2. Nagappan Sivakumar and Chendrasekaran Yogalakshmi
http://www.iaeme.com/IJARET/index.asp 2 editor@iaeme.com
from Baylis–Hillman adducts using acrylates, acrylonitrile, or methyl vinyl ketone
have been successfully synthesized and utilized for various organic transformations,
the synthesis of trisubstituted allyl halides derived from nitroolefins has not been
reported in the literature and applications of these trisubstituted allyl halides have yet
to be explored.
Therefore, we have undertaken a research program for the synthesis and
examination of the possible applications of trisubstituted allyl halides derived from
nitroolefins in various organic reactions.
Baylis–Hillman adducts and its derived compounds are extensively utilized in the
synthesis of biologically active molecules, heterocycles, and many natural products.
In particular bromo and acetate derivatives of Baylis–Hillman adducts are widely
utilized for various organic transformations.1–9
For example, Basavaiah and co-
workers10
successfully synthesized bonducellin methyl ether, a natural product
isolated from Caesalpinia bonducella and Caesalpinia pulcherrima. They also
synthesized antifungal agent using the bromo derivative of a Baylis– Hillman adduct
as a starting materia Many reports are available in the literature demonstrating the
synthetic utility of bromo derivatives of Baylis–Hillman adducts in the synthesis of b-
lactams, b-azido esters, polyfunctionalized decalins, urethane N-carboxyanhydrides11–
14
etc. Based on these reports, we envisaged that the bromo compounds derived from
nitroolefins will also serve as excellent building blocks for the synthesis of a wide
variety of useful compounds. Triggered by this idea, we decided to prepare the bromo
compound derived from nitroolefins, which will open new avenues for synthetic
transformations.15-21
In continuation of our research interest in the field of Baylis–Hillman
chemistry,15–20 we planned to synthesize 1-[(E)-3-bromo-2-nitroprop-1-enyl]arenes
3 which are very useful starting material for various transformations.
It occurs to us that the target compound i.e. 1-[(E)-3-bromo-2-nitroprop-1-enyl]
benzene (5) can be easily synthesized directly by treating methyl-nitrostyrene with
Nbromosuccinimide under allylic radical bromination conditions. Unfortunately we
did not obtain the desired bromocompound (5) Scheme1
Scheme1
To find an alternative method for the synthesis of bromo compound 3, we decided
to utilize (2E,2'E,2''E)-3,3',3''-(4,4',4''-nitrilotris(benzene-4,1-diyl))tris(2-nitroprop-2-
en-1-ol) (4), which can be synthesized by the treatment of a-nitrostyrene (3) with
aqueous formaldehyde in the presence of imidazole and anthranilic acid in
tetrahydrofuran as a solvent.21 We envisaged that the syn-thesized compound,
namely (2E,2'E,2''E)-3,3',3''-(4,4',4''-nitrilotris(benzene-4,1-diyl))tris(2-nitroprop-2-
en-1-ol) (4), can be conveniently transformed into the corresponding bromo derivative
5 by treatment with brominating agents. Accordingly, the Baylis–Hillman adduct 4,
derived from nitroolefin and formaldehyde, was treated with aqueous hydrobromic
3. Synthesis of Bromo and Chloro Derivatives of Baylis–Hillman Adducts
http://www.iaeme.com/IJARET/index.asp 3 editor@iaeme.com
acid (48%) with dichloromethane as the solvent to the desired product tris (4-((E)-3-
bromo-2-nitroprop-1-enyl) phenyl) amine (5) in 52% yield.
The 1H NMR spectrum of the compound 5 showed the CH2 protons as a singlet at
δ = 4.57 ppm, the olefinic proton as a singlet at δ = 8.23 ppm, and the aromatic
protons as multiplets in the regionn of δ = 7.57–7.69 ppm.
To further understand the reaction, we decided to synthesize the chloro derivatives
from the corresponding Baylis– Hillman adducts under mild reaction conditions. The
treatment of Baylis–Hillman adduct 3 with iron (III) chloride in dichloromethane over
a period of six hours successfully provided the desired tris(4-((E)-3-chloro-2-
nitroprop-1-enyl)phenyl)amine in 57 yield. The 1
H NMR spectrum of the compound
5 showed the CH2 protons as a singlet at δ = 4.81 ppm, the olefinic proton as a singlet
at δ = 8.37 ppm, and the aromatic protons as multiplets in the region of δ = 7.53–
7.67.in good yield scheme1.
Scheme 1
CONCLUSION
In conclusion, we have successfully developed a short and simple protocol for the
synthesis of bromo and chloro derivatives of Baylis–Hillman adducts derived from
nitroolefins
in good yields. This novel class of bromo and chloro derivatives can be utilized as
building blocks for wide variety of organic compounds. We also developed a facile
method for the transformation of these bromides into an interesting and novel class of
trisubstituted triallylamines which are core unit of dendrimers, thus demonstrating the
synthetic utility of the bromo derivatives of the Baylis–Hillman adducts. Hence this
novel protocol opens new opportunities for the preparation of libraries of wide variety
of new molecules
ACKNOWLEDGMENTS
We thank AMET University for the financial support. We also thank University of
Madras for the NMR facility. Indian institute of Technology, Chennai for IR, and
Mass Spectra.
4. Nagappan Sivakumar and Chendrasekaran Yogalakshmi
http://www.iaeme.com/IJARET/index.asp 4 editor@iaeme.com
Tris (4-((E)-3-bromo-2-nitroprop-1-enyl) phenyl) amine (5); Typical Procedure
To a stirred solution of (2E,2'E,2''E)-3,3',3''-(4,4',4''-nitrilotris(benzene-4,1-
diyl))tris(2-nitroprop-2-en-1-ol (4, (2.19g, 4 mmol) in CH2Cl2 (15 mL), 48% aq HBr
(2.03 mL) was added at r.t.. The mixture was cooled to 0 °C and then concd H2SO4
(1.00 mL) was added dropwise. The mixture was stirred well at r.t. for about 24 h. On
completion of the reaction (TLC analysis), the mixture was poured into H2O and the
aqueous layer was extracted with EtOAc (3 × 10mL). The combined organic layers
were washed with brine (10 mL) and concentrated. The crude product thus obtained
was purified by column chromatography (EtOAc–hexanes) to provide 5 (4.40 g, 60%)
as a yellow crystalline solid; mp 96–98 °C.
IR (KBr):, 1653, 1522, 1326, cm-1
1
H NMR (CDCl3, 300 MHz): δ 2.61 (s, 1H), 4.65 (s, 2H), 7.47–7.59 (m, 5H), 8.22 (s,
1H). 13
C NMR (CDCl3, 75 MHz): 53.65, 129.19, 130.29, 130.91, 131.36, 137. 87,
149.42.MS (m/z): 734 (M+
+1).Elemental Analysis for C27H21Br3N4O6 Calculated: C,
43.99; H, 2.87; N, 7.60. Found: C, 43.98; H, 2.86; N, 7.61
Tris(4-((E)-3-chloro-2-nitroprop-1-enyl)phenyl)amine (6); Typical Procedure
To a stirred soln of ((2E,2'E,2''E)-3,3',3''-(4,4',4''-nitrilotris(benzene-4,1-diyl))tris(2-
nitroprop-2-en-1-ol (4, 2.19g, 4 mmol) in CH2Cl2 (10 mL), FeCl3 (0.68 g, 5 mmol)
was added and the mixture was stirred well at r.t. for about 6 h. On completion of the
reaction (TLC analysis), the mixture was poured into H2O and the aqueous layer was
extracted with EtOAc (3 × 10 mL). The combined organic layers were washed with
brine (10 mL) and concentrated. The crude product thus obtained was purified by
column chromatography (EtOAc–hexanes) to afford pure 6 (3.80 g, 63%) as a white-
colored solid. mp 116–118 °C
IR (KBr): 1639, 1515, 1323 cm–1
.
1
H NMR (300 MHz, CDCl3): δ = 4.73 (s, 2 H), 7.42–7.56 (m, 5 H), 8.23 (s, 1 H). 13
C
NMR (75 MHz, CDCl3): δ = 61.61, 129.13, 130.27, 131.27, 131.43, 138.79, 147.66.
MS: m/z = 602 (M+), 604 (M+ + 2). Elemental Analysis for C27H21Cl3N4O6
Calculated: C, 53.70; H, 3.51; N, 9.28;. Found: C, 53.71; H, 3.52; Cl, 17.62; N, 9.27.
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