NaHCO3-Catalyzed Hihgly Regiospecific Aminobromination of ?,?-Dicyanostyrene Derivatives with 1,3-Dibromo-5,5-dimethylhydantoin (DBDMH)

Article abstract of DOI:10.1002/jccs.201400526

The aminobromination of β,β-dicyanostyrene derivetives with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) has been systematic studied. The reaction afforded the vicinal haloamino products in good to excellent yields at room temperature (the highest yield was up to 94 %), and the full regiospecificity of all products were achieved catalyzed by NaHCO₃ in CH₃CN. A possible pathway involving a Michael Addition reaction for this aminobromination was proposed. A new method for the NaHCO₃-catalyzed aminobromination of β,β-dicyanostyrene derivatives with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) has been developed. The reaction afforded the vicinal haloamino products in good to excellent yields at room temperature(the highest yield was up to 94 %). A possible pathway involving a Michael addition fashion for this aminobromination was proposed.

Full text of DOI:10.1002/jccs.201400526

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CHEMICAL SOCIETY
Article
NaHCO3-Catalyzed Hihgly Regiospecific Aminobromination of b,b-Dicyanostyrene
Derivatives with 1,3-Dibromo-5,5-dimethylhydantoin (DBDMH)
Zhanguo Chen,* Wei Xia, De’e Liu, Yali Liu, Manfei Du and Chenxi Cao
Key Laboratory for Macromolecular Science of Shaanxi Province, Xi’an, 710119, People’s Republic of China, and
School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an, 710119, People’s Republic of China
(Received: Dec. 11, 2014; Accepted: Oct. 13, 2015; Published Online: Dec. 21, 2015; DOI: 10.1002/jccs.201400526)
The aminobromination of b,b-dicyanostyrene derivetives with 1,3-dibromo-5,5-dimethylhydantoin
(DBDMH) has been systematic studied. The reaction afforded the vicinal haloamino products in good to
excellent yields at room temperature (the highest yield was up to 94%), and the full regiospecificity of all
products were achieved catalyzed by NaHCO3 in CH3CN. A possible pathway involving a Michael Addi-
tion reaction for this aminobromination was proposed.
Keywords: Aminobromination; b,b-dicyanostyrene derivetives; 1,3-Dibromo-5,5-dimethylhydantoin
(DBDMH)
INTRODUCTION
Aminohalogenation has become one of the most use-
a bromination reagent, the combination of DBDMH with
other compound was also used as an electrophilic reagent
for the additive reaction in the carbon-carbon double bond
to produce the bromocompound. Sharma developed a me-
thod for the build up the unit of bromohydrin methyl ether
to the carbon-carbon double bond of stilbene-type (imino-
stilbene) with the combination of DBDMH and methanol
in the good yield at 5-10 °C.29 Recently, You and co-work-
ers developed an efficient method to provide function-
alized azaspirocyclohexadienones via intramolecular al-
kene electrophilic bromination initiated dearomative cy-
clization.30 The method features a wide substrate scope, the
high yields, and the mild conditions. Our group recent de-
veloped an efficient protocol of the high region-and ste-
reoselective aminobromination of olefins with the combi-
nation of DBDMH and p-toluenesulfonamide (TsNH2) as
bromine/nitrogen sources catalyzed by Zn powder. This
protocol gets the vicinal haloamine products in high yield
(up to 99%) at room temperature.31 Besides it was used as a
bromination reagent, DBDMH was also used as an efficient
oxidizing reagent. In this field, stannylene derivatives of
monosaccharides can be oxidized into hydroxy-ketones,32
1,2- and 1,3-diols can be converted into methylene acetals
in the presence of methoxymethylphenylsulfide,33 and
thiols can be oxidized into disulfides.34 DBDMH was also
certainly used as an efficient catalytic reagent. Khazaei1
and co-authors described trimethylsilylation of hydroxyl.35
In this method, various alcohols and phenols reacted with
hexamethyldisilazane (HMDS) to generate trimethylsilyl
ful and attractive tool for organic chemistry because of its
effectiveness and convenience in constructing carbon–ni-
trogen and carbon–halogen bonds at the same time in one
reaction. The vicinal haloamino belong to an important
class of building blocks for the constructing numerous de-
rivatives.1-6 In the past decade, many aminohalogenation
protocols were developed to the variety compound of sim-
ple olefins and electron-deficient olefins, including a,b-
unsaturated ketones,7-11 cinnamates,10,12-16 and unsaturated
nitriles15,17 with an array of nitrogen/halogen sources, such
as 4-TsNCl2, 2-NsNCl2,13 2-NsNNaCl,13,18 dichlorocar-
bamates,18-21 TsNHBr,2,22 2-NsNCl2/2-NsNHNa,10,14,18 or
TsNH2/NBS.11,23 The effective catalysts covered Lewis ac-
ids,7-23 Brønsted acids,7 metal and nonmetal powders as
well as other species.24-27
The structure of 1,3-dibromo-5,5-dimethylhydantoin
(DBDMH) is a N-bromoimide-type compound. It was
widely used in the substitution reaction by way of a bro-
mination reagent for the both benzylic bromination and
aromatic-ring bromination. Shibatomi and co-workers de-
scribed a highly effective method of Lewis acid catalyzed
side-chain bromination of aromatic compounds reacted
with DBDMH. In this method, zirconium (IV) chloride
catalyst showed excellent catalytic activity toward various
benzylic bromination (bromination of aromatic side chain).
In contrast, Brønsted acid could selectively catalyzed aro-
matic-ring bromination without benzylic bromination.28 As
* Corresponding author. Tel: + 86-029-81530726; Fax: +86-029-81530727; Email: chzhg@snnu.edu.cn
Supporting information for this article is available on the www under http://dx.doi.org/10.1002/jccs.201400526
158
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Aminobromination of Double Carbon-carbon
ethers smoothly catalyzed by DBDMH. Habibzadeha1 and
Ghasemnejad reported an expeditious synthesis of 1-ami-
doalkyl-2-naphthols.36 Using the condensation of 2-na-
phthole with various araldehydes and acetamide, various
1-amidoalkyl-2-naphthol compounds was formed. This
green protocol was catalyzed by DBDMH, and it pro-
ceeded efficiently in the absence of any organic solvent un-
der thermal condition and microwave irradiation.
a most efficient catalyst (Table 1, Entry 8). Reducing the
amount of NaHCO3 to the 10 mol%, the highest yield
(91%) of the product 3e was achieved (Table 1, Entry 9).
Continuing reducing the amount of NaHCO3 to the 5
mol%, the lower yield (80%) of the corresponding product
was obtained (Table 1, Entry 10). The control experiment
showed that the reaction failed to give any of the corre-
sponding products when compound 1e reacted with DBDMH
in absence of any of the base even if the reaction time was
prolonged up to 48 h (entry 11). This result indicated that
the base is a key role in this reaction.
Although the various aminohalogenation of olefins
have been developed successfully in the past decade as
mentioned above, the new and efficient synthetic protocol
is still required.Indeed, the study of the aminohalogenation
of a,b-unsaturated nitriles have not been well documented
so far. Only two literatures touched on this research. One
literature is an aminohalogenation of b,b-dicyanostyrene
with NBA in the presence of K3PO4 (5%, molar fraction) in
CH2Cl2.37 Another literature is an aminohalogenation of
b,b-dicyanostyrene with NBS catalyzed by NaOAc (10
mol%) in CH2Cl2.38 However, the successful aminohalo-
genation of b,b-dicyanostyrene with DBDMH has not be
reported. In the course of our recent study on the amino-
bromination of electron-deficient olefins,37-40 we found
that DBDMH can be used as an efficient nitrogen/halogen
source alone toward this reaction. Herein, we wish to report
the detailed study of the reaction.
Solvent affects the reaction dramatically. For the opti-
mizing reaction conditions, some common solvents were
examined, too. As shown in Table 1, CH3CN was still
found to be the best solvent for the reaction among the
screened solvents including CH3CN, PhMe, THF, DMSO,
CHCl3, CH2Cl2, DMF, EtOH and acetone. Indeed, when
compound 1e reacted with DBDMH catalyzed by NaHCO3
(10 mol%) in PhMe, THF and DMSO at room temperature,
RESULTS AND DISCUSSION
The effect of the catalyst and solvent for the
aminobromination
According to the electron-deficient structural feature
of b,b-dicyanostyrene,37-38 we believed that the aminobro-
mination of b,b-dicyanostyrene derivatives with DBDMH
should proceed in a Michael Addition fashion. Thus, se-
veral bases were screened by using DBDMH as nitrogen/
halogen sources in CH3CN. Initially, strong bases of solid
KOH and NaOH attracted our attention. When the com-
pound 1e was employed as model substrate, to our delight,
the reaction proceeded smoothly catalyzed by these strong
bases in amount of 20 mol% and the corresponding amino-
brominated products 3e were obtained in the yields of 81%
and 80%, respectively (Table 1, Entries 1-2). In order to
find more efficient catalyst, the other mild bases were ex-
amined. As shown in Table 1, some common mild bases in-
cluding NaHCO3, NaOOCCOONa, Na2CO3, CH3COONa,
K2CO3, K3PO4 were investigated, and their catalytic activ-
ity were found to be the similar to that of the strong bases
(Table 1, Entries 3-8). However, NaHCO3 was found to be
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the reaction failed to give any aminobrominated product
even if the reaction time was prolonged up to 24 h (Entries
12-14). CHCl3, CH2Cl2, DMF, EtOH were found to be the
less effectiveness (Entries 15-18). However, the acetone
was found to be an effective solvent, too.
Generality of the aminobromonation
With the optimized reaction conditions in hand, we
next turned our attention to the generality of the reaction. A
variety of the b,b-dicyanostyrene derivatives 1 reacted
with the DBDMH were examined under those optimized
conditions and the results are showed in Table 2. As shown
in Table 2, the various substituted b,b-dicyanostyrene de-
rivatives 1 reacted with the DBDMH worked smoothly and
the reaction produced the compounds 3 as the sole amino-
brominated products in full regioselectivity and in good to
excellent yields except heterocycle compound 1l. Indeed,
no matter what substituent is on the phenyl ring of sub-
strates, such as electron-withdrawing groups (EWGs) or
electron-donating groups (EDGs), those substrates could
tolerate the reaction. For the b,b-dicyanostyrene deriva-
tives have a EWG (such as F, Cl, Br or NO2) on the 4-
positon of the benzene ring, the reaction gave the expected
adducts in good to excellent yields (Table 2, Entries 1-4,
61%-94% yield). When the substrates bearing strong EDG
(OCH3) on the benzene ring, the reaction also proceeded
readily and the high yields of the corresponding products
were obtained (Table 2, Entries 7-10, 66%-82% yield). Ob-
viously, these yields are slightly lower than that of sub-
strates bearing a EWG. When the substrate without any
substituent on the benzene ring or with a mild EDG on the
benzene ring, e.g. CH3, they also gave the corresponding
products in good to excellent yields under the identical
conditions (Table 2, Entries 5-6, 80%-91% yield). Notably,
when 1-naphthyl-type b,b-dicyanostyrene derivative 1k
was as a substrate, the corresponding product was obtained
in excellent yields, too (Table 2, Entries 11, 89% yield).
However, 2-furyl-type 1l was unsuitable substrate for this
reaction (Entry 12).
There are two N-Br bounds in the 1,3-dibromo-5,5-
dimethylhydantoin (DBDMH). If the heterolytic cleavage
process of two N-Br bounds are the identical in the reac-
tion, the reaction should give two products simultaneously
possible (product (I) and product (II), seeing Scheme 1).
For the product (I), the chemical shift (d) of H atom on
N-1H in 1H NMR should be about 6. For the product (II),
1
however, the chemical shift (d) of H atom on N-3H in H
NMR should be about 10. Indeed, only product (I) was ob-
tained in our reaction because the chemical shift (d) of
N-1H in 1H NMR of all products were observed in d 6.35-d
6.70. The result revealed that the nitrogen atom of posi-
tion-3 of DBDMH was added to the a-position of car-
bon-carbon double bond of the b,b-dicyanostyrene deriva-
tives.
The regioselectivity of the aminobromination
The regioselectivity of the aminohalo products was
confirmed by the prominent fragmented ions of part of the
products in their HRMS spectra, such as ([C6H5C6H9N2O2+
Na]+, 241.1010) for 3e, ([4-MeC6H4C6H9O2N2+Na]+,
255.1112) for 3f, ([4-MeOC6H4C6H9O2N2+Na]+, 271.1120)
for 3g. The result shows that the nitrogen atom of DBDMH
is added to the a-carbon of b,b-dicyanostyrene derivatives
while the bromine atom is added to the b-carbon.
Two products may be formed possible in the
aminobromination
Scheme 1
160
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Aminobromination of Double Carbon-carbon
The possible reaction pathway
The merit of this method
Herein, the exact mechanism of the NaHCO3-cata-
lyzed aminobromination of the b,b-dicyanostyrene deriva-
tives is not clear now. However, according to the regio-
selectivity of the reaction and the observed the chemical
shift (d) of the N-1H in all products as well as the structural
characteristic of the electron-deficient substrates (b,b-
dicyanostyrene derivatives), a possible pathway involving
a Michael addition toward this aminobromination was sug-
gested (Scheme 2). The first step was a heterolytic cleavage
process of N-Br bond toward the DBDMH catalyzed by
base to generate a negative ion (A) and a positive bromine
ion (step 1). The second step was the negative ion (A) at-
tacking the a-position carbon atom of carbon-carbon dou-
ble bond to generate the Michael intermediate (B), this in-
termediate was stabilized by the two EWGs (2CN) (step 2).
These processes are similar to that of literature.37 In the
third step, the Br+ ion reacted with (B) to form compound
(C) (step 3) which was converted into product via quench-
ing reaction with saturated aqueous Na2SO3 (step 4).
It is pleasure that a new and efficient nitrogen/halo-
gen source for the aminohalogenation toward olefins have
been discovered. This nitrogen/halogen source has the ad-
vantage of lower price, safety, stability in storage com-
pared to previously ones such as 4-TsNCl2, 2-NsNCl2,
2-NsNNaCl, TsNHBr, 2-NsNCl2/2-NsNHNa. Another ad-
vantage is that the reaction did not need protection with
inert gaseous. Additionally, NaHCO3 powder as catalyst
has the advantage of avoiding any hazardous metals re-
tained in products. The relative nontoxicity, low cost, re-
moved easily by washing process with water from reaction
mixture which make the methodology to be a useful tool for
preparation of the vicinal aminobromo products, especially
considering that the trace transition metal residues are
highly regulated.
EXPERIMENTAL
General: Unless otherwise stated, all reagents were pur-
chased from the commercial sources and used without further pu-
rification. The reaction progress was monitored by TLC using
Merck silica gel 60 F-254 with detection by UV. The flash chro-
matography was performed using Merck silica gel 60 with freshly
distilled solvents. The columns were typically packed as slurry
and equilibrated with the appropriate solvent system prior to use.
1H NMR (400 MHz) and 13C NMR (100 MHz) spectra were re-
corded using CDCl3 as a solvent. Chemical shifts (d) are reported
relative to TMS as an internal standard. HRMS was recorded on a
commercial apparatus (ESI source). Melting point spectrometer
was uncorrected.
The possible pathway of the NaHCO3-cata-
lyzed aminobromination of b,b-dicyanosty-
rene derivatives with DBDMH
Scheme 2
Preparation of b,b-dicyanostyrene derivatives 1: b,b-
dicyanostyrene derivatives were prepared by mechanochemical
method reference reported literature procedure.41 In an agate mor-
tar, an aromatic aldehyde (5.0 mmol), malononitrile (5.0 mmol)
and ammonium acetate (7.5 mmol) were loaded. Then, the mix-
ture was ground at room temperature in air. The reaction progress
was monitored by TLC. After the reaction was completed (until
the aromatic aldehyde was disappeared), the mixture product was
dissolved in ethyl acetate (20 mL) and washed by water (20 mL ´
3). The separated ethyl acetate solution was dried over by anhy-
drous sodium sulfate. After sodium sulfate was filtered off, the or-
ganic solution was concentrated under reduced pressure to give a
crude b,b-dicyanostyrene derivative which was recrystallized by
ethanol to obtain a pure product. Using this protocol, the all yield
of b,b-dicyanostyrene derivatives 1 was more than 95%.
General procedure for the synthesis of 3a-3k: Into a dry
round-bottomed flask were added the b,b-dicyanostyrene 1 (1.0
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mmol), 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) (0.2859
g, 1.0 mmol), NaHCO3 (0.0084 g, 0.1 mmol, 10 mol%), and
CH3CN (5 mL). The mixture was electromagnetically stirred at
room temperature in air until the starting material was consumed,
or by-product could be detected by TLC. Then the saturated aque-
ous Na2SO3 (20 mL) was added to the reaction system and the
mixture was continuance stirred for 10 min. The mixture solution
was separated and the organic phase was washed with brine (10
mL ´ 3) and water (10 mL ´ 3). The organic layer was dried over
by anhydrous sodium sulfate and concentrated under reduced
pressure to give the crude product which was purified by the col-
umn chromatography packed with silica gel with petroleum ether
and EtOAc as the eluent to afford the pure product 3a-3k.
1H), 1.51 (s, 6H); 13C NMR (100 MHz, CDCl3) d 176.4, 154.6,
130.9, 130.8, 129.8, 129.8, 129.4, 129.4 111.3, 111.0, 62,2, 59.3,
28.1, 25.0, 24.9; HRMS (ESI) [M+Na]+ 383.0118, calcd for
C15H13BrO2N4Na 383.0120. 3-[2-bromo-2,2-dicyano-1-(4-me-
thlphenyl)]ethyl-5,5-dimethylhydantoin 3f: white solid, 0.3002 g
(80% yield), mp 160-162 °C (EtOH); 1H NMR (400 MHz, CDCl3)
d 7.67 (d, J = 8.08 Hz, 2H), 7.27 (d, J = 7.88 Hz, 2H), 6.80 (s, 1H),
5.66 (s, 1H), 2.38 (s, 1H), 1.49 (s, 1H); 13C NMR (100 MHz,
CDCl3) d 176.4, 154.7, 141.2, 130.1, 130.1, 129.7, 129.7, 127.8,
111.4, 111.1, 62.0, 59.3, 28.3, 24.9, 24.9, 21.3; HRMS (ESI)
[M+Na]+ 397.0276, Calcd for C16H15BrO2N4Na 397.0276.
3-[2-bromo-2,2-dicyano-1-(3-methoxyphenyl)]ethyl-5,5-dime-
thylhydantoin 3g: white solid, 0.2582 g (66% yield), mp 167-
169 °C (EtOH); 1H NMR (400 MHz, CDCl3) d 7.31-7.38 (m, 3H),
7.01 (d, J = 8.00 Hz, 1H), 6.66 (s, 1H), 5.66 (s, 1H), 3.82 (s, 3H),
1.51 (s, 6H); 13C NMR (100 MHz, CDCl3) d 176.4, 160.1, 154.6,
132.0, 130.4, 122.0, 116.6, 115.3, 111.4, 111.0, 62.1, 59.3, 55.4,
28.0, 25.0, 24.9; HRMS (ESI) [M+Na]+ 413.0226, Calcd for
C16H15O3N4BrNa 413.0225. 3-[2-bromo-2,2-dicyano-1-(3,5-
dimethoxyphenyl)]ethyl-5,5-dimethylhydantoin 3h: yellow
3-[2-bromo-2,2-dicyano-1-(4-fluorophenyl)]ethyl-5,5-di-
methylhydantoin 3a: white solid, 0.3413 g (90% yield), mp
127-129 °C (EtOH); 1H NMR (400 MHz, CDCl3) d 7.82 (dd, J1 =
7.52 Hz, J2 = 5.48 Hz, 2H), 7.18 (t, J = 8.12 Hz, 2H), 6.70 (s, 1H),
5.69 (s, 1H), 1.51 (s, 6H); 13C NMR (100 MHz, CDCl3) d 176.3,
1
3
164.1 (d, JCF = 1002.68 Hz), 154.5, 132.2 (d, JCF = 34.76 Hz,
2C), 126.7 (d, 4JCF = 13.76 Hz), 116.7 (d, 2JCF = 87.36 Hz, 2C),
111.2, 110.9, 61.6, 59.4, 28.1, 25.0, 24.9; HRMS (ESI) [M+Na]+
401.0022, Calcd for C15H12O2N4FBrNa 401.0025. 3-[2-bromo-
2,2-dicyano-1-(4-chlorophenyl)]ethyl-5,5-dimethylhydantoin
3b: white solid, 0.2413 g (61% yield), mp 146-148 °C (EtOH); 1H
NMR (400 MHz, CDCl3) d 7.75 (d, J = 8.32 Hz, 2H), 7.46 (d, J =
8.40 Hz, 2H), 6.74 (s, 1H), 5.68 (s, 1H), 1.51 (s, 6H); 13C NMR
(100 MHz, CDCl3) d 176.3, 154.5, 137.4, 131.3, 131.3, 129.7,
129.7, 129.2, 111.1, 110.8, 61.6, 59.5, 27.8, 25.0, 24.9; HRMS
(ESI) [M+Na]+ 416.9731, Calcd for C15H12O2N4ClBrNa 416.9730.
3-[2-bromo-2,2-dicyano-1-(4-bromophenyl)]ethyl-5,5-dime-
thylhydantoin 3c: white solid, 0.2766 g (72% yield), mp 164-
166 °C (EtOH); 1H NMR (400 MHz, CDCl3) d 7.68 (d, J = 8.1 Hz,
2H), 7.62 (d, J = 8.44 Hz, 2H), 6.75 (s, 1H), 5.66 (s, 1H), 1.50 (s,
6H); 13C NMR (100 MHz, CDCl3) d 176.3, 154.5, 132.7, 132.7,
131.5, 131.5, 129.7, 125.7, 111.1, 110.8, 61.6, 59.5, 27.7, 25.0,
24.9; HRMS (ESI) [M+Na]+ 460.9229. Calcd for C15H12O2N4Br2Na:
460.9225. 3-[2-bromo-2,2-dicyano-1-(4-nitrophenyl)]ethyl-
5,5-dimethylhydantoin 3d: yellow solid, 0.3818 g (94% yield),
mp 102-104 °C (EtOH); 1H NMR (400 MHz, CDCl3) d 8.34 (d, J
= 8.36 Hz, 2H), 8.04 (d, J = 8.40 Hz, 2H), 6.60 (s, 1H), 5.83 (s,
1H), 1.53 (s, 6H); 13C NMR (100 MHz, CDCl3) d 176.2, 154.1,
149.0, 137.2, 131.3(2), 124.5(2), 110.8, 110.5, 61.3, 59.6, 27.1,
25.0, 24.9; HRMS (ESI) [M+Na]+ 427.9965, Calcd for
C15H12O4N5NaBr 427.9970. 3-(2-bromo-2,2-dicyano-1-phenyl)
ethyl-5,5-dimethyl hydantoin 3e: white solid, 0.3287 g (91%
1
solid, 0.3285 g (78% yield), mp 108-110 °C (EtOH); H NMR
(400 MHz, CDCl3) d 7.66 (s, 1H), 6.95 (s, 1H), 6.55 (s, 1H), 6.24
(s, 1H), 5.59 (s, 1H), 3.80-3.89 (t, 6H), 1.50 (d, J = 6.72 Hz, 6H);
13C NMR (100 MHz, CDCl3) d 176.1, 161.2, 160.1, 154.2, 132.0,
111.4, 111.0, 107.9, 106.8, 102.3, 62.3, 59.3, 55.8, 55.5, 27.9,
25.1, 25.0; HRMS (ESI) [M+Na]+ 443.0325, Calcd for
C17H17O4N4NaBr 443.0331. 3-[2-bromo-2,2-dicyano-1-(3,4,5-
trimethoxyphenyl)]ethyl-5,5-dimethylhydantoin 3i: yellow
1
solid, 0.3024 g (67% yield), mp 183-185 °C (EtOH); H NMR
(400 MHz, CDCl3) d 7.09 (s, 2H), 6.35 (s, 1H), 5.59 (s, 1H), 3.88
(s, 9H), 1.52 (d, J = 4.8 Hz, 6H); 13C NMR (100 MHz, CDCl3) d
176.3, 154.3, 153.6, 153.6, 140.0, 125.7, 111.5, 111.1, 107.5,
107.5, 62.5, 60.9, 59.2, 56.3, 56.3, 28.1, 25.1, 25.0; HRMS (ESI)
[M+Na]+ 473.0432, Calcd for C18H19O5N4NaBr 473.0437.
3-[2-bromo-2,2-dicyano-1-(4-methoxyphenyl)]ethyl-5,5-dime-
thylhydantoin 3j: yellow solid, 0.3208 g (82% yield), mp 70-72
°C (EtOH); 1H NMR (400 MHz, CDCl3) d 7.73 (d, J = 8.72 Hz,
2H), 6.97 (d, J = 8.72 Hz, 2H), 6.86 (s, 1H), 5.65 (s, 1H), 3.83 (s,
3H), 1.50 (s, 6H); 13C NMR (100 MHz, CDCl3) d 176.4, 161.4,
154.7, 131.4, 131.4, 122.6, 114.7, 114.7, 111.5, 111.1, 61.8, 59.3,
55.4, 28.5, 25.0, 24.9; HRMS (ESI) [M+Na]+ 413.0225, Calcd for
C16H15O3N4BrNa 413.0225. 3-[2-bromo-2,2-dicyano-1-(1-na-
phthyl)]ethyl-5,5-dimethylhydantoin 3k: green solid, 0.3661 g
(89% yield), mp 176-178 °C (EtOH); 1H NMR (400 MHz, CDCl3)
d 8.54 (d, J = 7.40 Hz, 1H), 8.23 (d, J = 8.64 Hz, 1H), 7.99 (d, J =
8.20 Hz, 1H), 7.92 (d, J = 8.08 Hz, 1H), 7.53-7.65 (m, 3H), 6.72
(s, 1H), 6.44 (s, 1H), 1.45 (d, J = 8.88 Hz, 6H); 13C NMR (100
1
yield); mp 138-140 °C (EtOH); H NMR (400 MHz, CDCl3) d
7.79 (d, J = 6.52 Hz, 2H), 7.44-7.50 (m, 3H), 6.69 (s, 1H), 5.70 (s,
162
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© 2016 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2016, 63, 158-164

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Aminobromination of Double Carbon-carbon
3112.
MHz, CDCl3) d 176.4, 154.5, 133.9, 131.6, 131.5, 129.4, 128.6,
127.8, 126.7, 126.4, 125.3, 122.0, 111.5, 111.4, 59.2, 55.8, 27.8,
25.0, 24.9; HRMS (ESI) [M+Na]+ 433.0273, Calcd for
C19H15O2N4NaBr 433.0276.
10. Timmons, C.; Chen, D. J.; Xu, X.; Li, G. Eur. J. Org. Chem.
2003, 3850.
11. Ma, L.; Du, D. M.; Xu, J. X. J. Org. Chem. 2005, 70, 10155.
12. Li, G.; Kim, S. H.; Wei, H. X. Tetrahedron Lett. 2000, 41,
8699.
CONCLUSIONS
13. Li, G.; Wei, H. X.; Kim, S. H. Tetrahedron 2001, 57, 8407.
14. Li, G.; Wei, H. X.; Kim, S. H. Org. Lett. 2000, 2, 2249.
15. Zhi, S. J.; Han, J.; Lin, C.; An, G.; Pan, Y.; Li, G. Synthesis
2008, 10, 1570.
We have demonstrated a new method for the NaHCO3-
catalyzed aminobromination of b,b-dicyanostyrene deriva-
tives with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH)
in CH3CN under ambient conditions. As a useful catalyst,
NaHCO3 has advantages of less toxic, more economic,
more efficient and more stable in storage. All of the reac-
tions proceeded conveniently under the aerobic conditions
at room temperature. The good to excellent yields of the
products were achieved with the extensive range of b,b-
dicyanostyrene derivatives. For the substrates, no matter
what substituent on the benzene ring, they could tolerate
the aminobromination reaction, and they gave the products
in the full regiospecificity. It is important that the 1,3-
dibromo-5,5-dimethylhydantoin could be used as new ni-
trogen/halogen sources for the aminohalogenation toward
electron-deficient olefins. The proposed possible mecha-
nism involving Michael Addition fashion explains well the
regiospecificity of the adductive products.
16. Kotti, S. R. S. S.; Xu, X.; Wang, Y. N.; Headley, A. D.; Li, G.
Tetrahedron Lett. 2004, 45, 7209.
17. Han, J. L.; Zhi, S. J.; Wang, L. Y.; Pan, Y.; Li, G. Eur. J. Org.
Chem. 2007, 1332.
18. Wang, Y. N.; Ni, B.; Headley, A. D.; Li, G. Adv. Synth. Catal.
2007, 349, 319.
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G. Org. Lett. 2005, 7, 921.
20. Han, J. L.; Li, Y. F.; Zhi, S. J.; Pan, Y.;, Timmons, C.; Li, G.
Tetrahedron Lett. 2006, 47, 7225.
21. Wang, Y. N.; Kattuboina, A.; Ai, T.; Banerjee, D.; Li, G. Tet-
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ACKNOWLEDGEMENTS
The authors are grateful to the Fundamental Research
Funds for the Central Universities (No. GK261001095),
the Natural Science Foundation of Shaanxi Province (No.
2009JM2001), and the Innovation Foundation of Post-
graduate Cultivation of Shaanxi Normal University (No.
2008CXB009).
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J. Chin. Chem. Soc. 2016, 63, 158-164