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Abstract Because internal alkenes are more challenging synthetic targets than terminal alkenes, metal‐catalyzed olefin mono‐transposition (i.e., positional isomerization) approaches have emerged to afford valuableE‐ orZ‐internal alkenes from their complementary terminal alkene feedstocks. However, the applicability of these methods has been hampered by lack of generality, commercial availability of precatalysts, and scalability. Here, we report a nickel‐catalyzed platform for the stereodivergentE/Z‐selective synthesis of internal alkenes at room temperature. Commercial reagents enable this one‐carbon transposition of terminal alkenes to valuableE‐ orZ‐internal alkenes via a Ni−H‐mediated insertion/elimination mechanism. Though the mechanistic regime is the same in both systems, the underlying pathways that lead to each of the active catalysts are distinct, with theZ‐selective catalyst forming from comproportionation of an oxidative addition complex followed by oxidative addition with substrate and theE‐selective catalyst forming from protonation of the metal by the trialkylphosphonium salt additive. In each case, ligand sterics and denticity control stereochemistry and prevent over‐isomerization.
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Experimental and Theoretical Investigation of Alkene Transformations in Oceanic Hydrothermal Fluids: A Mechanistic Study of Styrene
Abstract Natural organic matter plays an important role in oceanic hydrothermal systems through a combination of geological and chemical processes. However, identifying the hydrothermal pathways of organic compounds is still quite limited, preventing us from understanding how organic matter is transformed in hydrothermal systems. In this study, we focus on the reaction pathways of alkenes, which represent a key functional group intermediate linking the most abundant hydrocarbons in seafloor hydrothermal environments. Three major pathways are observed for alkenes under mild hydrothermal conditions, including hydration, oxidation, and dimerization. The pathway distributions of alkenes can be affected by the presence of dissolved metal salts; hydration of alkenes is driven by metal ions via the change of solution pH, while alkene dimerization is controlled by pH and the type of metal cations and complexes. Overall, this study identifies alkene hydrothermal pathways and highlights the important roles of metal salts in controlling hydrothermal transformations.
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- Award ID(s):
- 2042213
- PAR ID:
- 10444622
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 50
- Issue:
- 16
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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