Blue‐Light Induced Iron‐Catalyzed Synthesis of γ,δ‐Unsaturated Ketones

• Published in: ChemSusChem Vol. 17; no. 7; pp. e202301472 - n/a
• Main Authors: Joly, Nicolas, Colella, Alessandro, Mendy, Monique‐Edwige, Mbaye, Mbaye Diagne, Gaillard, Sylvain, Poater, Albert, Renaud, Jean‐Luc
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 08.04.2024; ChemPubSoc Europe/Wiley
• Subjects: Alcohols; Alkylation; Chemical Sciences; Chemical synthesis; Dehydrogenation; hydrogen auto-transfer; Iron; iron complex; Ketones; light activation; Reduction; Room temperature; Steric hindrance; γ,δ-unsaturated ketones; iron complex; hydrogen auto-transfer; light activation; γ,δ-unsaturated ketones
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.202301472

A visible‐light‐induced iron‐catalyzed α‐alkylation of ketones with allylic and propargylic alcohols as pro‐electrophiles is reported. The diaminocyclopentadienone iron tricarbonyl complex plays a dual role by harvesting light and facilitating dehydrogenation and reduction steps without the help of any exogenous photosensitizer. γ,δ‐Unsaturated ketones can now be accessed through this borrowing hydrogen methodology at room temperature. Mechanistic investigations revealed that the steric hindrance on the δ‐position of either the dienone or ene‐ynone intermediate is the key feature to prevent or decrease the competitive 1,6‐reduction (and consequently the formation of the saturated ketone) and to favor the synthesis of a set of non‐conjugated enones and ynones. A cyclopentadienone iron tricarbonyl complex, able to harvest light and catalyze both dehydrogenation and reduction, allows the synthesis of γ,δ‐unsaturated ketones using the borrowing hydrogen strategy in the presence of various substituted primary allylic or propargylic alcohols as alkylating reagents.