N-Benzyl­tetra­hydro­pyrido-anellated thio­phene derivatives: new anti­cholinesterases

The title compounds, tert-butyl 6-benzyl-2-(3,3-diethyl­ureido)-4,5,6,7-tetra­hydro­thieno[2,3-c]pyridine-3-carboxyl­ate, C₂₄H₃₃N₃O₃S, (I), 7-benzyl-2-diethyl­amino-5,6,7,8-tetra­hydro-3-oxa-9-thia-1,7-diaza­fluoren-4-one, C₂₀H₂₃N₃O₂S, (II), and N-(7-benzyl-4-oxo-5,6,7,8-tetra­hydro-4H-3,9-dithia-1,7-diaza­fluoren-2-yl)benzamide, C₂₃H₁₉N₃O₂S₂, (III), form monoclinic crystal systems. In (I) and (II), the mol­ecules are linked into a three-dimensional framework by weak inter­molecular C-H...O=C hydrogen bonds, whereas in (III) stronger inter­molecular N-H...O=C inter­actions are observed. The conformation of (I) is further stabilized by an intra­molecular N-H...O=C hydrogen bond, which effects the planarity of the ureido­thio­phene­carboxyl­ate moiety.