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X
X
Ph
Ph
X
X
Ph
Ph
Ph
Ph
Ph
Ph
X
X
X
X
100a :X=SR
100b :X= N
100c :X=Ph
Ph
Ph
Ph
Ph
99a :X= Cl
99b :X= Br
Ph
Ph
101
Fig. 30 Structures of highly substituted naphthalenes
NR
200 °C
103
Me 2 NN
102
4 , 100%
104 : R = NMe 2 , 82%
Scheme 22 Synthesis of octamethylnaphthalene [ 11 ]
substituents. Octamethylnaphthalene ( 4 ) exhibits a 26 end-to-end twist [ 12 ].
Octachloro- ( 99a )[ 91 ] and octabromonaphthalene ( 99b )[ 92 ] (Fig. 30 ) show twists
of 24 and 31 , respectively. Several highly twisted octakis(arylthio)naphthalenes
100a and octapyrrolylnaphthalene ( 100b ) have also been reported [ 8 ]. However,
octaphenylnaphthalene ( 100c ) has an essentially untwisted structure presumably
due to the effect of crystal packing [ 13 ]. A large 35 twist was observed for the
octaphenyl derivative 101 [ 93 ].
Condensation between N -dimethylaminopyrrole ( 102 ) and tetramethylbenzyne
( 103 ), generated in situ from 1,2-dibromo-3,4,5,6-tetramethylbenzene, to form the
cycloadduct 104 followed by pyrolysis to form 4 (Scheme 22 )[ 11 ] represents a
general pathway for highly substituted naphthalenes.
Condensation between tetraphenylcyclopentadienone ( 105 ) and tetraphe-
nylbenzyne ( 106 ), generated in situ by diazotization of tetraphenylanthranilic
acid, to form 107 followed by decarbonylation to form 100c (Scheme 23 )[ 13 ]
represents an alternative general pathway for highly substituted naphthalenes.
5.2 Highly Substituted Anthracenes
Decamethylanthracene and related compounds were synthesized by a pathway
similar to that outlined in Scheme 22 [ 11 ]. Decaphenylanthracene ( 5 ) was prepared
by condensation between hexaphenylisobenzofuran ( 108 ) and tetraphenylbenzyne
( 106 ) to form 109 followed by deoxygenation with zinc dust in refluxing acetic acid
(Scheme 24 )[ 13 ]. The X-ray structure of 5 exhibits a 63 end-to-end twist.
 
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