Method for transforming alkynes into (E)-dibromoalkenes

Article abstract of DOI:10.1021/jo501776b

The highly stereoselective bromination of alkynes has been realized by using copper(II) bromide as both the reacting partner and the catalyst, offering a generally efficient synthesis of (E)-dibromoalkenes. The reaction conditions are exceptionally mild, and a wide range of functional groups are well tolerated.

Full text of DOI:10.1021/jo501776b

Article
pubs.acs.org/joc
Method for Transforming Alkynes into (E)‑Dibromoalkenes
Jiannan Xiang, Rui Yuan, Ruijia Wang, Niannian Yi, Linghui Lu, Huaxu Zou, and Weimin He*
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University,
Changsha, 410082, P. R. China
S
* Supporting Information
ABSTRACT: The highly stereoselective bromination of alkynes has been
realized by using copper(II) bromide as both the reacting partner and the
catalyst, offering a generally efficient synthesis of (E)-dibromoalkenes. The
reaction conditions are exceptionally mild, and a wide range of functional
groups are well tolerated.
a
Table 1. Optimization of the Reaction Conditions
INTRODUCTION
■
Methods for the formation of the carbon−bromine bond are
important in organic synthesis.1 Organobromine compounds
containing fundamental functional groups are useful synthetic
intermediates, including allyl bromide, alkyl bromide, or aryl
bromide units.2 (E)-1,2-Vinylic dibromides represent one
particularly interesting bromine-containing functional group.
They have found widespread applications in organic synthesis,
biological research, and analytical chemistry.3
In general, the electrophilic addition of molecular bromine to
alkynes is one of the common methods for the synthesis of (E)-
dibromoalkenes.4 However, it suffers from the use of hazardous
chemicals and lack of chemoselectivity. Alternative methods for
the synthesis of these bromides are the reactions of alkyne with
other bromination reagents,5 such as KBr/Selectfluor,6 KBr/
diacetoxy iodobenzene,7 HBr/TBHP,8 and NBS.9 However,
these methods present several limitations, such as the
occurrence of side reactions, lack of stereoselectivity and low
functional group tolerance. Continuing with our interest in
alkyne chemistry,10 we focused our attention on the develop-
ment of a new method for the synthesis of (E)-dibromoalkenes.
Herein we report the results of our investigation which resulted
in a mild and highly stereoselective transformation of alkynes
into (E)-dibromoalkenes in the presence of copper(II)
bromide.
bc
,
entry
catalyst (equiv)
solvent
temperature
yield (%)
1
CuBr2 (1.0)
FeBr3 (1.0)
FeBr2 (1.0)
MgBr2 (1.0)
ZnBr2 (1.0)
AlBr3 (1.0)
CuBr2 (1.5)
CuBr2 (2.0)
CuBr2 (2.5)
CuBr2 (2.0)
CuBr2 (2.0)
CuBr2 (2.0)
CuBr2 (2.0)
CuBr2 (2.0)
CuBr2 (2.0)
CuBr2 (2.0)
CuBr2 (2.0)
CuBr2 (2.0)
CuCl2 (2.0)
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
MeOH
THF
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
56
25
−
−
−
2
3
4
5
6
−
7
76
92
92
36
57
46
40
21
−
8
9
10
11
12
13
14
15
16
17
DMF
DMSO
acetone
CH2Cl2
1,4-dioxane
toluene
CH3CN
CH3CN
−
13
97(93)
−
d
18
19
a
All reactions were performed with phenylacetylene (0.1 mmol), metal
RESULTS AND DISCUSSION
b
salts, and anhydrous solvent (0.5 mL). Estimated by 1H NMR
■
c
To develop conditions that would be highly compatible with
various functional groups, acidic additives and alkaline
cocatalysts were avoided in the screening. In an initial study,
phenylacetylene was treated with 1 equiv of CuBr2 at room
temperature in anhydrous acetonitrile for 4 h. Pleasingly, (E)-
(1,2-dibromovinyl) benzene 2a was observed in 56% yield
based on NMR analysis (Table 1, entry 1). Attempts to
increase the reaction efficiency were tried using different metal
bromides, and this study showed that CuBr2 was the best
reagent (Table 1, entries 2−6). Excitingly, when the loading of
CuBr2 was increased to 2 equiv, the yield of 2a was improved to
92% yield from NMR analysis (Table 1, entries 7−9). In the
next optimization step we screened different solvents (Table 1,
spectroscopy using diethyl phthalate as an internal reference. The
number in parentheses refers to the yield of isolated product. 5 mg 4
d
Å molecular sieves was added to the reaction mixture.
entries 10−17). None of the other anhydrous solvents was
superior to acetonitrile. These results prompted us to consider
that the acetonitrile may be critical to this reaction.11 Moreover,
the addition of 4 Å molecular sieves (MS) resulted in an
improvement of yield as otherwise ketone products may be
Received: August 2, 2014
© XXXX American Chemical Society
A
dx.doi.org/10.1021/jo501776b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
a
,
Table 2. Reaction Scope
a
[1] = 0.1 M.
produced in small amounts by the trace amount of water. No
chlorination product was obtained in the presence of
copper(II) chloride (Table 1, entry 19).
the low reactivity of the C−C triple bonds. To further exploit
the generality of this catalytic reaction, aliphatic terminal
alkynes were also investigated. Aliphatic alkynes generally led to
the corresponding products in good yield. Many synthetically
important functional groups were readily tolerated, including an
alkyl (2m), an alkyl chloride (2n), a free carboxylic acid moiety
(2o), a nitrile (2p), an oxidizable PhS group (2q), an
unprotected/protected OH (2r−x), a protected amino group
(2y−ab), and a cyclohexyl (2ac). Notably, alkyne conjugated
with L-phenylalanine was smoothly brominated to give
corresponding (E)-dibromoethene (2ad) in 87% yield under
our standard conditions. The internal alkyne, which was usually
much less reactive than the terminal alkyne, was also tested. To
our delight, 1-phenyl-1-butyne and 5-decyne could proceed
smoothly, giving 83% and 80% yield and absolute stereo-
selectivity for 2ae and 2af, respectively. However, our attempt
on diphenylacetylene resulted in no reaction. When 2-octene
Under the optimized reaction conditions, we embarked on
the evaluation of the substrate scope for this transformation
(Table 2). Distinct reactivities were observed with different
alkynes. First, a series of aromatic alkynes were tested and the
corresponding products were furnished in good to excellent
yields. The electronic effect of substituents at the para position
of the aryl acetylene was evaluated (2b−g). The reaction
tolerated both electron-donating and electron-withdrawing
groups. Aromatic alkynes with substituents at meta (2h−i)
and ortho (2j−k) positions also worked well, although giving
slightly lower yields. Electron-rich heterocycle-containing
alkynes (2l) were also suitable substrates for this trans-
formation. However, electron-poor alkynes, such as 2- and 3-
pyridylacetylenes, did not undergo the reaction, likely caused by
B
dx.doi.org/10.1021/jo501776b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
(cis- and trans-mixture) was used, the expected dibromoalkane
was not formed; instead, an unknown product was formed
which was hard to characterize.
Scheme 2. Proposed Mechanism for Dibromination of
Alkynes
We also explored the reactivity of the CuBr2-catalyzed
dibromination system for larger-scale synthesis shown in
Scheme 1. The reaction with 1.5 mmol of phenylacetylene
Scheme 1. Gram-Scale Dibromination of Phenylacetylene
(1a)
equiv of bromide ion. Reductive elimination through the
neutral transition state 6 provides the trans-dibromide and a
second equivalent of CuIBr coordinated to solvent. In 1986,
Mitsuo et al.13 reported a similar bromination of alkynes to a
mixture of acetylene bromide, (E)-dibromoalkene, and (E)-
tribromoalkene using alumina-supported CuBr2 (5 equiv) in
carbon tetrachloride, and it is reasonable to consider that the
bromination reaction has two key intermediates, δ-complex
(copper(I) acetylide intermediate) and π-complex 3.
produced excellent yield (93%). In the case of a 5 mmol scale
reaction, a yield of 90% was obtained. The bromination
proceeded smoothly even with a further increased amount of
substrate (10 mmol), affording (E)-(1,2-dibromovinyl)benzene
in 87% yield. These excellent results showed the promise of the
catalytic system for large-scale synthesis in the process of alkyne
bromination.
To probe the mechanism of this reaction, the copper(II)-
catalyzed competitive bromination reactions of para-substituted
ethynylbenzene derivatives were carried out. The reactivity
order for ethynylbenzene derivatives is as follows: p-OMe (kX/
kH = 2.23) > p-Me (1.66) > p-H (1.0) > p-F (0.83) > p-Cl
(0.51) > p-Br (0.50) > p-CF3 (0.19).12 As shown in Figure 1, a
CONCLUSIONS
■
In summary, we have established a facile and highly
stereoselective method to synthesize (E)-dibromoalkenes by
copper-catalyzed dibromination of alkynes. The presented
methodology delivers an attractive alternative to classical
procedures, as nonstereospecific, low functional group compat-
ibility, and environmental problems can be circumvented.
Various functional groups were tolerated in this method, and all
the bromination products could be obtained in good to
excellent yields. Due to the ready availability of the starting
materials and the relatively low cost of the copper salt, this
method provides a simplified way to synthesize these important
(E)-dibromo alkenes.
EXPERIMENTAL SECTION
■
General Information. Commercially available reagents were of
reagent grade (AR grade) and were used without further purification.
Reactions were monitored by thin layer chromatography (TLC) using
silicycle precoated silica gel plates. Flash column chromatography was
performed over silicycle silica gel (200−300 mesh). 1H NMR and 13
C
NMR spectra were recorded on 400 MHz NMR plus spectrometer
using residue solvent peaks as internal standards. Infrared spectra were
recorded with IR spectrometer and are reported in reciprocal
centimeter (cm−1). High resolution mass spectra were obtained
using GCT-TOF instrument with EI or ESI source.
General Procedure. CuBr2 (134 mg, 0.6 mmol) was added to a
solution of alkynes (0.30 mmol) 1 and 15 mg of 4 Å molecular sieves
in acetonitrile (1.5 mL) at room temperature. The reaction mixture
was stirred at room temperature, and the progress of the reaction was
monitored by TLC. The reaction typically took 4 h. Upon completion,
the mixture was concentrated and the residue was purified by
chromatography on silica gel (eluent: hexanes/ethyl acetate) to afford
the desired products 2.
(E)-(1,2-Dibromovinyl)benzene (2a). Colorless oil (71.53 mg, 93%
yield); 1H NMR (400 MHz, CDCl3) δ 7.55−7.52 (m, 2H), 7.44−7.38
(m, 3H), 6.83 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 137.0, 129.4,
129.1, 128.2 121.3, 103.0. The data match those of the literature
report.1
Figure 1. Hammett plot.
linear correlation with a slope of −1.3 was observed. This
negative value suggests that the bromination likely proceeds via
a positively charged transition state, with the positive charge on
the π-complex adjacent to the phenyl ring.
Next, a possible mechanism for the synthesis of (E)-
dibromoalkenes base on the above obtained results and the
previous reports11 is proposed. As shown in Scheme 2, a
paramagnetic π-complex 3 is formed from copper(II) bromide
and the alkyne. Bromide ion displaces the copper on carbon as
a molecule of solvent coordinates at the copper to give the
square planar Cu(II)-anion 4. The latter transfers an electron to
CuII−Br2 to yield the neutral copper species 5, CuIBr, and 1
(E)-1-(1,2-Dibromovinyl)-4-methylbenzene (2b). Light yellow oil
1
(75.35 mg, 91% yield); H NMR (400 MHz, CDCl3): δ 7.42 (d, J =
7.6 Hz, 2H), 7.20 (d, J = 7.6 Hz, 2H), 6.77 (s, 1H), 2.38 (s, 3H). 13C
C
dx.doi.org/10.1021/jo501776b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
NMR (100 MHz, CDCl3): δ 139.6, 134.1, 129.1, 128.9, 121.6, 102.4,
21.4. The data match those of the literature report.5b
(E)-1,2-Dibromo-5-chloropent-1-ene (2n). Yellow oil (70.38 mg,
1
85% yield); H NMR (400 MHz, CDCl3) δ 6.45 (s, 1H), 3.57 (t, J =
6.4 Hz, 2H), 2.65 (t, J = 6.8 Hz, 2H), 1.84−1.73 (m, 4H); 13C NMR
(100 MHz, CDCl3) δ 125.9, 102.9, 44.5, 35.9, 31.0, 24.3; IR (neat):
3084, 2929, 2859, 1461, 783, 721, 696 cm−1; HRMS (EI) m/z calcd
for C6H9Br81Br Cl: 275.8739; found: 275.8735.
(E)-1-(1,2-Dibromovinyl)-4-methoxybenzene (2c). Light yellow oil
1
(79.71 mg, 91% yield); H NMR (400 MHz, CDCl3): δ 7.44 (d, J =
8.8 Hz, 2H), 6.94 (s, 1H), 6.86 (d, J = 8.8 Hz, 2H), 3.82 (s, 3H). 13C
NMR (100 MHz, CDCl3): δ 160.5, 131.1, 130.9, 129.1, 113.9, 107.0,
55.4; IR (neat): 3052, 2832, 1563, 1466, 742, 680, 575 cm−1; HRMS
(EI) m/z calcd for C9H8Br81BrO: 291.8921; found: 291.8915.
(E)-1-(1,2-Dibromovinyl)-4-fluorobenzene (2d). Yellow oil (72.24
mg, 86% yield); 1H NMR (400 MHz, CDCl3) δ 7.52 (dd, J = 8.4 Hz,
5.2 Hz, 2H), 7.08 (t, J = 8.6 Hz, 2H), 6.81 (s, 1H); 13C NMR (100
MHz, CDCl3) δ 162.8 (d, JC−F = 249.3 Hz), 133.0 (d, J = 3.7 Hz),
131.3 (d, J = 8.8 Hz), 120.2, 115.4 (d, J = 21.9 Hz), 103.4; IR (neat):
3021, 1580, 1459, 1179, 702, 670 cm−1; HRMS (EI) m/z calcd for
C8H5Br81Br F: 279.8722; found: 279.8719.
(E)-5,6-Dibromohex-5-enoic Acid (2o). Yellow oil (69.49 mg, 81%
1
yield); H NMR (400 MHz, CDCl3) δ 6.44 (s, 1H), 2.63 (t, J = 6.6
Hz, 2H), 2.41 (t, J = 6.6 Hz, 2H), 1.70−1.64 (m, 4H); 13C NMR (100
MHz, CDCl3) δ 179.6, 126.0, 102.8, 36.4, 33.7, 26.3, 23.2; IR (neat):
3298, 3089, 2947, 2871, 1752, 937, 721, 644 cm−1; HRMS (EI) m/z
calcd for C7H10Br81BrO2: 285.9027; found: 285.9023.
(E)-5,6-Dibromohex-5-enenitrile (2p). Yellow oil (63.75 mg, 84%
1
yield); H NMR (400 MHz, CDCl3) δ 6.53 (s, 1H), 2.77 (t, J = 7.2
Hz, 2H), 2.39 (t, J = 6.8 Hz, 2H), 2.01−1.94 (m, 2H); 13C NMR (100
MHz, CDCl3) δ 123.6, 118.9, 104.6, 35.6, 23.1, 15.9; IR (neat): 3063,
2938, 2856, 2249, 698, 608 cm−1; HRMS (EI) m/z calcd for
C6H7Br81BrN: 252.8925; found: 252.8922.
(E)-1-Chloro-4-(1,2-dibromovinyl)benzene (2e). Colorless oil
1
(79.03 mg, 89% yield); H NMR (400 MHz, CDCl3) δ 7.47−7.45
(m, 2H), 7.39−7.36 (m, 2H), 6.82 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ 135.4, 135.3, 130.5, 128.5, 120.0, 103.7. IR (neat): 3079,
1571, 1469, 735, 702, 670 cm−1; HRMS (EI) m/z calcd for
C8H5Br81Br35Cl: 295.8426; found: 295.8421. The data match those
of the literature report.14
(E)-(2,3-Dibromoallyl)(phenyl)sulfane (2q). Yellow oil (64.68 mg,
70% yield); 1H NMR (400 MHz, CDCl3) δ 7.52−7.49 (m, 2H), 7.31−
7.28 (m, 3H), 6.45 (s, 1H), 3.96 (s, 2H); 13C NMR (100 MHz,
CDCl3) δ 133.2, 133.0, 128.9, 127.9, 122.5, 105.3, 41.8; IR (neat):
3073, 2921, 1579, 1478, 746, 691, 618 cm−1; HRMS (EI) m/z calcd
for C9H8Br81Br S: 307.8693; found: 307.8690.
(E)-1-Bromo-4-(1,2-dibromovinyl)benzene (2f). Yellow oil (89.76
1
mg, 88% yield); H NMR (400 MHz, CDCl3) δ 7.53 (d, J = 8.4 Hz,
2H), 7.39 (d, J = 8.4 Hz, 2H), 6.83 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ 135.8, 131.5, 130.7, 123.6, 120.0, 103.7; IR (neat): 3083,
1568, 1423, 769, 742, 696 cm−1; HRMS (EI) m/z calcd for
C8H5Br281Br: 339.7921; found: 339.7918.
(E)-4,5- Dibromopent-4-en-1-ol (2r). Yellow oil (64.24 mg, 83%
1
yield); H NMR (400 MHz, CDCl3) δ 6.41 (s, 1H), 3.65 (t, J = 6.2
Hz, 2H), 2.62 (t, J = 6.8 Hz, 2H), 1.68−1.57 (m, 4H); 13C NMR (100
MHz, CDCl3) δ 126.4, 102.5, 62.3, 36.4, 31.2, 23.3; IR (neat): 3316,
3084, 2929, 2861, 1066, 694, 634 cm−1; HRMS (EI) m/z calcd for
C6H10Br81Br O: 257.9078; found: 257.9075.
(E)-1-(1,2-Dibromovinyl)-4-(trifluoromethyl)benzene (2g). Yellow
oil (75.24 mg, 76% yield); 1H NMR (400 MHz, CDCl3) δ 7.65 (q, J =
8.0 Hz, 4H), 6.89 (s, 1H); 13C NMR (100 MHz, CDCl3) δ 140.5,
131.2 (q, JC−F = 32.8 Hz), 129.6, 125.4 (JC−F = 3.7 Hz), 122.3, 119.4,
104.7; IR (neat): 3020, 1688, 1331, 1138, 829, 720, 607 cm−1; HRMS
(EI) m/z calcd for C9H5Br81BrF3: 329.8690; found: 329.8688.
(E)-1-(1,2-Dibromovinyl)-3-methylbenzene (2h). Yellow oil (74.52
(E)-3,4-Dibromobut-3-en-1-ol (2s). Yellow oil (63.89 mg, 93%
1
yield); H NMR (400 MHz, CDCl3): δ 6.56 (s, 1H), 3.86 (t, J = 6.0,
2H), 2.88 (t, J = 5.6, 2H); 13C NMR (100 MHz, CDCl3): δ 122.5,
104.7, 59.7, 40.0; IR (neat): 3315, 3086, 2930, 1059, 698, 640 cm−1;
HRMS (EI) m/z calcd for C4H6Br81Br O: 229.8765; found: 229.8760.
(E)-(((5,6-Dibromohex-5-en-1-yl)oxy)methyl)benzene (2t). Yellow
oil (83.52 mg, 80% yield); 1H NMR (400 MHz, CDCl3) δ 7.35 (d, J =
4.4 Hz, 4H), 7.31−7.27 (m, 1H), 6.42 (s, 1H), 4.52 (s, 2H), 3.51 (t, J
= 6.0 Hz, 2H), 2.63 (t, J = 6.8 Hz, 2H), 1.71−1.66 (m, 4H); 13C NMR
(100 MHz, CDCl3) δ 138.5, 128.4, 127.6, 127.5, 126.6, 102.5, 72.9,
69.8, 36.5, 28.4, 23.8; IR (neat): 3054, 2936, 1569, 1478, 1156, 706,
632 cm−1; HRMS (EI) m/z calcd for C13H16Br81Br O: 347.9547;
found: 347.9541.
1
mg, 90% yield); H NMR (400 MHz, CDCl3) δ 7.31−7.24 (m, 3H),
7.17 (d, J = 6.4 Hz, 1H), 6.78 (s, 1H), 2.38 (s, 3H); 13C NMR (100
MHz, CDCl3); δ 138.0, 136.9, 130.2, 129.6, 128.1, 126.1, 121.5, 102.8,
21.3; IR (neat): 3059, 2923, 1608, 1518, 712, 668, 560 cm−1; HRMS
(EI) m/z calcd for C9H8Br81Br: 275.8972; found: 275.8970.
(E)-1-Bromo-3-(1,2-dibromovinyl)benzene (2i). Yellow oil (90.78
1
mg, 89% yield); H NMR (400 MHz, CDCl3) δ 7.61−7.59 (m, 1H),
7.45−7.42 (m, 1H), 7.39−7.37 (m, 1H), 7.22−7.19 (m, 1H), 6.77 (s,
1H); 13C NMR (100 MHz, CDCl3): δ 138.8, 132.4, 132.0, 129.8,
127.8, 122.1, 119.4, 104.3; IR (neat): 3083, 1565, 1466, 787, 742, 696
cm−1; HRMS (EI) m/z calcd for C8H5Br281Br: 339.7921; found:
339.7918.
(E)-2,3-Dibromoallyl Pivalate (2u). Yellow oil (63.9 mg, 71%
yield); 1H NMR (400 MHz, CDCl3) δ 6.67 (s, 1H), 4.92 (s, 1H), 1.25
(s, 9H) 13C NMR (100 MHz, CDCl3): δ 177.8, 120.1, 106.6, 64.1,
38.8, 27.1; IR (neat): 3074, 2956, 1716, 1288, 717, 686 cm−1; HRMS
(EI) m/z calcd for C8H12Br81Br O2: 299.9184; found: 299.9188.
(E)-2,3-Dibromoallyl 4-Methylbenzenesulfonate (2v). Yellow oil
(92.13 mg, 83% yield); 1H NMR (400 MHz, CDCl3) δ 7.82 (d, J = 8.4
Hz, 2H), 7.35 (d, J = 8.8 Hz, 2H), 6.66 (s, 1H), 4.88 (s, 2H), 2.44 (s,
3H); 13C NMR (100 MHz, CDCl3) δ145.3, 132.5, 129.8, 128.1, 117.0,
109.4, 69.3, 21.6; IR (neat): 3039, 2919, 1598, 1497, 1198, 693, 562
cm−1; HRMS (EI) m/z calcd for C10H10Br81Br O3S: 369.8697; found:
369.8693.
(E)-1-(1,2-Dibromovinyl)-2-methylbenzene (2j). Yellow oil (74.52
1
mg, 90% yield); H NMR (400 MHz, CDCl3) δ 7.35−7.23 (m, 4H),
6.85 (s, 1H), 2.38 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 137.1,
135.8, 130.4, 129.4, 128.5, 126.1, 120.9, 105.1, 19.1; IR (neat): 3057,
2918, 1589, 1487, 738, 668, 560 cm−1; HRMS (EI) m/z calcd for
C9H8Br81Br: 275.8972; found: 275.8969.
(E)-1-Bromo-2-(1,2-dibromovinyl)benzene (2k). Yellow oil (81.6
mg, 80% yield); 1H NMR (400 MHz, CDCl3) δ 7.64 (d, J = 8.0, 1H),
7.38 (t, J = 7.4, 1H), 7.31−7.23 (m, 2H), 6.87 (s, 1H); 13C NMR (100
MHz, CDCl3): δ 138.4, 133.2, 130.7, 130.3, 127.7, 122.1, 119.5, 107.0.
The data match those of the literature report.5b
(E)-3,4-Dibromobut-3-en-1-yl Methanesulfonate (2w). Yellow oil
1
(85.01 mg, 92% yield); H NMR (400 MHz,CDCl3): δ 6.63 (s, 1H),
4.42 (t, J = 6.0, 2H), 3.06 (t, J = 5.6, 2H), 3.04 (s, 3H); 13C NMR (100
MHz, CDCl3): δ 119.8, 106.2, 65.6, 37.4, 36.7; IR (neat): 3082, 2969,
2938, 702, 525 cm−1; HRMS (EI) m/z calcd for C5H8Br81Br O3S:
307.8540; found: 307.8534.
(E)-3-(1,2-Dibromovinyl)thiophene (2l). Yellow oil (65.93 mg, 82%
1
yield); H NMR (400 MHz, CDCl3) δ 7.72 (s, 1H), 7.43 (d, J = 5.2
Hz, 1H), 7.28−7.26 (m, 1H), 6.69 (s, 1H); 13C NMR (100 MHz,
CDCl3) δ 136.6, 128.4, 128.0, 125.1, 116.3, 101.8; IR (neat): 3073,
1408, 1256, 834, 714, 625 cm−1; HRMS (EI) m/z calcd for
C6H4Br81Br S: 267.8380; found: 267.8378.
(E)-3,4-Dibromobut-3-en-1-yl Benzoate (2x). Yellow oil (89.18
mg, 89% yield); 1H NMR (400 MHz, CDCl3) δ 8.06 (d, J = 7.6, 2H),
7.56 (t, J = 6.8, 1H), 7.44 (t, J = 7.6, 2H), 6.59 (s, 1H), 4.53 (t, J = 6.2,
2H), 3.09 (t, J = 6.2, 2H); 13C NMR (100 MHz, CDCl3): δ 166.3,
133.0, 129.8, 129.7, 128.3, 121.7, 105.1, 61.3, 36.6; IR (neat): 3063,
2921, 1721, 1536, 1204, 736, 602 cm−1; HRMS (EI) m/z calcd for
C11H10Br81Br O2: 333.9027; found: 333.9031.
(E)-1,2-Dibromodec-1-ene (2m). Yellow oil (74.20 mg, 83% yield);
1H NMR (400 MHz, CDCl3) δ 6.40 (s, 1H), 2.59 (t, J = 7.6 Hz, 2H),
1.59−1.54 (m, 2H), 1.34−1.28 (m, 10H), 0.89 (t, J = 6.8 Hz, 3H); 13
C
NMR (100 MHz, CDCl3) δ 127.0, 102.1, 36.8, 31.8, 29.3, 29.2, 28.4,
(E)-2-(4,5-Dibromopent-4-en-1-yl)isoindoline-1,3-dione (2y). col-
27.0, 22.6, 14.1. The data match those of the literature report.15
orless solid (97.35 mg, 87% yield); mp 102−104 °C; H NMR (400
1
D
dx.doi.org/10.1021/jo501776b | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
MHz, CDCl3) δ 7.84−7.82 (m, 2H), 7.71−7.70 (m, 2H), 6.42 (s, 1H),
3.71 (t, J = 7.4 Hz, 2H), 2.66 (t, J = 7.4 Hz, 2H), 2.00−1.93 (m, 2H);
13C NMR (100 MHz, CDCl3) δ 168.1, 133.9, 132.0, 124.9, 123.2,
103.2, 36.8, 34.5, 26.0; IR (neat): 3094, 2964, 1707, 1510, 1465, 723,
691, 532 cm−1; HRMS (EI) m/z calcd for C13H11Br81Br NO2:
372.9136; found: 372.9133.
Foundation (no. 2013M540625), Hunan Provincial Natural
Science Foundation of China (no. 4JJ7028), and the
Fundamental Research Funds for the Central Universities.
REFERENCES
■
(1) Adimurthy, S.; C. Ranu, B.; Ramachandraiah, G.; Ganguly, B.; K.
Ghosh, P. Curr. Org. Chem. 2013, 10, 864.
(E)-N-(5,6-Dibromohex-5-en-1-yl)-4-methylbenzenesulfonamide
(2z). Yellow oil (104.8 mg, 85% yield); 1H NMR (400 MHz, CDCl3) δ
7.75 (d, J = 8.4 Hz, 2H), 7.30 (d, J = 8.0 Hz, 2H), 6.37 (s, 1H), 4.90 (t,
J = 6.2 Hz, 1H), 2.95 (q, J = 6.8 Hz, 2H), 2.52 (t, J = 7.0 Hz, 2H), 2.41
(s, 3H), 1.59−1.45 (m, 4H); 13C NMR (100 MHz, CDCl3) δ 143.3,
136.8, 129.7, 127.0, 125.9, 102.8, 42.8, 36.1, 28.0, 23.9, 21.5; IR (neat):
3321, 3041, 2919, 2860, 1587, 1465, 686, 564 cm−1; HRMS (EI) m/z
calcd for C13H17Br81Br NO2S: 410.9326; found: 410.9323.
(E)-Benzyl (3,4-Dibromobut-3-en-1-yl)carbamate (2aa). Yellow
oil (78.41 mg, 72% yield); 1H NMR (400 MHz, CDCl3) δ 7.36−7.31
(m, 5H), 6.52 (s, 1H), 5.11 (s, 2H), 3.44 (t, J = 6.2, 2H), 2.84 (t, J =
6.2, 2H); 13C NMR (100 MHz, CDCl3): δ 156.2, 136.3, 128.4, 128.1,
128.0, 122.9, 104.9, 66.7, 38.4, 37.2; IR (neat): 3345, 3081, 2937,
1521, 701, 630 cm−1; HRMS (EI) m/z calcd for C12H13Br81Br NO2:
362.9293;found: 362.9289.
(E)-tert-Butyl (2,3-Dibromoallyl)carbamate (2ab). Yellow oil (75.6
mg, 80% yield); 1H NMR (400 MHz, CDCl3) δ 6.54 (s, 1H), 4.89 (bs,
1H), 4.18 (s, 2H), 1.45 (s, 9H); 13C NMR (100 MHz, CDCl3):
δ155.6, 123.3, 104.2, 80.0, 44.5, 28.3; IR (neat): 3348, 3079, 2981,
1716, 1269, 709, 628 cm−1; HRMS (EI) m/z calcd for C8H13Br81Br
NO2: 314.9293; found: 314.9290.
(2) Ioffe, D.; Kampf, A. In Kirk-Othmer Encyclopedia of Chemical
Technology; John Wiley & Sons, Inc.: New York, 2000.
(3) (a) De Laet, M.; Tilquin, B. Talanta 1992, 39, 769. (b) Bayatyan,
R.; Bayatyan, B.; Saakyan, L. Russ. J. Appl. Chem. 2006, 79, 1849.
(c) Yang, Y.; Zhang, X.; Liang, Y. Tetrahedron Lett. 2012, 53, 6557.
(d) Schuh, K.; Glorius, F. Synthesis 2007, 2297. (e) Karim, A. K.;
Armengol, M.; Joule, J. A. Heterocycles 2002, 55, 2139. (f) Pilli, R. A.;
Robello, L. G. J. Brazilian Chem. Soc. 2004, 15, 938.
(4) Eissen, M.; Lenoir, D. Chem.Eur. J. 2008, 14, 9830.
(5) (a) Kawakami, K.; Tsuda, A. Chem.Asian J. 2012, 7, 2240.
(b) Adimurthy, S.; Ghosh, S.; Patoliya, P. U.; Ramachandraiah, G.;
Agrawal, M.; Gandhi, M. R.; Upadhyay, S. C.; Ghosh, P. K.; Ranu, B.
C. Green Chem. 2008, 10, 232. (c) Schmidt, R.; Stolle, A.; Ondruschka,
B. Green Chem. 2012, 14, 1673. (d) Kavala, V.; Naik, S.; Patel, B. K. J.
Org. Chem. 2005, 70, 4267.
(6) Ye, C.; Shreeve, J. n. M. J. Org. Chem. 2004, 69, 8561.
(7) Das, B.; Srinivas, Y.; Sudhakar, C.; Damodar, K.; Narender, R.
Synth. Commun. 2009, 39, 220.
(8) Barhate, N. B.; Gajare, A. S.; Wakharkar, R. D.; Bedekar, A. V.
Tetrahedron 1999, 55, 11127.
(E)-(1,2-Dibromovinyl)cyclohexane (2ac). Yellow oil (58.69 mg,
1
(9) Liu, J.; Li, W.; Wang, C.; Li, Y.; Li, Z. Tetrahedron Lett. 2011, 52,
4320.
73% yield); H NMR (400 MHz, CDCl3) δ 6.33 (s, 1H), 2.87−2.80
(m, 1H), 1.82−1.17 (m, 10H); 13C NMR (100 MHz, CDCl3) δ 133.7,
100.0, 42.9, 30.4, 25.5; IR (neat): 3065, 2928, 2853, 1460, 686, 560
cm−1; HRMS (EI) m/z calcd for C8H12Br81Br: 267.9285; found:
267.9282.
(10) (a) Ye, L.; He, W.; Zhang, L. J. Am. Chem. Soc. 2010, 132, 8550.
(b) He, W.; Li, C.; Zhang, L. J. Am. Chem. Soc. 2011, 133, 8482.
(c) Ye, L.; He, W.; Zhang, L. Angew. Chem., Int. Ed. 2011, 50, 3236.
(d) He, W.; Xie, L.; Xu, Y.; Xiang, J.; Zhang, L. Org. Biomol. Chem.
2012, 10, 3168. (e) Wu, C.; Huang, W.; He, W.; Xiang, J. Chem. Lett.
2013, 42, 1233. (f) Wu, C.; Liang, Z.; Yan, D.; He, W.; Xiang, J.
Synthesis 2013, 45, 2605. (g) Wu, C.; Liang, Z.-W.; Xu, Y.-Y.; He, W.-
M.; Xiang, J.-N. Chin. Chem. Lett. 2013, 24, 1064. (h) Xie, L.; Liang,
Z.; Yan, D.; He, W.; Xiang, J. Synlett 2013, 24, 1809. (i) Xie, L.; Wu,
Y.; Yi, W.; Zhu, L.; Xiang, J.; He, W. J. Org. Chem. 2013, 78, 9190.
(j) Huang, W.; Xiang, J.; He, W. Chem. Lett. 2014, 43, 893. (k) Xie, L.;
Yuan, R.; Wang, R.; Peng, Z.; Xiang, J.; He, W. Eur. J. Org. Chem. 2014,
2014, 2668.
(E)-3,4-Dibromobut-3-en-1-yl 2-(((benzyloxy)carbonyl)amino)-3-
phenylpropanoate (2ad). Yellow oil (133.37 mg, 87% yield); 1H
NMR (400 MHz, CDCl3) δ 7.25−7.14 (m, 8H), 7.03−7.01 (m, 2H),
6.41 (s, 1H), 5.21 (d, J = 8.4, 1H), 4.99(s, 2H), 4.59(q, J = 6.0, 1H),
4.21−4.18 (m, 2H), 3.04−2.99 (m, 2H), 2.82−2.77 (m, 2H), 13C
NMR (100 MHz, CDCl3): δ 171.1, 155.5, 136.1, 135.6, 129.2, 128.5,
128.4, 128.0, 127.9, 127.0, 121.0, 105.4, 66.8, 61.7, 54.7, 38.0, 36.2
(E)-(1,2-Dibromobut-1-en-1-yl)benzene (2ae). Light yellow oil
1
(72.2 mg, 83% yield); H NMR (400 MHz, CDCl3) δ 7.32−7.28 (m,
5H), 2.83 (q, J = 7.4 Hz, 2H), 1.20 (t, J = 7.4 Hz, 3H); 13C NMR (100
MHz, CDCl3); δ 140.8, 129.1, 128.5, 128.2, 124.8, 115.6, 35.1, 12.1.
The data match those of the literature report.9
(11) Rodebaugh, R.; Debenham, J. S.; Fraser-Reid, B.; Snyder, J. P. J.
Org. Chem. 1999, 64, 1758.
(E)-5,6-Dibromodec-5-ene (2af). Colorless oil (71.5 mg, 80%
yield); 1H NMR (400 MHz, CDCl3) δ 2.66 (t, J = 7.6 Hz, 4H), 1.59−
1.51 (m, 4H), 1.39−1.30 (m, 4H), 0.93 (t, J = 7.2 Hz, 6H); 13C NMR
(100 MHz, CDCl3); δ 121.6, 40.5, 29.6, 21.7, 13.9. The data match
those of the literature report.9
(12) (a) Swain, C. G.; Lupton, E. C. J. Am. Chem. Soc. 1968, 90,
4328. (b) Hansch, C.; Leo, A.; Taft, R. W. Chem. Rev. 1991, 91, 165.
(13) Kodomari, M.; Satoh, H.; Yoshitomi, S. Nippon Kagaku Kaishi
1986, 1813.
(14) Shao, L.-X.; Shi, M. Synlett 2006, 1269.
(15) Kabalka, G. W.; Yang, K. Synth. Commun. 1998, 28, 3807.
ASSOCIATED CONTENT
■
S
* Supporting Information
1H and 13C NMR spectra of compounds 2a−af. This material is
available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: wmhe@hnu.edu.cn.
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (no. 21302048 and no. 21271070),
Specialized Research Fund for the Doctoral Program of Higher
Education (no. 20130161120035), China Postdoctoral Science
E
dx.doi.org/10.1021/jo501776b | J. Org. Chem. XXXX, XXX, XXX−XXX