(+)-tartaric acid-catalyzed high regio- and stereoselective aminobromination of olefins

Article abstract of DOI:10.1002/cjoc.201180302

(+)-Tartaric acid-catalyzed aminobromination of α,β-unsaturated ketones, α,β-unsaturated esters and simple olefins utilizing TsNH₂/NBS as the nitrogen/halogen sources at room temperature without protection of inert gases achieved good yields (u

Full text of DOI:10.1002/cjoc.201180302

FULL PAPER
(＋)-Tartaric Acid-Catalyzed High Regio- and Stereoselective
Aminobromination of Olefins
Chen, Zhanguo(陈战国)
Wei, Junfa*(魏俊发)
Li, Wenli(李文丽)
Wang, Yun(王芸)
Zhao, Pengfei(赵朋飞)
Shi, Xianying(石先莹)
School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an, Shaanxi 710062, China
Key Laboratory for Macromolecular Science of Shaanxi Province, Xi'an, Shaanxi 710062, China
(＋)-Tartaric acid-catalyzed aminobromination of α,β-unsaturated ketones, α,β-unsaturated esters and simple
olefins utilizing TsNH2/NBS as the nitrogen/halogen sources at room temperature without protection of inert gases
achieved good yields (up to 92% yield) of vicinal haloamino products with excellent regio- and stereoselectivity,
even just 10% of (＋)-tartaric acid was used as catalyst. The regio- and stereochemistry was unambiguously
confirmed by X-ray structural analysis of products 2b and 12c. The electron-rich and deficient olefins show signifi-
cant differences in activity to the aminobromination reaction and give the opposite regioselectivities. The 21 cases
have been investigated which indicated that our protocol has the advantage of a large scope of olefins. Additionally,
tartaric acid as catalyst has the advantage of avoiding any hazardous metals retained in products.
Keywords tartaric acid, aminobromination, regioselectivity, alkenes
Introduction
catalysts is highly desirable. For this aim, the sulfuric
acid-catalyzed aminochlorination of olefins with
Chloramine-T was developed by Wang and co-
worker,26 and CO2-promoted aminohalogenation has
also been reported.27
In recent years, increasing attention has been paid to
organocatalysts due to their great advatages: (i) The
organocatalysts are usually commercially available,
inexpensive and environmentally friendly. (ii) Reactions
catalyzed by organic small moleculars often proceed
under an aerobic atmosphere even in wet solvents. (iii)
In contrast to metallic Lewis acids, organocatalysts can
be recovered and reused. Despite of the developments of
organocatalysts in many reactions,28-39 no report has
been found on organocatalyst-promoted aminohaloge-
nation of olefins.
Bearing in mind the advantages of organocatalysts,
and considering both Lewis acid and Brønsted acid can
catalyze aminohalogenation of electron-deficient olefins,
we decided to explore small molecular organic acids as
organocatalysts for this reaction. An array of organic
acids were investigated and the (＋)-tartaric acid was
found to be an efficient catalyst for the reaction. Herein,
we wish to disclose the outcome of the (＋)-tartaric
acid-catalyzed regio- and stereoselective aminobromi-
nation of olefins in CH2Cl2 with TsNH2 and NBS
(Scheme 1). To the best of our knowledge, (＋)-tartaric
acid is the first nontoxic and convenient organocatalyst
for aminohalogenation of olefins.
Aminohalogenations for installing vicinal haloamino
moieties of multiply functionalized olefins have become
an interesting topic in organic synthesis and medicinal
chemistry because the products, the vicinal haloamines,
are important building blocks which can readily be
converted into numerous derivatives.1-9
In the past three decades, G. Li and others have de-
veloped many approaches to catalytic aminohalogena-
tion of olefins with the aid of different nitrogen/halogen
sources and catalysts. The common nitrogen/halogen
sources included 4-TsNCl2, 4-TsNNaCl,10,11 2-NsN-
NaCl (Ns＝2-nitrophenylsulfonyl), 2-NsNCl2/2-NsNH-
Na,12,13 and NBS/TsNH2.14 Different metal complexs
and salts, such as dichloro(1,10-phenanthroline)palla-
dium(II),11 CuI, V2O5, MnSO4, Mn(III)-salen,14
CuOTf,15-17
{(C3F7CO2)2Rh}2,18,19
CuCl2•2H2O,20
CuCN, Cu(OAc)2, and SnCl4/BF3•OEt2,21 were utilized
as catalysts. Very recently, we have reported some
novel and highly efficent reaction systems for amino-
bromination of olefins by use of TsNH2/NBS as the ni-
trogen/halogen sources in the presence of elemental
copper powders,22 aluminium powder,23 silicon pow-
der24 and KI25 as catalysts. This method provides de-
sired products in excellent yields (up to 98% yield) even
when just 1% catalyst was used. However, since
metal-catalyst is generally limited in pharmaceutical
industry, more readily available and nontoxic metal-free
* E-mail: weijf@snnu.edu.cn; Tel.: 0086-029-85303734; Fax: 0086-029-85307774
Received December 26, 2010; revised March 29, 2011; accepted April 12, 2011.
Project supported by the National Natural Science Foundation of China (No. 20572066), the Natural Science Foundation of Shaanxi Province
(2009JM2011), and the Innovation Foundation of Postgraduate Cultivation of Shaanxi Normal University (2008CXB009).
Chin. J. Chem. 2011, 29, 1689— 1696
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Chen et al.
FULL PAPER
Scheme 1
of aliphatic monocarboxylic acids (Entries 7—9). Some
amino acids have also been investigeted (Entries 10—
15, 10 mol% loading, 24 h), none of them afforded good
result under the current conditions.
In the ongoing investigation of this reaction, we
turned our attention to the dicarboxylic acid, whereas
similar disappointing results were observed in most
cases (Entries 16—18). To our delight, we found that, in
the presence of 10 mol% ( ± )-tartaric acid, the
aminobromination reaction could proceed smoothly to
afford the expected product in good yield (Entry 19,
72%). Interestingly, the (＋)-tartaric acid (10 mol%)
slightly increased this reaction yield from 72% to 76%
within 24 h (Entry 20). The reaction time could be
shortened as the loading of ( ＋)-tartaric acid was
increased from 10 mol% to 100 mol% (Entries 21—22).
Unfortunately, the vicinal haloamino product has no
optical activity, meaning it is a racemic mixture.
Various solvent systems were also screened for this
reaction. The results showed that hexane, toluene, THF,
and ethanol were not suitable solvents for this reaction.
In contrary, CH2Cl2, CH3CN and some aqueous media
such as CH2Cl2/H2O (V/V 1∶1) system were efficient
solvents for this reaction. Best results were observed by
the use of CH2Cl2 as solvent.
With the optimized condition in hand, the scope of
(＋)-tartaric acid-catalyzed aminobromination of the
olefins was explored. As illustrated in Table 2, the reac-
tion works well for a wide range of olefins. The
α,β-unsaturated ketones (1a—11a) led to the haloamino
products in moderate to good yields with high di-
astereoselecties (1b—3b, 4c—7c, 8b—11b) except for
7c. Notably, the reactivity of the chalcone derivatives
depends greatly on the substituents of both benzene
rings, especially those on the 4-position of the phenyl
Results and discussion
In our initial study, the catalytic activities of various
organic acids were examined for the aminobromination
of 1,3-diphenylpropen-1-one (the model substrate), with
TsNH2 and NBS as nitrogen/halogen source at room
temperature without protection of inert gases. The result
is summarized in Table 1. Among the monocarboxylic
acid, the acetic acid (10 mol% loading) was first em-
ployed to perform the reaction in CH2Cl2, which af-
forded desired product only in 36% yield (Table 1, En-
try 2). When the amount of catalyst went up from 50
mol% to 100 mol%, the yields were correspondingly
increased from 43% to 62% (Entries 3 and 4). The
long-chain aliphatic acid also gave unsatisfactory result
(46% yield) after stirring at room temperature for 48 h
(Entry 5). When stronger trifluoroethanoic acid was
used as catalyst (10 mol%), the reaction yield was not
improved (Entry 6, 33%) although reaction time was
prolonged up to 72 h, which indicates the catalytic ac-
tivities of organic acids were not related with their
acidities. Aromatic acids led to similar results to those
Table 1 Aminobromination of chalcone catalyzed by various organic acidsa
Entry
Cat./mol%
Time/h
48
Yieldb/%
23
Entry
12
Cat./mol%
Aspartic acid (10)
Histidine (10)
Time/h
24
Yieldb/%
38
1
2
Non
Acetic acid (10)
48
36
13
24
16
3
Acetic acid (50)b
48
43
14
Lycine (10)
24
21
4
Acetic acid (100)b
Palmitic acid (10)
Trifluoroethanoic acid (10)
Benzonic acid (10)
Salicylic acid (10)
3,5-Dinitrobenzonic acid (10)
DL-Threonine(10)
L-Alanine(10)
48
62
15
L-Phenylalanine (10)
Succinic acid (10)
Oxalic acid (10)
24
26
5
48
46
16
48
41
6
72
33
17
48
13
7
24
45
18
Citric acid (10)
48
38
8
48
22
19
(±)-Tartaric acid (10)
(＋)-Tartaric acid (10)
(＋)-Tartaric acid (50)
(＋)-Tartaric acid (100)
24
72
9
48
38
20
24
76
10
24
22
21
16
75
11
24
15
22
10
76
a Unless otherwise specified, all reactions were performed with chalcone (5.0 mmol), TsNH2 (5.0 mmol), NBS (6.0 mmol), acid (0.5
mmol) in CH2Cl2 (10.0 mL). b Isolated yields by flash column chromatography.
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(＋)-Tartaric Acid-Catalyzed High Regio- and Stereoselective Aminobromination of Olefins
Table 2 (＋) Tartaric acid-catalyzed aminobromination of electron-deficient olefins in CH2Cl2
a
Entry
1a
R1
R2
Product
1b
Anti∶ Synb/%
＞95
＞95
＞95
＞95
＞95
＞95
—
Time/h
24
48
48
0.25
24
48
48
24
48
48
48
1
m.p./℃
124—126
139—140
159—159.5
155—156
152—153
167—168
—
Yieldc/%
76
C6H5
C6H5
C6H5
C6H5CO
2a
4'-ClC6H4CO
4'-MeOC6H4CO
C6H5CO
2b
66
3a
3b
60
4a
4-MeOC6H4
2-Br-4,5-(MeO)2C6H2
3,4,5-(MeO)3C6H2
3-MeOC6H4
4-FC6H4
4c
92
5a
C6H5CO
5c
91
6a
C6H5CO
6c
68
7a
C6H5CO
7c
Trace
49
8a
C6H5CO
8b
＞95
＞95
＞95
＞95
＞95
＞95
＞95
＞95
＞95
＞95
＞95
＞95
＞95
＞95
150—151
164—165
140—141
170—172
177—179
93—95
9a
4-FC6H4
4'-MeOC6H4CO
4'-ClC6H4CO
C6H5CO
9b
59
10a
11a
12a
13a
14a
15a
16a
17a
18a
19a
20a
21a
4-FC6H4
10b
11b
12c
13c
14c
15c
16b
17b
18b
19b
20b
21b
67
4-BrC6H4
61
3,4,5-(MeO)3C6H2
4-MeOC6H4
2-Br-4,5-(MeO)2C6H2
4-MeOC6H4
C6H5
MeCO
48
MeCO
1
75
MeCO
2
88—90
84
CH3OCO
C2H5OCO
CH3(CH2)3
1
90—91
79
48
24
24
6
121—123
84—86
62
H
45
CH2CH2CH2CH2
116—117
115—116
159—160
168—169
33
CH2CH2CH2CH2CH2CH2
70
C6H5
H
C6H5
C6H5
24
24
31
60
a Unless otherwise specified, all reactions were performed with olefins (5.0 mmol), TsNH2 (5.0 mmol), NBS (6.0 mmol), (＋)-tartaric acid
(0.5 mmol) in CH2Cl2 (10.0 mL). b The ratio of anti∶syn products, ＞95% means no minor isomer was detected by 1H NMR. c Isolated
yields by flash column chromatography.
of α,β-unsaturated ketones, α,β-unsaturated esters and
simple olefins catalyzed by (＋)-tartaric acid depends
remarkably on the electron density of double-bond in
the substrates. The higher the electron density is on the
carbon-carbon double bond of the substrates due to
electron-donating group (for example, CH3O) being
bearded on the 4-position of benzene ring, the higher the
reaction activity of substrates is behaved. Such experi-
mental evidences indicate that aminobromination of
α,β-unsaturated carbonyl compound and simple olefins
catalyzed by (＋)-tartaric acid is an electrophilic addi-
tion reaction.
attached directly to the double bond. The chalcones
bearing a strong electron-donating group (e.g., OCH3)
on the 4-position of the benzene ring afforded the trans
isomers as the sole adductive products in nearly quanti-
tative yields (92%, 4c). The substrates bearing a poor
electron-withdrawing group (e.g., F or Br) on the same
position gave products in moderate yields (49%—67%,
8b—11b). This approach could be successfully ex-
tended to the aromatic enones, leading to the desired
products in moderate to good yields (48%—75%, 12c—
14c).
α,β-Unsaturated esters and simple olefins were also
examined in our reaction system. Much to our gratifica-
tion, the aminobrominated products were obtained eas-
ily in both types of substrates. The aminobromination of
α,β-unsaturated esters, methyl 4-methoxycinnamate
(15a) and ethyl cinnamate (16a), afforded the adductive
products in 79% (15c) and 62% (16b) yields, respec-
tivly. For various simple olefins (17a—21a), the reac-
tion gave the expected products in moderate yields
(31%—70%, 17b—21b).
In all cases we examined, the regioselectivities of
products have been completely controlled as revealed
by their 1H NMR and 13C NMR analysis. The part of the
aminobromination of α,β-unsaturated ketones and
α,β-unsaturated esters catalyzed by (＋)-tartaric acid
gave the anti-α-amono-β-bromo isomer as the sole
products. The identities of compounds (1b—3b, 8b—
11b and 16b) were confirmed by comparison of their
NMR, m.p. and elemental analytic data with the re-
ported ones.11,13,22-25,27,40-43 X-ray crystallographic study
The experimental results revealed that the reactivity
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of 1-(4'-chlorophenyl)-3-phenyl-2-(p-toluenesulfon ami-
do)-3-bromopropan-1-one (2b, Figure 1) showed clearly
that nitrogen atom was attached to the α-carbon and
bromine atom to the β-carbon of α,β-unsaturated ke-
tones in a trans relative stereochemistry.
parison of its NMR data and m.p. value with literature
reported ones.14,23-25 The regioselectivity of the amino-
brominted product of 1-hexene, 1-bromo-2-(p-toluene-
sulfonamido) hexane (15b), was confirmed by MS data
in which two prominent fragmented＋ ions,
[CH3(CH2)4CHNHTs]＋ and [CHNHTsCH2Br] , were
clearly identified.
The electron-rich and deficient olefins give the op-
posite regioselectivities in our reaction. There was no
explanation for these observations although they have
been found in a few examples previously reported.14,26 It
seems reasonable to believe there are two possible
pathways of the present aminobromination existing
during the reaction process: a bromonium intermediate
and an aziridinium intermediate formation pathway. For
the electron-rich olefins, NBS can produce a positive
bromine ion as well as radical.44-46 Thus, the first step is
that the substrate was reacted with NBS to yield a bro-
monium ion and negative succinimide ion [Figure 3,
pathway 1, Eq. (1)] which was previously reported by
Sudalai and co-workers.14 For the second step, the nega-
tive p-toluenesulfonamide would be produced from
negative succinimide reacting with p-toluenesulfona-
mide [pathway 1, Eq. (2)]. At the last step, the SN2
mechanism of this three-membered ring (bromonium
ion) opened by negative p-toluenesulfonamide accounts
for the excellent anti-stereoselectivty. The regioselec-
tivity can be explained by the fact that the β-position of
the bromonium ion intermediate is loaded by more posi-
tive charge than its α-position because of the stabiliza-
tion effect from the phenyl ring.
For the electron-deficient olefins without a 4-OMe,
the reaction proceed via the aziridinium intermed＋iate
mechanism (Pathway 2) wherein the species of TsN Br
is formed by the heterolytic cleavage of the N—Br bond
from N,N-dibromo-p-toluene sulfonamide (TsNBr2, 2).
The formation of N,N-dibromo-p-toluenesulfonamide
from NBS and TsNH2 has been reported in literature.23
The ＋formation of the aziridinium intermediate from
TsN X has been demonstrated in the aminohalogena-
tion of olefins with N,N-dihalo-p-toluene sulfona-
mide.10,19,47-49 Herein, we believe that the species of
TsN＋Br is formed by the heterolytic cleavage of the
N—Br bond from N,N-dibromo-p-toluene sulfonamide
helped by (＋)-tartaric acid in our reaction [pathway 2,
Eq. (2)]. Following reaction processes [pathway 2, Eqs.
(3) and (4)] are similar to [pathway 1, Eqs. (1) and (3)].
The regioselectivity can be explained by the fact that the
β-position of the aziridinium ion intermediate is loaded
by more positive charge than its α-position because of
the stabilization effect from the phenyl ring.
Figure 1 X-ray crystal structure of product 2b.
A noteworthy feature of the aminobromination
process is that the reversal isomers in regioselectivity
were observed when the 4-position of benzene ring car-
ried a strong electron-donating group (OCH3) under our
reaction condition. The regioselectivity of these reversal
products (4c—7c, 12c—15c) was confirmed by MS
analysis. The prominent fragmented ions, [ArCHNHTs]＋
and [ArCO]＋ or [RCO]＋, were clearly identified. Fur-
ther supported evidence was X-ray crystallographic
analysis of 4-(3,4,5-trimethoxyphenyl)-4-(p-toluenesul-
fonamido)-3-bromobutan-2-one (12c, Figure 2), which
has been reported previously in literature.23 The result
showed that nitrogen atom was added to β-carbon and
bromine atom to α-carbon of corresponding α,β-unsatu-
rated ketone.
Figure 2 X-ray crystal structure of product 12c reported in
literature 23.
Conclusion
We have demonstrated a regio- and stereoselective
aminobromination of olefins catalyzed by (＋)-tartaric
acid in good yields. The reaction catalyzed by organo-
For simple olefins, the styrene gave the α-amino-
β-bromo product (19b), which is determined by com-
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Chin. J. Chem. 2011, 29, 1689— 1696

(＋)-Tartaric Acid-Catalyzed High Regio- and Stereoselective Aminobromination of Olefins
catalyst provides a novel and convenient protocol to
synthesize civinal haloamino derivatives with the com-
bination of TsNH2/NBS as nitrogen/bromine sources at
room temperature. The method is successfully applied
to
a
wide range of α,β-unsaturated ketones,
α,β-unsaturated esters and simple olefins. Among the
α,β-unsaturated carbonly compounds, higher regioselec-
tive isomers of α-bromo-β-amino products have been
obtained when 4-position of benzene ring bears OCH3
group. On the contrary, the other α,β-unsaturated car-
bonyl compounds afforded corresponding α-amino
β-bromo isomers.
Experimental
General information
Unless otherwise stated, all reagents were purchased
from commercial sources and used without further puri-
fication. Reaction progress was monitored by TLC us-
ing Merck silica gel 60 F-254 with detection by UV.
Flash chromatography was performed using Merck sil-
ica gel 60 with freshly distilled solvents. Columns were
typically packed as slurry and equilibrated with the ap-
1
propriate solvent system prior to use. H NMR (300
MHz) and 13C NMR (75.45 MHz) spectra were re-
corded using CDCl3 as a solvent. Chemical shifts (δ) are
relative to TMS as an internal standard. Data are pre-
sented as follows: chemical shift, multiplicity (s＝
singlet, d＝doublet, t＝triplet, q＝quartet, sept＝septet,
m＝multiplet), coupling constant J (Hz) and integration.
Elemental analysis was carried on an analyzer. Melting
point spectrometer is uncorrected. The crystal structure
was recorded on an X-ray diffraction spectrometer.
Mass data were obtained with a GCMS-QP2010nc Plus
mass spectrometer (EI).
General experimental procedure
A mixture of ollifens (5 mmol), (＋)-tartaric acid
catalyst (10 mol%), TsNH2 (855 mg, 5 mmol) and NBS
(1068 mg, 6 mmol) was put into a dried convenience
vessel. Then, 10 mL of CH2Cl2 was added to the vessel
with stirring at room temperature in air. The reaction
was monitored by TLC up to desired products with no
increase or starting material complete consumed. After
completion of the reaction, the reaction mixture was
diluted with EtOAc (20 mL) and washed with brine (15
mL×3) and water (15 mL×3). The organic layer was
dried by anhydrous Na2SO4 and concentrated under re-
duced pressure to give crude product which was purified
by column chromatography packed with silica gel using
petroleum ether and EtOAc as eluent to afford pure
product.
Physical and spectroscopic data, m.p., and element
analysis results of all the synthesized compounds are
given below.
Figure 3 Prossible pathway for the aminobromination process
for electron-rich olefins (pathway 1) and electron-deficient ole-
fins (pathway 2)
( ± )-3-Bromo-1,3-diphenyl-2-(p-toluenesulfona-
mido) propan-1-one (1b) m.p. 124—126 ℃ (EtOH);
1H NMR (CDCl3, 300 MHz) δ: 7.78 (d, J＝7.50 Hz,
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2H), 7.59—7.40 (m, 10H), 7.00 (d, J＝8.10 Hz, 2H),
5.50 (d, J＝3.60 Hz, 1H), 5.12—5.10 (m, 1H), 2.26 (s,
3H); 13C NMR (CDCl3, 75.45 MHz) δ: 196.3, 143.6,
136.7, 136.4, 135.2, 134.1 (2), 129.0 (2), 129.5 (2),
128.9 (2), 128.7 (2), 128.6 (2), 127.1 (2), 60.8, 51.7,
21.4. Anal. calcd for C22H20BrNO3S: C 57.64, H 4.37, N
3.06; found C 57.62, H 4.36, N 3.05.
( ± )-3-Bromo1-(4'-chlorophenyl)-3-phenyl-2-(p-
toluene sulfonamido) propan-1-one (2b) m.p. 139—
140 ℃ (EtOH); 1H NMR (CDCl3, 300 MHz) δ: 7.74 (d,
J＝8.10 Hz, 2H), 7.44—7.38 (m, 4H), 7.25 (s, 5H), 7.00
(d, J＝7.80 Hz, 2H), 5.60 (d, J＝9.60 Hz, 1H), 5.44 (dd,
J＝8.0, 9.0 Hz), 5.07 (d, J＝7.50 Hz, 1H), 2.28 (s, 3H);
13C NMR (CDCl3, 75.45 MHz) δ: 195.6, 143.4, 140.5,
136.3, 133.5, 130.0 (2), 129.2 (2), 128.8 (2), 128.7 (2),
128.4 (2), 128.3 (2), 126.8 (2), 60.0, 51.3, 21.1. Anal.
calcd for C22H19BrClNO3S: C 53.57, H 3.86, N 2.84;
found C 53.59, H 3.88, N 2.87.
m.p. 167—168 ℃ (EtOH); 1H NMR (CDCl3, 300
MHz) δ: 7.79 (d, J＝7.80 Hz, 2H), 7.57 (d, J＝7.80 Hz,
2H), 7.42—7.37 (m, 2H), 7.09 (d, J＝7.8 Hz, 2H), 6.85
(d, J＝8.70 Hz, 1H), 6.31 (s, 2H), 5.42 (d, J＝4.50 Hz,
1H), 5.08—5.05 (m, 1H), 3.72—3.67 (m, 9H), 2.33 (s,
3H); 13C NMR (CDCl3, 75.45 MHz) δ: 193.7, 152.8,
142.7, 137.6, 137.4, 134.1, 134.0, 131.9, 128.8 (2),
128.5 (2), 128.4 (2), 127.0 (2), 126.8 (2), 104.4, 60.7,
60.4, 55.7, 45.6, 21.1; MS m/z (%): 65 (5), 77 (25), 91
(25), 105 (100), 155 (5), 195 (30), 350 (80), 549 (M＋＋
1, 5). Anal. calcd for C25H26BrNO6S: C 54.74, H 4.75,
N 2.56; found C 54.72, H 4.79, N 2.60.
( ± )-3-Bromo-3-(4-fluorophenyl)-1-phenyl-2-(p-
toluene sulfonamido) propan-1-one (8b) m.p. 150—
151 ℃ (EtOH); 1H NMR (CDCl3, 300 MHz) δ: 7.79 (d,
J＝7.50 Hz, 2H), 7.60—7.54 (m, 2H), 7.44—7.39 (m,
2H), 7.19—7.12 (m, 4H), 6.86—6.81 (m, 2H), 6.72 (d,
J＝8.70 Hz, 1H), 5.39 (d, J＝4.80 Hz, 1H), 5.09—5.05
(m, 1H), 2.36 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ:
193.4, 163.7, 142.9, 137.54, 134.1, 133.9, 132.4, 129.7
(2), 128.9 (2), 128.5 (2), 127.1 (2), 119.1, 116.4, 115.4,
115.1, 59.8, 45.5, 21.1. Anal. calcd for C22H19BrFNO3S:
C 55.46, H 3.99, N 2.94; found C 55.48, H 4.01, N 2.93.
( ± )-3-Bromo-3-(4-fluorophenyl)-1-(4'-methoxy-
phenyl)-2-(p-toluenesulfonamido)propan-1-one (9b)
m.p. 164—165 ℃ (EtOH); 1H NMR (CDCl3, 300
MHz) δ: 7.81 (d, J＝8.70 Hz, 2H), 7.45 (d, J＝7.50 Hz,
2H), 7.29 (d, J＝9.9 Hz, 2H), 7.15 (s, 2H), 7.02 (d, J＝
7.50 Hz, 2H), 6.94—6.85 (m, 2H), 5.46 (d, J＝9.30 Hz,
1H), 5.06 (d, J＝6.60 Hz, 1H), 3.92 (s, 3H), 2.33 (s, 3H);
13C NMR (CDCl3, 75.45 MHz) δ: 194.2, 164.3, 142.8,
136.5, 132.4 (2), 131.1 (2), 130.1 (2), 129.1, 128.9,
127.4, 126.7 (2), 115.3, 115.0, 113.8 (2), 60.1, 55.3,
45.4, 21.0. Anal. calcd for C23H21BrFNO4S: C 54.55, H
4.15, N 2.77; found C 54.58, H 4.16, N 2.79.
( ± )-3-Bromo-1-(4'-methoxyphenyl)-3-phenyl-2-
(p-toluene sulfonamido) propan-1-one (3b) m.p.
159—159.5 ℃ (EtOH); 1H NMR (CDCl3, 300 MHz) δ:
7.78 (d, J＝8.40 Hz, 2H), 7.46 (d, J＝7.95 Hz, 2H),
7.01 (d, J＝7.80 Hz, 2H), 6.90 (d, J＝8.40 Hz, 2H),
5.526—5.424 (m, 2H), 5.11 (d, J＝6.60 Hz, 1H), 3.89 (s,
3H), 2.265 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ:
194.5, 164.5, 143.4, 136.8, 136.7, 131.4 (2), 129.4 (2),
129.0 (2), 128.6 (2), 128.1 (2), 127.1 (2), 114.0 (2), 60.4,
55.7, 51.9, 21.4. Anal. calcd for C23H22BrNO4S: C
56.56, H 4.54, N 2.87; found C 56.62, H 4.58, N 2.87.
( ± )-2-Bromo-3-(4-methoxyphenyl)-1-phenyl-3-
(p-toluene sulfonamido) propan-1-one (4c) m.p.
1
155—156 ℃ (EtOH); H NMR (CDCl3, 300 MHz) δ:
7.78 (d, J＝7.50 Hz, 2H), 7.60—7.53 (m, 2H), 7.42—
7.38 (m, 2H), 7.12—7.07 (m, 4H), 6.71—6.64 (m, 3H),
5.40 (d, J＝4.20 Hz, 1H), 5.06—5.02 (m, 1H), 3.70 (s,
3H), 2.34 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ:
193.7, 159.0, 142.6, 137.6, 134.1, 133.9, 128.8(2),
128.5(3), 128.4 (2), 128.3 (2), 126.8 (2), 113.7 (2), 59.9,
54.9, 46.0, 21.1; MS m/z (%): 77 (35), 91 (45), 105
(100), 155 (15), 290 (50), 408 (15). Anal. calcd for
C23H22BrNO4S: C 56.56, H 4.54, N 2.87; found C 56.60,
H 4.58, N 2.87.
( ± )-3-Bromo-1-(4-chlorophenyl)-3-(4-fluorophe-
ny)-2-(tosylamino)-propan-1-one (10b) m.p. 140—
141 ℃ (EtOH); 1H NMR (CDCl3, 300 MHz) δ: 7.78 (d,
J＝8.40 Hz, 2H), 7.42—7.39 (m, 2H), 7.11 (d, J＝7.82
Hz, 2H), 6.82—7.02 (m, 2H), 5.58 (d, J＝6.00 Hz, 1H),
5.43—5.32 (m, 1H), 4.13—4.08 (m, 1H), 2.34 (s, 3H);
13C NMR (CDCl3, 75.45 MHz) δ: 195.6, 163.9, 160.7,
143.3, 140.4, 136.2, 133.2, 132.1 (2), 129.9 (2), 128.96
(2), 128.86 (2), 126.5 (2), 115.3, 114.9, 59.7, 49.8, 20.8.
Anal. calcd for C22H18BrClFNO3S: C 51.73, H 3.55, N
2.74; found C 51.75, H 3.56, N 2.76.
( ± )-trans-2-Bromo-3-(2-bromo-4,5-dimethoxy-
phenyl)-1-phenyl-3-(p-toluenesulfonamido)propan-1-
one (5c) m.p. 152 — 153 ℃ (EtOH); 1H NMR
(CDCl3, 300 MHz) δ: 7.77—7.53 (m, 5H), 7.40 (dd, J＝
7.2, 7.3 Hz, 2H), 7.15 (d, J＝7.5 Hz, 2H), 6.93 (d, J＝
8.70 Hz, 2H), 6.86 (s, 1H), 5.58 (d, J＝6.00 Hz, 1H),
5.32 (dd, J＝4.2, 4.7 Hz, 1H), 3.78 (s, 3H), 3.65 (s, 3H),
2.35 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ: 193.74,
148.97, 147.96, 142.72, 137.08, 133.90, 133.83, 128.70
(2), 128.36 (2), 128.15 (2), 127.20 (2), 126.67, 114.82,
112.39, 111.72, 59.4, 55.7, 55.4, 42.4, 20.9; MS m/z (%):
77 (40), 91 (30), 105 (100), 155 (15), 399 (55), 597 (M＋,
5). Anal. calcd for C24H23Br2NO5S: C 48.26, H 3.88, N
2.34; found C 48.30, H 3.92, N 2.41.
(±)-3-Bromo-3-(4-bromopheny)-1-phenyl-2-(to-
sylamino) propan-1-one (11b) m.p. 170—172 ℃
1
(EtOH); H NMR (CDCl3, 300 MHz) δ: 7.86 (d, J＝
7.47 Hz, 2H), 7.65 (s, 1H), 7.52—7.26 (m, 6H), 7.04 (d,
J＝7.5 Hz, 2H), 5.55—5.44 (m, 2H), 5.01 (d, J＝7.05
Hz, 1H), 2.30 (s, 3H); 13CNMR (CDCl3, 75.45 MHz) δ:
196.1, 143.2, 136.2, 135.3, 134.6, 133.8, 131.2 (2),
129.6 (2), 128.9 (2), 128.4 (2), 128.3 (2), 126.5 (2),
122.7, 59.9, 49.8, 20.9. Anal. calcd for C22H19Br2NO3S:
C 49.18, H 3.56, N 2.61; found C 49.21, H 3.54, N 2.65.
(±)-3-Bromo-4-(3,4,5-trimethoxyphenyl)-4-(p-to-
luenesulfonamido)butan-2-one (12c) m.p. 177—179
(±)-trans-2-Bromo-1-phenyl-3-(3,4,5-trimethoxy-
phenyl)-3-(p-toluenesulfonamido)propan-1-one (6c)
1694
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© 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2011, 29, 1689— 1696

(＋)-Tartaric Acid-Catalyzed High Regio- and Stereoselective Aminobromination of Olefins
℃ (EtOH); 1H NMR (CDCl3, 300 MHz) δ: 7.49 (d, J＝
7.80 Hz, 2H), 7.08 (d, J＝7.80 Hz, 2H), 6.58 (d, J＝
9.60 Hz, 1H), 6.27 (s, 2H), 4.76 (d, J＝9.30 Hz, 1H),
4.51 (d, J＝7.50 Hz, 1H), 3.77—3.72 (m, 9H), 2.36 (s,
3H), 2.32 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ:
201.8, 152.6, 142.8, 137.3, 136.8, 131.1, 128.6 (2),
126.6 (3), 104.1 (2), 60.3, 60.1, 55.5 (2), 53.3, 26.6,
H 4.74, N 3.30.
1-Bromo-2-(tosylamino)hexane (17b) m.p. 84—
86 ℃ (EtOH); 1H NMR (CDCl3, 300 MHz) δ: 7.78 (d,
J＝7.88 Hz, 2H), 7.32 (d, J＝7.62 Hz, 2H), 4.70 (s, 1H),
3.41—3.30 (m, 3H), 2.43 (s, 3H), 1.55—0.78 (m, 9H);
13C NMR (CDCl3, 75.45 MHz) δ: 143.7, 137.8, 129.8
(2), 127.5 (2), 60.4, 38.2, 32.9, 27.3, 22.1, 21.5, 14.2;
MS m/z (%): 334 (M＋, 8), 240 (50) C4H9CH (NHTs).
Anal. calcd for C13H20BrNO2S: C 46.71, H 6.03, N 4.19;
found C 46.72, H 6.04, N 4.21.
( ± )-trans-1-Bromo-2-(p-toluenesulfonamido)cy-
clohexane (18b) m.p. 116 — 117 ℃ (EtOH); 1H
NMR (CDCl3, 300 MHz) δ: 7.79 (d, J＝6.13 Hz, 2H),
7.31 (d, J＝7.80 Hz, 2H), 5.34 (s, exchangeable with
D2O, 1H), 3.88 (s, 1H), 3.20 (d, J＝3.60 Hz, 1H), 2.43
(s, 3H), 2.25 (s, 2H), 1.80—1.64 (m, 3H), 1.31 (d, J＝
6.00 Hz, 3H); 13C NMR (CDCl3, 75.45 MHz) δ: 143.0,
136.8, 129.1 (2), 126.8 (2), 58.1, 54.5, 35.2, 32.3, 24.7,
22.9, 21.0. Anal. calcd for C13H18BrNO2S: C 46.99, H
5.46, N 4.22; found C 46.96, H 5.48, N 4.21.
( ± )-trans-1-Bromo-2-(p-toluenesulfonamido)cy-
clooctane (19b) m.p. 115—116 ℃; 1H NMR (CDCl3,
300 MHz) δ: 7.77 (d, J＝8.10 Hz, 2H), 7.31 (d, J＝7.80
Hz, 2H), 4.76 (s, 1H), 4.07—4.02 (m, 1H), 3.45 (s, 1H),
2.44 (s, 3H), 2.30—1.98 (m, 3H), 1.78—1.30 (m, 9H);
13C NMR (CDCl3, 75.45 MHz) δ: 143.5, 136.2, 129.5
(2), 127.6 (2), 61.0, 59.6, 32.2, 31.7, 25.7, 25.5, 25.4,
25.0, 21.6. Anal. calcd for C15H22BrNO2S: C 50.00, H
6.15, N 3.89; found C 49.98, H 6.18, N 3.97.
( ± )-trans-1-Bromo-1,2-diphenyl-2-(p-toluenesul-
fonamido) ethane (20b) m.p. 159—160 ℃ (EtOH);
1H NMR (300 MHz, CDCl3) δ: 7.44 (d, J＝7.80 Hz,
2H), 7.26—7.06 (m, 10H), 6.88 (d, J＝7.20 Hz, 2H),
5.17 (d, J＝2.70 Hz, 1H), 5.1 (s, 1H), 4.8—4.76 (m,
1H), 2.34 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ:
143.3, 136.8, 136.3, 129.4, 129.3, 129.2, 128.9, 128.7,
128.7, 128.5, 128.4, 128.4, 128.1(2), 127.9, 127.8, 127.2,
127.1, 63.1, 58.4, 21.4. Anal. calcd for C21H20BrNO2S:
C 58.61, H 4.68, N 3.25; found C 58.63, H 4.69, N 3.28.
2-Bromo-1-phenyl-1-(p-toluenesulfonamido)-
20.9; MS m/z (%): 65 (10), 91 (35), 195 (40), 350 (100),
＋
406 (10), 487 (M ＋ 1, 13). Anal. calcd for
C20H24BrNO6S: C 49.39, H 4.97, N 2.88; found C 49.41,
H 4.94, N 2.86.
(±)-3-Bromo-4-(4-methoxyphenyl)-4-(p-toluene-
sulfon amido)butan-2-one (13c) m.p. 93—95 ℃
1
(EtOH); H NMR (CDCl3, 300 MHz) δ: 7.50 (d, J＝
7.80 Hz, 2H), 7.07 (d, J＝7.80 Hz, 4H), 7.68 (d, J＝
8.10 Hz, 2H), 6.30 (d, J＝9.30 Hz, 1H), 4.80 (d, J＝
8.70 Hz 1H), 4.48 (d, J＝6.60 Hz, 1H), 3.72 (s, 3H),
2.33 (s, 3H), 2.26 (s, 3H); 13C NMR (CDCl3, 75.45
MHz) δ: 201.5, 159.0, 142.5, 136.9, 128.7 (2), 128.4 (2),
128.0, 126.6 (2), 113.4 (2), 59.1, 54.7, 53.6, 27.0, 20.9;
MS m/z (%): 65 (10), 77 (5), 91 ＋(65), 134 (15), 155 (30),
290 (100), 346 (10), 426 (M , 2). Anal. calcd for
C18H20BrNO4S: C 50.71, H 4.73, N 3.29; found C 50.74,
H 4.72, N 3.28.
( ± )-3-Bromo-4-(2-bromo-4,5-dimethoxyphenyl)-
4-(p-toluenesulfonamido)butan-2-one (14c)
m.p.
1
88—90 ℃ (EtOH); H NMR (CDCl3, 300 MHz) δ:
7.57 (d, J＝7.50 Hz, 2H), 7.09 (d, J＝7.80 Hz, 2H),
6.85 (s, 1H), 6.65 (s, 1H), 6.57 (d, J＝9.00 Hz, 1H),
5.17—5.12 (m, 1H), 4.63 (d, J＝5.28 Hz, 1H), 3.82 (s,
3H), 3.72 (s, 3H), 2.33 (s, 3H), 2.24 (s, 3H); 13C NMR
(CDCl3, 75.45 MHz) δ: 201.5, 148.9, 148.0, 142.8,
136.7, 128.7 (2), 126.9, 126.6 (2), 114.8, 112.7, 111.4,
58.9, 55.7, 55.5, 49.6, 27.5, 20.9; MS m/z (%): 77 (20),
91 (25), 105 (100), 155 (35), 399 (65). Anal. calcd for
C19H21Br2NO5S: C 42.64, H 3.95, N 2.62; found C
42.67, H 3.90, N2.68.
( ± )-Methyl 2-bromo-3-(4-methoxyphenyl)-3-
(tosylamino) propionate (15c) m.p. 90 — 91 ℃
1
(EtOH); H NMR (CDCl3, 300 MHz) δ: 7.56 (d, J＝
1
7.95 Hz, 2H), 7.25 (d, J＝5.52 Hz, 2H), 7.12 (d, J＝
7.59 Hz, 2H), 7.02 (d, J＝8.37 Hz, 2H), 6.69 (d, J＝
8.37 Hz, 2H), 6.19 (d, J＝9.15 Hz, 1H), 4.85—4.83 (m,
1H), 4.45 (d, J＝5.76 Hz, 1H), 3.74 (s, 3H), 3.65 (s, 3H),
2.35 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ: 168.2,
159.1, 142.6, 137.1 (2), 128.7 (2), 127.7 (2), 126.7 (2),
113.5 (2), 59.1, 54.7, 52.6, 46.3, 20.9. Anal. calcd for
C18H20BrNO5S: C 48.88, H 4.56, N 3.17; found C 49.01,
H 4.52, N 3.10.
ethane (21b) m.p. 168—169 ℃ (EtOH); H NMR
(CDCl3, 300 MHz) δ: 7.63 (d, J＝7.80 Hz, 2H), 7.34—
7.12 (m, 7H), 5.38 (s, exchangeable with D2O, 1H),
4.57 (d, J＝6.21 Hz, 1H), 3.58 (d, J＝6.21 Hz, 2H),
2.37 (s, 3H); 13C NMR (CDCl3, 75.45 MHz) δ: 143.1,
137.2, 136.6, 129.0 (2), 128.2 (2), 127.8, 126.7 (2),
126.2 (2), 57.6, 36.1, 21.0. Anal. calcd for
C15H16BrNO2S: C 50.86, H 4.55, N 3.95; found C 50.82,
H 4.57, N 3.96.
(±)-Ethyl 3-bromo-3-phenyl-2-(tosylamino)pro-
1
pionate (16b) m.p. 121—123 ℃ (EtOH); H NMR
References
(CDCl3, 300 MHz) δ: 7.63 (d, J＝7.8 Hz, 2H), 7.41—
7.23 (m, 8H), 5.18—5.12 (m, 2H), 4.48—4.43 (m, 1H),
3.98 (q, J＝6.9 Hz, 2H), 2.41 (s, 3H), 1.26 (t, J＝6.5 Hz,
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C18H20BrNO4S: C 50.71, H 4.73, N 3.29; found C 50.75,
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