Palladium-catalyzed selective C-C bond cleavage and stereoselective alkenylation between cyclopropanol and 1,3-diyne: one-step synthesis of diverse conjugated enynes

The stereoselective synthesis of 1,3-enynes from 1,3-diynes is demonstrated by palladium-catalyzed selective C-C bond cleavage of cyclopropanol. Exclusive formation of mono-alkenylated adducts was achieved by eliminating the possibility of di-functionalization with high stereoselectivity. Indeed, this protocol worked very well with electronically and sterically diverse substrates. Several studies, including deuterium labeling experiments and intermolecular competitive experiments, were carried out to understand the mechanistic details. The atomic-level mechanism followed in the catalytic process was also validated using DFT calculations, and the rate-controlling states in the catalytic cycle were identified. Furthermore, preliminary mechanistic investigations with radical scavengers revealed the non-involvement of the radical pathway in this transformation.

Automated summary

The stereoselective synthesis of 1,3-enynes from 1,3-diynes was achieved by palladium-catalyzed selective C-C bond cleavage of cyclopropanol. The protocol showed high stereoselectivity with diverse substrates. Mechanistic investigations and DFT calculations were carried out to validate the atomic-level mechanism and identify rate-controlling states in the catalytic cycle. Preliminary investigations ruled out the involvement of the radical pathway in this transformation.