Reactions of arylvinylidenecyclopropanes with bromine and iodine

Article abstract of DOI:10.1055/s-2006-947337

Reactions of arylvinylidenecyclopropanes 1 with equimolar amount of bromine or iodine at low temperature produced the corresponding addition products 2, 3 and 5, 6 in moderate to good yields at -40 °C and -100 °C, respectively. On the other hand, the reac

Full text of DOI:10.1055/s-2006-947337

LETTER
1943
Reactions of Arylvinylidenecyclopropanes with Bromine and Iodine
a
a
a
b
R
M
eactions of
A
rylvinyl
i
idenecy
n
clopropanes Shi,* Ming Ma, Zhi-Bin Zhu, Li Wei
a
School of Chemistry & Pharmaceutics, East China University of Science and Technology, 130 Mei Long Road, Shanghai 200237,
P. R. of China
Fax +86(21)64166128; E-mail: Mshi@pub.sioc.ac.cn
b
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin
Road, Shanghai 200032, P. R. of China
Received 25 April 2006
Using diphenylvinylidenecyclopropane (1a, 0.3 mmol) as
substrate, we examined the addition reaction with halogen
Abstract: Reactions of arylvinylidenecyclopropanes
1 with
equimolar amount of bromine or iodine at low temperature pro-
duced the corresponding addition products 2, 3 and 5, 6 in moderate
to good yields at –40 °C and –100 °C, respectively. On the other
such as bromine (Br ) or iodine (I ) (0.3 mmol) in a vari-
2
2
5
ety of solvents at –40 °C. The corresponding addition
hand, the reactions of 1 with equimolar amount of iodine gave the product 2a (X = Br) or 3a (X = I) was formed as a sole
corresponding iodinated naphthalene derivatives
corresponding addition products 3 under similar conditions at
5 °C. The further transformation of the addition product 6a has
4 via the
product with anti-configuration rather than the cyclopro-
pane ring-opened product. The results are summarized in
Table 1. As can be seen from Table 1, 1,2-dichloroethane
2
been presented.
(
DCE) is the solvent of choice (Table 1, entries 4–7). At
Key words: arylvinylidenecyclopropanes, bromine, iodine, addi-
tion reaction, iodinated naphthalene derivatives
low temperature (–40 °C) in DCE, the corresponding ad-
dition products 2a and 3a were obtained in higher yields
(
Table 1, entries 3 and 9). With the addition of water (5.0
equiv), the yield of 2a decreased to 61% under identical
conditions, indicating that a cationic process might be
involved in this addition reaction (Table 1, entry 4).
Thermal and photochemical skeletal conversions of
vinylidenecyclopropanes 1 have attracted much attention
from mechanistic, theoretical, spectroscopic, and synthet-
1
,2
Under these optimised reaction conditions, we next exam-
ined a variety of vinylidenecyclopropanes 1 with bromine.
The results are summarized in Table 2. For symmetrical
ic viewpoints in the past decades. Vinylidenecyclo-
propanes 1 also undergo a variety of unique addition
reactions with electrophiles to give novel products some-
times along with the formation of cyclopropane ring-
Table 1 Addition Reaction of 1a (88 mg, 0.3 mmol) with Bromine
and Iodine (0.3 mmol) at –40 °C
3
opened products.
Previously we reported the reaction of gem-aryl disub-
stituted methylenecyclopropanes (MCPs) and vinylidene-
cyclopropanes with diaryl diselenide to give either 1,2-
Ph
Ph
X
Ph
solvent
.
+
X2
X
bis(arylselanyl)-3,3-diarylcyclobut-1-ene,
bered ring, or the corresponding addition products in the
presence of iodosobenzene diacetate [PhI(OAc) ] in mod-
four-mem-
Ph
–40 °C, 6 h
Ph
Ph
1
a
2
a, X = Br
3a, X = I
2
4
a,4b
erate to good yields under mild conditions.
In addition,
we also reported that diarylvinylidenecyclopropanes un- Entry
dergo a novel ring-opening reaction upon treatment with
Solvent
X
Temp. (°C) Yield of 2a
and 3a (%)a
2
excess iodine or bromine at 0–25 °C in 1,2-dichloroethane
to give the corresponding diiodinated or dibrominated
1
DCE
Br2
0
–10
–40
–40
–40
–40
–40
0
2a, 58
2a, 62
2a, 70
2a, 61b
2a, 63
2a, 51
2a, 46
3a, 56
3a, 81
2
DCE
Br2
naphthalene derivatives in good to high yields within
4
c
three hours.
3
4
5
6
7
8
9
DCE
Br2
In this paper, we wish to report the addition reactions of
arylvinylidenecyclopropanes 1 with equimolar amount of
bromine and iodine to produce either the corresponding
addition products 2, 3 and 5, 6 at low temperature or the
corresponding iodinated naphthalene derivatives 4 at
room temperature in moderate to good yields under mild
conditions.
DCE
Br2
Br2
Br2
Br2
I2
THF
MeCN
Toluene
DCE
DCE
I2
–40
a
SYNLETT 2006, No. 12, pp 1943–1947
Advanced online publication: 24.07.2006
0
1
.0
8
.2
0
0
6
Isolated yields.
With the addition of 5.0 equiv of H O.
b
2
DOI: 10.1055/s-2006-947337; Art ID: U04806ST
©
Georg Thieme Verlag Stuttgart · New York

1
944
M. Shi et al.
LETTER
vinylidenecyclopropanes 1b–e, the corresponding addi- Under these reaction conditions, we found that the addi-
tion products 2b–e were obtained in moderate to good tion reactions of a variety of arylvinylidenecyclopropanes
yields (Table 2, entries 1–4). In order to confirm further 1 with iodine produced the corresponding iodinated
the anti-configuration of the addition product, the naphthalene derivatives 4 in good yields. The results are
structure of 2c was determined by X-ray diffraction shown in Table 3.
6
(Figure 1).
Table 3 Addition Reaction of Arylvinylidenecyclopropane 1a–e with
Iodine in DCE at –40 °C and then at 25 °C
Table 2 Addition Reaction of 1b–e (88 mg, 0.3 mmol) with
Bromine (0.3 mmol) at –40 °C in DCE
R1
R2
R2
R1
I
DCE
DCE
R2
+ I2
[3]
R1
Br
R1
–40 °C, 6 h
25 °C
R
Me
DCE
.
+
Br2
R2
1
R1
–40 °C, 6 h
R1
Br
R1
4
1b–e
2
b–e
1
2
Entry
1 (R /R )
Time
Temp
(°C)
Yield
(%) 4
a
1
2
Yield (%)a
(h)
10
30
10
10
10
Entry
1 (R /R )
1
2
3
4
1a (Ph/Ph)
25
25
25
25
25
4a, 80
4b, 53
4c, 72
4d, 77
4e, 82
1
2
3
1b (p-FC H /C H )
2b, 85
2c, 61
2d, 81
2e, 53
6
4
6
5
1b (4-FC H /Ph)
1c (Ph/p-MeC H )
6
4
6
4
1c (Ph/4-MeC H )
1d (p-ClC H /Ph)
6
4
6
4
1d (p-MeOC H /Ph)
4
1e (Ph/p-MeOC H )
6
4
6
4
a
Isolated yields.
5
1e (Ph/4-MeOC
Isolated yields.
H )
6 4
a
The structures of products 2, 3a, and 4 were determined
1
13
by H NMR and C NMR spectroscopic data and HRMS
or microanalyses.7
In order to identify the reaction pathway, radical scaven-
gers 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and
2
,6-di-tert-butyl-4-methylphenol (BHT) were added into
the reaction solution, respectively. We found that the ad-
dition reaction also proceeded smoothly in the presence of
these radical scavengers TEMPO and BHT. In addition,
with the addition of five equivalents of water, the yield of
2
a decreased to 61% (Table 1, entries 3 and 4). Moreover,
with the addition of an amino compound such as DBU (10
mol%), 2a was formed in trace. All these results suggest
that these above addition reactions proceed via the corre-
sponding cationic intermediates. A plausible reaction
Figure 1 The ORTEP drawing of 2c
On the other hand, in the addition reaction of 1a (0.3 mechanism is shown in Scheme 2 on the basis of previous
mmol) with iodine (0.3 mmol) under similar conditions, literature and above control experiments. The addition of
we found that the corresponding addition product 3a is halogen (X ) to a double bond of arylvinylidenecyclo-
2
labile at room temperature (25 °C) and it can rearrange to propane 1 gives the cationic cyclized intermediate A-1,
the corresponding iodinated naphthalene derivative 4a in which is stabilized by a cyclopropane. The backside at-
–
good yield under the reaction conditions at room temper- tack of the formed X to the intermediate A-1 produces the
ature (25 °C; Scheme 1).
anti-addition product 2 or 3. In the case of addition reac-
tion with iodine, the corresponding addition product is
labile, which can release one iodine anion to give the cor-
responding cationic intermediate B-1 at room tempera-
ture. The intramolecular Friedel–Crafts reaction affords
the intermediate C-1, which produces the intermediate d-
Ph
Ph
– I–
I
DCE
I
8
1a
+ I2
I
–
40 °C, 6 h
25 °C
Me
Ph Ph
Ph
1
after the proton transfer. This process also can proceed
3a
4a
via a concerted 1,3-hydrogen transfer. The reprotonation
Scheme 1 The addition reaction of diphenylvinylidenecyclopro- and aromatization of the intermediate E-1 furnish the
pane (1a) with iodine at –40 °C and then at room temperature (25 °C)
iodinated naphthalene derivative 4a.
Synlett 2006, No. 12, 1943–1947 © Thieme Stuttgart · New York

LETTER
Reactions of Arylvinylidenecyclopropanes
1945
Ph
Ph
X–
unsymmetric arylvinylidenecyclopropane 1j, the corre-
sponding adduct 5e was obtained as mixtures of E- and Z-
isomers (Table 4, entry 5).
Ph
Ph
X
Ph
Ph
Ph
Ph
X2
Ph
+
X
X
A-1
The mechanism of this addition reaction is shown in
2, X = Br, 3, X = I
Scheme 3 using 1f as substrate. The addition of halogen
(
X ) to a double bond of 1f produces the corresponding
2
Ph
Ph
I
Ph
+
– I–
Ph
Ph
I
– H+
Ph
cationic intermediates A-2 and B-2, which give the corre-
sponding ring-opened cationic intermediates C-2 and D-
2
intramolecular
Friedel–Crafts
reaction
I
B-1
. Then, elimination of proton takes place to give the cor-
responding products 5a and 6a via cationic intermediate
D-2 (Scheme 3).
Ph
Ph
Ph
Ph
Ph
Ph
+
I
I
H+
I
– H+
X2
+
4a
+
+
–
100 °C, CH2Cl2
X
X
H
1f
A-2
B-2
C-1
D-1
E-1
Ph
Ph
Ph
Ph
H+
–
Ph
Ph
+
+
Scheme 2 A plausible reaction mechanism of arylvinylidenecyclo-
propanes 1a–e with halogen
X
X
X
C-2
D-2
5a, X = Br, 88%
a, X = I, 80%
6
Interestingly, in the reaction of diphenylvinylidenecyclo-
propane (1f), having four methyl groups at the cyclo-
propane moiety, with halogen Br or I under similar
Scheme 3 Addition reaction of arylvinylidenecyclopropane 1f with
halogen
2
2
conditions, the corresponding halogenated products 5a
X = Br) and 6a (X = I) were obtained in 68% and 46% Moreover, in order to further explore the transformation
(
yields, respectively. When the reaction was carried out at of 5 and 6, we employed compound 6a (0.1 mmol) to the
lower temperature (–100 °C) and within short reaction Suzuki type cross-coupling reaction with phenyl boronic
9
time, 5a and 6a were obtained in 88% and 80%, respec- acid in the presence of Pd(0) catalyst. After careful
tively. The results are summarized in Table 4. As can be examination of the reaction conditions, we found that us-
seen from Table 4, under these reaction conditions the ing Pd (dba) (5 mol%) as catalyst and Cy P (10 mol%) as
2
3
3
addition reactions of a variety of diarylvinylidenecyclo- a ligand in DMF (1.0 mL) and water (0.3 mL), the corre-
propanes 1g–j with bromine and iodine produced the cor- sponding product 7 was obtained in 68% yield in the
1
0
responding halogenated alkenes 5 and 6 in good yields in presence of Cs CO (Scheme 4).
2
3
dichloromethane (CH Cl , Table 4, entries 2–5). For
2
2
Table 4 Addition Reaction of Arylvinylidenecyclopropanes 1f–j with iodine in CH Cl at –100 °C
2
2
R1
X
R1
R2
Br2 or I2 (1 equiv)
CH2Cl2, –100 °C
R2
1f–j
5
6
a–e: X = Br
a–d: X = I
1
2
Yield (%)a
(X = Br)
Entry
1 (R /R )
Time (min)
5
6 (X = I)
6a, 80
6b, 80
6c, 89
1
2
3
4
1f (Ph/Ph)
5
5
5a, 88
5b, 78
5c, 87
5d, 95
5e, 73b
1g (4-MeC H /4-MeC H )
6
4
6
4
1h (4-MeOC H /4-MeOC H )
10
5
6
4
6
4
1i (4-FC H /4-FC H )
6d, 79
6
4
6
4
5
1j (4-ClC H /Ph)
5
6
4
a
Isolated yields.
Mixtures of E- and Z-isomers (E:Z = 1:1).
b
Synlett 2006, No. 12, 1943–1947 © Thieme Stuttgart · New York

1
946
M. Shi et al.
LETTER
Pd2(dba)3 (5 mol%)
Cs2CO3 (2 equiv)
PCy3 (10 mol%)
(2) For the synthesis of vinylidenecyclopropanes, please see:
(a) Isagawa, K.; Mizuno, K.; Sugita, H.; Otsuji, Y. J. Chem.
Soc., Perkin Trans. 1 1991, 2283; and references cited
therein. (b) Sasaki, T.; Eguchi, S.; Ohno, M.; Nakata, F. J.
Org. Chem. 1976, 41, 2408. (c) Sasaki, T.; Eguchi, S.;
Ogawa, T. J. Org. Chem. 1974, 39, 1927. (d) Sasaki, T.;
Eguchi, S.; Ogawa, T. Heterocycles 1975, 3, 193.
I
+
PhB(OH)2
DMF, H2O, 70 °C
6a
7, 68%
(
1
e) Eguchi, S.; Arasaki, M. J. Chem. Soc., Perkin Trans. 1
988, 1047. (f) Sugita, H.; Mizuno, K.; Mori, T.; Isagawa,
K.; Otsuji, Y. Angew. Chem., Int. Ed. Engl. 1991, 30, 984.
g) Patrick, T. B. Tetrahedron Lett. 1974, 15, 1407. (h) Al-
Dulayymi, J. R.; Baird, M. S. J. Chem. Soc., Perkin Trans. 1
994, 1547. (i) Patrick, T. B.; Schmidt, D. J. J. Org. Chem.
Scheme 4 Suzuki type coupling reaction of 6a
(
In conclusion, we disclosed an interesting addition reac-
tion of arylvinylidenecyclopropanes with halogen to pro-
duce the corresponding addition products 2, 3 and 5, 6 or
the corresponding iodinated naphthalene derivatives 4 in
moderate to good yields under mild conditions.11 The
plausible mechanism has been discussed on the basis of
control experiments. In addition, the further possible
transformation of 6a has been also disclosed. The reason
for the bromination and iodination selectively occurred at
the cyclopropane-substituted alkene leading to vinyl
cyclopropanes is probably due to the stabilization of the
corresponding cyclized cationic halogenated intermediate
by the cyclopropane. Efforts are underway to elucidate the
mechanistic details of this reaction and to disclose the
scope and limitations of this transformation. Work along
this line is currently in progress.
1
1977, 42, 3354. (j) Hartzler, H. D. J. Am. Chem. Soc. 1971,
93, 4527.
(
3) The other papers related to vinylidenecyclopropanes. For the
reactions of vinylidenecyclopropanes with carbenes and
carbene complexes, see: (a) Crandall, J. K.; Paulson, D. R.;
Bunnell, C. A. Tetrahedron Lett. 1969, 48, 4217. (b) Hwu,
C.-C.; Wang, F.-C.; Yeh, M.-C. P. J. Organomet. Chem.
1
994, 474, 123. (c) Billups, W. E.; Haley, M. M.; Boese, R.;
Blaser, D. Tetrahedron 1994, 50, 10693. (d) Maeda, H.;
Hirai, T.; Sugimoto, A.; Mizuno, K. J. Org. Chem. 2003, 68,
7
Chem., Int. Ed. Engl. 1970, 9, 798. (f) Pasto, D. J.; Yang, S.
H. J. Org. Chem. 1986, 51, 1676. For the addition reactions
to vinylidenecyclopropanes, see: (g) Pasto, D. J.; Miles, M.
F. J. Org. Chem. 1976, 41, 2068. (h) Pasto, D. J.; Chen, A.
F.-T.; Binsch, G. J. Am. Chem. Soc. 1973, 95, 1553.
700. (e) Bloch, R.; Perchec, P. L.; Conia, J.-M. Angew.
(
(
i) Pasto, D. J.; Chen, A. J. Am. Chem. Soc. 1971, 93, 2562.
j) Pasto, D. J.; Borchardt, J. K.; Fehlner, T. P.; Baney, H. F.;
Acknowledgment
Schwartz, M. E. J. Am. Chem. Soc. 1976, 98, 526.
k) Pasto, D. J.; Fehlner, T. P.; Schwartz, M. E.; Baney, H.
(
We thank the State Key Project of Basic Research (Project 973)
F. J. Am. Chem. Soc. 1976, 98, 530. (l) Pasto, D. J.; Miles,
M. F. J. Org. Chem. 1976, 41, 425. (m) Pasto, D. J.; Chen,
A. F.-T.; Cuirdaru, G.; Paquette, L. A. J. Org. Chem. 1973,
3
1
(
No. G2000048007), Shanghai Municipal Committee of Science
and Technology (04JC14083), Chinese Academy of Sciences
KGCX2-210-01), and the National Natural Science Foundation of
(
8, 1015. (n) Gompper, R.; Lach, D. Tetrahedron Lett.
973, 29, 2683. (o) Poutsma, M. L.; Ibarbia, P. A. J. Am.
China for financial support (20472096, 203900502, and 20272069).
Chem. Soc. 1971, 93, 440. (p) Gompper, R.; Lach, D.
Tetrahedron Lett. 1973, 29, 2687. (q) Pasto, D. J.;
Wampfler, D. Tetrahedron Lett. 1974, 22, 1933. (r) Sasaki,
T.; Eguchi, S.; Ogawa, T. J. Am. Chem. Soc. 1975, 97, 4413.
References and Notes
(
1) (a) Poutsma, M. L.; Ibarbia, P. A. J. Am. Chem. Soc. 1971,
3, 440. (b) Smadja, W. Chem. Rev. 1983, 83, 263.
c) Paulson, D. R.; Crandall, J. K.; Bunnell, C. A. J. Org.
9
(
(
s) Pasto, D. J.; Whitmer, J. L. J. Org. Chem. 1980, 45,
1987. (t) Pasto, D. J.; Brophy, J. E. J. Org. Chem. 1991, 56,
Chem. 1970, 35, 3708. (d) Hendrick, M. E.; Hardie, J. A.;
Jones, M. J. Org. Chem. 1971, 36, 3061. (e) Patrick, T. B.;
Haynie, E. C.; Probst, W. J. J. Org. Chem. 1972, 37, 1553.
4554. (u) Cairns, P. M.; Combie, L.; Pattenden, G.
Tetrahedron Lett. 1982, 23, 1405. (v) Crombie, L.;
Maddocks, P. J.; Pattenden, G. Tetrahedron Lett. 1978, 19,
(
9
f) Aue, D. H.; Meshishnek, M. J. J. Am. Chem. Soc. 1977,
9, 223. (g) Sasaki, T.; Eguchi, S.; Ogawa, T. J. Am. Chem.
3
483.
4) (a) Shi, M.; Wang, B.-Y.; Li, J. Eur. J. Org. Chem. 2005,
59. (b) Shi, M.; Lu, J.-M. Synlett 2005, 2352. (c) Shi, M.;
(
(
Soc. 1975, 97, 4413. (h) Sadler, I. H.; Stewart, J. A. G. J.
Chem. Soc., Perkin Trans. 2 1973, 3, 278. (i) Sugita, H.;
Mizuno, K.; Saito, T.; Isagawa, K.; Otsuji, Y. Tetrahedron
Lett. 1992, 33, 2539. (j) Mizuno, K.; Sugita, H.; Kamada,
T.; Otsuji, Y. Chem. Lett. 1994, 449. (k) Akasaka, T.;
Misawa, Y.; Ando, W. Tetrahedron Lett. 1990, 31, 1173.
7
Ma, M.; Shao, L.-X. Tetrahedron Lett. 2005, 46, 7609.
5) For the addition of olefinic compounds with halogen, see:
(
a) de la Mare, D. P.; Bolton, R. In Electrophilic Additions
to Unsaturated System, 2nd ed.; Elsevier: New York, 1982,
36–197. (b) Schmidt, G. H.; Garratt, D. G. In The
1
(
l) Mizuno, K.; Sugita, H.; Isagawa, K.; Goto, M.; Otsuji, Y.
Chemistry of Double Bonded Functional Groups,
Supplement A, Part 2; Patai, S., Ed.; Wiley-Interscience:
New York, 1977, Chap. 9.
Tetrahedron Lett. 1993, 34, 5737. (m) Mizuno, K.; Nire, K.;
Sugita, H.; Otsuji, Y. Tetrahedron Lett. 1993, 34, 6563.
(
2
n) Mizuno, K.; Sugita, H.; Hirai, T.; Maeda, H. Chem. Lett.
000, 1144. (o) Mizuno, K.; Nire, K.; Sugita, H.; Maeda, H.
(
6) The crystal data of 2c has been deposited in CCDC with
number 273885. Empirical formula: C H Br ; formula
2
4
20
2
Tetrahedron Lett. 2001, 42, 2689. (p) Mizuno, K.; Maeda,
H.; Sugita, H.; Nishioka, S.; Hirai, T.; Sugimoto, A. Org.
Lett. 2001, 3, 581. (q) Mizuno, K.; Sugita, H.; Hirai, T.;
Maeda, H.; Otsuji, Y.; Yasuda, M.; Hashiguchi, M.; Shima,
K. Tetrahedron Lett. 2001, 42, 3363. (r) Maeda, H.; Zhen,
L.; Hirai, T.; Mizuno, K. ITE Lett. Batteries, New Technol.
Med. 2002, 3, 485. (s) Sydnes, L. K. Chem. Rev. 2003, 103,
weight: 468.22; crystal color, habit: colorless, prismatic;
crystal dimensions: 0.506 × 0.367 × 0.331 mm; crystal
system: triclinic; lattice type: primitive; lattice parameters:
a = 8.721 (3)Å, b = 11.157 (3)Å, c = 11.857 (3)Å,
a = 109.253 (5)°, b = 106.367 (5)°, g = 95.731 (5)°,
3
V = 1021.1 (5)Å ; space group: P-1; Z = 2; D
= 1.523 g/
calcd
3
cm ; F = 468; diffractometer: Rigaku AFC7R; residuals:
0
00
1133.
Synlett 2006, No. 12, 1943–1947 © Thieme Stuttgart · New York

LETTER
R1 = 0.0739, wR2 = 0.1669. A colorless solid, mp 175.1–
Reactions of Arylvinylidenecyclopropanes
1947
1992, 92, 69. (c) Carey, F. A.; Sundberg, R. J. Advanced
Organic Chemistry, 5th ed.; Plenum Press: New York, 1998,
221. (d) Carey, F. A.; Sundberg, R. J. Advanced Organic
Chemistry, 5th ed.; Plenum Press: New York, 1998, 419.
(e) Carey, F. A.; Tremper, H. S. J. Am. Chem. Soc. 1969, 91,
2967.
1
76.3 °C. IR (CH Cl ): 3052, 3018, 2960, 2920, 2851, 1613,
2 2
1
591, 1513, 1488, 1442, 1381, 1261, 1030, 813, 699, 745
–
1 1
cm . H NMR (300 MHz, CDCl , TMS): d = 1.22 (1 H, dd,
3
J = 8.1 Hz, J = 8.1 Hz, CH), 1.70 (1 H, dd, J = 8.7 Hz,
1
2
1
J = 8.7 Hz, CH), 2.40 (3 H, s, Me), 2.90 (1 H, dd, J = 8.1
2
1
Hz, J = 8.1 Hz, CH), 6.94–7.08 (4 H, m, Ar), 7.16–7.26 (5
(9) (a) Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun.
1981, 11, 513. (b) Miyaura, N.; Suzuki, A. Chem. Rev. 1995,
95, 2457.
(10) (a) Larock, R. C.; Campo, M. A. J. Am. Chem. Soc. 2002,
124, 14326. (b) Huang, Q.; Campo, M. A.; Yao, T.; Tian, Q.;
Larock, R. C. J. Org. Chem. 2004, 69, 8251.
2
H, m, Ar), 7.33–7.43 (5 H, m, Ar). MS (EI): m/z (%) = 468
+
(
(
1.75) [M ], 389 (13.50), 388 (21.71), 387 (14.75), 309
15.26), 308 (67.40), 307 (100), 293 (26.93), 292 (32.96),
2
29 (55.53), 215 (85.84), 189 (18.23), 105 (13.53). HRMS
+
(
EI): m/z calcd for C H Br [M ]: 465.9916; found:
2
4
20
2
4
65.9932.
(11) General Reaction Procedure.
7) The spectroscopic data ( H NMR and 13C NMR spectral
data) and analytic data of the compounds shown in Tables
1
A solution of iodine (88 mg, 0.3 mmol) in DCE (5.0 mL) was
added dropwise into a solution of diphenylvinylidene-
cyclopropane (1a, 76 mg, 0.3 mmol) in DCE (2.0 mL). The
reaction mixture was stirred for 6 h at –40 °C (monitored by
TLC). After the starting materials 1a were consumed. The
solvent in filtration was removed under reduced pressure and
the residue was subjected to a flash column chromatography
to give the desired product 3a (133 mg, 81%) as a yellow
solid.
(
1
– 4, Scheme 1 and the detailed description of experimental
procedures are available free of charge via the Internet.
8) (a) Siehl, H.-U.; Aue, D. H. Dicoordinated Carbocations;
Rappoport, Z.; Stang, P. J., Eds.; John Wiley and Sons: New
York, 1997, 137–138. The stabilizing effect of cyclopropyl
substituents in carbocations is well documented. See:
(
(b) Olah, G. A.; Reddy, V. P.; Prakash, G. K. S. Chem. Rev.
Synlett 2006, No. 12, 1943–1947 © Thieme Stuttgart · New York