Molecules, Vol. 29, Pages 2036: Novel Bicyclic P,S-Heterocycles via Stereoselective hetero-Diels & ndash;Alder Reactions of Thiochalcones with 1-Phenyl-4H-phosphinin-4-one 1-Oxide

Molecules, Vol. 29, Pages 2036: Novel Bicyclic P,S-Heterocycles via Stereoselective hetero-Diels–Alder Reactions of Thiochalcones with 1-Phenyl-4H-phosphinin-4-one 1-Oxide Molecules doi: 10.3390/molecules29092036 Authors: Grzegorz Mlostoń Katarzyna Urbaniak Marcin Palusiak Elżbieta Łastawiecka Sławomir Frynas Kazimierz Michał Pietrusiewicz Heinz Heimgartner 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.
Source: Molecules - Category: Chemistry Authors: Tags: Article Source Type: research
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