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Organic Process Research & Development: Latest Articles (ACS Publications)

Synthesis
DOI: 10.1055/s-0040-1705962

A catalytic method for the synthesis of pentafluoroethyl ketones­ has been developed. The cesium fluoride catalyst can be used to convert acyl fluorides into the pentafluoroethyl ketones under tetrafluoroethylene pressure without generating stoichiometric quantities of chemical waste. Mechanistic studies suggest that high reaction temperature is crucial for the ketone to be the major product.
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
Table of contents  |  Abstract  |  Full text

Tetrabromomethane enhances the aldehyde–acyl hydrazide condensation to give N‐acyl hydrazones. This simple, inexpensive, and commercially available halomethane provides up to 14‐fold acceleration of the Schiff reaction; the kinetic data indicate that the studied condensation exhibits the first order on CBr₄.

Tetrabromomethane functions as an organic catalyst for non‐redox reactions of carbonyl species and, in particular, it enhances the aldehyde–acyl hydrazide condensation to give N‐acyl hydrazones. This simple, inexpensive, and commercially available halomethane provides up to 14‐fold acceleration of the Schiff reaction; the kinetic data indicate that the studied condensation exhibits the first order on CBr₄. The catalytic activity of CBr₄ is significantly higher than the activity of other halogen‐containing species, such as CHX₃ or ArX (X = Cl, Br, I).

Organic Process Research & Development: Latest Articles (ACS Publications)

Organic Process Research & Development: Latest Articles (ACS Publications)

The present review demonstrates that the synthetic potential of heterocyclic N‐oxides performs it possible to successfully use them in the synthesis and modification of substances with high molecular complexity, including natural targets. Several effective catalyst‐free approaches for regioselective C–O, C–S, C–P, C–N, and C–C cross‐coupling, including Suzuki‐ and Heck‐like reactions, are especially noteworthy.

Considerable attention holds on the chemistry and application of heterocyclic N‐oxides due to their advantages as building‐blocks in organic synthesis and importance in biomedical research. On the other hand, in recent years the development of selective methods for constructing C–C, C–N, C–P, C–S, and C–O bonds via direct C–H functionalization has become especially demand in organic synthesis. These circumstances determine the significance of this minireview, which present recent advances in the field of C–H functionalization of heterocyclic N‐oxides. Data on various type reactions which formal result is the replacement of a hydrogen atom in a heterocycle, with the exclusion of methods using heterogeneous and homogeneous catalysts based on transition metals, are summarized. Presented works for the last 15 years, since 2006.