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Different Rearrangement Behaviour of the Cation or Anion Derived from the Diels–Alder Adduct of 9‐Ferrocenylanthracene and 1,4‐Benzoquinone: Ring‐Opening or Paddlewheel Formation
Author(s) -
Nikitin Kirill,
MüllerBunz Helge,
Ortin Yannick,
McGlinchey Michael J.
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201101854
Subject(s) - chemistry , adduct , anthracene , moiety , medicinal chemistry , benzoquinone , ring (chemistry) , ferrocene , photochemistry , hydride , bond cleavage , stereochemistry , organic chemistry , catalysis , electrochemistry , hydrogen , electrode
Prototropic rearrangement of the Diels–Alder adduct ( 3 a ) of 9‐ferrocenylanthracene and 1,4‐benzoquinone potentially furnishes 9‐ferrocenyl‐1,4‐dihydroxytriptycene ( 3 b ) incorporating a C 2 v symmetrical paddlewheel moiety. However, reaction of 3 a with HBF 4 unexpectedly yields instead 9‐ferrocenyl‐10‐(2,5‐dihydroxyphenyl)anthracene ( 4 ) via cleavage of the C9C12 bond to generate initially a ferrocenyl‐stabilized cation. Treatment of 3 a with sodium hydride and iodomethane yields 1,4‐dimethoxy‐9‐ferrocenyltriptycene ( 3 c ) in high yield but, surprisingly, also leads to fission of the C9C12 bond resulting, after methylation, in the formation of 9‐hydroxy‐9‐ferrocenyl‐10‐(2‐hydroxy‐5‐methoxyphenyl)dihydroanthracene ( 12 ), which readily dehydrates on silica to form 9‐ferrocenyl‐10‐(2‐hydroxy‐5‐methoxyphenyl)anthracene ( 8 ). The X‐ray crystal structures of 3 a , 3 c and 4 are reported.
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