Reductive electrosynthesis has faced long-standing challenges in applications to complex organic substrates at scale. Here, we show how decades of research in lithium-ion battery materials, electrolytes, and additives can serve as an inspiration for achieving practically scalable reductive electrosynthetic conditions for the Birch reduction. Specifically, we demonstrate that using a sacrificial anode material (magnesium or aluminum), combined with a cheap, nontoxic, and water-soluble proton source (dimethylurea), and an overcharge protectant inspired by battery technology [tris(pyrrolidino)phosphoramide] can allow for multigram-scale synthesis of pharmaceutically relevant building blocks. We show how these conditions have a very high level of functional-group tolerance relative to classical electrochemical and chemical dissolving-metal reductions. Finally, we demonstrate that the same electrochemical conditions can be applied to other dissolving metal–type reductive transformations, including McMurry couplings, reductive ketone deoxygenations, and epoxide openings.
The use of electric current as a traceless activator and reagent is experiencing a renaissance. This sustainable synthetic method is evolving into a hot topic in contemporary organic chemistry. Since researchers with various scientific backgrounds are entering this interdisciplinary field, different parameters and methods are reported to describe the experiments. The variation in the reported parameters can lead to problems with the reproducibility of the reported electroorganic syntheses. As an example, parameters such as current density or electrode distance are in some cases more significant than often anticipated. This Minireview provides guidelines on reporting electrosynthetic data and dispels myths about this technique, thereby streamlining the experimental parameters to facilitate reproducibility.
The formation of discrete macrocycles wrapped around single-walled carbon nanotubes (SWCNTs) has recently emerged as an appealing strategy to functionalize these carbon nanomaterials and modify their properties.H ere,w e demonstrate that the reversible disulfide exchange reaction, which proceeds under mild conditions,c an install relatively large amounts of mechanically interlocked disulfide macrocycles on the one-dimensional nanotubes.S ize-selective functionalization of am ixture of SWCNTs of different diameters were observed, presumably arising from error correction and the presence of relatively rigid, curved p-systems in the key building blocks.Acombination of UV/Vis/NIR, Raman, photoluminescence excitation, and transient absorption spectroscopyindicated that the small (6,4)-SWCNTs were predominantly functionalizedbythe small macrocycles 1 2 ,whereas the larger (6,5)-SWCNTs were an ideal matchf or the larger macrocycles 2 2 .T his sizes electivity,w hich was rationalized computationally,c ould prove useful for the purification of nanotube mixtures,s ince the disulfide macrocycles can be removed quantitatively under mild reductive conditions.
A new and powerful active anode system that can be operated in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) has been discovered. In HFIP the molybdenum anode forms a compact, conductive, and electroactive layer of higher-valent molybdenum species. This system can replace powerful but stoichiometrically required Mo reagents for the dehydrogenative coupling of aryls. This electrolytic reaction is more sustainable and allows the conversion of a broad scope of activated arenes.
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