Efficient synthesis of imidazole and pyrimidine derivatives
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Efficient synthesis of imidazole and pyrimidine derivatives Oleksii O. Kolomoitsev1*, Eugene S. Gladkov1,2, Volodymyr M. Kotlyar1, Polina I. Pedan3, Oleksandr V. Onipko3, Oleksandr V. Buravov3, Valentyn A. Chebanov1,2 1
V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine; е-mail: [email protected] 2 State Scientific Institution ''Institute for Single Crystals'', National Academy of Sciences of Ukraine, 60 Nauky Ave., Kharkiv 61072, Ukraine 3 Enamine Ltd., 67 Chervonotkatska St., Kyiv 02660, Ukraine Published in Khimiya Geterotsiklicheskikh Soedinenii, 2020, 56(10), 1329–1334
Submitted March 5, 2020 Accepted after revision July 9, 2020
A convenient and affordable synthetic pathway for obtaining new α-aminoamidines starting from aminonitriles is proposed. The α-aminoamidines obtained can be applied as substrates for further transformations and synthesis of imidazole- and pyrimidine-containing building blocks. Keywords: α-aminoamidine, 1-chloropropan-2-one, 3-(diethylamino)prop-2-enal, heterocycle, imidazole, pyrimidine.
Amidines are known reagents in some synthetic methods for obtaining heterocyclic compounds as well as they are used as suitable reagents in numerous cycloaddition processes. An example of their application is the synthesis of pyrimidines and imidazoles shown by Vidal and coauthors.1 Also, a new efficient and convenient approach was proposed to the synthesis of pyrimidines by Cu-catalyzed and 4-HO-TEMPO-mediated [3+3] annulation of commercially available amidines with saturated ketones.2 On the other hand, diazaheterocyclic compounds are interesting from various scientific aspects3 and have a significant potential as modern functional materials,4 as well as they could be considered as objects which have a significant interest from the point of view of biological activity.5 The aim of the work was to develop on the basis of known procedures6 a method for the synthesis of N,N'-unsubstituted α-aminoamidines and ways for their further modification to synthesize new promising imidazoleand pyrimidine-containing compounds. We proposed and optimized a convenient and affordable pathway for the synthesis of previously undescribed α-aminoamidines 4a–e starting from N-protected amino0009-3122/20/56(10)-1329©2020 Springer Science+Business Media, LLC
nitriles 1a–e, which can be easily obtained by described methods (Scheme 1).7,8 The key stage of the approach is a procedure of hydrogenation of O-acetyl-substituted aminooximes 3a–e in the presence of palladium catalyst.9,10 It should be noted, that our attempts to perform direct reduction of aminooximes 2a–e to aminoamidines 4a–e were unsuccessful, though such transformations for amidines had been described in literature earlier.11–16 Therefore, we carried out preliminary O-acylation of compounds 2a–e by acetic anhydride. Scheme 1
1329
Chemistry of Heterocyclic Compounds 2020, 56(10), 1329–1334 Scheme 2
α-Aminoamidines 4a–e can be applied as reagents for further synthesis of different heterocyclic systems. Thus, protected N
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