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Konformationsanalysen von pyrolytisch erzeugten [2.2]phanen des 4‐Pyranons
Author(s) -
Massa Werner,
Schween Michael,
Steuber Friedrich W.,
Wocadlo Sigrid
Publication year - 1990
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19901230527
Subject(s) - chemistry , sulfone , crystal structure , methylene , crystallography , coalescence (physics) , pyrolysis , nmr spectra database , stereochemistry , planar , spectral line , medicinal chemistry , polymer chemistry , organic chemistry , physics , astronomy , astrobiology , computer graphics (images) , computer science
Conformational Analyses of [2.2]Phanes of 4‐Pyranone Generated by Pyrolysis 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°C) and exhibit anti conformation as shown by X‐ray structural analysis ( 11 ). Like 9 and 11, 5 , exists in a staircase‐like structure in the crystal. 1 H‐NMR spectra of the metaparacyclophane 10 shows coalescence of the signals of the methylene protons at room temperature. The flexibility at 10 at 60°C is interpreted as a swinging process. The crystal structure of bis(sulfone) 8a shows that the two planar rings are tilted by 60°C with respect to each other.