Bauer AK, Conrad J, Beifuss U. Efficient approach to 1,1'-bisindoles
via copper(I)-catalyzed double domino reaction.
Org Biomol Chem 2023;
21:8003-8019. [PMID:
37767762 DOI:
10.1039/d3ob01231j]
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Abstract
A highly efficient copper(I)-catalyzed approach for the synthesis of 1,1'-bisindoles that is based on the formation of four bonds in one step has been developed. The unprecedented three component reaction between one molecule of a 1,2-bis(2-bromoaryl)hydrazine and two molecules of a 1,3-diketone employing 10 mol% CuI as a catalyst and Cs2CO3 as a base in DMSO at 100 °C for 24 h delivers substituted 1,1'-bisindoles with yields up to 92%. The new method proceeds as a double domino condensation/Ullmann type C-C coupling. It allows an efficient and practical access to substituted 1,1'-bisindoles in one step from easily available starting materials.
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