Several functionalized and non-functionalized perfluoroarenes were catalytically transformed into their para-hydrodefluorinated products by using catalytic amounts of titanocene difluoride and stoichiometric amounts diphenylsilane. Turnover numbers of up to 93 were observed. Solution density functional theory calculations at the M06-2X/TZ(PCM)//M06-2X/TZ(PCM)level of theory provided insight into the mechanism of Ti(III)-catalyzed aromatic hydrodefluorination. Two different substrate approaches, with a Ti–F interaction (pathway A) and without a Ti–F interaction (pathway B), are possible. Pathway A leads to a s-bond metathesis transition state, whereas pathway B proceeds by means of a two-step mechanism through a syn-hydrometalation intermediate or through a Meisenheimer intermediate. Both pathways are competitive over a broad range of substrates.
Competition of Nucleophilic Aromatic Substitution, σ-Bond Metathesis, and syn Hydrometalation in Titanium(III)-Catalyzed Hydrodefluorination of Arenes / Krüger, Juliane; Leppkes, Jakob; Ehm, Christian; Lentz, Dieter. - In: CHEMISTRY - AN ASIAN JOURNAL. - ISSN 1861-4728. - 11:21(2016), pp. 3062-3071. [10.1002/asia.201601036]
Competition of Nucleophilic Aromatic Substitution, σ-Bond Metathesis, and syn Hydrometalation in Titanium(III)-Catalyzed Hydrodefluorination of Arenes
Ehm, Christian
;
2016
Abstract
Several functionalized and non-functionalized perfluoroarenes were catalytically transformed into their para-hydrodefluorinated products by using catalytic amounts of titanocene difluoride and stoichiometric amounts diphenylsilane. Turnover numbers of up to 93 were observed. Solution density functional theory calculations at the M06-2X/TZ(PCM)//M06-2X/TZ(PCM)level of theory provided insight into the mechanism of Ti(III)-catalyzed aromatic hydrodefluorination. Two different substrate approaches, with a Ti–F interaction (pathway A) and without a Ti–F interaction (pathway B), are possible. Pathway A leads to a s-bond metathesis transition state, whereas pathway B proceeds by means of a two-step mechanism through a syn-hydrometalation intermediate or through a Meisenheimer intermediate. Both pathways are competitive over a broad range of substrates.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.