- Dialkyl Ether Formation at High-Valent Nickel
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In this article, we investigated the I2-promoted cyclic dialkyl ether formation from 6-membered oxanickelacycles originally reported by Hillhouse. A detailed mechanistic investigation based on spectroscopic and crystallographic analysis revealed that a putative reductive elimination to forge C(sp3)-OC(sp3) using I2 might not be operative. We isolated a paramagnetic bimetallic NiIII intermediate featuring a unique Ni2(OR)2 (OR = alkoxide) diamond-like core complemented by a μ-iodo bridge between the two Ni centers, which remains stable at low temperatures, thus permitting its characterization by NMR, EPR, X-ray, and HRMS. At higher temperatures (>-10 °C), such bimetallic intermediate thermally decomposes to afford large amounts of elimination products together with iodoalkanols. Observation of the latter suggests that a C(sp3)-I bond reductive elimination occurs preferentially to any other challenging C-O bond reductive elimination. Formation of cyclized THF rings is then believed to occur through cyclization of an alcohol/alkoxide to the recently forged C(sp3)-I bond. The results of this article indicate that the use of F+ oxidants permits the challenging C(sp3)-OC(sp3) bond formation at a high-valent nickel center to proceed in good yields while minimizing deleterious elimination reactions. Preliminary investigations suggest the involvement of a high-valent bimetallic NiIII intermediate which rapidly extrudes the C-O bond product at remarkably low temperatures. The new set of conditions permitted the elusive synthesis of diethyl ether through reductive elimination, a remarkable feature currently beyond the scope of Ni.
- Le Vaillant, Franck,Reijerse, Edward J.,Leutzsch, Markus,Cornella, Josep
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supporting information
p. 19540 - 19550
(2020/12/01)
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- A CONVENIENT METHOD FOR THE SYNTHESIS OF DIIODO COMPOUNDS. FACILE CLEAVAGE OF CYCLIC ETHERS BY PHENYL DICHLOROPHOSPHATE AND SODIUM IODIDE
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Cyclic ethers were found to react readily with phenyl dichlorophosphate and sodium iodide to give diiodo compounds under mild reaction conditions.
- Liu, Hsing-Jang,Shewchuk, Lisa M.,Llinas-Brunet, Montse
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p. 3043 - 3046
(2007/10/02)
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