Tetracyanoethylene as a building block in the facile synthesis of heteroyl-tetrasubstituted thiazoles
- PDF / 994,685 Bytes
- 7 Pages / 595.276 x 790.866 pts Page_size
- 114 Downloads / 197 Views
RIGINAL PAPER
Tetracyanoethylene as a building block in the facile synthesis of heteroyl‑tetrasubstituted thiazoles Alaa A. Hassan1 · Ashraf A. Aly1 · Nasr K. Mohamed1 · Lamiaa E. Abd El‑Haleem1,2 · Stefan Bräse2,3 · Martin Nieger4 Received: 22 November 2019 / Accepted: 10 August 2020 / Published online: 10 September 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The transformation of N-substituted 2-heteroylthiosemicarbazides to N-(2-substituted imino)-4-amino-5-cyanothiazol-3(2H)3-yl)-heteroyl-2-carboxamides was achieved via the reaction with tetracyanoethylene, which is used as a building block in this transformation. The structures of the products have been confirmed unambiguously by single-crystal X-ray structure analysis. A rationale for the formation of the products is presented. Graphic abstract R
NC
CN CN
+
NC
R
H N
1
O
S N H
N H
R
O
2
R
1
2
N N H
S CN
N NH2
Keywords 2,3,4,5-Tetrasubstituted thiazoles · N-Substituted 2-heteroylthiosemicarbazides · Heterocycles · Donor–acceptor effects · NMR spectroscopy · X-ray structure determination
Introduction Due to the accessibility and ability of carbothioamides and their analogs to act as bifunctional nucleophiles [1–6], they play a significant role among other nitrogen and Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00706-020-02669-4) contains supplementary material, which is available to authorized users. * Alaa A. Hassan [email protected] 1
Chemistry Department, Faculty of Science, Minia University, El‑Minia 61519, Egypt
2
Institute of Organic Chemistry, Karlsruhe Institute of Technology, Fritz‑Haber‑Weg 6, 76131 Karlsruhe, Germany
3
Institute of Biological and Chemical Systems‑Functional Molecular Systems (IBCS‑FMS), Karlsruhe Institute of Technology, Hermann‑von‑Helmholtz‑Platz 1, 76344 Eggenstein‑Leopoldshafen, Germany
4
Department of Chemistry, University of Helsinki, A. I. Virtasen aukio I, P.O. Box 55, 00014 Helsinki, Finland
sulfur-containing compounds. Carbothioamides contain several nucleophilic centers and are used as building blocks for the synthesis of different heterocyclic rings [7–9]. Tetracyanoethylene (TCNE) is utilized as a part of a wide range of reactions either as a building block or as a reaction mediator [10]. The addition of nucleophiles to the double bond of TCNE followed by loss of cyanated fragments was considered as the most common reaction [11–13]. Direct nucleophilic addition to the nitrile can also occur but is less common [14, 15]. Thiosemicarbazide is one of the carbothioamide derivatives. Due to the presence of several nucleophilic centers in thiosemicarbazides, they are also ideal candidates and valuable building blocks for the synthesis of different heterocyclic rings. Different families of heterocyclic compounds such as thiadiazoles, thiadiazines, thiadiazepines, and pyrazoles were prepared upon the reaction of TCNE with 2,4-disubstituted thiosemicarbazides [16]. N-Substituted-2-phenylthiosemi
Data Loading...
