Electrochemistry offers opportunities to promote single-electron transfer (SET) redox-neutral chemistries similar to those recently discovered using visible-light photocatalysis but without the use of an expensive photocatalyst. Herein, we introduce a microfluidic redox-neutral electrochemistry (μRN-eChem) platform that has broad applicability to SET chemistry, including radical-radical cross-coupling, Minisci-type reactions, and nickel-catalyzed C(sp2)–O cross-coupling. The cathode and anode simultaneously generate the corresponding reactive intermediates, and selective transformation is facilitated by the rapid molecular diffusion across a microfluidic channel that outpaces the decomposition of the intermediates. μRN-eChem was shown to enable a two-step gram-scale electrosynthesis of a nematic liquid crystal compound, demonstrating its practicality.
Using a mechanistically guided ligand design approach, a new ligand (SEGFAST) for the CuHcatalyzed hydroamination reaction of unactivated terminal olefins has been developed, providing a 62-fold rate increase over reactions compared to DTBM-SEGPHOS, the previous optimal ligand. Combining the respective strengths of computational chemistry and experimental kinetic measurements, we were able to quickly identify potential modifications that lead to more effective ligands, thus avoiding synthesizing and testing a large library of ligands. By optimizing the combination of attractive, non-covalent ligand-substrate interactions and the stability of the catalyst under the reaction conditions, we were able to identify a finely-tuned hybrid ligand that greatly enables accelerated hydrocupration rates with unactivated alkenes. Moreover, a modular and robust synthetic sequence was devised, which allowed for practical, gram-scale synthesis of these novel hybrid ligand structures.
With recent advances in the computer-aided synthesis planning (CASP) powered by data science and machine learning, modern CASP programs can rapidly identify thousands of potential pathways for a given target...
The first total syntheses of aflavazole (6) and 14-hydroxyaflavinine (8), two sterically congested indole diterpenoids, were accomplished. AlI-promoted alkyne Prins cyclization was exploited to construct their key structural motifs. An electrocyclization-aromatization sequence assembled the pentasubstituted arene of 6, and a Stille-Migita coupling furnished the tetrasubstituted olefin of 8. The benzylic and allylic C-O bonds were reductively cleaved at the late stage of the syntheses, respectively.
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