Novel Bicyclic <i>P</i>,<i>S</i>-Heterocycles via Stereoselective <i>hetero</i>-Diels–Alder Reactions of Thiochalcones with 1-Phenyl-4<i>H</i>-phosphinin-4-one 1-Oxide
Grzegorz Mlostoń,
Katarzyna Urbaniak,
Marcin Palusiak,
Elżbieta Łastawiecka,
Sławomir Frynas,
Kazimierz Michał Pietrusiewicz,
Heinz Heimgartner
Affiliations
Grzegorz Mlostoń
Department of Organic and Applied Chemistry, Faculty of Chemistry, University of Lodz, Tamka 12, 91-403 Lodz, Poland
Katarzyna Urbaniak
Department of Organic and Applied Chemistry, Faculty of Chemistry, University of Lodz, Tamka 12, 91-403 Lodz, Poland
Marcin Palusiak
Department of Physical Chemistry, Faculty of Chemistry, University of Lodz, Pomorska 163/165, 90-236 Lodz, Poland
Elżbieta Łastawiecka
Department of Organic and Crystal Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Skłodowska University, Gliniana 33, 20-614 Lublin, Poland
Sławomir Frynas
Department of Organic and Crystal Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Skłodowska University, Gliniana 33, 20-614 Lublin, Poland
Kazimierz Michał Pietrusiewicz
Department of Organic and Crystal Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Skłodowska University, Gliniana 33, 20-614 Lublin, Poland
Heinz Heimgartner
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
Thiochalcones undergo cycloaddition reactions in THF solution at 60 °C with the synthetically unexplored 1-phenyl-4H-phosphinin-4-one 1-oxide in a highly regio- and stereoselective manner, yielding hitherto unknown bicyclic P,S-heterocycles containing fused thiopyran and phosphinine rings. The stereochemical structures of two of the obtained (4+2)-cycloadducts were unambiguously assigned by means of the X-ray single-crystal analysis. Based on these assignments, a concerted mechanism of the hetero-Diels–Alder reaction via the preferred endo approach of the heterodiene from the less hindered P=O side of the phosphininone molecule is postulated to explain the established rac-(4RS,8SR,9SR,10SR)-configured (4+2)-cycloadducts isolated as major products.
