Chemistry Reference
In-Depth Information
O
R
R
R
R
R
R
R
FeCl
3
79%
R
76
(4)
95%
R
R
75
R
R
R= C
12
H
25
77
78
R
R
R
75
FeCl
3
90%
(5)
O
75%
R
R
R
79
80
R= C
12
H
25
81
Scheme 17 Preparation of graphene-type structures via the Diels-Alder/dehydrogenation
strategy
R
R
R
R
R
R
Co
2
(CO
)
8
R
R
82
R
R
R
R
R
R
83
84
Scheme 18 General concept for the synthesis of HBCs by alkyne cyclotrimerization
molecules with six redox-active triarylamine sites were used to study electron
transfer pathways [
49
].
The versatility of the cyclotrimerization and the easy access to substituted
phenylacetylene by modern coupling methods offers a wide range of variously
decorated HBCs. An intriguing example is shown in Scheme
20
. Permethoxylated
hexa-
-hexabenzocoronene (permethoxylated HBC) 90, which results in a dou-
ble concave conformation, was easily synthesized via cyclotrimerization of a
hexamethoxysubstituted phenylacetylene 88 followed by the usual cyclodehydro-
genation reaction [
50
]. The non-planarity of the system is explained by the steric
peri