Scope of tetrazolo[1,5- a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

Laura Holzhauer; Chloé Liagre; Olaf Fuhr; Nicole Jung; Stefan Bräse

doi:10.3762/bjoc.18.111

Scope of tetrazolo[1,5- a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof

Beilstein J Org Chem. 2022 Aug 24:18:1088-1099. doi: 10.3762/bjoc.18.111. eCollection 2022.

Authors

Laura Holzhauer¹, Chloé Liagre¹, Olaf Fuhr^{2

3}, Nicole Jung^{1

3

4}, Stefan Bräse^{1

4}

Affiliations

¹ Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
² Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
³ Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
⁴ Institute of Organic Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.

Abstract

The conversion of tetrazolo[1,5-a]quinoxalines to 1,2,3-triazoloquinoxalines and triazoloimidazoquinoxalines under typical conditions of a CuAAC reaction has been investigated. Derivatives of the novel compound class of triazoloimidazoquinoxalines (TIQ) and rhenium(I) triazoloquinoxaline complexes as well as a new TIQ rhenium complex were synthesized. As a result, a small 1,2,3-triazoloquinoxaline library was obtained and the method could be expanded towards 4-substituted tetrazoloquinoxalines. The compatibility of various aliphatic and aromatic alkynes towards the reaction was investigated and the denitrogenative annulation towards imidazoloquinoxalines could be observed as a competing reaction depending on the alkyne concentration and the substitutions at the quinoxaline.

Keywords: CuAAC; click reaction; denitrogenative annulation; imidazole; metal complexes; quinoxaline; tetrazole; triazole.

Grants and funding

L.H. acknowledges funding by the Landesgraduiertenförderung Baden-Württemberg. C.L. acknowledges funding by the ERASMUS program and the regional international mobility scholarship of Lyon. We acknowledge the support by the Joint Lab VirtMat within the Helmholtz research area Information. This work was supported by the Helmholtz program Information. We acknowledge support by Deutsche Forschungsgemeinschaft for the DFG-core facility Molecule Archive, to which all target compounds were registered for further re-use (DFG project number: 284178167).