Crystal structures of methyl 3-(4-iso-propyl-phen-yl)-1-methyl-1,2,3,3a,4,9b-hexa-hydro-thio-chromeno[4,3-b]pyrrole-3a-carboxyl-ate, methyl 1-methyl-3-(o-tol-yl)-1,2,3,3a,4,9b-hexa-hydro-thio-chromeno[4,3-b]pyrrole-3a-carboxyl-ate and methyl 1-methyl-3-(o-tol-yl)-3,3a,4,9b-tetra-hydro-1H-thio-chromeno[4,3-c]isoxazole-3a-carboxyl-ate.

In the title compounds, C23H27NO2S, (I), and C21H23NO2S, (II), the pyrrole rings have envelope conformations with the C atom substituted by the benzene ring as the flap. In the third title compound, C20H21NO3S, (III), the isoxazole ring has a twisted conformation on the C-C bond substituted by the benzene ring and the carboxyl-ate group. In all three compounds, the thio-pyran ring has a half-chair conformation. The mean plane of the pyrrole ring is inclined to the mean plane of the thio-pyran ring by 57.07 (9), 58.98 (9) and 60.34 (12)° in (I), (II) and (III), respectively. The benzene rings are inclined to one another by 73.26 (10)° in (I), 65.781)° in (II) and 63.37 (13)° in (III). In the crystals of all three compounds, there are no classical hydrogen bonds present. Only in the crystal of compound (I) are mol-ecules linked by a pair of C-H⋯π inter-actions, forming inversion dimers. The isopropyl group in compound (I) is disordered over two sets of sites and has a refined occupancy ratio of 0.586 (13):0.414 (13).