Authors:Klára Lövei, István Greiner, János Éles, Áron Szigetvári, Miklós Dékány, Sándor Lévai, Zoltán Novák and György István Túrós
In medicinal chemistry, the development of synthetic procedures for the access of new heterocyclic systems as potential scaffolds is elementary. Herein, we report our results on the formation of small drug-like heterocycles, utilizing flow chemistry. This approach enables the extension of the reaction parameter window, including high-pressure/high-temperature or hazardous chemistry. In our work, various novel condensed tricyclic benzothiazoles fused with furo- and thieno-rings were synthesized applying a multistep continuous-flow protocol. The process includes two ring closure steps and a nitro group reduction step. Batch and telescoped continuous-flow syntheses were also designed and performed.
Authors:Tamás Fődi, József Kupai, György Túrós, Tamás Németh, Eszter Rojik, Eszter Riethmüller, György Tibor Balogh and Péter Huszthy
This paper reports a new continuous-flow synthesis of chiral and achiral pyridino-18-crown-6 ethers. Macrocyclizations have been performed in a packed-bed flow reactor where deprotonation of a bifunctional primary or a secondary alcohol takes place with potassium hydroxide as a heterogeneous base avoiding the use of stronger and more dangerous one, sodium hydride. Ditosylate derivatives of pyridine as precursors for the macrocyclization used in batch condition were replaced by the appropriate diiodides and optimization of the parameters provided higher yields in shorter reaction times. The setup presented here is suitable for the preparation of different ethers by Williamsontype syntheses in continuous-flow reactions.