What is it about?
Fluorinated organic compounds play important roles in modern chemistry, but replacing fluorine with other carbon groups can be challenging. In this study, we investigated the reactions of 1-fluoroalk-1-enylmagnesium chlorides with Grignard reagents. These reactions proceed through an unusual nucleophilic vinylic substitution (SNV) process, allowing a variety of alkyl, aryl, and alkenyl groups to be introduced onto a carbon–carbon double bond. We examined the scope of the reaction, confirmed the stereochemical outcome, and performed mechanistic studies using stereochemical probes. The results revealed that the reaction occurs with inversion at the vinylic carbon atom and proceeds through a rearrangement pathway rather than through alkylidene carbene intermediates.
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Why is it important?
Substitution reactions at vinylic carbon atoms are generally much more difficult than reactions at saturated carbon centers. This work demonstrates that fluorinated vinyl Grignard reagents can undergo efficient SNV reactions with a broad range of carbon nucleophiles, providing a useful method for carbon–carbon bond formation. More importantly, the study clarifies the reaction mechanism of a unique transformation that differs from conventional nucleophilic substitution pathways. The discovery that the reaction proceeds with stereochemical inversion and is consistent with a 1,2-rearrangement mechanism provides new insight into the behavior of organomagnesium compounds and fluorinated intermediates. These findings may help guide the design of new substitution reactions involving organometallic reagents and vinyl electrophiles.
Perspectives
Our research group has long been interested in the chemistry of 1-halovinyl p-tolyl sulfoxides and magnesium alkylidene carbenoids. During these studies, we found that fluorinated vinylmagnesium species displayed an unusual reactivity that could not be fully explained by existing mechanistic models. I hope this study encourages further exploration of fluorinated organometallic compounds and inspires the discovery of other unconventional substitution reactions.
Associate Professor Tsutomu Kimura
Read the Original
This page is a summary of: Nucleophilic vinylic substitution of 1-fluoroalk-1-enylmagnesium chlorides with Grignard reagents via C–F bond cleavage, Tetrahedron, March 2025, Elsevier,
DOI: 10.1016/j.tet.2025.134459.
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