Two Independent Intermolecular 1D-Polymeric H-Bonds between Each Enantiomer in Octahydro-1H-Xanthene-1,8(2H)-Diones and Bis-Xanthen Analogues: Synthesis and Crystal Structure

Reaction of 1,3-cyclohexanedione, aldehydes, and cyanogen bromide leads to the selective formation of octahydro-1H-xanthene-1,8(2H)-diones in moderate to good yields at room temperature under basic condition. The reaction of dialdehydes such as phthalaldehyde and terphthalaldehyde gaves tetrahydrodibenzo[b,e]oxepin-1(2H)-one and bifunctiolalized linked bis-xanthen analogues, respectively. All structures were characterized by FT IR, 1H and 13C NMR spectroscopy and Mass analysis techniques. The structure of 3c was analyzed by X-ray crystallography. The pKa and hydrogen bond strength (EHB) were determined in results of ≈11.7 and to ≈5 kcal.mol-1, respectively, via d(O•••••O) distance.