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Structurally Characterized Hetero‐Oligopolyphenylenes: Synthetic Advances Toward Next‐Generation Heterosuperbenzenes
Author(s) -
Gregg Daniel J.,
Ollagnier Cecile M. A.,
Fitchett Christopher M.,
Draper Sylvia M.
Publication year - 2006
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.200501289
Subject(s) - heteroatom , chemistry , acetylene , cycloaddition , imine , derivative (finance) , ring (chemistry) , crystal structure , stereochemistry , medicinal chemistry , polymer chemistry , crystallography , organic chemistry , financial economics , economics , catalysis
The successful Diels–Alder [2+4] cycloaddition1 of dipyrimidyl acetylene and suitably substituted 2,3,4,5‐tetraarylcyclopenta‐2,4‐dien‐1‐ones ( 3 – 7 ) generates a series of selectively functionalized hexaarylbenzenes. Each has two pairs of peripheral functional groups (R′ and R= tert ‐butyl 8 and R=methyl 9 , methoxy 10 , bromo 11 , triisopropylsilylethynyl 12 ) and four ortho ‐imine nitrogen atoms. The dibromo derivative 11 is a useful precursor for the formation of a mono ethynyl 13 and diethynyl 14 substituted polyphenylene. Changing the dienophile to di(2‐thienyl)acetylene gives an S‐heteroatom polyphenylene 15 . The compounds were fully characterized by using 1 H, 13 C and a range of 2 D NMR spectroscopic techniques, elemental analysis, and mass spectrometry. Oxidative cyclodehydrogenation of dimethoxy hexaphenylbenzene 10 by using iron( III ) chloride results in the formation of a spirocyclic dienone 16 , which in a separate reaction undergoes dienone/phenol rearrangement to give the first 4‐fused‐ring, N‐heterosuperbenzene (HSB) 17. Six single crystal molecular structures reveal the commonality of unidirectional twisting of the external aromatic rings in these heteroatom polyphenylenes. The twist angles and any H‐bonding or interdigitation in these structures are discussed.