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a
b
c
Ar
2
Ph
Ph
Ph
Ph
Ph
Ar
2
Ph
Ar
1
Ar
1
Ar
1
Ar
1
82
83
Ph
Ar
1
=C
6
H
4
OMe, Ar
2
=C
6
H
4
OPr
Ar
2
84
Fig. 16 Structures of multiple pentalene-containing (a) 82,(b) 83, and (c) 84 [
98
]
a
R
1
R
2
IPrAuNTf
2
C
6
H
6
,80 C
R
1
R
1
R
1
R
2
85a
:R
1
,R
2
=H
85b
:R
1
= OMe, R
2
=H
85c
:R
1
=-OCH
2
O-, R
2
=H
85d
:R
1
=H,R
2
=
n
Bu
85e
:R
1
=H,R
2
= OMe
56b
,54%
86b
,68%
86c
:62%
86d
:60%
86e
:80%
b
S
IPrAuNTf
2
C
6
H
6
,80 C
20%
87
S
88
Scheme 23 Gold-catalyzed rearrangements of (a) 1,2-diethynylarenes 85 to DAPs 86 and (b) 87
to benzo[
a
]-thieno[
e
]pentalene 88 [
99
]
Ph
Ph
Ph
Ph
90
, 28%
TIPS
TIPS
TIPS
TIPS
I
I
Li
Li
TIPS
I
2
Li
Ph
TIPS
TIPS
Li
89
91
,7%
Li
TIPS
TIPS
Scheme 24 Reduction of TIPS-substituted phenylacetylene to give dilithium dibenzopentalenide
89, and subsequent treatment with
I
2
to give DAP 91 [
100
]
the monoanion 92 formed which could then be trapped with an electrophile to give
methylene-bridged stilbene 93 (Scheme
25
a) [
101
]. DAP 91 also reacted with
excess bromine and iodine to give 5,10-dihalo-DAPs 94a/b in good yields
(Scheme
25
b).
