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Updated: Aug 16, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
A novel method for the synthesis of imidazo[5,1-f][1,2,4]triazin-4(3H)-ones
Alexander Heim-Riether1, Jason Healy
1Lexicon Pharmaceuticals, 350 Carter Road, Princeton, New Jersey 08540, USA. aheim@lexpharma.com
Abstract:
[reaction: see text] Imidazo[5,1-f][1,2,4]triazinones, as isosteres of purine, are of interest for pharmaceutical research. The syntheses reported in the literature generally require several steps. We report a novel method to access a broad range of diversely substituted derivatives. The key step is the electrophilic N-amination of 3H-imidazoles containing a 4-carbonyl group. Several different substituted imidazoles have been N-aminated in this manner. The resulting N-aminoimidazoles were cyclized under different conditions to the corresponding imidazotriazinones, which allowed for additional diversification. This novel method was applied in a formal synthesis of vardenafil, a well-known representative of this class of compounds. Furthermore, we report the first synthesis of a 7-aryl-imidazotriazinone via bromination of an unsubstituted imidazotriazinone followed by a Suzuki coupling.
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