(2S,3R)-3-(2-Bromo­phen­yl)-2-nitro-2,3,6,7-tetra­hydro-1-benzo­furan-4(5H)-one

The title compound, C₁₄H₁₂BrNO₄, has two chiral C atoms. The C atom next to the O atom in the di­hydro­furan ring has an S configuration, while the adjacent chiral C atom has an R configuration. The cyclo­hex-2-enone and di­hydro­furan rings both adopt envelope conformations, with the flap atoms (middle CH₂ in cyclo­hex-2-enone and NO₂-substituted C in di­hydro­furan) lying 0.612 (3) and 0.295 (2) Å, respectively, from the mean plane of the remaining atoms. The dihedral angle between the mean planes of the furan and benzene rings is 80.0 (3)°. In the crystal, the mol­ecules are linked by C—H...O inter­actions, generating a three-dimensional network.

(2S,3S)-3-(3-Bromo­phen­yl)-6,6-dimethyl-2-nitro-2,3,6,7-tetra­hydro­benzo­furan-4(5H)-one

The title compound, C₁₆H₁₆BrNO₄, has two adjacent chiral C atoms and both have an S configuration. The fused cyclo­hex-2-enone and di­hydro­furan rings both adopt envelope conformations, with the quaternary C atom and the nitro-substituted C atoms as the respective flap. The flap atoms lie 0.607 (3) and −0.253 (2) Å, respectively, from the mean plane of the remaining ring atoms on opposite sides. The dihedral angle between the mean plane of the four coplanar atoms of the di­hydro­furan ring and the phenyl ring is 86.16 (3)°. In the crystal, mol­ecules are linked by weak C—H...O inter­actions, forming a ladder motif parallel to the b axis.