Ph<sub>3</sub>PCN<sub>2</sub>: A stable reagent for carbon-atom transfer.
basic_science · Level V
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- Record sourced from PubMed, PMID 39024456.
- Also identified by DOI 10.1126/science.ado4564.
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Abstract
Precise modification of a chemical site in a molecule at the single-atom level is one of the most elegant yet difficult transformations in chemistry. A reagent specifically designed for chemoselective introduction of monoatomic carbon is a particularly formidable challenge. Here, we report a straightforward, azide-free synthesis of a crystalline and isolable diazophosphorus ylide, Ph<sub>3</sub>PCN<sub>2</sub>, a stable compound with a carbon atom bonded to two chemically labile groups, triphenylphosphine (PPh<sub>3</sub>) and dinitrogen (N<sub>2</sub>). Without any additives, the diazophosphorus ylide serves as a highly selective transfer reagent for fragments, including Ph<sub>3</sub>PC, to deliver phosphorus ylide-terminated heterocumulenes and CN<sub>2</sub> to produce multisubstituted pyrazoles. Ultimately, even exclusive carbon-atom transfer is possible. In reactions with aldehydes and acyclic and cyclic ketones (R<sub>2</sub>C=O), the carbon-atom substitution forms a vinylidene (R<sub>2</sub>C=C:) en route to alkynes or butatrienes.