caa a22 4500 467919860 CHVBK 20180406152913.0 cr unu---uuuuu 170328e20061001xx s 000 0 eng 10.1007/s00706-006-0531-z doi (NATIONALLICENCE)springer-10.1007/s00706-006-0531-z Synthesis of 2,3-Dihydrothiazolo[3,2- a ]pyrimidin-5-ones by a Michael -type Tandem Reaction [Elektronische Daten] [Yvonne Syha, Charlene Valmalle, Jan W. Bats, Michael Kock, Mona Abdel-Tawab, Manfred Schubert-Zsilavecz] Summary.: Although various thiazoles are known in literature for their biological and pharmacological properties only a few multi-step synthesis pathways for the preparation of thiazolo[3,2-a]pyrimidinones have been reported, which are tedious and time-consuming. An alternative synthesis pathway is described, which allows the preparation of 2,3-dihydrothiazolo[3,2-a]pyrimidin-5-ones in a one-step process based on a Michael-type tandem reaction. By heating of 2-thiobarbituric acid with ethyl 4-bromocrotonate in ethanol at 60°C for 2 h, a 2,3-dihydrothiazolo[3,2-a]pyrimidin-5-one was obtained in 73% yield, whereas carrying out the reaction at room temperature results in the formation of an unstable unsaturated ester. The structures of both, the α,β-unsaturated ester as well as the 2,3-dihydrothiazolo[3,2-a]pyrimidin-5-one were confirmed by NMR spectroscopy. Additionally, the structure of the 2,3-dihydrothiazolo[3,2-a]pyrimidin-5-one was investigated by single-crystal X-ray analysis. The described approach offers a significant improvement over previously reported synthesis pathways because it allows the simple preparation of 2,3-dihydrothiazolo[3,2-a]pyrimidin-5-ones with good yields in a one-step reaction. Springer-Verlag, 2006 Keywords. Cyclization nationallicence 2,3-Dihydrothiazolo[3,2- a ]pyrimidin-5-ones nationallicence Michael -type tandem reaction nationallicence Syha Yvonne Institut für Pharmazeutische Chemie/ZAFES, Universität Frankfurt am Main, Frankfurt am Main, Germany aut Valmalle Charlene Ecole Normale Supérieure de Lyon (ENS Lyon), Lyon Cedex 07, France aut Bats Jan W. Institut für Organische Chemie, Universität Frankfurt am Main, Frankfurt am Main, Germany aut Kock Michael Phenion GmbH & Co. KG, Frankfurt am Main, Germany aut Abdel-Tawab Mona Zentrallaboratorium Deutscher Apotheker, Eschborn, Germany aut Schubert-Zsilavecz Manfred Institut für Pharmazeutische Chemie/ZAFES, Universität Frankfurt am Main, Frankfurt am Main, Germany aut Monatshefte für Chemie / Chemical Monthly Springer-Verlag 137/10(2006-10-01), 1357-1364 0026-9247 137:10<1357 2006 137 706 https://doi.org/10.1007/s00706-006-0531-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00706-006-0531-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Syha Yvonne Institut für Pharmazeutische Chemie/ZAFES, Universität Frankfurt am Main, Frankfurt am Main, Germany aut NATIONALLICENCE 700 1- Valmalle Charlene Ecole Normale Supérieure de Lyon (ENS Lyon), Lyon Cedex 07, France aut NATIONALLICENCE 700 1- Bats Jan W. Institut für Organische Chemie, Universität Frankfurt am Main, Frankfurt am Main, Germany aut NATIONALLICENCE 700 1- Kock Michael Phenion GmbH & Co. KG, Frankfurt am Main, Germany aut NATIONALLICENCE 700 1- Abdel-Tawab Mona Zentrallaboratorium Deutscher Apotheker, Eschborn, Germany aut NATIONALLICENCE 700 1- Schubert-Zsilavecz Manfred Institut für Pharmazeutische Chemie/ZAFES, Universität Frankfurt am Main, Frankfurt am Main, Germany aut NATIONALLICENCE 773 0- Monatshefte für Chemie / Chemical Monthly Springer-Verlag 137/10(2006-10-01), 1357-1364 0026-9247 137:10<1357 2006 137 706 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer