Molecular and crystal structure of selected compounds containing 8,11-dioxa[4.3.3]propellane moiety

The molecular and crystal structures of two derivatives containing 8,11-dioxa[4.3.3]propellane moiety: 8,11-dioxa[3,4-(4′-methylbenzo)]-[4.3.3]propellane and 8,11-dioxa[3,4-(4′-tert-butylbenzo)]-[4.3.3]propellane, were determined and compared with those found for 1,2,4,5-bis{8′,11′-dioxa[4.3.3]propella(3′,4′)}benzene. The discussion of the most stable conformation of cyclohexene and tetrahydrofurane rings for isolated 8,11-dioxa(3,4-benzo)]-[4.3.3]propellane molecule was made using the DFT calculations. The results were compared with those performed for tetraline and 2,2,3,3-tetramethyltetraline. 8,11-Dioxa[3,4-(4′-methylbenzo)]-[4.3.3]propellane is important as a reference compound because the unsubstituted 8,11-dioxa(3,4-benzo)-[4.3.3]propellane cannot be obtained in the form of crystalline phase suitable for X-ray diffraction. 1H NMR spectroscopic analysis showed that the methyl group does not induce expected splitting of the appropriate signals, observed in the case of tert-butyl derivative.