890525-44-7Relevant articles and documents
Structurally characterized hetero-oligopolyphenylenes: Synthetic advances toward next-generation heterosuperbenzenes
Gregg, Daniel J.,Ollagnier, Cecile M. A.,Fitchett, Christopher M.,Draper, Sylvia M.
, p. 3043 - 3052 (2008/09/16)
The successful Diels-Alder [2+4] cycloaddition[1] of dipyrimidyl acetylene and suitably substituted 2,3,4,5-tetraarylcyclopenta-2,4-dien-lones (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 polyphen ylene. Changing the dienophile to di(2thienyl)acetylene gives an S-heteroatom polyphenylene 15. The compounds were fully characterized by using 1H, 13C and a range of 2D 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.
