Adding a Structural Context to the Deprotometalation and Trans‐Metal Trapping Chemistry of Phenyl‐Substituted Benzotriazole |
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| Authors: | Dr M Ángeles Fuentes Dr Alan R Kennedy Prof Robert E Mulvey Dr John A Parkinson Dr Toni Rantanen Dr Stuart D Robertson Prof Victor Snieckus |
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| Affiliation: | 1. WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL (UK), Fax: (+44)?141‐548‐4787;2. Snieckus Innovations, Innovation Park, 945 Princess Street, Kingston, Ontario, K7L 3N6 (Canada);3. Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario, K7L 3N6 (Canada) |
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| Abstract: | Organometallic bases are becoming increasingly complex, because mixing components can lead to bases superior to single‐component bases. To better understand this superiority, it is useful to study metalated intermediate structures prior to quenching. This study is on 1‐phenyl‐1H‐benzotriazole, which was previously deprotonated by an in situ ZnCl2 ? TMEDA/LiTMP (TMEDA=N,N,N′,N′‐tetramethylethylenediamine; TMP=2,2,6,6‐tetramethylpiperidide) mixture and then iodinated. Herein, reaction with LiTMP exposes the deficiency of the single‐component base as the crystalline product obtained was {4‐R‐1‐(2‐lithiophenyl)‐1H‐benzotriazole ? 3THF}2], R=2‐C6H4(Ph)NLi], in which ring opening of benzotriazole and N2 extrusion had occurred. Supporting lithiation by adding iBu2Al(TMP) induces trans‐metal trapping, in which C?Li bonds transform into C?Al bonds to stabilise the metalated intermediate. X‐ray diffraction studies revealed homodimeric (4‐R′‐1‐phenyl‐1H‐benzotriazole)2], R′=(iBu)2Al(μ‐TMP)Li], and its heterodimeric isomer (4‐R′‐1‐phenyl‐1H‐benzotriazole){2‐R′‐1‐phenyl‐1H‐benzotriazole}], whose structure and slow conformational dynamics were probed by solution NMR spectroscopy. |
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| Keywords: | lithium metalation structure elucidation triazoles zinc |
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