We have previously reported the facile preparation methods of 4,4,4-trifluorobut-2-yn-1-ols from industrially available 2-bromo-3,3,3-trifluoropropene and 1-chloro-3,3,3-trifluoropropene, and these propargylic alcohols have been employed for the syntheses of trifluorinated sugars, allenes, heterocyclic compounds, and so on.  During our search for further utilization of these alcohols, we have found out that the propargylic proton is acidic enough to be abstracted by weak tertiary amines.  For example, after appropriate protection of the hydroxy group by sulfonyl or acyl groupss, treatment of these compounds by these bases affected interesting transformations to the corresponding allenyl tosylates, 2-(2,2,2-trifluoroethyl)but-2-enones, or 1-substituted 4,4,4-trifluoro-1-tosyloxybutan-2-one.  Our model computation clarified that the terminal trifluoromethyl group effectively and unanimously increased the acidity of the propargylic proton possibly by its strong electron-withdrawing nature, which enabled these novel reactions to proceed in a smooth manner.

Novel transformations of 4,4,4-trifluorobut-2-yn-1-ol initiated by abstraction of the propargylic protons

245th National Meeting (2013)

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