124945-40-0Relevant academic research and scientific papers
Conformational Analyses of Phanes of 4-Pyranone Generated by Pyrolysis
Massa, Werner,Schween, Michael,Steuber, Friedrich W.,Wocadlo, Sigrid
, p. 1119 - 1128 (2007/10/02)
The synthesis of the first phanes of 4-pyranone is accomplished by pyrolysis of bis(sulfone) 4.Analogously, 9, 10, and 11 are synthesized.While 5 is conformationally mobile in solution, 9 and 10 are fixed ( up to 100 deg C) and exhibit anti conformation as shown by X-ray structural analysis (9) and computer simulation of the 1H-NMR spectra (11).Like 9 and 11, 5 exists in a staircase-like structure in the crystal.The 1H-NMR spectra of the metaparacyclophane 10 shows coalescence of the signals of the methylene protons at room temperature.The flexibility of 10 at 60 deg C is interpreted as a swinging process.The crystal structure of bis(sulfone) 8a shows that the two planar rings are tilted by 60 deg C with respect to each other.
