Key indicators: single-crystal X-ray study; T = 296 K; mean (C-C) = 0.009 Å; R factor = 0.067; wR factor = 0.178; data-to-parameter ratio = 19.2.In the title compound, C 11 H 10 Br 2 O 2 , the cyclopentene ring fused to the benzene ring adopts an envelope conformation, with the C atom attached to the Br atom as the flap. The crystal structure does not exhibit any classical hydrogen bonds. The molecular packing is stabilized by van der Waals forces and -stacking interactions with a centroid-centroid distance of 3.811 (4) Å . Related literature

In the title compound, C9H8BrNO, the non-H-atom framework is essentially planar, with a maximum deviation of 0.087 (3) Å. In the crystal, mol­ecules are inter­connected into a three-dimensional network by C—H⋯O and N—H⋯O hydrogen bonds. In addition, C—H⋯π inter­actions and a π–π stacking inter­action, with a centroid–centroid distance of 3.5535 (19) Å, are also observed.

In the title compound, C9H8Br2O, the cyclo­pentene ring adopts an envelope conformation with the brominated C atom as the flap. In the crystal, mol­ecules are linked by strong O—H⋯O hydrogen bonds into zigzag C(4) chains along [010]. In addition, a C—H⋯π inter­action involving the benzene ring and the H atom attached to the hy­droxy­lated C atom is observed.

The bromination reactions of 5-aminoindane, 5-acetamidoindane, and 5-acetamidoindan-1-one were investigated using NBS, molecular bromine and photobromination, and the optimum reaction conditions were presented. The reaction of 5-aminoindane with glacial acetic acid at reflux temperature resulted in the formation of 5-acetamidoindane in high yield. 5-Acetamidoindan-1-one was generated by the reaction of 5-acetamidoindane with CrO 3 in acetic acid. Selective bromination at C-6 position of 5-acetamidoindane was achieved by treatment of title compound with bromine in acetic acid and thus afforded 5-acetamido-6-bromoindane. Further bromination reactions of bromoindanones were achieved in various reaction conditions.

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