Taming nonclassical carbocations to control small ring reactivity.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38215201.
- Also identified by DOI 10.1126/sciadv.adj9695 and PMC identifier 10786418.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Prediction of the outcome of ring opening of small organic rings under cationic conditions can be challenging due to the intermediacy of nonclassical carbocations. For example, the solvolysis of cyclobutyl or cyclopropylmethyl derivatives generates up to four products on nucleophilic capture or elimination via cyclopropylcarbinyl and bicyclobutonium ions. Here, we show that such reaction outcomes can be controlled by subtle changes to the structure of nonclassical carbocation. Using bicyclo[1.1.0]butanes as cation precursors, the regio- and stereochemistry of ring opening is shown to depend on the degree and nature of the substituents on the cationic intermediates. Reaction outcomes are rationalized using computational models, resulting in a flowchart to predict product formation from a given cation precursor.