A practical synthesis of 1,2-nitroamines by Michael addition of N-nucleophiles to nitroalkenes

Article abstract of DOI:10.1055/s-0030-1258176

A practical method for the synthesis of-nitroamines by Michael addition of azide to nitroalkene has been developed. This reaction proceeds in high yields under very mild conditions (phase-transfer catalysis) and is found to be general; good yields are obtained with both aryl and alkyl derivatives as well as with 1,1-di-substituted ones. Georg Thieme Verlag Stuttgart - New York.

Full text of DOI:10.1055/s-0030-1258176

3138
PAPER
A Practical Synthesis of 1,2-Nitroamines by Michael Addition of
N-Nucleophiles to Nitroalkenes
S
ynthesis of 1,2-
a
itroamine
p
s
haël Robiette,*a Trieu-Van Tran,a Alex Cordi,b Bernard Tinant,a Jacqueline Marchand-Brynaert*a
a
Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Place Louis Pasteur 1, 1348 Louvain-la-Neuve,
Belgium
Fax +3210474168; E-mail: raphael.robiette@uclouvain.be; E-mail: jacqueline.marchand@uclouvain.be
Institut de Recherches Servier, Rue des Moulineaux 11, 92150 Suresnes, France
b
Received 20 April 2010; revised 28 May 2010
adducts to be easily deprotectable to provide the corre-
sponding primary amines. Enders and co-workers nicely
addressed this issue and showed that (–)-(2S,3R,4R,5S)-1-
amino-3,4-dimethoxy-2,5-bis(methoxymethyl)pyrrolidine
Abstract: A practical method for the synthesis of a-nitroamines by
Michael addition of azide to nitroalkene has been developed. This
reaction proceeds in high yields under very mild conditions (phase-
transfer catalysis) and is found to be general; good yields are ob-
tained with both aryl and alkyl derivatives as well as with 1,1-di- (ADMP) could act as a chiral equivalent of ammonia.8g
substituted ones.
This hydrazine adds onto nitroalkenes and subsequent re-
duction furnishes corresponding vicinal diamines in mod-
erate yields and diastereoselectivities. The drawback of
this method is that this ammonia equivalent must be syn-
thesized in seven steps.
Key words: azides, amines, Michael addition, nitroalkenes, nitro-
amines
Nitroamines are versatile intermediates in organic synthe-
sis as they can lead to both a-amino acids, after Nef oxi-
dation, and 1,2-diamines, upon reductive conditions.1–3
Two strategies can be envisaged for their preparation
(Scheme 1). The most developed method consists in the
addition of nitro compounds to activated imines, the aza-
Henry reaction.4,5 This method has, however, some limi-
tations: (1) it is restricted, with only few exceptions, to
non-enolizable imines and (2) examples of addition of ni-
tro compounds to ketimines are very limited.6 An alterna-
tive route is the addition of amines to nitroalkenes.
However, although addition of carbon nucleophiles to ni-
troalkenes is well documented,7 surprisingly there are
only a few reports on the Michael addition of N-nucleo-
philes onto these activated olefins.8 We report herein our
results on the development of the synthesis of 1,2-ni-
troamines by Michael addition of azide onto nitroalkene
under very mild conditions.
Mioskowski and co-workers reported that addition of
oxazolidinone derivatives onto nitroalkenes gives corre-
sponding Michael adducts in high yield (and diastereose-
lectivity).8f Cleavage of the oxazolidinone by Li/NH3
reduction allows access to the primary amine. However,
Michael addition of oxazolidinone derivatives (as well as
their cleavage) involves harsh conditions, which limit
their use in the synthesis of complex molecules. Indeed,
due to the low nucleophilicity of oxazolidinone deriva-
tives, their addition necessitates prior activation by quan-
titative deprotonation using a strong base (n-BuLi, NaH,
t-BuOK, etc.). In order to avoid the harsh conditions for
the addition, good N-nucleophiles (not necessitating prior
deprotonation) are needed, keeping in mind that the ad-
duct formed must also be easily cleavable to lead to the
corresponding primary amine.
We began our search for such a suitable nitrogen nucleo-
phile by considering the addition of benzotriazole to ni-
troalkenes 1a and 1b (Scheme 2).9 It has been shown that
benzotriazole reacts via both N1 and N2 with a regioselec-
tivity depending on the reaction conditions, N2-regioiso-
mer being usually the thermodynamic product. However,
none of the reaction conditions tested for the addition of
benzotriazole to 1a and 1b gave N2-regioisomer 3 as the
major product.10,11 Further, all attempts to isomerize N1-
adduct 2 into its N2-isomer 3 (expected to be more
stable12) led to no significant change in 2/3 ratio. This is
unfortunate since, for our purpose, a high regioselectivity
for N2-adduct 3 was required. Indeed, only the N2-regio-
isomer 3a allows obtaining the primary amine quantita-
tively after hydrogenation (see Scheme 2). Although not
very efficient in this particular case due to a low regiose-
lectivity in the addition, this method constitutes, to the
best of our knowledge, the first example of the use of ben-
zotriazole as ammonia equivalent.
H2N
R
NO2
α-amino acids
1,2-diamines
PG
NO2
N
MeNO2
+
+
"
"
NH2
R
R
Scheme 1 Strategies toward 1,2-diamines
If the development of a general synthesis of 1,2-nitro-
amines is desired, it is important for the obtained Michael
SYNTHESIS 2010, No. 18, pp 3138–3142
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Advanced online publication: 16.07.2010
DOI: 10.1055/s-0030-1258176; Art ID: P06310SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of 1,2-Nitroamines
3139
tempts of deprotection and cleavage of the O–N bond led
however to complex mixtures.
x
The use of sodium azide as N-nucleophile was then con-
sidered. Zard and co-workers have shown that, in hot
DMSO, sodium azide reacts with nitroalkenes to give the
corresponding 1,2,3-triazoles.17 However, we found that,
at room temperature and under phase-transfer conditions,
the azide anion adds smoothly to nitroalkenes to give the
corresponding Michael adducts 5 (Scheme 3).18,19 These
are obtained in excellent yields (88–99%), even in the
case of sterically hindered substrates (see 5d).
1
2
N
N
NH
N
N
N
quinine
N
N
N
R
NO2
(10 mol%)
NO2
+
+
CH2Cl2, r.t.
R
R
NO2
2
3
n-C6H13 (1a)
Ph (1b)
R
yield
R =
2/3
n-C6H13 97% 72:28
Ph
97% 83:17
NO2
N3
R
NO2
CH2Cl2/H2O
NaN3
N
+
Bu4N⋅HSO4/HCl
N
H2N
NH2
⋅2HCl
N
NO2
R
1) H2, Pd(OH)2
2) HCl
r.t.
5
R = n-C6H13 (5a)
Ph (5b)
99%
n-C6H13
n-C6H13
3a
97%
90%
93%
4a
Et (5c)
quant.
t-Bu (5d)
Scheme 2 Addition of benzotriazole to nitroalkenes
H2, Pd/C
HCl
We then turned our attention to other nitrogen nucleo-
philes. Since Yadav and co-workers reported that
Sm(OTf)3 efficiently catalyzes the addition of N-nucleo-
philes to activated olefins under smooth conditions,13
these conditions were applied. Benzylamine and 1,2-di-
carbethoxyhydrazine were found to be unreactive toward
nitroalkenes 1a and 1b under these conditions (Table 1,
entries 1–4). A more nucleophilic amine such as methyl-
hydrazine leads to corresponding Michael adducts but in
low yield (Table 1, entries 5 and 6).14
H2N
R
NH2
⋅2HCl
quant.
4a
4b quant.
Scheme 3 Addition of azide to nitroalkenes and reduction
Next, the transformation of the azide function into the cor-
responding primary amine was investigated. Several con-
ditions [BHCl2,20 PPh3/H2O,21 HS(CH2)3SH/Et3N22] were
tested and palladium-catalyzed hydrogenation was found
to give the corresponding diamines in quantitative yield
(see Scheme 3).
Table 1 Addition of Amine Nucleophiles to Nitroalkenes
Sm(OTf)3
NO2
R'2N
R
NO2
(5–10 mol%)
CH2Cl2, r.t.
nucleophile
+
R
As mentioned above, one limitation of the aza-Henry
strategy (see Scheme 1) is that examples of addition of ni-
tro compounds to ketimines are very limited.6 According-
ly, we tested our methodology on a 2,2-disubstituted
nitroalkene 6 and found that it allows the formation of the
corresponding 1,1-disubstituted vicinal diamine 8 in ex-
cellent yield (Scheme 4).
Entry
Nucleophile
BnNH2
H
R
Yield (%)a
1
2
n-C6H13
Ph
NR
NR
3
4
n-C6H13
Ph
NR
NR
EtO2C
N
N
CO2Et
H
In summary, we have developed a practical and general
methodology for the synthesis of a-nitroamines. The first
step of this method is the addition of azide to nitroalkene.
This reaction proceeds in high yields under very mild con-
ditions (phase-transfer catalysis). The obtained Michael
adducts can then undergo reduction to furnish the corre-
sponding 1,2-diamines in good yields. This method works
not only with alkyl derivatives but also with aromatic and
1,1-disubstituted derivatives. The application of this
methodology to the synthesis of biologically active com-
pounds is underway in our laboratory.
5
6
n-C6H13
Ph
38
32
MeNHNH2
BnONH2
7
8
n-C6H13
Ph
76 (91)b
81 (96)b
a Isolated yield.
b Yields in parentheses correspond to reactions carried out by stirring
at reflux a solution of nitroalkene (1 equiv) and hydroxylamine (1
equiv) in the presence of SiO2 (10 equiv) in MeCN for 4 h.
The best yields were obtained with O-benzylhydroxyl-
amine (Table 1, entries 7,8).15 The reaction proceeds
smoothly (6 h) in the presence of 5 mol% of Sm(OTf)3 at
room temperature (76–81%).13 We found that even SiO2
was an efficient catalyst for this reaction.16 All our at-
Nitroalkenes were prepared according to reported procedures.23,24
Flash chromatography was performed on silica gel (230–400 mesh).
TLC was performed on aluminum-backed silica plates, which were
Synthesis 2010, No. 18, 3138–3142 © Thieme Stuttgart · New York

3140
R. Robiette et al.
PAPER
13C NMR (75 MHz, CDCl3): d = 13.9, 22.4, 25.3, 28.4, 31.3, 33.0,
NO2
N3
NO2
63.9, 77.2, 118.2, 126.8, 144.2.
NaN3
15N NMR (50 MHz, CDCl3): d = 253.3, 308.5, 371.9.
MeCN–H2O
Bu4N⋅HSO4/HCl
r.t.
MS (APCI): m/z = 277.3, 120.2.
HRMS (APCI): m/z calcd for C14H21N4O2: 277.1670; found:
277.1665.
6
7
87%
1-(2-Nitro-1-phenylethyl)-1H-benzo[d][1,2,3]triazole (2b;
R = Ph)
White crystals; yield: 546 mg (70%); mp 88–89 °C.
H2, Pd/C
HCl
IR (KBr): 3068.5, 3035.8, 2925.8, 2252.7, 1562.2, 1496.7, 1454.2,
1375.1, 1163.0 cm–1.
H2N
NH2
1H NMR (300 MHz, CDCl3): d = 5.14 (dd, J = 4.9, 14.6 Hz, 1 H,
HaCHNO2), 5.94 (dd, J = 9.6, 14.6 Hz, 1 H, HbCHNO2), 6.57 (dd,
J = 4.9, 9.6 Hz, 1 H, CHN), 7.3–7.5 (m, 8 Harom), 8.08 (d, J = 8.0 Hz,
1 Harom).
13C NMR (75 MHz, CDCl3): d = 59.9, 76.7, 109.5, 120.4, 124.7,
127.0, 128.2, 129.6, 130.0, 132.8, 134.1, 146.4.
⋅2HCl
8
quant.
Scheme 4 Reaction with 2,2-disubstituted nitroolefins
MS (ESI): m/z = 269.1, 120.1.
HRMS (ESI): m/z calcd for C14H13N4O2: 269.1027; found:
269.1039.
developed using standard visualizing agents: UV fluorescence (254
and 366 nm), KMnO4, p-anisaldehyde. NMR spectra were recorded
on Bruker AC-300 Avance II and Bruker DRX 500 spectrometers.
Chemical shifts (NMR) are quoted in parts per million (ppm), refer-
enced to TMS (for 1H and 13C) and NH3 (for 15N). IR spectra were
recorded on a Shimadzu FTIR-8400S spectrophotometer. Mass
spectra (MS) were recorded on a Finnigan MAT LCQ apparatus.
HRMS were measured at the University College of London.
2-(2-Nitro-1-phenylethyl)-2H-benzo[d][1,2,3]triazole (3b;
R = Ph)
White crystals; yield: 133 mg (16%); mp 92–93 °C.
IR (KBr): 3037.7, 2922.0, 2852.5, 2358.8, 1550.7, 1496.7, 1456.2,
1415.7, 1373.2, 1323.1, 1271.0, 970.1 cm–1.
1H NMR (300 MHz, CDCl3): d = 5.06 (dd, J = 4.4, 14.8 Hz, 1 H,
HaCHNO2), 5.89 (dd, J = 10.3, 14.8 Hz, 1 H, HbCHNO2), 6.80 (dd,
J = 4.4, 10.3 Hz, 1 H, CHN), 7.35–7.45 (m, 8 Harom), 7.86 (m, 1
Addition of Benzotriazole to Nitroalkenes; General Procedure
A solution of the nitroalkene 1 (3.0 mmol) in CH2Cl2 (5 mL) was
added to a solution of benzotriazole (357 mg, 3.0 mmol) and qui-
nine (97 mg, 0.3 mmol) in CH2Cl2 (30 mL) at –40 °C. The reaction
mixture was allowed to warm to r.t. and stirred for 3 days. The so-
lution was concentrated under vacuum to give a mixture of regio-
isomers, which were purified (and separated) by column
chromatography (hexanes–EtOAc, 70:30).
Harom).
13C NMR (75 MHz, CDCl3): d = 66.7, 76.6, 118.5, 127.1, 129.6,
129.9, 134.1, 144.1.
MS (ESI): m/z = 269.1, 120.0.
HRMS (ESI): m/z calcd for C14H12N4O2: 268.09547; found:
268.09489.
1-(1-Nitrooctan-2-yl)-1H-benzo[d][1,2,3]triazole (2a; R = n-C6H13)
Liquid; yield: 580 mg (70%).
Octane-1,2-diamine Dihydrochloride (4a)25
IR (neat): 2954.7, 2927.7, 2858.3, 1556.4, 1452.3, 1377.1, 1163.0
cm–1.
A solution of 3a (200 mg, 1.05 mmol, 1 equiv), concd HCl (0.86
mL, ~10 equiv), 10% Pd/C (1 mg) in EtOH (20 mL) was stirred
overnight under a H2 atmosphere (3 atm). The reaction mixture was
filtered on Celite and concentrated under reduced pressure.
1H NMR (300 MHz, CDCl3): d = 1.1–1.35 (m, 11 H, n-C6H13),
1.95–2.4 (m, 2 H, n-C6H13), 4.93 (dd, J = 4.2, 14.0 Hz, 1 H,
HaCHNO2), 5.29 (dd, J = 9.4, 14.0 Hz, 1 H, HbCHNO2), 5.51 (m, 1
H, CHN), 7.40 (m, 1 Harom), 7.5–7.65 (m, 2 Harom), 8.08 (d, J = 8.4
Hz, 1 Harom).
13C NMR (75 MHz, CDCl3): d = 14.1, 21.3, 25.8, 28.8, 31.6, 33.0,
56.9, 78.1, 109.8, 121.1, 125.3, 128.9, 134.4, 146.8.
White solid; yield: 225 mg (quant.); mp 153–155 °C.
1H NMR (300 MHz, DMSO-d6): d = 0.90 (t, J = 6.9 Hz, 3 H, CH3),
1.0–1.5 (m, 8 H, CH2), 1.63 (m, 2 H, CH2), 3.05 (m, 1 H, CHN),
3.40 (m, 2 H, CH2N), 8.36 (br s, 6 H, NH).
13C NMR (75 MHz, DMSO-d6): d = 14.9, 22.9, 25.4, 29.3, 31.2,
31.9, 41.9, 50.3.
MS (APCI): m/z = 277.2, 120.2.
HRMS-APCI: m/z calcd for C14H21N4O2: 277.1671; found:
277.1665.
Sm(OTf)3-Catalyzed Michael Addition of Amine Nucleophiles
to Nitroalkenes; General Procedure
Sm(OTf)3 (60 mg, 1 mmol) was added to a solution of amine nu-
cleophile (1.2 mmol) listed in Table 1 and nitroalkene (1 mmol) in
CH2Cl2 (10 mL). The reaction mixture was stirred for 6 h at r.t.. The
mixture was washed with H2O (3 mL) and brine (3 mL). The organ-
ic phase was dried (Na2SO4) and concentrated under reduced pres-
sure. Products were purified by flash chromatography over silica
gel. The data of the products obtained from O-benzylhydroxyl-
amine as the amine nucleophile are described below.
2-(1-Nitrooctan-2-yl)-2H-benzo[d][1,2,3]triazole (3a; R = n-C6H13)
Liquid; yield: 224 mg (27%).
IR (neat): 2954.7, 2927.7, 3858.3, 1556.4, 1450.4, 1375.2, 1326.9,
1271.0, 1197.7 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.1–1.4 (m, 11 H), 1.9–2.3 (m, 2
H), 4.85 (dd, J = 9.2, 13.9 Hz, 1 H, HbCHNO2), 5.31 (dd, J = 4.4,
13.9 Hz, 1 H, HaCHNO2), 5.66 (m, 1 H, CHN), 7.40 (AA¢XX¢ sys-
tem, J = 1.0, 6.7, 8.7 Hz, 2 Harom), 7.85 (AA¢XX¢ system, J = 0.8,
1.0, 8.7 Hz, 2 Harom).
Synthesis 2010, No. 18, 3138–3142 © Thieme Stuttgart · New York

PAPER
Synthesis of 1,2-Nitroamines
3141
O-Benzyl-N-(1-nitrooctan-2-yl)hydroxylamine (R = n-C6H13,
Nu = PhCH2ONH2)
HRMS (CI): m/z calcd for C8H8N4O2: 193.07255; found:
193.07222.
Liquid; yield: 213 mg (76%).
2-Azido-1-nitrobutane (5c; R = Et)
Liquid; yield: 389 mg (90%).
IR (neat): 2954.7, 2927.7, 2954.7, 2858.3, 2360.7, 2343.3, 1552.6,
1454.2, 1380.9, 1209.3 cm–1.
IR (neat): 2974.0, 2939.3, 2881.4, 2131.2, 2106.1, 1556.4, 1380.9,
1267.1 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.06 (t, J = 8.6 Hz, 3 H, CH3),
1.64 (m, 2 H, CH2), 4.06 (m, 1 H, HCN3), 4.28–4.45 (m, 2 H,
CH2NO2).
1H NMR (300 MHz, CDCl3): d = 0.88 (t, J = 5.7 Hz, 3 H, CH3),
1.25–1.60 (m, 10 H), 3.49–3.55 (m, 1 H, CHNH), 4.44 (dd, J = 4.3,
12.4 Hz, 1 H, HaCHNO2), 4.59 (dd, J = 7.1, 12.4 Hz, 1 H,
HbCHNO2), 4.69 (s, 2 H, CH2O), 7.2–7.40 (m, 5 Harom).
13C NMR (75 MHz, CDCl3): d = 14.2, 22.7, 26.0, 29.2, 29.3, 31.7,
59.3, 76.7, 76.9, 128.2, 128.6, 128.7, 137.4.
13C NMR (75 MHz, CDCl3): d = 10.2, 25.2, 60.9, 77.7.
MS (ESI): m/z = 281.2, 91.0.
MS (CI): m/z = 145.0, 71.4, 70.2, 56.2.
HRMS (ESI): m/z calcd for C15H25N2O3: 281.18651; found:
HRMS (CI): m/z calcd for C4H9N4O2: 145.07255; found:
281.18691.
145.07226.
O-Benzyl-N-(2-nitro-1-phenylethyl)hydroxylamine (R = Ph,
Nu = PhCH2ONH2)
2-Azido-3,3-dimethyl-1-nitrobutane (5d; R = t-Bu)25
Liquid; yield: 480 mg (93%).
Liquid; yield: 220 mg (81%).
IR (neat): 2970.2, 2873.7, 2133.1, 2094.6, 1380.9, 1269.1 cm–1.
IR (neat): 3249.8, 3062.7, 3031.9, 2918.1, 2869.9, 2387.7, 2289.3,
1552.6, 1494.7, 1454.2, 1379.0 cm–1.
1H NMR (300 MHz, CDCl3): d = 4.57 (dd, J = 4.8, 11.9 Hz, 1 H,
CHNH), 4.62–4.91 (m, 3 H, CH2NO2 and CH2O), 7.25–7.40 (m, 10
1H NMR (300 MHz, CDCl3): d = 1.02 (s, 9 H, CH3), 3.91 (dd,
J = 2.4, 10.6 Hz, 1 H, CHN3), 4.29 (dd, J = 10.6, 13.6 Hz, 1 H,
HaCHNO2), 4.52 (dd, J = 2.4, 13.6 Hz, 1 H, HbCHNO2).
13C NMR (75 MHz, CDCl3): d = 26.4, 35.7, 69.5, 75.8.
Harom).
MS (CI): m/z = 173.1, 83.8, 56.9.
13C NMR (75 MHz, CDCl3): d = 63.2, 77.2, 78.0, 127.8, 128.3,
128.6, 128.8, 129.1, 129.2, 135.8, 137.1.
HRMS (CI): m/z calcd for C6H13N4O2: 173.10385; found:
173.10339.
MS (ES): m/z = 273.2, 90.9.
HRMS (ES): m/z calcd for C15H17N2O3: 273.1236; found:
1-Azido-1-(nitromethyl)cyclohexane (7)
273.1239.
Liquid; yield: 481 mg (87%).
IR (neat): 2939.3, 2862.2, 2106.1, 1552.6, 1450.4, 1429.1, 1379.0,
1326.9, 1294.1, 1251.7 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.25–1.85 (m, 10 H, cyclohexyl
CH2), 4.46 (s, 2 H, CH2NO2).
Addition of Sodium Azide to Nitroalkenes; General Procedure
A solution of NaN3 (1 g, 15 mmol) and Bu4NHSO4 (50 mg, 5 mol%)
in H2O (30 mL) was added to a solution of the nitroalkene (3 mmol)
in CH2Cl2 (30 mL). The acidity of the solution was adjusted to
pH 1–2 with aq 1 N HCl. The reaction mixture was stirred vigorous-
ly overnight. The two phases were separated and the organic layer
was washed with H2O (until the pH of the aqueous phase was equal
to 7). The organic phase was dried (MgSO4) and concentrated under
reduced pressure.
13C NMR (75 MHz, CDCl3): d = 21.6, 24.8, 32.8, 61.9, 82.6.
MS (ESI): m/z = 186.2, 184.2, 142.0, 130.1.
Reduction of the Azide Adducts 5; General Procedure
A solution of 5 (2 mmol, 1 equiv), concd HCl (2 mL, ~10 equiv),
and 10% Pd/C (2 mg) in EtOH (40 mL, volume adjusted to reach
~0.05 M of 5) was stirred overnight under a H2 atmosphere (3 atm).
The reaction mixture was filtered on Celite and concentrated under
reduced pressure.27
2-Azido-1-nitrooctane (5a; R = n-C6H13)
Liquid; yield: 595 mg (99%).
IR (neat): 2956.7, 2929.7, 2860.2, 2127.3, 1560.3, 1465.8, 1380.9,
1263.3 cm–1.
1H NMR (300 MHz, CDCl3): d = 0.90 (m, 3 H, CH3), 1.2–1.7 (m,
Octane-1,2-diamine Dihydrochloride (4a; R = n-C6H13)
White solid; yield: 436 mg (quant.); for analytical and spectral data,
see above.
10 H, CH2), 4.13 (m, 1 H, HCN3), 4.37 (m, 2 H, CH2NO2).
13C NMR (75 MHz, CDCl3): d = 14.1, 22.6, 25.7, 28.9, 31.6, 31.9,
59.6, 77.8.
1-Phenylethane-1,2-diamine Dihydrochloride (4b; R = Ph)28
MS (CI): m/z = 201.0, 112.0, 69.8.
White solid; yield: 418 mg (quant.); mp 160 °C (dec.).
HRMS (CI): m/z calcd for C8H17N4O2: 201.13514; found:
201.13531.
1H NMR (300 MHz, DMSO-d6): d = 3.30 (dd, J = 6.3, 13.1 Hz, 1 H,
CHaHbNH3), 3.56 (dd, J = 6.8, 13.1, 1 H, CHaHbNH3), 4.70 (dd,
J = 6.3, 6.8 Hz, 1 H, CHNH3), 7.40–7.70 (m, 5 H, C6H5), 8.61 (br s,
3 H, NH3), 9.16 (br s, 3 H, NH3).
(1-Azido-2-nitroethyl)benzene (5b; R = Ph)26
Liquid; yield: 559 mg (97%).
13C NMR (75 MHz, DMSO-d6): d = 42.8, 53.0, 128.9, 130.0, 130.4,
IR (neat): 3111.0, 3064.7, 3033.8, 2922.0, 2110.0, 1633.6, 1556.4,
1519.8, 1377.1, 1344.3, 1261.4, 966.3 cm–1.
1H NMR (300 MHz, CDCl3): d = 4.55 (m, 2 H, CH2NO2), 4.32 (dd,
J = 5.2, 11.9 Hz, 1 H, HCN3), 7.25–7.65 (m, 5 H, C6H5).
13C NMR (75 MHz, CDCl3): d = 62.6, 78.5, 127.1, 129.4, 129.8,
134.2.
135.3.
1-Aminomethylcyclohexylamine Dihydrochloride (8)29
White solid; yield: 402 mg (quant.); mp 120 °C (dec.).
1H NMR (300 MHz, DMSO-d6): d = 1.6–2.0 (m, 10 H, cyclohexyl
CH2), 3.23 (s, 2 H, CH2NH3), 8.71 (br s, 6 H, NH3).
13C NMR (75 MHz, DMSO-d6): d = 21.2, 25.2, 32.0, 44.4, 55.7.
MS (CI): m/z = 193.2, 150.1, 104.0.
Synthesis 2010, No. 18, 3138–3142 © Thieme Stuttgart · New York

3142
R. Robiette et al.
PAPER
(9) For a review on benzotriazole, see: Katritzky, A. R.;
Acknowledgment
Xiangfu, L.; Yang, J. Z.; Denisko, O. V. Chem. Rev. 1998,
98, 409.
The authors thank the Fonds de la Recherche Scientifique – FNRS
(F.R.S.–FNRS) for financial support. R. R. and J. M.-B. are Cher-
cheur qualifié F.R.S.-FNRS. We thank Cécile Le Duff for NMR
analysis.
(10) The structure of 3b has been confirmed by X-ray
crystallography. The X-ray data have been deposited at the
Cambridge Crystallographic Data Centre (deposition
number: CCDC 769007). These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or
from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; fax: +44(1223)336033, E-
mail: deposit@ccdc.cam.ac.uk].
(11) This is consistent with a previous study on addition of
benzotriazole on nitroalkene. See ref. 8c.
(12) Katritzky, A. R.; Perumal, S.; Fan, W. Q. J. Chem. Soc.,
Perkin Trans. 2 1990, 2059.
(13) Yadav, J. S.; Reddy, A. R.; Rao, Y. G.; Narsaiah, A. V.;
Reddy, B. V. S. Synthesis 2007, 3447.
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Synthesis 2010, No. 18, 3138–3142 © Thieme Stuttgart · New York