Towards Substrate–Reagent Interaction of Lochmann–Schlosser Bases in THF: Bridging THF Hides Potential Reaction Site of a Chiral Superbase. Issue 69 (17th October 2022)

• Record Type: Journal Article
• Authors: Brieger, Lukas; Schrimpf, Tobias; Scheel, Rebecca; Unkelbach, Christian; Strohmann, Carsten
• Is Part Of: Chemistry. Volume 28:Issue 69(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-10-17
• Subjects: alkali metals -- chirality -- lithium -- potassium -- X-ray diffraction; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202202660
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The metalation of N, N ‐dimethylaminomethylferrocene in THF by the superbasic mixture of n BuLi/KO t Bu proceeds readily at low temperatures to afford a bimetallic Li2 K2 aggregate containing ferrocenyl anions and tert ‐butoxide. Starting from an enantiomerically enriched ortho ‐lithiated aminomethylferrocene, an enantiomerically pure superbase can be prepared. The molecular compound exhibits superbasic behavior deprotonating N, N ‐dimethylbenzylamine in the α ‐position and is also capable of deprotonating toluene. Quantum chemical calculations provide insight into the role of the bridging THF molecule to the possible substrate–reagent interaction. In addition, a benzylpotassium alkoxide adduct gives a closer look into the corresponding reaction site of the Lochmann–Schlosser base that is reported herein. Abstract : The isolation of a new THF‐solvated, ferrocene‐based Lochmann–Schlosser base with all four components lithium, potassium, carbanion, and alkoxide led to the observation of new structural motifs with respect to these superbasic reagents. The "kick out" of a THF leads to the detachment, providing the typical Li/K reaction site, whereas the "smart pass" leads to the favorable THF‐displacement and the K/K reaction site provided for substrates.