Abstractmagnified imageA series of tetracyclic imidazole derivatives9a,9b,9c,9d,9e,9f,9g,9h,9i,9j,9k,9l,9m,9n,9o,9p,9r,9s,9t,9vand10a,10b,10c,10d,10e,10f,10g,10hare prepared by multistep route starting from the known tricyclic diketones2a,2b,2c,2d. Intermediary dibenzooxepin[4,5‐d]imidazoles (3a,3c) and dibenzothiepin[4,5‐d]imidazoles (3b,3d) areN‐protected to4e,4fand to the isomeric compounds5a,5band6a,6b. The isomeric compounds5and6are separated. Compounds4,5,and6are formylated at C(2) to afford7a,7b,7c,7d,7e,7f,7g,7h,7i,7j. In the last steps, aldehyde group is reduced, then alkylated to the two sets of isomeric ω‐dimethylaminoalkyl derivatives9a,9b,9c,9d,9e,9f,9g,9h,9i,9j,9k,9l,9m,9n,9o,9p,9r,9s,9t,9v.N‐deprotection of9i–9vled to the compounds10a,10b,10c,10d,10e,10f,10g,10h. Assignment of thesyn/antistructure to5aand6awas supported by 1D selective ROESY NMR spectra, whereas conformational mobility for the selected representatives8aand8bis studied by dynamic NMR. Activation energies (energy barriers for interconversion) are determined to be ∼11.5 and 16.2 kcal/mol, respectively. A series of derivatives9and10were testedin vitrofor their anti‐inflammatory activity. J. Heterocyclic Chem., (2010).