Tin(II)chloride mediated addition reaction of bromonitromethane to aldehydes

Article abstract of DOI:10.1515/znb-2005-0411

Bromonitromethane adds to aliphatic aldehydes in the presence of tin(II) chloride to yield β-nitro alcohols via a Reformatsky-type reaction in high yields, while aromatic aldehydes give low yields. The products were characterized by IR, NMR, and mass spectroscopy and by elemental analysis.

Full text of DOI:10.1515/znb-2005-0411

Tin(II)chloride Mediated Addition Reaction of Bromonitromethane to
Aldehydes
Ali S. Mahasneh
Department of Chemistry, Mutah University. P. O. Box 7, Karak-Jordan
Reprint requests to Dr. A. S. Mahasneh. E-mail: asmahasneh@hotmail.com
Z. Naturforsch. 60b, 416 – 418 (2005); received August 2, 2004
Bromonitromethane adds to aliphatic aldehydes in the presence of tin(II) chloride to yield β-nitro
alcohols via a Reformatsky-type reaction in high yields, while aromatic aldehydes give low yields.
The products were characterized by IR, NMR, and mass spectroscopy and by elemental analysis.
Key words: Bromonitromethane, Aliphatic Aldehydes, β-Nitro Alcohols, Reformatsky Reaction
Introduction
product can be reduced to an amino group; (b) α-
hydrogen atoms adjacent to the nitro group in the prod-
uct, being acidic, are consequently useful for further
C-C bond formation via deprotonation-alkylation re-
actions [3]. It was found that bromonitromethane re-
acts with imines derived from aromatic aldehydes and
ring substituted anilines in the presence of tin(II) chlo-
ride to give β-nitroamines via an addition reaction
(Scheme 1) [4]. The polarity of bromonitromethane
is thereby reversed from an electrophile to a nucleo-
phile.
As an electrophile, bromonitromethane was used
as a versatile reagent in the synthesis of aminothio-
phenes and their derivatives as well as in the reac-
tion with nucleophiles such as thiolates, sulphides,
thiourea, thiocyanate, iodide and phosphorus based
species [1]. Bromonitromethane contains only one
carbon atom, therefore it is relevant to C-1 chem-
istry [2]. In chemical synthesis, it has two advantages
over other C-1 synthons: (a) the nitro group of the
H
H
H
Ar2
1) SnCl2/ether, 0.5-1.0 h
2) H3O+
Ar1
C
N
C
+ BrCH2NO2
Ar1
N
Ar2
CH2NO2
Scheme 1.
Similarly β-nitro alcohols can be prepared by preparation of amino alcohols, some of them are bio-
a tin(II) chloride mediated addition of bromoni- logically important.
tromethane and aliphatic aldehydes as reported here.
Nitroalcohols were prepared in good yields by the ad-
dition of α,α-doubly metalated nitroalkanes to alde-
hydes at −90 ◦C [5] or from the reaction of ni-
troalkanes and aldehydes on an alumina surface [6] or
alumina-supported potassium fluoride in the absence
of a solvent [7], and from nitroalkanes and aldehy-
des using sodium hydroxide and a phase transfer cat-
alyst [8]. All of these reactions are considered as ex-
amples of the general Henry reaction. In this work an
alternative route for the synthesis of β-nitroalcohols
is reported. Nitroalcohols are useful precursors for the
Results and Discussion
As shown in Scheme 2, bromonitromethane was re-
acted with cinnamaldehyde, for example, in the pres-
ence of tin(II)chloride in diethyl ether at room temper-
ature for 1 h. After the workup of the reaction mix-
ture and purification of the product, 1-nitro-4-phenyl-
3-buten-2-ol (2e) was isolated in 65% yield.
The 1H NMR spectrum of the compound 2e showed
a broad singlet at 2.7 ppm (OH group) which could
be quenched with deuterium oxide, and a doublet at
c
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A. S. Mahasneh · Tin(II)chloride Mediated Addition Reaction
417
Table 1. Yields of the reactions of aliphatic aldehydes and
bromonitromethane.
OH
1-SnCl2/ether RT
2-RCHO
3-H3O+
NO2
CH2BrNO2
2
a
b
c
d
e
f
R
CH3
C2H5
Yields [%]
[Ref.]
[9]
[10]
R
75
70
68
72
72
70
Scheme 2.
CH3CH=CH
CH3(CH2)4CH2
C6H5CH=CH
C6H5CH2CH2
4.5 ppm for CH2NO2 methylene protons, while the
13C NMR spectrum showed a signal at 70.0 ppm for
a CHOH carbon atom and at 80.0 ppm for CH2NO2
carbon atom. The IR spectrum showed a broad absorp-
tion band at 3439 cm−1 corresponding to the hydroxyl
group and another one at 1556 cm−1 corresponding to
the nitro group. All other prepared nitroalcohols gave
1H NMR, 13C NMR and IR signals consistent with the
assigned structures.
The electron impact mass spectrum of compound 2e
at 70 eV showed the M+ peak at m/e = 193 with an in-
tensity less than 1%, [M+-H2O] (1.5%) at 175, [M+-
NO2–H] (13%) at 146, [M+-CH3NO2] (22%) at 132,
and [M+-CH3NO2-H] (44%) at 131. Loss of CO from
the 131 peak gives a peak at 103 (55%) which possi-
bly produces the base peak at 77. The electron impact
mass spectra of the other products did not show any
M+ peak, therefore, their composition was confirmed
by elemental analysis together with spectroscopic
methods.
When the reactions were performed in tetrahydro-
furan, dimethyl sulfoxide, or acetonitrile, no dramatic
increase in the yields of the products was noticed. But
the yields were enhanced when the amount of SnCl2
was increased. As an example, the yield of 2e was in-
creased from 65% to 72% when the mole ratio was
changed from1:1:1 to 1:1.5:1 (aldehyde/ tin(II) chlo-
ride/ bromonitromethane). Different aliphatic aldehy-
des were reacted with bromonitromethane in the pres-
ence of tin(II) chloride to give yields summarized in
Table 1. On the other hand the reaction of aromatic
aldehydes with bromonitromethane in the presence of
SnCl2 gave low yields of the corresponding alcohols,
which were unstable and decomposed readily at room
temperature. It was also found that ketones were prac-
tically not reactive.
(denitration) using tributyltin hydride make bromoni-
tromethane an interesting useful synthon. High yields,
relatively short reaction time, low cost of starting ma-
terials and easy handling of the reactions are other re-
markable advantages.
The mechanism of this reaction is not studied yet
but a Reformatsky-type mechanism is proposed [11].
Cl
H
ether
RCHO
BrCH2NO2 + SnCl2
OSnBrCl2
Br
Sn
Cl
C
H
NO2
OH
H3O+
R
C
H
CH2NO2
R
C
H
CH2NO2
Experimental Section
All reagents were commercial grade and were used with-
out further purification. IR spectra were determined on a
Mattson 5000 spectrometer. NMR spectra were determined
on a Bruker AC 200 MHz instrument. In all cases, samples
were dissolved in CDCl3 using TMS as internal standard.
Mass spectra were recorded on a Finnigian Mat 731 spec-
trometer at 70 eV. Elemental analysis were performed at the
Middle East Technical University-Analyses center.
Bromonitromethane was prepared according to the fol-
lowing improved procedure [7]:
A mixture of water (500 ml), ice (200 g), NaOH (20 g,
0.50 mol) and nitromethane (36.6 g, 0.60 mol) was vigor-
ously stirred using a mechanical stirrer for 30 min during
which the temperature was kept around 0 ◦C. Bromine (60 g,
0.40 mol) was added at once to the solution with continu-
ous stirring. After 4 h the solution was steam distilled. The
crude product was isolated, dried over anhydrous MgSO4
and fractionally redistilled. Bromonitromethane was col-
lected at 134 – 136 ◦C to produce 30 g (56% yield). 1H NMR:
Conclusion
Bromonitromethane proved to be a valuable C-1
unit in C-C bond formation. Functionalities present in
the products may be suitable for a wide range of other
chemical manipulations. A potential conversion of the
nitro group into amino group via reduction and the ease
of replacement of the nitro group by a hydrogen atom
˜
δ = 5.45 ppm (s, CH2). IR (neat): ν = 1565, 1373, 1260 and
747 cm−1
.
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418
A. S. Mahasneh · Tin(II)chloride Mediated Addition Reaction
General procedure for the synthesis of β-nitroalcohols (CHNO2). – MS (EI, 70 eV): m/e (%) = M+ (absent) 128 (<
(2a−f)
1), 113 (5), 97 (15), 95 (26), 90 (15), 83 (14), 81 (20),
69 (74), 57 (68), 55 (79), 43 (100), 41 (82). – C8H17NO3
(175.232): calcd. C 54.85, H 9.78, N 7.83; found C 54.56,
H 9.81, N 7.83.
To a mixture of SnCl2 (1.42 g, 7.5 mmol) in Et2O (40 ml),
the aldehyde (5 mmol) was added at 0 C. To this mixture
◦
while stirring bromonitromethane (5 mmol) dissolved in 2 ml
of dry ether was added. The mixture was left stirring for 4 h
during which the reaction was monitored by TLC. The reac-
tion mixture was then diluted with ether (50 ml) and washed
successively with 1M HCl, H2O, saturated NaHCO3 solution
and brine. The organic layer was separated and dried over an-
hydrous Na2SO4. The crude product was purified by TLC to
give the following nitroalcohols:
˜
1-Nitro-4-phenyl-3-buten-2-ol (2e): IR (film): ν = 3439
(OH), 1556 (NO2), 914 cm−1. – 1H NMR (200 MHz,
CDCl3): δ = 2.70 (broad, 1 H, OH), 4.50 (d, 3J = 5 Hz, 2 H,
CHNO2), 5.05 (q, 3J = 5 Hz, 1 H, CHOH), 6.10 (dd, 3J = 5,
3J = 15 Hz, 3-H), 6.80 (d, 1 H, 3J = 15 Hz, 4-H), 7.40 (m,
5 H, ArH). – 13C{ H} NMR (200 MHz, CDCl3): δ = 70.0
1
(CHOH), 80.0 (CHNO2), 124.9, 126.7, 128.5, 128.8, 133.5,
135.5 (C6H5CH=CH). – MS (EI, 70 eV): m/e (%) = M+
193 (< 1), 175 (1.5), 146 (13), 132 (22), 103 (55), 77
(100), 51 (98). C10H11NO3 (193.24): calcd. C 62.17, H 5.74,
N 7.25; found C 62.12, H 5.76, N 7.20.
˜
1-Nitro-3-penten-2-ol (2c): IR (film): ν = 3447 (OH),
1556 (NO2), 1453, 1385, 1202, 1132 cm−1. – 1H NMR
3
(200 MHz, CDCl3): δ = 1.75 (d, J = 5 Hz, 3 H, CHMe),
3
2.60 (broad, 1 H, OH), 4.45 (d, J = 5 Hz, 2 H, CHNO2),
1-Nitro-4-phenyl-2-butanol (2f): M.p. 82 – 83 ◦C. – IR
4.80 (m, 1 H, CHOH), 5.50 and 5.90 (m, 2 H, CH=CH). –
1
13C{ H} NMR (200 MHz, CDCl3): δ = 17.5 (CHMe),
˜
(KBr): ν = 3402 (OH), 2949, 1549 (NO2), 1493, 1454, 1423,
1384, 1205 cm−1. – 1H NMR (200 MHz, CDCl3): δ = 1.80
(m, 2 H, PhCH2), 2.60 (d , 3J = 5 Hz, 1 H, OH), 2.80 (m, 2 H,
PhCH2CH2), 4.30 (m, 1 H, CHOH), 4.40 (d, 2 H, 3J = 5 Hz,
69.5 (CHOH), 80.3 (CHNO2), 128.6, 131.0 (CH=CH). –
C5H9NO3 (131.132): calcd. C 45.70, H 6.92, N 10.68; found
C 45.75, H 6.88, N 10.66.
CH2NO2). 7.25 (m, 5H, Ph). – 13C{ H} NMR (200 MHz,
1
˜
1-Nitro-2-octanol (2d): IR (film): ν = 3440 (OH), 3931,
3861, 1554 (NO2), 1480, 1430, 911 cm−1. – 1H NMR
CDCl3): δ = 31.2 (PhCH2), 35.3 (C-3), 68.0 (CHOH), 80.5
(CH2NO2), 126.3, 128.3, 128.6, 140.8 (C6H5). – MS (EI,
70 eV): m/e (%) = M+ (absent), 133 (32), 130 (46), 105 (86),
104 (70), 91 (100), 92 (70), 77 (48), 65 (37), 51 (26), 43 (48).
C10H13NO3 (195.24) calcd. C 61.15, H 6.69, N 7.17; found
C 61.17, H 6.72, N 7.20.
3
(200 MHz, CDCl3): δ = 0.85 (t, J = 5 Hz, 3 H, CHMe),
1.3 – 1.5 (m, 10 H, 5×CH2), 3.00 (broad, 1 H, OH), 4.30
3
(broad, 1 H, CHOH), 4.40 (d, 2 H, J = 5 Hz, CHNO2). –
1
13C{ H} NMR (200 MHz, CDCl3): δ = 14.2 (CHMe),
22.5, 25.2, 28.8, 31.6, 33.8 (5×CH2), 68.8 (CHOH), 80.7
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