Convenient synthesis of α-bromo ketones by the Meerwein reaction

Article abstract of DOI:10.1134/S1070428012040094

A simple and convenient procedure was proposed for the synthesis of 4-aryl-3-bromobutan-2-ones from methyl vinyl ketone and arenediazonium bromides under Meerwein reaction conditions. Pleiades Publishing, Ltd., 2012.

Full text of DOI:10.1134/S1070428012040094

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 4, pp. 519–522. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © Yu.V. Ostapiuk, V.S. Matiichuk, N.I. Pidlypnyi, N.D. Obushak, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48,
No. 4, pp. 521–524.
Convenient Synthesis of α-Bromo Ketones
by the Meerwein Reaction
Yu. V. Ostapiuk, V. S. Matiichuk, N. I. Pidlypnyi, and N. D. Obushak
Ivan Franko National University of Lviv, ul. Kirilla i Mefodiya 6, Lviv, 79005 Ukraine
e-mail: obushak@in.lviv.ua
Received September 27, 2011
Abstract—A simple and convenient procedure was proposed for the synthesis of 4-aryl-3-bromobutan-2-ones
from methyl vinyl ketone and arenediazonium bromides under Meerwein reaction conditions.
DOI: 10.1134/S1070428012040094
α-Bromo ketones are widely used in organic syn-
thesis [1], e.g., as difunctional electrophiles in the syn-
thesis of heterocycles [1, 2] and intermediate products
in the preparation of biologically active substances [3].
α-Bromo ketones are generally prepared by bromina-
tion of the corresponding ketones with N-bromosuccin-
imide or bromine in the presence of an acid [1, 4]. In
recent time other synthetic approaches have also been
proposed [5].
The present communication describes a new proce-
dure for the synthesis of α-bromo ketones by reaction
of methyl vinyl ketone with arenediazonium salts.
Arylation of unsaturated compounds with diazonium
salts (Meerwein reaction) provides a convenient
method for the preparation of polyfunctionalized com-
pounds [6, 7]. Bromoarylation of α,β-unsaturated
ketones according to Meerwein was not described
previously.
(Va) was formed in a moderate yield (40%) together
with bromobenzene (37%) as product of side Sand-
meyer reaction. We also tried to synthesize compound
Va by three-component reaction, i.e., using benzenedi-
azonium tetrafluoroborate (II) or hydrogen sulfate
(III) and potassium bromide instead of benzenediazo-
nium bromide (Ia) (Scheme 1). In all cases, compound
Va was isolated in approximately equal yields. Varia-
tion of the solvent showed that no reaction occurs in
nonpolar solvents, carboxylic acids, and alcohols. The
reactions in DMF, DMSO, and dioxane gave, respec-
tively, 14, 15, and 5% of compound Va.
After having determined the optimal conditions, we
extended the above reaction over a number of arene-
diazonium salts Ia–Iq prepared by diazotization of the
corresponding aromatic amines with sodium nitrite in
40% aqueous HBr. In all cases, bromo ketones Va–Vq
were formed in 40–50% yield (Scheme 2). The reac-
tion temperature was varied from 20 to 44°C, depend-
ing on the substituent in the aromatic ring of initial
diazonium salt I. The yield of bromo ketones Va–Vq
increased when a mixture of methyl vinyl ketone (IV)
and copper(II) bromide was preliminarily stirred over
a period of 10 min (prior to addition of arenediazoni-
um salt I). Presumably, a complex of methyl vinyl
We examined copper-catalyzed reaction of ben-
zenediazonium bromide (Ia) with methyl vinyl ketone
(IV). The reaction was carried out at room tempera-
ture by adding an aqueous solution of diazonium salt
Ia to a solution of methyl vinyl ketone (IV) in acetone
in the presence of a catalytic amount of copper(II)
bromide. As a result, 3-bromo-4-phenylbutan-2-one
Scheme 1.
O
CuBr2, Me2CO–H2O (X = Br)
O
N2 X–
or KBr, CuBr2, Me2CO–H2O (X = BF4, HSO4)
Me
H2C
+
Me
Br
Ia, II, III
IV
Va
Ia, X = Br; II, X = BF4; III, X = HSO4.
519

OSTAPIUK et al.
520
Scheme 2.
O
O
N2 Br–
CuBr2, Me2CO–H2O
Me
H2C
+
R
R
Me
Br
Ia–Iq
IV
Va–Vq
R = H (a), 3-Me (b), 4-Me (c), 2-CF3 (d), 3-CF3 (e), 3-Br (f), 2-Cl (g), 3-Cl (h), 4-Cl (i), 2-F (j), 3-F (k), 4-F (l),
4-MeO (m), 4-O2N (n), 4-SO2NH2 (o), 2,4-Cl2 (p), 2,5-Cl2 (q).
ketone with the catalyst is formed, which favors the
arylation process [8]. Cooper(I) bromide showed
a lower catalytic efficiency than copper(II) bromide:
the yield of Va–Vq decreased by 5–10%. For example,
the yields of Va, Vc, and Ve in the presence of CuBr
were 35, 37, and 59%, respectively, against 40, 43, and
69% in the reaction catalyzed by CuBr2.
water. The product was filtered off and recrystallized
from benzene (Vn) or ethanol (Vo).
3-Bromo-4-phenylbutan-2-one (Va). Reaction
temperature 20–25°C. Yield 9.08 g (40%), yellow oily
substance, nD20 = 1.5578, bp 113–115°C (3 mm).
1H NMR spectrum, δ, ppm: 2.30 s (3H, CH3), 3.10 d.d
2
3
(1H, CH2, J = 14.7, J = 7.8 Hz), 3.39 d.d (1H, CH2,
3
2J = 14.7, J = 5.9 Hz), 4.45–4.51 m (1H, CH), 7.25–
To conclude, we have proposed a simple and con-
venient procedure for the synthesis of 4-aryl-3-bromo-
butan-2-ones from accessible aromatic amines and
methyl vinyl ketone.
7.31 m (5H, C6H5). Found, %: C 52.74; H 4.80.
C10H11BrO. Calculated, %: C 52.89; H 4.88.
3-Bromo-4-(3-methylphenyl)butan-2-one (Vb).
Reaction temperature 20–27°C. Yield 9.4 g (39%),
yellow oily substance, nD20 = 1.5420, bp 132–133°C
(3 mm). 1H NMR spectrum, δ, ppm: 2.30 s (3H, CH3),
EXPERIMENTAL
2
3
1
The H and 13C NMR spectra were recorded from
2.32 s (3H, CH3), 3.12 d.d (1H, CH2, J = 14.4, J =
2
3
7.4 Hz), 3.41 d.d (1H, CH2, J = 14.4, J = 7.6 Hz),
4.46 t (1H, CH, J = 7.4 Hz), 6.97–7.20 m (4H, C6H4).
13C NMR spectrum, δC, ppm: 21.4 (C6H4CH3), 27.0
(CH3), 39.5 (CH2), 53.2 (CH), 126.1, 127.9, 128.5,
129.9, 136.9, 138.3, 201.5 (C=O). Found, %: C 54.88;
H 5.32. C11H13BrO. Calculated, %: C 54.79; H 5.43.
solutions in CDCl3 (or DMSO-d6 for compound Vo) on
a Varian Gemini spectrometer at 200 and 50 MHz,
respectively, using TMS as internal reference.
Arenediazonium bromides Ia–Iq (general proce-
dure). The corresponding aromatic amine, 0.1 mol,
was added to 34.3 ml (0.22 mol) of 40% aqueous HBr,
the mixture was cooled to –5°C, and 7.6 g (0.11 mol)
of a saturated solution of sodium nitrite was added
dropwise at such a rate that the temperature did not
exceed 5°C.
3-Bromo-4-(4-methylphenyl)butan-2-one (Vc).
Reaction temperature 20–25°C. Yield 10.36 g (43%),
yellow oily substance, nD20 = 1.5415, bp 129–131°C
(3 mm). 1H NMR spectrum, δ, ppm: 2.30 s (3H, CH3),
2
3
2.31 s (3H, CH3), 3.12 d.d (1H, CH2, J = 14.4, J =
2
3
4-Aryl-3-bromobutan-2-ones Va–Vc (general
procedure). A cold solution of diazonium salt Ia–Ic
(see above) was added dropwise under stirring to
a mixture of 0.2 g of CuBr2, 8.9 ml (0.11 mol) of
methyl vinyl ketone, and 50 ml of acetone. The rate of
the addition was selected so that nitrogen evolved at
a rate of 2–3 bubbles per second (addition time 0.5–
1 h). The mixture was then stirred until nitrogen no
longer evolved, 200 ml of water was added, the
organic layer was separated, and the aqueous layer was
extracted with CH2Cl2 (3×20 ml). The extracts were
combined with the organic phase, dried over MgSO4,
and evaporated, and the residue was distilled under re-
duced pressure. In the synthesis of Vn and Vo, a solid
precipitated from the reaction mixture after addition of
7.4 Hz), 3.40 d.d (1H, CH2, J = 14.4, J = 7.6 Hz),
3
4.46 t (1H, CH, J = 7.4 Hz), 7.10 br.s (4H, C6H4).
13C NMR spectrum, δC, ppm: 21.1 (C6H4CH3), 27.0
(CH3), 39.2 (CH2), 53.4 (CH), 129.0, 129.3, 133.9,
136.8, 201.4 (C=O). Found, %: C 54.62; H 5.29.
C11H13BrO. Calculated, %: C 54.79; H 5.43.
3-Bromo-4-[2-(trifluoromethyl)phenyl]butan-
2-one (Vd). Reaction temperature 35–37°C. Yield
15.35 g (52%), yellow oily substance, nD20 = 1.4991,
1
bp 125°C (8 mm). H NMR spectrum, δ, ppm: 2.36 s
2
3
(3H, CH3), 3.31 d.d (1H, CH2, J = 14.6, J = 8.0 Hz),
2
3
3.67 d.d (1H, CH2, J = 14.6, J = 6.0 Hz), 4.52 t (1H,
CH, J = 7.0 Hz), 7.39–7.50 m (3H, C6H4), 7.66 d (1H,
C6H4, J = 7.0 Hz). Found, %: C 44.55; H 3.35.
C11H10BrF3O. Calculated, %: C 44.77; H 3.42.
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CONVENIENT SYNTHESIS OF α-BROMO KETONES BY THE MEERWEIN REACTION
521
(2H, C6H4, J = 8.0 Hz). Found, %: C 45.74; H 3.68.
C10H10BrClO. Calculated, %: C 45.92; H 3.85.
3-Bromo-4-[3-(trifluoromethyl)phenyl]butan-
2-one (Ve). Reaction temperature 39–43°C. Yield
20.36 g (69%), yellow oily substance, nD20 = 1.5211,
3-Bromo-4-(2-fluorophenyl)butan-2-one (Vj).
Reaction temperature 33–37°C. Yield 12.5 g (51%),
yellow oily substance, nD20 = 1.5325, bp 125–126°C
(3 mm). 1H NMR spectrum, δ, ppm: 2.35 s (3H, CH3),
1
bp 120–121°C (5 mm). H NMR spectrum, δ, ppm:
2
3
2.32 s (3H, CH3), 3.38 d.d (1H, CH2, J = 14.5, J =
2
3
8.7 Hz), 3.70 d.d (1H, CH2, J = 14.5, J = 6.0 Hz),
4.48–4.55 m (1H, CH), 7.38–7.68 m (4H, C6H4).
Found, %: C 44.63; H 3.31. C11H10BrF3O. Calculated,
%: C 44.77; H 3.42.
2
3
3.19 d.d (1H, CH2, J = 14.4, J = 8.0 Hz), 3.46 d.d
2
3
(1H, CH2, J = 14.4, J = 7.0 Hz), 4.56 d.d (1H, CH,
J = 8.0, 7.0 Hz), 7.04–7.12 m and 7.20–7.29 m (2H
each, C6H4). 13C NMR spectrum, δC, ppm: 26.9 (CH3),
33.2 (CH2), 51.5 (CH), 115.2, 115.6, 124.2, 129.1,
131.9, 161.5 d (C–F, JCF = 245 Hz), 201.0 (C=O).
Found, %: C 48.90; H 4.07. C10H10BrFO. Calculated,
%: C 49.01; H 4.11.
3-Bromo-4-(3-bromophenyl)butan-2-one (Vf).
Reaction temperature 28–33°C. Yield 9.49 g (31%),
yellow oily substance, nD20 = 1.5831, bp 156–157°C
(3 mm). 1H NMR spectrum, δ, ppm: 2.35 s (3H, CH3),
2
3
3.10 d.d (1H, CH2, J = 14.4, J = 7.6 Hz), 3.43 d.d
2
3
(1H, CH2, J = 14.4, J = 6.8 Hz), 4.44 d.d (1H, CH,
J = 7.6, 6.8 Hz), 7.12–7.40 m (4H, C6H4). 13C NMR
spectrum, δC, ppm: 27.1 (CH3), 38.8 (CH2), 52.6 (CH),
122.5, 127.9, 130.3, 131.3, 132.2, 139.3, 200.8 (C=O).
Found, %: C 39.08; H 3.21. C10H10Br2O. Calculated,
%: C 39.25; H 3.29.
3-Bromo-4-(3-fluorophenyl)butan-2-one (Vk).
Reaction temperature 30–33°C. Yield 11.03 g (45%),
yellow oily substance, n2D0 = 1.5272, bp 118–119°C
(5 mm). 1H NMR spectrum, δ, ppm: 2.26 s (3H, CH3),
2
3
3.06 d.d (1H, CH2, J = 14.4, J = 7.6 Hz), 3.36 d.d
2
3
(1H, CH2, J = 14.4, J = 7.2 Hz), 4.37 t (1H, CH, J =
7.4 Hz), 6.78–7.20 m (4H, C6H4). 13C NMR spectrum,
δC, ppm: 27.0 (CH3), 39.0 (CH2), 52.5 (CH), 114.3,
3-Bromo-4-(2-chlorophenyl)butan-2-one (Vg).
Reaction temperature 25–30°C. Yield 13.6 g (52%),
yellow oily substance, nD20 = 1.5670, bp 142–146°C
(6 mm). 1H NMR spectrum, δ, ppm: 2.35 s (3H, CH3),
116.3, 124.9, 130.0, 139.4, 162.7 d (C–F, JCF
=
245 Hz), 200.9 (C=O). Found, %: C 48.73; H 4.00.
C10H10BrFO. Calculated, %: C 49.01; H 4.11.
2
3
3.24 d.d (1H, CH2, J = 14.4, J = 7.8 Hz), 3.57 d.d
2
3
(1H, CH2, J = 14.4, J = 6.8 Hz), 4.65 d.d (1H, CH,
J = 7.8, 6.8 Hz), 7.18–7.39 m (4H, C6H4). 13C NMR
spectrum, δC, ppm: 27.2 (CH3), 37.2 (CH2), 50.9 (CH),
126.8, 128.7, 129.6, 132.2, 134.0, 134.7, 200.9 (C=O).
Found, %: C 45.81; H 3.76. C10H10BrClO. Calculated,
%: C 45.92; H 3.85.
3-Bromo-4-(4-fluorophenyl)butan-2-one (Vl).
Reaction temperature 37–41°C. Yield 11.76 g (48%),
yellow oily substance, nD20 = 1.5373, bp 129–130°C
(8 mm). 1H NMR spectrum, δ, ppm: 2.33 s (3H, CH3),
2
3
3.12 d.d (1H, CH2, J = 14.4, J = 7.6 Hz), 3.41 d.d
2
3
(1H, CH2, J = 14.4, J = 7.4 Hz), 4.42 d.d (1H, CH,
J = 7.6, 7.4 Hz), 6.95–7.03 m (2H, C6H4), 7.17 d.d (2H,
C6H4, JHF = 5.4, JHH = 8.6 Hz). Found, %: C 48.79;
H 4.17. C10H10BrFO. Calculated, %: C 49.01; H 4.11.
3-Bromo-4-(3-chlorophenyl)butan-2-one (Vh).
Reaction temperature 34–39°C. Yield 11.5 g (44%),
yellow oily substance, nD20 = 1.5610, bp 134–136°C
(3 mm). 1H NMR spectrum, δ, ppm: 2.34 s (3H, CH3),
3-Bromo-4-(4-methoxyphenyl)butan-2-one (Vm).
Reaction temperature 20–21°C. Yield 7.20 g (28%),
yellow oily substance, nD20 = 1.5506, bp 160–161°C
(5 mm). 1H NMR spectrum, δ, ppm: 2.30 s (3H, CH3),
2
3
3.11 d.d (1H, CH2, J = 14.4, J = 7.6 Hz), 3.42 d.d
2
3
(1H, CH2, J = 14.4, J = 7.0 Hz), 4.44 t (1H, CH, J =
7.4 Hz), 7.07–7.12 m (1H, C6H4), 7.20–7.26 m (3H,
C6H4). 13C NMR spectrum, δC, ppm: 27.1 (CH3), 38.8
(CH2), 52.5 (CH), 127.3, 127.5, 129.3, 129.8, 134.3,
139.0, 200.8 (C=O). Found, %: C 45.68; H 3.71.
C10H10BrClO. Calculated, %: C 45.92; H 3.85.
2
3
3.12 d.d (1H, CH2, J = 14.6, J = 7.0 Hz), 3.33 d.d
2
3
(1H, CH2, J = 14.6, J = 7.8 Hz), 3.75 s (3H, CH3O),
4.11 d.d (1H, CH, J = 7.8, 7.0 Hz), 6.86 d and 7.13 d
(2H each, C6H4, J = 7.2 Hz). Found, %: C 51.23;
H 4.98. C11H13BrO2. Calculated, %: C 51.38; H 5.10.
3-Bromo-4-(4-chlorophenyl)butan-2-one (Vi).
Reaction temperature 25–30°C. Yield 9.15 g (35%),
yellow oily substance, nD20 = 1.5615, bp 135–137°C
(3 mm). 1H NMR spectrum, δ, ppm: 2.33 s (3H, CH3),
3-Bromo-4-(4-nitrophenyl)butan-2-one (Vn).
Reaction temperature 38–44°C. Yield 12.24 g (45%),
1
yellow crystals, mp 90°C. H NMR spectrum, δ, ppm:
2
3
2
3
3.10 d.d (1H, CH2, J = 14.4, J = 7.4 Hz), 3.43 d.d
2.39 s (3H, CH3), 3.25 d.d (1H, CH2, J = 14.4, J =
2
3
2
3
(1H, CH2, J = 14.4, J = 7.0 Hz), 4.43 d.d (1H, CH,
J = 7.4, 7.0 Hz), 7.15 d (2H, C6H4, J = 8.0 Hz), 7.28 d
8.2 Hz), 3.56 d.d (1H, CH2, J = 14.4, J = 6.6 Hz),
4.49 d.d (1H, CH, J = 8.2, 6.6 Hz), 7.41 d and 8.18 d
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 4 2012

OSTAPIUK et al.
522
(2H each, C6H4, J = 8.8 Hz). 13C NMR spectrum, δC,
ppm: 27.2 (CH3), 38.8 (CH2), 51.9 (CH), 123.7, 130.2,
144.6, 147.1, 200.4 (C=O). Found, %: C 44.02;
H 3.58; N 5.02. C10H10BrNO3. Calculated, %: C 44.14;
H 3.70; N 5.15.
REFERENCES
1. Larock, R.C., Comprehensive Organic Transformations:
A Guide to Functional Group Preparations, New York:
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Chem., 2007, vol. 9, p. 1104.
4-(2-Bromo-3-oxobutyl)benzenesulfonamide
(Vo). Reaction temperature 30–33°C. Yield 12.24 g
1
(40%), white crystals, mp 133°C. H NMR spectrum,
δ, ppm: 2.34 s (3H, CH3), 3.13 d.d (1H, CH2, 2J = 14.8,
2
3
3J = 9.2 Hz), 3.48 d.d (1H, CH2, J = 14.8, J =
5.4 Hz), 5.01 d.d (1H, CH, J = 9.2, 5.4 Hz), 7.48 d and
7.77 d (2H each, C6H4, J = 8.2 Hz). 13C NMR spec-
trum, δC, ppm: 27.7 (CH3), 39.0 (CH2), 54.8 (CH),
126.4, 130.4, 142.4, 143.3, 202.0 (C=O). Found, %:
C 39.20; H 3.82; N 4.41. C10H12BrNO3S. Calculated,
%: C 39.23; H 3.95; N 4.57.
3. Ke, X., Hu, H., Zhang, K., Xu, W., Zhu, Q., Wu, L., and
Hu, X., Chem. Commun., 2009, p. 1037.
3-Bromo-4-(2,4-dichlorophenyl)butan-2-one
(Vp). Reaction temperature 35–37°C. Yield 12.73 g
(43%), yellow oily substance, nD20 = 1.5650, bp 155–
158°C (3 mm). 1H NMR spectrum, δ, ppm: 2.34 s (3H,
4. Pavlinac, J., Zupan, M., Laali, K.K., and Stavber, S.,
Tetrahedron, 2009, vol. 65, p. 5625.
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Goswami, P., and Choudhury, L.H., J. Org. Chem., 2006,
vol. 71, p. 8961; Chen, J.-M. and Huang, X., Synthesis,
2004, p. 1577.
2
3
CH3), 3.16 d.d (1H, CH2, J = 14.7, J = 8.8 Hz),
2
3
3.43 d.d (1H, CH2, J = 14.7, J = 5.9 Hz), 4.52–
4.58 m (1H, CH), 7.28 d and 7.40 d (1H each, C6H3,
J = 8.6 Hz), 7.51 s (1H, C6H3). Found, %: C 40.43;
H 3.10. C10H9BrCl2O. Calculated, %: C 40.58; H 3.06.
6. Heinrich, M.R., Chem. Eur. J., 2009, vol. 15, p. 820.
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Russ. J. Org. Chem., 2002, vol. 38, p. 38.
3-Bromo-4-(2,5-dichlorophenyl)butan-2-one
(Vq). Reaction temperature 35–37°C. Yield 12.14 g
(41%), yellow oily substance, nD20 = 1.5769, bp 155–
156°C (3 mm). 1H NMR spectrum, δ, ppm: 2.37 s (3H,
2
3
CH3), 3.18 d.d (1H, CH2, J = 14.7, J = 8.8 Hz),
2
3
3.44 d.d (1H, CH2, J = 14.7, J = 6.0 Hz), 4.51–
4.57 m (1H, CH), 7.29 d and 7.43 d (1H each, C6H3,
J = 8.8 Hz), 7.48 s (1H, C6H3). Found, %: C 40.48;
H 2.98. C10H9BrCl2O. Calculated, %: C 40.58; H 3.06.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 4 2012