Structural Studies of the Deprotometalation and Trans-Metal-Trapping Chemistry of a Substituted Benzotriazole

The data set contains three files. These data relate to the research discussed in the manuscript, “Adding a Structural Context to the Deprotometalation and Trans-Metal-Trapping Chemistry of Phenyl-substituted Benzotriazole” which has been published in Chem. Eur. J. 2015, 21, 14812 – 14822.
The work was carried out in relation to the EPSRC grant, “A co-operative bimetallic approach for the transformation of lithiation”. EP/K001183/1. PI: Professor R E Mulvey; PDRA: Dr M. Angeles Fuentes.

Organometallic bases are considered one of the most important synthetic tools for the regio-, chemo- and enantio-selective functionalisation of aromatic compounds. Mixing organometallic reagents can lead to superior bases giving different chemistry from to single-component bases.
Previous work within the Mulvey research group has shown that lithium amide LiTMP (TMP = 2,2,6,6-tetramethylpiperidide) does not co-complex with bulky alkyl-TMP-aluminium reagents, instead LiTMP will deprotonate a substrate while the aluminium moiety can function as an effective trans-metal trapping agent. For example, anisole can be metallated by LiTMP in a very low yield (˂5%) but in the presence of trapping agent iBu2Al(TMP) this C-H deprotonation becomes near quantitative.1
The benzotriazole ring is a heterocyclic scaffold present in many important synthetic and bioactive molecules. One of the challenges in this area is to bring about the regioselective functionalization of 1-phenyl-1H-benzotriazole, 1, which was previously deprotonated by an in situ ZnCl2·TMEDA/LiTMP (TMEDA = N,N,N’,N’-tetramethylethylenediamine) mixture and then iodinated.2 No information on intermediates was obtained from this in situ quenching approach.
We have studied this molecule with different organometallic bases and attempted to gain insight into the metallo intermediates involved. Contrasting results have been obtained using the harsh base LiTMP on its own or in the more interesting LiTMP/iBu2Al(TMP) trapping protocol. All the complexes in this project can undergo quenching with electrophiles giving high value compounds potentially of significance for the fine chemicals industry.

Files present:
1. General procedures and synthesis.pdf
2. NMR spectroscopy and elemental analysis.pdf
3. X-Ray crystallographic structures.pdf


References
1. D.R. Armstrong, E. Crosbie, E. Hevia, R.E. Mulvey, D.L. Ramsay and S.D. Robertson, Chem. Sci. 2014, 5, 3031.
2. E. Nagaradja, F. Chevallier, T. Roisnel, V. Dorcet, Y.S. Halauko, O.A. Ivashkevich, V.E. Matulis and F. Mongin, Org. Biomol. Chem. 2014, 12, 1475.