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Class IA
Class II
R n
Shallower bowl
Lower
Deeper bowl
Higher
Class IB
G inv
G inv
Δ
Δ
X
Scheme 35 The correlations between structures and bowl-to-bowl inversion energy [ 57 ]
for some corannulene derivatives. They found the relationship can be empirically
expressed as in ( 1 ). This simple quartic equation provided a reasonable fit to the
experimental results [ 57 ]:
h
mol i
4
G inv ¼
ʔ
ð
bowl depth
=
0
:
87
Þ
11
:
5 kcal
=
ð
1
Þ
3 Sumanene
Sumanene (tricyclopenta[ def , jkl , pqr ]triphenylene, 2)saC 21 -hydrocarbon
containing three periphery methylene bridges, and it is also a basic bowl-shaped
fragment of buckminsterfullerene. Sumanene (2) is named after “suman”, the Hindi
and Sanskrit word for a type of flower [ 133 ]. In contrast to corannulene, the
chemistry of sumanene is relatively new because this compound was first success-
fully synthesized in the laboratory in 2003 [ 134 ].
3.1 Sumanene and Simple Sumanene Derivatives
3.1.1 Synthesis
In 1993, an attempt was made to synthesize sumanene (2) from tris(bromomethyl)-
triphenylene under FVP conditions [ 133 , 135 ]. Unfortunately, this protocol closed
up to two five-membered rings. Ten years later, Sakurai et al. provided a new
synthetic approach to prepare 2 in solution phase under mild conditions [ 134 ]. Sim-
ilar to Lawton's synthetic strategy for corannulene, they first constructed the three-
dimensional framework using tetrahedral sp 3
carbons and later aromatized the
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