Chemistry Reference
In-Depth Information
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.