What is it about?
Alkynes are important building blocks in organic synthesis and are widely used to prepare pharmaceuticals, functional materials, and other valuable molecules. In this study, we developed an efficient method for synthesizing alkynes from readily available 1-chlorovinyl p-tolyl sulfoxides. Treatment with a Grignard reagent generates magnesium alkylidene carbenoids, which undergo the Fritsch–Buttenberg–Wiechell (FBW) rearrangement to form carbon–carbon triple bonds. By comparing different heteroatom-substituted vinyl sulfoxides, we identified the combination that most efficiently produces alkynes. We also investigated the reaction mechanism using ¹³C-labeling experiments and density functional theory (DFT) calculations, providing new insight into how the rearrangement proceeds.
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Why is it important?
Alkynes are versatile intermediates in organic synthesis, making efficient and reliable methods for their preparation highly valuable. This study demonstrates that 1-chlorovinyl p-tolyl sulfoxides are practical precursors to magnesium alkylidene carbenoids, enabling efficient alkyne synthesis through the FBW rearrangement. In addition to establishing an effective synthetic method, the combination of isotopic-labeling experiments and DFT calculations provides a detailed picture of the rearrangement mechanism. These findings deepen our understanding of magnesium carbenoid chemistry and provide a foundation for developing new reactions based on these highly reactive intermediates.
Perspectives
This work marked an important step in our continuing exploration of magnesium alkylidene carbenoid chemistry. While FBW rearrangements have long been recognized as a useful route to alkynes, relatively little was known about how magnesium alkylidene carbenoids participate in this transformation. By combining synthetic experiments with isotopic labeling and DFT calculations, we were able to identify the most effective carbenoid precursor and gain a clearer mechanistic understanding of the rearrangement. I hope that these findings encourage further applications of magnesium carbenoids in synthetic methodology and stimulate additional mechanistic studies of these fascinating reactive intermediates.
Associate Professor Tsutomu Kimura
Read the Original
This page is a summary of: Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes, Beilstein Journal of Organic Chemistry, May 2021, Beilstein Institut,
DOI: 10.3762/bjoc.17.94.
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