Improved and practical synthesis of [2,4,5-tris(trimethylsilyl)- Phenyl](phenyl)iodonium triflate and utilization as a 1,4-benzdiyne synthon

Article abstract of DOI:10.1002/adsc.201400081

An efficient and improved method for preparing [2,4,5-tris(trimethylsilyl) phenyl](phenyl)iodonium triflate as a 1,4-benzdiyne synthon was developed by using phenyiodonium diacetate/boron triflouride diethyl etherate [PhI(OAc) ₂/BF₃ OEt₂] reagent. The iodonium triflate generated 3,4-bis(trimethylsilyl)benzyne quantitatively to give cycloadducts with tetraphenylcyclopentadienone, furan and anthracene in high yields. These cycloadducts bearing two trimethylsilyl groups were transformed into the corresponding aryne precursors, which underwent subsequent cycloaddition reactions to afford polycyclic aromatic compounds such as 1,4-dihydro-1,4- epoxyanthracene, naphthotriazole, triptycene, and anthratriazole derivatives in good to high yields. The total reactions are formally considered as double cycloaddition reactions of 1,4-benzdiyne. This practical and useful formal benzdiyne strategy is described.

Full text of DOI:10.1002/adsc.201400081

UPDATES
DOI: 10.1002/adsc.201400081
Improved and Practical Synthesis of [2,4,5-Tris(trimethylsilyl)-
phenyl](phenyl)iodonium Triflate and Utilization as a
G
1,4-Benzdiyne Synthon
Keisuke Gondoa and Tsugio Kitamuraa,*
a
Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University,
Honjo-machi, Saga 840-8502, Japan
Fax : (+81)-952-28-8548; e-mail: kitamura@cc.saga-u.ac.jp
Received: January 21, 2014; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201400081.
Abstract: An efficient and improved method for
preparing [2,4,5-tris(trimethylsilyl)phenyl](phenyl)-
iodonium triflate as a 1,4-benzdiyne synthon was
developed by using phenyiodonium diacetate/boron
triflouride·diethyl etherate [PhI(OAc)2/BF3·OEt2]
reagent. The iodonium triflate generated 3,4-bis(tri-
methylsilyl)benzyne quantitatively to give cycload-
ducts with tetraphenylcyclopentadienone, furan and
anthracene in high yields. These cycloadducts bear-
ing two trimethylsilyl groups were transformed into
the corresponding aryne precursors, which under-
went subsequent cycloaddition reactions to afford
polycyclic aromatic compounds such as 1,4-dihydro-
though the direct generation of 1 for double cycload-
dition is fascinating in organic synthesis due to its
simple and straightforward nature, trapping highly re-
active benzdiyne 1 seems to be difficult because
1 easily isomerizes to ring-opening products such as
hexatriyne.[2] Therefore, a sequential, stepwise process
for double cycloaddition is superior to the direct
method from the standpoint of organic synthesis. In
addition, the sequential method enables the synthesis
of unsymmetrical cycloadducts which are difficult to
prepare by the direct method. Apart from a direct
benzdiyne strategy involving generation and cycload-
dition of benzdiyne 1, a formal benzdiyne strategy via
a sequential processe as shown in Scheme 1 is more
useful and practical in organic synthesis.
However, only few methods giving unsymmetrical
cycloadducts with different dienes under mild and
neutral conditions have been reported. Winling and
Russel reported that (phenyl)[2,4,5-tris(trimethylsi-
lyl)phenyl]iodonium triflate prepared from 1,2,4,5-tet-
rakis(trimethylsilyl)benzene was the good reagent for
the synthesis of unsymmetrical adducts of benzdiyne
1.[6] Furthermore, Wong and co-workers demonstrated
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
1,4-epoxyanthracene, naphthotriACTHNUTRGNEUNGazole, triptycene,
and anthratriazole derivatives in good to high
yields. The total reactions are formally considered
as double cycloaddition reactions of 1,4-benzdiyne.
This practical and useful formal benzdiyne strategy
is described.
Keywords: arynes; 1,4-benzdiyne; cycloaddition;
hypervalent iodine; iodonium salts
1,4-Benzdiyne or 1,2,4,5-tetradehydrobenzene (1) is
considerably higher in energy than benzyne and has
been a target compound for theoretical studies[1] and
for matrix isolation and characterization so far.[2] Al-
though benzdiyne 1 is regarded as a useful intermedi-
ate to construct polycyclic aromatic molecules, there
are few reports on the utilization of benzdiyne 1 for
organic synthesis because of its inherent instability.
Furthermore, the cycloaddition reaction of benzdiyne
precursors such as tetrahaloarenes,[3] benzeneditri-
flates,[4] and diaminobenzobistriazoles[5] gives double
cycloadducts, but it is not clear whether the genera-
Scheme 1. Benzdiyne strategies for constructing aromatic
tion of benzdiyne 1 is involved in these reactions. Al- compounds.
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Keisuke Gondo and Tsugio Kitamura
lyl)phenyl]iodonium triflate (3) using a milder hyper-
valent iodine reagent system and develop a benzdiyne
strategy. We want to report here a stepwise approach
to benzydiyne adducts using [2,4,5-tris(trimethylsilyl)-
phenyl]iodonium triflate 3, as shown in Scheme 2.
Fist we examined the synthesis of [2,4,5-tris(trime-
thylsilyl)phenyl]iodonium triflate 3 from 1,2,4,5-tetra-
kis(trimethylsilyl)benzene (2). The results are given in
Table 1. According to this procedure for the synthesis
of [2-(trimethylsilyl)phenyl]iodonium triflate,[10] tetra-
kis(trimethylsilyl)benzene
PhI(OAc)2 activated with 2 equiv. of TfOH However,
The reaction with PhI
2
was treated with
AHCTUNGTRENNUNG
Scheme 2. A benzdiyne strategy using [tris(trimethylsilyl)-
phenyl]iodonium triflate 3.
(OAc)2/2TfOH at À208C or at
À208C to room temperature afforded a complex mix-
ture of products (Table 1, entries 1 and 2). It was con-
the synthesis of linear polycyclic aromatic hydrocar- sidered that the use of TfOH as an activating agent
bons using 5,6-bis(trimethylsilyl)benzo[c]furan, which caused desilylation. Then, we examined a reagent
was prepared in two steps from [2,4,5-tris(trimethylsi- system of PhIO and BF3·Et2O for phenyliodination.[11]
lyl)phenyl]iodonium triflate.[7] Lee and co-workers de- Tetrakis(trimethylsilyl)benzene 2 was reacted with
veloped a synthesis of fused triptycenes and extended PhIO activated with BF3·Et2O at 08C and the reaction
triptycene derivatives from benzobisoxadisilole as mixture was then treated with aqueous NaOTf. In this
a 1,4-benzdiyne equivalent.[8] However, regrettably, procedure, the desired iodonium triflate 3 was isolat-
[tris(trimethylsilyl)phenyl]iodonium triflate and the ed as a solid in 23% yield (entry 3). Increasing the
related iodonium triflates were not isolated but used amount of PhIO/BF3·Et2O improved the yield of 3
for further reactions without isolation.
slightly (entries 4 and 5). After increasing the amount
Very recently, we discovered a safe and efficient of activating agent BF3·Et2O, the desired iodonium
procedure for the synthesis of 1,2-bis(trimethylsilyl)- triflate 3 was obtained in 58% yield (entry 6). Finally,
benzene from 1,2-dichlorobenzene; this procedure we examined on use of PhI
provides 1,2,4,5-tetrakis(trimethylsilyl)benzene (2) in BF3·Et2O. The reaction of tetrakis(trimethylsilyl)ben-
a high yield.[9] Encouraged by this discovery, we stud- zene 2 with PhI
(OAc)2 activated by 2 equiv. of
ACHTUNGRTEN(NNUG OAc)2 together with
AHCTUNGTRENNUNG
ied a facile approach to benzdiyne adducts using hy- BF3·Et2O followed by treatment with aqueous NaOTf
pervalent iodine compounds because a hypervalent gave the desired iodonium triflate 3 in 84% yield
benzyne precursor, (phenyl)[2-(trimethylsilyl)phen
ACHTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
zyne generation and is easy to handle. We could im- BF3·Et2O reagent was the best.
prove the synthesis of (phenyl)[2,4,5-tris(trimethylsi-
Table 1. Preparation of [tris(trimethylsilyl)phenyl]iodonium triflate 3.
Entry
PhIX (mmol)
Activator (mmol)
Temp. [8C]
Time [h]
Yield [%][a]
[b]
1
2
PhI
PhI
PhIO (1.2)
PhIO (2)
PhIO (3)
PhIO (1.2)
N
TfOH (2)
TfOH (3.8)
À20
0.5
17
3
3
3
–
–
[b]
À20 to r.t.
3[c]
4[c,d]
5[c,e]
6[c]
7[c,f]
BF3·OEt2 (1.2)
BF3·OEt2 (2)
BF3·OEt2 (3)
BF3·OEt2 (6)
BF3·OEt2 (2.4)
0
0
0
0
23
27
31
58
86
1
0.5
PhI
r.t.
[a]
Isolated yield.
A complex mixture of products.
Product was isolated after treating the reaction mixture with aqueous NaOTf.
CH2Cl2 (6 mL).
CH2Cl2 (8 mL).
CH2Cl2 (10 mL).
[b]
[c]
[d]
[e]
[f]
2
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Synthesis of [2,4,5-Tris(trimethylsilyl)phenyl]ACTHNUTRGNEUG(N phenyl)iodonium Triflate
Since we confirmed that the first step of the consec-
utive benzdiyne strategy proceeded successfully, we
then conducted further transformations of cycload-
ducts 5–7. Treatment of bis(trimethylsilyl)naphthalene
5 with PhIACTHNUTRGNEG(UN OAc)2/BF3·Et2O reagent followed by aque-
ous NaOTf gave (trimethylsilyl)naphthyliodonium tri-
flate 8 in 92% yield. Reaction of the iodonium triflate
8 with Bu4NF in the presence of furan afforded cyclo-
adduct 10 in 99% yield (Scheme 5), suggesting that
tetraphenyldidehydronaphthalene 9 was generated
quantitatively. Next, we conducted the trapping reac-
tion with tetraphenylpentadienone under the same
conditions and obtained octaphenylanthracene 11 in
89% yield. Although the synthesis of octaphenylan-
thracene 11 was reported by different methods,[12] the
yields were low or moderate. In addition, 1,3-dipolar
cycloaddition of 9 with phenyl azide proceeded effi-
ciently to give naphthotriazole 12 in 64% yield. These
results indicate that this consecutive benzdiyne ap-
proach is excellent. Encouraged by these results, we
continued examining the consecutive benzdiyne strat-
egy.
Scheme 3. Attempted synthesis of a benzdiyne precursor
(see Scheme 4).
Since the furan adduct 6 derived from bis(trime-
thylsilyl)benzyne 4 has a reactive double bond toward
an electrophilic hypervalent iodine reagent, it must be
transformed into its naphthalene derivative by deoxy-
genative aromatization. The deoxygenation reaction
of furan adduct 6 was conducted according to the lit-
erature method using TiCl4/LiAlH4/Et3N in THF,[13]
Scheme 4. Generation and reaction of bis(trimethylsilyl)ben-
zyne 4.
In order to explore the synthesis of a benzdiyne
precursor, we attempted an additional phenyliodina-
tion of tris(trimethylsilyl)phenyliodonium triflate 3
using PhIACHTUNGTRENNUNG(OAc)2/BF3·Et2O reagent. However, no bis-
iodonium ditriflates were obtained (Scheme 3). Sever-
al attempted reactions using other reagents such as
PhIO/BF3·Et2O and PhIACTHNUGTRENNUG(OAc)2/TfOH also failed.
Thus, we turned our approach into a stepwise, consec-
utive method for the benzdiyne strategy.
To achieve the consecutive benzdiyne strategy, the
trimethylsilyl group must be tolerant against fluoride
ion under the reaction conditions. Then, we examined
the trapping reaction of 4,5-bis(trimethylsilyl)benzyne
(4) using furan, tetraphenylcyclopentadienone, and
anthracene (Scheme 4). When iodonium triflate 3 was
treated with Bu4NF in CH2Cl2, the cycloadducts 5 and
6 of bis(trimethylsilyl)benzyne 4 with furan and tetra-
phenylcyclopentadienone were obtained quantitative-
ly in both cases. In the trapping reaction with anthra-
cene, bis(trimethysilyl)triptycene 7 was isolated in
86% yield. Two trimethylsilyl groups were tolerated
under the reaction conditions and existed on the cy-
cloadducts 5–7 without any damage.
Scheme 5. Preparation and reaction of (trimethylsilyl)naph-
thyliodonium triflate 9.
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Keisuke Gondo and Tsugio Kitamura
Scheme 6. Preparation and reaction of naphthyliodonium
triflate 14.
affording 2,3-bis(trimethylsilyl)naphthalene (13) in
90% yield (Scheme 6). Treatment of bis(trimethylsi-
lyl)naphthalene 13 with PhIACHTNUTRGNEUNG(OAc)2/BF3·Et2O reagent
followed by aqueous NaOTf gave (phenyl)[3-(trime-
thylsilyl)naphthyl]iodonium triflate (14) in 92% yield.
In the previous synthesis of the same iodonium salt
Scheme 7. Preparation and reaction of triptycenyliodonium
triflate 16.
14 using PhI
54%.[14] Therefore, the synthesis of the benzyne pre-
cursor was much improved by use of PhI(OAc)2/
BF3·Et2O reagent. Reaction of the iodonium triflate
14 with Bu4NF in the presence of furan afforded cy- phenyl azide was conducted by reaction of iodonium
cloadduct 15 in 96% yield. triflate 16 with Bu4NF in the presence of phenyl
Recently triptycene and the related compounds azide, affording cycloadduct 20 in 78% yield.
have attracted much attention due to their unique In conclusion, we have demonstrated that tris(tri-
ACHTUNGTRENNUNG(OAc)2/TfOH reagent, the yield was
AHCTUNGTRENNUNG
structures and have been applied to molecular ma- methylsilyl)phenyliodonium triflate 3 can be isolated
chines, supramolecular chemistry, and material sci- and applied as a synthon of 1,4-benzdiyne (1). In the
ence.[15] However, there are only a few reports on the present paper, we improved the synthesis of iodonium
synthesis of triptycyne precursors.[8c,16] Thus, we con- trifalte 3 using a PhI
ACHTNUGTRNE(UNG OAc)2/BF3·OEt2 reagent. Reac-
ducted the synthesis of a 2,3-triptycyne equivalent tion of 3 with Bu4NF efficiently generated 4,5-bis(tri-
from bis(trimethylsilyl)triptycene 7. Treatment of bis- methylsilyl)benzyne (4) to afford bis(trimethylsilyl)-
ACHTUNGTRENNUNG(trimethylsilyl)triptycene 7 with PhIACHTUGNTRENN(UGN OAc)2/BF3·Et2O naphthalenes 5 and 6 and bis(trimethylsilyl)triptycene
reagent followed by aqueous NaOTf afforded tripty- 7 in high yields. These products were converted into
cenyliodonium triflate 16 in 85% yield (Scheme 7). the corresponding silyl-substituted iodonium triflates
The triptycenyliodonium triflate 16 readily reacted 9, 15, and 17, and applied to subsequent cycloaddition
with Bu4NF to generate 2,3-triptycyne (17), which un- reactions. The consecutive cycloaddition reactions
derwent cycloaddition with furan and anthracene to constructed several polycyclic aromatic compounds
give the cycloadducts 18 and 19 in 94 and 73% yields, which are formally considered as double cycloaddi-
respectively. From the result of the cycloaddition with tion products of 1,4-benzdiyne. The present results in-
furan, 2,3-triptycyne is considered to be formed dicate that the consecutive benzdiyne strategy using
almost quantitatively. Pentiptycene (19) was first pre- tris(trimethylsilyl)phenyliodonium triflate 3 is practi-
pared through the addition of 2,3-triptycyne to an- cal and useful for the synthesis of such polycyclic aro-
thracene but the yield was low.[17] A one-pot synthesis matic compounds.
of pentiptycene was conducted by the reaction of
1,2,4,5-tetrabromobenzene with BuLi in the presence
of anthracene.[16] However, there were some technical
difficulties so that the yield based on 1,2,4,5-tetrabro-
Experimental Section
mobenzne was only 26% and the remaining anthra-
cene must be separated from the product. Therefore,
the present procedure is considered to be valuable in
Preparation of (Phenyl)[2,4,5-tris(trimethylsilyl)-
phenyl]iodonium Triflate (3)
the synthesis of tri-/pentiptycene derivatives. Further-
more, the cycloaddition of 2,3-pentycyne 17 with (5 mmol) and PhIAHCTUNTGRENNUNG
To a mixture of 1,2,4,5-tetrakis(trimethylsilyl)benzene (2)
(OAc)2 (6 mmol) in CH2Cl2 (30 mL) was
4
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Synthesis of [2,4,5-Tris(trimethylsilyl)phenyl]ACTHNUTRGNEUG(N phenyl)iodonium Triflate
added BF3·OEt2 (12 mmol). The mixture was stirred at
room temperature for 30 min. The reaction mixture was
poured into an aqueous solution of NaOTf (25 mmol) and
stirred vigorously. The product was extracted with CH2Cl2
(20 mLꢁ3). The combined organic extract was dried over
anhydrous Na2SO4 and concentrated under reduced pres-
sure. The resulting solid was filtered and washed with
hexane to give a white solid; yield: 2.28 g (86%); mp 115–
into an aqueous solution of NaOTf (2 mmol) and stirred vig-
orously. The product was extracted with CH2Cl2 (2 mL ꢁ 3).
The combined organic extract was dried over anhydrous
Na2SO4 and concentrated under reduced pressure. The re-
sulting solid was filtered and washed with hexane to give
a crystalline product.
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
1
1178C. H NMR (400 MHz, CDCl3): d=0.31 (s, 9H), 0.39 (s,
a
9H), 0.43 (s, 9H), 7.48 (t, J=7.6 Hz, 2H), 7.60 (t, J=7.6 Hz,
1H), 7.82 (d, J=7.6 Hz, 2H), 7.92 (s, 1H), 7.98 (s, 1H);
13C NMR (100 MHz, CDCl3): d=À0.4, 1.0, 1.2, 113.0, 125.1,
132.1, 132.2, 133.4, 142.6, 144.4, 151.1, 154.3 (one carbon
overlapped); HR-MS (FAB): m/z=497.1020, calcd. for
C21H34ISi ([MÀOTf]+): 497.1013.
1H NMR (400 MHz, CDCl3): d=0.28 (s, 9H), 6.78–7.28 (m,
20H), 7.41 (t, J=8.0 Hz, 2H), 7.58 (t, J=8.0 Hz, 1H), 7.70
(d, J=8.0 Hz, 2H), 7.95 (s, 1H), 8.22 (s, 1H); 13C NMR
(100 MHz, CDCl3): d=À0.1, 114.4, 118.2, 126.0, 126.8, 127.2,
127.5, 127.8, 128.1, 130.7, 130.8, 130.9, 132.2, 132.37, 132.44,
133.4, 134.0, 137.1, 137.6, 138.0, 138.6, 138.9, 139.1, 139.2,
140.0, 142.0, 142.7 (four carbons overlapped); HR-MS
(FAB): m/z=707.1633, calcd. for C43H36ISi ([MÀOTf]+):
707.1631.
Trapping Reaction of 4,5-Bis(trimethylsilyl)benzyne
(4) with Dienophiles
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
To a solution of iodonium triflate 3 (2 mmol) and a dieno-
phile (10 mmol) in CH2Cl2 (10 mL) was slowly added a THF
solution of TBAF (2 mmol). The mixture was stirred at
room temperature for 20 min. The reaction mixture was
poured into water and extracted with CH2Cl2 (10 mLꢁ3).
The combined organic extract was washed with brine, dried
over anhydrous Na2SO4, and concentrated under reduced
pressure. The product was separated by column chromatog-
raphy on silica gel (hexane/AcOEt).
1,2,3,4-Tetraphenyl-6,7-bis(trimethylsilyl)naphthalene (5):
The product was obtained as a white solid; yield: 1.118 g
(97%); mp 310–3128C; 1H NMR (400 MHz, CDCl3): d=
0.22 (s, 18H), 6.84–6.85 (m, 10H), 7.21–7.25 (m, 10H), 7.97
(s, 2H); 13C NMR (100 MHz, CDCl3): d=1.6, 125.3, 126.4,
126.6, 127.4, 130.6, 131.2, 131.3, 134.6, 138.3, 139.1, 139.4,
140.5, 142.0. HR-MS (FAB): m/z=576.2666, calcd. for
C40H40Si2: 576.2669.
(1.2 mmol) in CH2Cl2 (6 mL) in the presence of BF3·OEt2
(2.4 mmol) gave 14 as a white solid; yield: 0.530 g (96%);
mp 187–1888C; 1H NMR (400 MHz, CDCl3): d=0.45 (s,
9H), 7.40 (t, J=8.0 Hz, 2H), 7.51 (t, J=8.0 Hz, 1H), 7.66–
7.70 (m, 2H), 7.84 (d, J=8.0 Hz, 2H), 7.91 (d, J=8.8 Hz,
1H), 7.97 (d, J=9.2 Hz, 1H), 8.12 (s, 1H), 8.84 (s, 1H);
13C NMR (100 MHz, CDCl3): d=0.2, 114.3, 117.1, 128.21,
128.23, 128.7, 129.8, 131.9, 132.3, 133.0, 133.8, 135.1, 139.5,
140.6, 140.8.
ACHTUNGERTN[NUNG 1’,2’]-benzenoanthra-
cen-2-yl)(phenyl)iodonium triflate (16): The product was ob-
tained as a white solid; yield: 0.788 g (85%); mp 241–
2448C; H NMR (400 MHz, CDCl3): d=0.37 (s, 9H), 5.49
(s, 1H), 5.58 (s, 1H), 7.02–7.05 (m, 4H), 7.36–7.50 (m, 7H),
7.65 (s, 1H), 7.83 (d, J=7.6 Hz, 2H), 8.12 (s, 1H); 13C NMR
(100 MHz, CDCl3): d=0.2, 52.9, 53.8, 114.0, 116.3, 124.0,
124.4, 125.8, 125.9, 132.2, 132.4, 132.8, 133.6, 143.5, 143.6,
144.4, 150.3, 151.7 (one carbon overlapped); HR-MS (FAB):
m/z=529.0850, calcd. for C29H26ISi ([MÀOTf]+): 529.0849.
(9,10-Dihydro-3-trimethylsilyl-9,10
AHCTUNGTRENNUNG
1
6,7-Bis(trimethylsilyl)-1,4-dihydro-1,4-epoxynaphthalene
(6): The reaction of 3 (1 mmol) with furan (5 mmol) in
CH2Cl2 (5 mL) in the presence of a THF solution of TBAF
(1 mmol) gave the product 6 as a white solid; yield: 0.288 g
1
(100%); mp 97–998C; H NMR (400 MHz, CDCl3): d=0.35
(s, 18H), 5.71 (s, 2H), 7.02 (s, 2H), 7.59 (s, 2H); 13C NMR
(100 MHz, CDCl3): d=2.1, 82.3, 126.5, 142.8, 143.4, 148.3;
HR-MS (EI): m/z=288.1363, calcd. for C16H24OSi2:
288.1366.
Trapping Reaction of an Aryne with a Dienophile
To a solution of an aryne precursor 8, 14, or 16 (0.2 mmol)
and a dienophile (1 mmol) in CH2Cl2 (2 mL) was slow
added a THF solution of TBAF (0.2 mmol) and the mixture
was stirred at room temperature for 20 min. The reaction
mixture was poured into water and the product was extract-
ed with CH2Cl2 (2 mLꢁ3). The combined organic extract
was washed with brine, dried over anhydrous Na2SO4, and
concentrated under a reduced pressure. The crude product
was purified by column chromatography on silica gel with
hexane/EtOAc as eluent.
1,4-Dihydro-5,6,7,8-tetraphenyl-1,4-epoxyanthracene (10):
The product was obtained as a white solid; yield: 0.099 g
(99%); mp 274–2768C; 1H NMR (400 MHz, CDCl3): d=
5.66 (s, 2H), 6.80–6.82 (m, 8H), 6.87 (s, 2H), 7.16–7.23 (m,
12H), 7.39 (s, 2H); 13C NMR (100 MHz, CDCl3): d=81.8,
117.6, 125.3, 126.4, 126.5, 126.6, 127.5, 127.6, 130.2, 131.13,
131.18, 131.21, 131.24, 138.8, 139.2, 139.7, 140.4, 141.6, 144.2
(nineteen peaks were observed by inhibiting free rotation of
phenyl groups due to steric repulsion); HR-MS (FAB):
m/z=499.2060, calcd. for C38H27O ([M+H]+): 499.2062.
9,10-Dihydro-2,3-bis(trimethylsilyl)-9,10ACHTNUTRGNEUNG[1’,2’]-benzenoan-
thracene (7): The reaction of 3 (1 mmol) with anthracene
(5 mmol) in CH2Cl2 (30 mL) in the presence of a THF solu-
tion of TBAF (1 mmol) gave the product 7 as a white solid;
yield; 0.342 g (86%); mp 187–1898C; 1H NMR (400 MHz,
CDCl3): d=0.31 (s, 18H), 5.40 (s, 2H), 6.97–6.99 (m, 4H),
7.37 (m, 4H), 7.67 (s, 2H); 13C NMR (100 MHz, CDCl3):
d=2.1, 54.0, 123.6, 125.1, 130.2, 143.0, 144.4, 145.2; HR-MS
(FAB): m/z=398.1884, calcd. for C26H30Si2: 398.1886.
General Procedure for Preparation of Functionalized
Aryne Precursors 8, 14, 16
To a mixture of a bis(trimethylsilyl)arene (0.2 mmol) and
PhIACHTUNGTRENNUNG(OAc)2 (0.24 mmol) in CH2Cl2 (2 mL) was added
BF3·OEt2 (0.24 mmol). The mixture was stirred at room
temperature for 30 min. The reaction mixture was poured
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UPDATES
Keisuke Gondo and Tsugio Kitamura
1,2,3,4,5,6,7,8-Octaphenylanthracene (11):[5] The product
was obtained as a yellow solid; yield: 0.140 g (89%). This
compound did not dissolve in any organic solvents; mp
>4008C. HR-MS (FAB): m/z=786.3290, calcd. for C62H42:
786.3287.
Yabe, Chem. Lett. 1998, 337–338; c) T. Sato, S. Arul-
mozhiraja, H. Niino, S. Sasaki, T. Matsuura, A. Yabe, J.
Am. Chem. Soc. 2002, 124, 4512–4521.
[3] a) G. Wittig, H. Hꢂrle, Justus Liebigs Ann. Chem. 1959,
623, 17–34; b) H. Hart, C.-Y. Lai, G. Nwokogu, S. Sha-
mouilian, A. Teuerstein, C. Zlotogorski, J. Am. Chem.
Soc. 1980, 102, 6649–6651; c) H. Hart, S. Shamouilian,
Y. Takehira, J. Org. Chem. 1981, 46, 4427–4432; d) H.
Hart, G. C. Nwokogu, Tetrahedron Lett. 1983, 24, 5721–
5724; e) H. Hart, N. Raju, M. A. Meador, D. L. Ward,
J. Org. Chem. 1983, 48, 4357–4360; f) H. Hart, C.-Y.
Lai, G. C. Nwokogu, S. Shamouilian, Tetrahedron 1987,
43, 5203–5224.
[4] H. M. Duong, M. Bendikov, D. Steiger, Q. Zhang, G.
Sonmez, J. Yamada, F. Wudl, Org. Lett. 2003, 5, 4433–
4436.
[5] H. Hart, D. Ok, J. Org. Chem. 1986, 51, 979–986.
[6] A. Winling, R. A. Russell, J. Chem. Soc. Perkin Trans.
1 1998, 3921–3923.
5,6,7,8-Tetraphenyl-1H-naphthoACTHUNTGRNEUNG[2,3-d]triazole (12): The
product was obtained as a yellow solid; yield: 0.070 g
(64%); mp 232–2338C; 1H NMR (400 MHz, CDCl3): d=
6.85–7.24 (m, 10H), 7.25–7.31 (m, 10H), 7.41 (t, J=8.0 Hz,
1H), 7.52 (t, J=8.0 Hz, 2H), 7.74 (d, J=8.0 Hz, 2H), 8.01
(s, 1H), 8.53 (s, 1H); 13C NMR (100 MHz, CDCl3): d=
106.0, 118.4, 121.7, 125.5, 125.6, 126.6, 126.8, 126.9, 127.77,
127.81, 127.9, 129.7, 130.2, 130.4, 131.0, 131.14, 131.16, 131.2,
133.0, 137.4, 138.0, 138.3, 139.1, 139.3, 139.4, 140.11, 140.12,
140.2, 145.7 (one carbon overlapped); HR-MS (FAB): m/z=
550.2282, calcd. for C40H28N3 ([M+H]+): 550.2283.
1,4-Dhydro-1,4-epoxyanthracene (15):[14] The product was
obtained as a white solid; yield: 0.037 g (96%); mp 163–
1
1658C; H NMR (400 MHz, CDCl3): d=5.80 (s, 2H), 6.97
(s, 2H), 7.41–7.45 (m, 2H), 7.59 (s, 2H), 7.69–7.73 (m, 2H);
13C NMR (100 MHz, CDCl3): d=81.8, 118.6, 126.1, 128.1,
131.9, 141.6, 144.1.
[7] S.-H. Chan, C.-Y. Yick, H. N. C. Wong, Tetrahedron
2002, 58, 9413–9422.
[8] a) Y.-L. Chen, J.-Q. Sun, X. Wei, W.-Y. Wong, A. W. M.
Lee, J. Org. Chem. 2004, 69, 7190–7197; b) Y.-L. Chen,
C. K. Han, H. Wang, H. He, M.-S. Wong, A. W. M. Lee,
J. Org. Chem. 2006, 71, 3512–3517; c) B.-J. Pei, W.-H.
Chan, A. W. M. Lee, J. Org. Chem. 2010, 75, 7332–
7337.
1,4,6,11-Tetrahydro-6,11ACTHUNRGTNE[NUG 1’,2’]-benzeno-1,4-epoxynaphtha-
cene (18):[16] The product was obtained as a white solid;
yield: 0.060 g (94%); mp 211–2138C; 1H NMR (400 MHz,
CDCl3): d=5.36 (s, 2H), 5.61 (s, 2H), 6.94 (s, 2H), 6.95–7.01
(m, 4H), 7.34 (s, 2H), 7.36–7.39 (m, 4H); 13C NMR
(100 MHz, CDCl3): d=54.3, 82.3, 116.9, 123.40, 123.44,
125.01, 125.04, 143.1, 143.2, 145.4, 145.5, 146.7.
[9] T. Kitamura, K. Gondo, T. Katagiri, J. Org. Chem.
2013, 78, 3421–3424.
5,7,12,14-Tetrahydro-5,14ACTHNUTRGNENG[U 1’,2’]:7,12ACHUTNGTREN[NUNG 1’’,2’’]-dibenzenopen-
[10] a) T. Kitamura, M. Yamane, J. Chem. Soc. Chem.
Commun. 1995, 983–984; b) T. Kitamura, M. Yamane,
K. Inoue, M. Todaka, N. Fukatsu, Z. Meng, Y. Fuji-
wara, J. Am. Chem. Soc. 1999, 121, 11674–11679; c) T.
Kitamura, M. Todaka, Y. Fujiwara, Org. Synth. 2002,
78, 104–112.
tacene (19):[3c] The product was obtained as a white solid;
yield: 0.063 g (73%); mp 408–4108C; 1H NMR (400 MHz,
CDCl3): d=5.30 (s, 4H), 6.89–6.92 (m, 8H), 7.26–7.30 (m,
8H), 7.43 (s, 2H); 13C NMR (100 MHz, CDCl3): d=53.9,
119.7, 123.4, 125.0, 142.4, 145.4.
5,10ACHTUNGTRENNUNG[1’,2’]-Benzeno-1-phenyl-1H-anthraACHTUNGTNER[NUGN 2,3-d]triazole
[11] a) M. Ochiai, M. Kunishima, K. Sumi, Y. Nagao, E.
Fujita, M. Arimoto, H. Yamaguchi, Tetrahedron Lett.
1985, 26, 4501–4504; b) M. Ochiai, K. Sumi, Y. Takao-
ka, M. Kunishima, Y. Nagao, M. Shiro, E. Fujita, Tetra-
hedron 1988, 44, 4095–4112; c) T. Kitamura, P. J. Stang,
J. Org. Chem. 1988, 53, 4105–4106.
(20): The product was obtained as a yellow solid; yield:
0.058 g (78%); mp 197–1998C; H NMR (400 MHz, CDCl3):
1
d=5.50 (s, 1H), 5.59 (s, 1H), 7.03–7.06 (m, 4H), 7.39–7.7
(m, 10H) 8.03 (s, 1H); 13C NMR (100 MHz, CDCl3): d=
53.7, 54.2, 105.4, 114.2, 123.0, 123.7, 123.8, 125.6, 125.8,
128.6, 129.7, 130.9, 136.9, 142.1, 143.9, 144.5, 144.6, 146.0;
HR-MS (FAB): m/z=372.1051, calcd. for C26H18N3 ([M+
H]+): 372.1051.
[12] J. Lu, J. Zhang, X. Shen, D. M. Ho, R. A. Pascal Jr, J.
Am. Chem. Soc. 2002, 124, 8035–8041.
[13] Y. D. Xing, N. Z. Huang, J. Org. Chem. 1982, 47, 140–
142.
[14] T. Kitamura, N. Fukatsu, Y. Fujiwara, J. Org. Chem.
1998, 63, 8579–8581.
References
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6
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ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 0000, 000, 0 – 0
ÝÝ
These are not the final page numbers!

UPDATES
Improved and Practical Synthesis of [2,4,5-
7
Tris(trimethylsilyl)-phenyl]ACTHNUTRGNEUGN(phenyl)iodonium Triflate and
Utilization as a 1,4-Benzdiyne Synthon
Adv. Synth. Catal. 2014, 356, 1 – 7
Keisuke Gondo, Tsugio Kitamura*
Adv. Synth. Catal. 0000, 000, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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7
ÞÞ
These are not the final page numbers!