Paioti, Paulo H. S. published the artcileCatalytic Enantioselective Boryl and Silyl Substitution with Trifluoromethyl Alkenes: Scope, Utility, and Mechanistic Nuances of Cu-F β-Elimination, Application In Synthesis of 83706-94-9, the publication is Journal of the American Chemical Society (2019), 141(50), 19917-19934, database is CAplus and MEDLINE.
Catalytic enantioselective methods are introduced that allow access to a variety of allyl boronates and silanes that contain a difluoroalkene unit; the resulting products may be used for the preparation of organofluorine compounds in high enantiomeric purity. Also, a number of key mechanistic aspects of the transformations were studied and analyzed. Thus, 1st, an NHC-Cu-catalyzed method for boryl substitution with F3C-substituted alkenes is introduced. These processes, unlike the previously reported strategies, are applicable to alkyl as well as aryl substituted substrates, afford allyl boronates bearing a difluoroalkene moiety (up to 98% yield and 95:5 er). Second, the corresponding silyl substitutions, the 1st reported cases of their kind, are presented (up to 94% yield and 97:3 er). Third, exptl. and computational (DFT) studies are described that shed light on key mechanistic aspects of the catalytic processes. Evidence (x-ray structures of Cu-alkyl intermediates and kinetic studies) is put forth illustrating that the initial Cu-boryl and Cu-silyl addition is significantly faster than the ensuing Cu-F elimination, and that the latter step can be facilitated by either a mild Lewis acid (e.g., a Li or Na cation) or a nucleophilic promoter (e.g., an alkoxide). These findings together with DFT studies demonstrate that Cu-F β-elimination probably proceeds with anti-stereochem. Representative cases of ways through which the new mechanistic understanding may be used to rationalize previously disclosed findings, significantly improve a transformation, or develop new diastereo- and enantioselective catalytic methods are provided. For example, an explanation is provided regarding why bisphosphine-Cu complexes do not efficiently promote boryl substitutions with aryl-substituted substrates, but the corresponding silyl substitutions are facile, and how the size of a ligand can impact regioselectivity and efficiency.
Journal of the American Chemical Society published new progress about 83706-94-9. 83706-94-9 belongs to alcohols-buliding-blocks, auxiliary class Trifluoromethylated Building Blocks, name is (E)-4,4,4-Trifluorobut-2-en-1-ol, and the molecular formula is C4H5F3O, Application In Synthesis of 83706-94-9.
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