Chemistry Reference
In-Depth Information
FVP
1080 ºC
Cl
Cl
20%
108
109
Scheme 32 Synthesis of acenaphtho[1,2,3-
bcd
]corannulene (109)[
48
]
Cl
Cl
R
R
Br
2
HC
CHBr
2
FVP
1000 ºC
5% to
111
-H
BrH
2
C
CH
2
Br
B
or
C
BrH
2
C
CH
2
Br
R
Br
2
HC
CHBr
2
R
Cl
Cl
112
111
-H
111
-Br
110
B
: 1) Ti*, 2) DDQ
22% yield to
111
-H
C
: NaOH, dioxane, H
2
O
26% yield to
111
-Br
NiCl
2
(dppp)
AlMe
3
, DME
111
-Me
80%
Scheme 33 Synthesis of semibuckminsterfullerenes 111 [
35
,
130
-
132
]
2.6.2 Acenaphtho[1,2,3-bcd]corannulene
The FVP synthesis of acenaphtho[1,2,3-
bcd
]corannulene (109) started with
arylethenylcorannulene 108 (Scheme
32
)[
48
]. A reaction mechanism was pro-
posed in which the aryl radical, generated by chlorine atom loss one at a time, first
closes a six-membered ring, and subsequently a five-membered ring, to yield 109.
2.6.3 Semibuckminsterfullerene
Semibuckminsterfullerene (111) is a bowl-shaped polyarene comprising 50% of the
C
60
skeleton. Similar to the synthesis of corannulene (1)showninScheme
2
,
Rabideau, Sygula, and co-workers subjected 110 to the cyclization under FVP
conditions to prepare semibuckminsterfullerene (111-H) (Scheme
33
)[
130
,
131
]. A
few years later the same group reported the solution-phase synthesis of semibuckmin-
sterfullerenes 111-H [
35
]and111-Br [
132
], which were easily accessed from
dodecabromide 112 using the McMurry reaction and the carbenoid coupling, respec-
tively. The four bromine substituents in 111-Br were easily replaced by methyl groups
to furnish tetramethyl derivative 111-Me in good yield [
132
]. Based on crystallo-
graphic analysis, the highest POAV pyramidalization angle in 111-Me was deter-
mined to be 11.6
, which is almost identical to buckminsterfullerene (11.64
).
