Illuminating -hydrozirconation: controlled geometric isomerization of an organometallic species

• Published in: Chemical science (Cambridge) 2021-08, Vol.12 (31), p.1643-1648
• Main Authors: Hostmann, Theresa, Neveselý, Tomáš, Gilmour, Ryan
• Format: Article
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d1sc02454j

A general strategy to enable the formal anti -hydrozirconation of arylacetylenes is reported that merges cis -hydrometallation using the Schwartz Reagent (Cp 2 ZrHCl) with a subsequent light-mediated geometric isomerization at λ = 400 nm. Mechanistic delineation of the contra -thermodynamic isomerization step indicates that a minor reaction product functions as an efficient in situ generated photocatalyst. Coupling of the E -vinyl zirconium species with an alkyne unit generates a conjugated diene: this has been leveraged as a selective energy transfer catalyst to enable E → Z isomerization of an organometallic species. Through an Umpolung metal-halogen exchange process (Cl, Br, I), synthetically useful vinyl halides can be generated (up to Z  :  E = 90 : 10). This enabling platform provides a strategy to access nucleophilic and electrophilic alkene fragments in both geometric forms from simple arylacetylenes. A general strategy to enable the formal anti -hydrozirconation of arylacetylenes is reported that merges cis -hydrometallation using the Schwartz Reagent (Cp 2 ZrHCl) with a subsequent light-mediated geometric isomerization at λ = 400 nm.