Palladium-catalyzed allene synthesis enabled by β-hydrogen elimination from sp<sup>2</sup>-carbon.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33526773.
- Also identified by DOI 10.1038/s41467-020-20740-w and PMC identifier 7851150.
- 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
The rational design based on a deep understanding of the present reaction mechanism is an important, viable approach to discover new organic transformations. β-Hydrogen elimination from palladium complexes is a fundamental reaction in palladium catalysis. Normally, the eliminated β-hydrogen has to be attached to a sp<sup>3</sup>-carbon. We envision that the hydrogen elimination from sp<sup>2</sup>-carbon is possible by using thoroughly designed reaction systems, which may offer a new strategy for the preparation of allenes. Here, we describe a palladium-catalyzed cross-coupling of 2,2-diarylvinyl bromides and diazo compounds, where a β-vinylic hydrogen elimination from allylic palladium intermediate is proposed to be the key step. Both aryl diazo carbonyl compounds and N-tosylhydrazones are competent carbene precursors in this reaction. The reaction mechanism is explored by control experiments, KIE studies and DFT calculations.