E-Olefins through intramolecular radical relocation

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Science  25 Jan 2019:
Vol. 363, Issue 6425, pp. 391-396
DOI: 10.1126/science.aav1610

Olefin shuffle for just a nickel

Controlling the geometry of carbon-carbon double bonds is a central component of chemical manufacturing. One useful trick is to shift hydrogen atoms around to interconvert C=C isomers selectively. However, this approach typically requires precious metals. Kapat et al. now report that more-abundant nickel can catalyze rapid conversion of terminal olefins into internal olefins with high selectivity for trans geometry. The odd-electron nickel complex relies on a radical mechanism to shuttle hydrogen to the terminal carbon from the saturated carbon adjacent to the double bond.

Science, this issue p. 391


Full control over the selectivity of carbon–carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach. We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.

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