of perfluoroalkyl ketones by the oxoammonium salt 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (4-NHAc-TEMPO+BF4-, Bobbitt's salt, 1) is described. The reaction proceeds under mildly basic conditions and appears to be unique to perfluoroalkyl ketones. A proposed mechanism for this unusual transformation is given. The byproduct of the reaction, 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy (1a), can easily be recovered and used to regenerate the oxoammonium salt. The dehydrogenation of perfluoroalkyl ketones by using an oxoammonium salt is reported. The reaction proceeds under mildly basic conditions and affords α,β-unsaturated products in fair to excellent yields. The reaction likely proceeds through a two-step sequence. The spent oxidant can easily be recovered and used to regenerate the oxoammonium salt. Copyright
NOUVELLE SYNTHESE DE TRIFLUOROMETHYLCETONES ET D' α-BROMO TRIFLUOROMETHYLCETONES
Begue, J. P.,Mesureur, D.
, p. 271 - 282 (2007/10/02)
We report a new method for the preparation of trifluoromethylketones, as an alternative to the use of organometallics.The condensation of phosphonium ylides with trimethylsilyl trifluoroacetate provides silyloxy enol ethers whose hydrolysis leads to trifluoromethylketones.Bromation of the same silyloxy enol ether is also a convenient preparation of α-bromo trifluoromethylketone.
