Premium
Adding a Structural Context to the Deprotometalation and Trans‐Metal Trapping Chemistry of Phenyl‐Substituted Benzotriazole
Author(s) -
Fuentes M. Ángeles,
Kennedy Alan R.,
Mulvey Robert E.,
Parkinson John A.,
Rantanen Toni,
Robertson Stuart D.,
Snieckus Victor
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201502534
Subject(s) - benzotriazole , trapping , context (archaeology) , metal , chemistry , organic chemistry , geography , archaeology , forestry
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‐1 H ‐benzotriazole, which was previously deprotonated by an in situ ZnCl 2 ⋅ 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)‐1 H ‐benzotriazole ⋅ 3THF} 2 ], [R=2‐C 6 H 4 (Ph)NLi], in which ring opening of benzotriazole and N 2 extrusion had occurred. Supporting lithiation by adding i Bu 2 Al(TMP) induces trans‐metal trapping, in which CLi bonds transform into CAl bonds to stabilise the metalated intermediate. X‐ray diffraction studies revealed homodimeric [(4‐R′‐1‐phenyl‐1 H ‐benzotriazole) 2 ], [R′=( i Bu) 2 Al(μ‐TMP)Li], and its heterodimeric isomer [(4‐R′‐1‐phenyl‐1 H ‐benzotriazole){2‐R′‐1‐phenyl‐1 H ‐benzotriazole}], whose structure and slow conformational dynamics were probed by solution NMR spectroscopy.