Chemoselective Trifluoromethylation of Methyl Esters Using an Et3GeNa/C6H5SCF3 Combination: Efficient Synthesis of Trifluoromethyl Ketones
Various trifluoromethyl ketones were synthesized from the corresponding methyl esters by effective nucleophilic trifluoromethylation using an Et3GeNa/C6H5SCF3 combination. This trifluoromethylation proceeded che
Efficient Asymmetric Biomimetic Aldol Reaction of Glycinates and Trifluoromethyl Ketones by Carbonyl Catalysis
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.
A new entry for the oxidation of fluoroalkyl-substituted methanol derivatives: Scope and limitation of the organoiodine(V) reagent-catalyzed oxidation
Oxidation of various fluoroalkyl-substituted methanol derivatives under the influence of a catalytic amount of sodium 2-iodobenzenesulfonate and Oxone in CH3CN or CH3NO2 was investigated in detail. The efficiency of the newly developed oxidation was also evaluated by comparison to other oxidations, such as Dess-Martin, PDC, and Swern oxidation.
Tanaka, Yusuke,Ishihara, Takashi,Konno, Tsutomu
experimental part
p. 99 - 104
(2012/05/07)
A New and Efficient Synthesis of Trifluoromethyl Ketones from Carboxylic Acids. Part I.
Trifluoromethyl ketones can be prepared in good yield from primary carboxylic acid chlorides by reaction with pyridine and trifluoroacetic anhydride followed by aqueous work up.
Boivin, Jean,El Kaim, Laurent,Zard, Samir Z.
p. 2573 - 2584
(2007/10/02)
An expedient access to trifluoromethyl ketones from carboxylic acids
Trifluoromethyl ketones are prepared in good yield from carboxylic acid chlorides by reaction with pyridine and trifluoroacetic anhydride.
Boivin, Jean,El Kaim, Laurent,Zard, Samir Z.
p. 1285 - 1288
(2007/10/02)
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