M. Chruszcz, K. Stadnicka, A. Budzowski
May 30, 2002
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Influential Citations
3
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Journal
Journal of Molecular Structure
Abstract
Abstract The crystal structures of 2-((dimethylamino)carbonyl)-6-(2-thienyl)-2 H -thiopyran-3-carboxylic acid ( I ) and 2-((dimethylamino)carbonyl)-6-(2-furyl)-2 H -thiopyran-3-carboxylic acid ( II ) have been determined by single-crystal X-ray diffraction. Both the compounds crystallise in monoclinic system, but in different space groups. The crystals data are: ( I ) a =6.5464(1), b =7.5651(2), c=27.6851(7) A , β =96.867(1)°, Z =4, space group P 2 1 ; ( II ) a =10.2683(2), b =10.6690(3), c=12.3477(3) A , β =101.773(1)°, Z =4, space group P 2 1 /c . Substitution of the thienyl- ( I ) by the furyl-group ( II ) in the 2 H -thiopyrans dramatically changes interactions between the molecules in solid state. The packing for these compounds and the hydrogen bond network are different. The crystals of the thienyl-derivative ( I ) have an inclination towards a twinning, which could be explained by some features of the packing. The X-ray analysis indicates that the mechanism for the formation of 2-thienyl and 2-furyl substituted 2 H -thiopyrans in the reaction of enaminothiones (dienes) with maleic anhydride occurs via a rearrangement of the preliminarily formed endo -cycloadducts and five-membered transition state.