Solvent-free synthesis of tartramides under microwave activation

Article abstract of DOI:10.1055/s-2001-18724

The preparation of aliphatic, aromatic or functionalized tartramides directly from tartaric acid and amines under microwave activation is described. The inexpensive, solvent free and fast reaction conditions are the important features of the procedure.

Full text of DOI:10.1055/s-2001-18724

PAPER
2441
Solvent-Free Synthesis of Tartramides Under Microwave Activation
Synthesisof
T
.
artramides Massicot, R. Plantier-Royon,* C. Portella,* D. Saleur, A. V. R. L. Sudha
Laboratoire “Réactions Sélectives et Applications”, Associé au CNRS (UMR 6519), Université de Reims, Faculté des Sciences, B.P. 1039,
51689 Reims Cedex 2, France
Fax +33(3)26913166; E-mail: richard.plantier-royon@univ-reims.fr, charles.portella@univ-reims.fr
Received 10 September 2001; revised 4 October 2001
of the polar imidazolium carboxylic acid salts. Irradiation
Abstract: The preparation of aliphatic, aromatic or functionalized
in the microwave oven resulted in condensation reactions
tartramides directly from tartaric acid and amines under microwave
producing amides from monoacids and imides from diac-
activation is described. The inexpensive, solvent free and fast reac-
ids. These results prompted us to study the amidification
of tartaric acid under such conditions, owing to the inter-
est of the expected C2-symmetric compounds and to the
simplicity of the procedure.
tion conditions are the important features of the procedure.
Key words: tartaric acid, amine, tartradiamides, microwave irradi-
ation, solvent free conditions
In our hands, irradiation of a mixture of benzylamine, tar-
taric acid and imidazole (2 equiv) resulted in the diamides
even when only one equivalent of amine was used. Inter-
estingly, addition of imidazole proved to be unnecessary.
After some experiments, optimized reaction conditions
(2.8 equiv of benzylamine, 12 min irradiation) were deter-
mined.
Several tartramides have shown interesting properties in
different fields. For example, N, N’-diisopropyltartradia-
mides has been used as chiral additive in the resolution of
hydroxy and amino acid derivatives or diols by liquid
chromatography.1 Chiral HPLC stationary phases exhibit-
ing excellent stability and enantioselectivity have been
obtained by adsorbing the unsymmetrical diamides onto
porous graphitic carbon.2 Tartramides were also used as
chiral titanium (IV) ligands in Sharpless epoxidation.3
These conditions were successfully applied to a series of
aliphatic and aromatic primary amines (Table 1). Under
the same conditions (2.8 equiv of benzylamine, 180 °C),
16 hours of classical heating were needed to give the N,
N’-dibenzyl tartramide with 68% yield.
The most general method for the preparation of symmet-
rical tartaric acid diamides is the well known aminolysis
of dimethyl or diethyl tartrate with excess of alkylamine.4
With aryl amines, thermal condensation with tartaric acid
can be used.5 Finally, the reaction of an amine with in situ
prepared active esters of tartaric acid provided the desired
diamides.6
Table 1 Synthesis of Tartramides from Aliphatic or Aromatic Pri-
mary Amines under Microwave Irradiation
R-NH2
HO
HO
COOH
COOH
HO
HO
CONHR
CONHR
2.8 equiv.
Over the last years, a large number of publications and re-
views have demonstrated the interest in the use of micro-
wave technology in organic and organometallic
synthesis.7 Recently, for environmental, economical and
safety reasons, solvent free reactions (dry reactions) were
successfully used with the microwave activation.8 Devel-
opment of monomode focused reactors also presents a
number of advantages such as increased efficiencies and
reliabilities, and improvements in yields even with large
amounts of products.7a,8b
microwave
12 mn
Entry
R
Product
Yield (%)
1
2
3
4
5
6
CH2Ph
C10H21
C6H13
1
2
3
4
5
6
80
82
81
71
30
83
C4H9
The preparation of amides from a carboxylic acid (aliphat-
ic or aromatic) and an amine (primary or secondary) by a
microwave-mediated process was previously studied and
the conditions used gave good yields with primary amines
and lower yields for hindered amines.9 The use of imida-
zole to promote reaction of amines with sterically hin-
dered carboxylic acids gave interesting results under mild
irradiation conditions.10 An efficient microwave energy
absorption was exhibited with the intermediate formation
cyclohexyl
phenyl
The reaction can also be performed with low boiling
points amines since the reaction goes through the ammo-
nium salt, which can absorb significantly the microwave
energy. The reaction mixture was monitored versus the
time and we observed, after about 2 minutes, a break in the
increasing curve at about 110 °C. This point corresponds
precisely to the melting point of the ammonium tartrate
and homogenization of the reaction mixture, which then
absorbs effectively the microwave energy (Figure).
Synthesis 2001, No. 16, 30 11 2001. Article Identifier:
1437-210X,E;2001,0,16,2441,2444,ftx,en;Z10501SS.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881

2442
F. Massicot et al.
PAPER
Table 3 Synthesis of Tartramides from Tartaric Acid Salts and
Ammonium Salts under Microwave Irradiation
C6H13NH3+ Cl-
HO
HO
COO- +M
COO- +
HO
HO
CONHC6H13
CONHC6H13
2.8 equiv.
microwave
25 mn
M
Entry
M
Na
K
Product
Yield (%)
1
2
3
3
40
13
Thus we have described a convenient, solvent-free, eco-
nomical and clean method for the preparation of tartra-
mides directly from tartaric acid. Application to
functionalized amines such as amino alcohols, amino
ethers or aminopyridines led to new compounds with po-
tential ligand properties, which are under investigation.
Figure Power and temperature evolutions during microwave irra-
diation for the synthesis of (R,R)-(+)-di-N,N’-hexyltartramide (3)
All reagents were previously recrystallized or distilled. Petroleum
ether used refers to the fraction boiling between 35–60 °C.The mi-
As previously reported, reaction with more hindered pri-
mary amines gave poor yields, even with longer irradia- crowaves reactions were performed with a Synthewave 402® mono-
mode reactor from Prolabo with temperature control using power
tion times, and no reaction was observed with secondary
modulation. Melting points: open glass capillaries, Buchi 510 (Tot-
amines even with imidazole addition. On the other hand,
toli apparatus) are uncorrected. Optical rotations, [ ]D20 were deter-
application of the above conditions to functionalized pri-
mary amines (amino alcohols, amino ethers, aminopy-
ridines) gave good yields of the corresponding new
functionalized tartramides (Table 2). The potential of
such compounds, possibly after further simple transfor-
mations, is under investigation.
mined with a Perkin-Elmer 241 polarimeter. FT-IR spectra were
recorded on a Avatar 320 FT-IR spectrophotometer; all spectra
were taken as KBr pellets; wavelength reported in cm–1. 1H and 13
C
NMR spectra were recorded on AC 250 Bruker; chemical shifts ( )
reported in ppm downfield of residual DMSO for spectra acquired
in DMSO-d6 and of residual water for spectra acquired in pyridine-
1
d5; operating frequency: 250 MHz for H and 62.5 MHz for 13C
NMR. EI-MS data were obtained on a Jeol D 300 apparatus at 70eV
at the U.F.R. Pharmacie, Reims (France). Elemental analysis were
performed on a Perkin-Elmer CHN 2400 apparatus.
Table 2 Synthesis of Tartramides from Functionalized Amines un-
der Microwave Irradiation
n NH2
X
Tartramides 1–10; General Procedure
HO
HO
COOH
COOH
HO
HO
CONH(CH2)nX
CONH(CH2)nX
2.8 equiv.
L-(+)-Tartaric acid (10 mmol) and the amine (28 mmol, 2.8 equiv)
were taken in the reaction flask and the resultant mixture was placed
in the Synthewave 402® microwave reactor. After reflux condenser
was placed on the top of the reactor, the microwave apparatus was
programmed for a temperature control using power modulation (un-
less otherwise specified, programming: 20–180 °C, 3 min; 180 °C,
9 min; minimal power: 5%; maximal power: 90%). The stirring sys-
tem and the microwave irradiation were started, and the reaction
temperature was monitored on the computer. The mixture was then
cooled to r.t. and worked up as given below.
microwave
12 mn
Entry
n
2
2
3
1
Y
Product
Yield (%)
1
2
3
4
OH
OMe
OMe
7
8
68
65
60
73
9
(R,R)-(+)-Di-N,N’-benzyltartramide (1)
2-pyridyl
10
After cooling, the reaction mixture was stirred with MeOH, filtered
and recrystallized from EtOAc–petroleum ether to obtain 1 as a
white solid; yield: 80%; mp 199 °C (Lit.5 mp 199 °C); [ ]D20 +22.7
(c = 1, DMSO).
As crude tartaric derivatives are actually salts (potassium
hydrogen tartrate, sodium and potassium tartrate, calcium
tartrate), it was interesting to consider a possible direct
conversion into the corresponding mono or diamides. For-
mation of tartramides was tested by reaction of tartaric
acid salts (sodium, potassium salts) and ammonium salt.
The diamides are obtained but the yields remain low, even
after irradiation for 25 minutes (Table 3).
IR (KBr): 3298 (OH), 1630 (C=O), 1554 (Ph), 1103 cm–1 (C–O).
1H NMR (DMSO-d6): = 4.27–4.39 (m, 6 H, CH2, CH), 5.79 (d, 1
H, 3J = 7.2 Hz, OH), 5.97 (d, 1 H, 3J = 5.3 Hz, OH), 7.30 (m, 10 H,
C6H5), 8.13 (t, 1 H, 3J = 6.5 Hz, NH), 8.29 (t, 1 H, 3J = 6.5 Hz, NH).
13C NMR (DMSO-d6): = 41.7, 41.9, 72.7, 73.9, 126.5, 127.1,
128.1, 139.4, 139.5, 171.0, 172.1.
EI-MS: m/z (%) = 328 (M+, 14), 194 (100), 177 (9), 165 (19), 133
(128), 106 (75).
Synthesis 2001, No. 16, 2441–2444 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Synthesis of Tartramides
2443
(R,R)-(+)-Di-N,N’-decyltartramide (2)
After cooling, the reaction mixture was stirred with MeOH, filtered
and recrystallized from EtOAc–petroleum ether to obtain 2 as a
white solid; yield: 82%; mp 148 °C; [ ]D +13.6 (c = 0.96, pyri-
dine).
IR (KBr): 3248 (OH), 1618 (C=O), 1064 cm–1 (C–O).
1H NMR (pyridine-d5): = 0.49 (t, 6 H, J = 6.5 Hz, CH3), 0.66–
1.30 (m, 32 H, CH2), 3.09–3.19 (m, 4 H, NHCH2), 4.82 (s, 1 H, CH),
5.15 (s, 1 H, OH), 7.94 (t, 1 H, 3J = 5 Hz, NH), 8.09 (t, 1 H, 3J = 5.7,
NH).
13C NMR (pyridine-d5): = 14.3, 22.9, 27.3, 29.6, 29.7, 29.8, 30.3,
CH), 4.16 (s, 1 H, CH), 5.56 (s, 1 H, OH), 5.75 (s, 1 H, OH), 7.22
(d, 1 H, 3J = 8.4 Hz, NH), 7.34 (d, 1 H, 3J = 8.4 Hz, NH).
13C NMR (DMSO-d6): = 24.8, 29.9, 31.4, 32.6, 47.5, 49.2, 53.4,
72.7, 171.1.
20
EI-MS: m/z (%) = 313 (M + 1, 45), 276 (52), 186 (100), 157 (51),
126 (45).
3
Anal. Calcd for C16H28O4N2: C, 61.51; H, 9.03; N, 8.96. Found: C,
61.86; H, 9.36; N, 8.84.
(R,R)-(+)-di-N,N’-phenyltartramide (6)
After cooling, the reaction mixture was dried in vacuum and recrys-
tallized in EtOAc to afford 6 as a white solid; yield: 83%; mp
258 °C (Lit.12 mp 255–256 °C); [ ]D20 +196.8 (c = 1, pyridine).
IR (KBr): 3336 (OH), 1671 (C=O), 1600 (phenyl), 1121 cm–1
(C–O).
32.1, 39.5, 74.2, 172.0, 173.5.
EI-MS: m/z (%) = 430 (M + 2, 32), 272 (24), 244 (100), 215 (17),
184 (13).
Anal. Calcd for C24H48O4N2: C, 67.25; H, 11.28; N, 6.53. Found: C,
67.34; H, 11.43; N, 6.55.
1H NMR (DMSO-d6): = 4.56 (s, 2 H, CH), 6.11 (s, 2 H, OH),
7.10–7.81 (m, 10 H, phenyl), 9.68 (s, 2 H, NH).
(R,R)-(+)-Di-N,N’-hexyltartramide (3)
13C NMR (DMSO-d6): = 71.7, 118.0, 122.0, 127.1, 136.9, 169.3.
EI-MS: m/z (%) = 300 (M+, 19), 180 (76), 151 (34), 120 (100).
After cooling, the reaction mixture was stirred with H2O and fil-
tered. The resultant solid was washed with petroleum ether, filtered
and recrystallized from EtOAc–petroleum ether to afford 3 as a
20
(R,R)-(+)-Di-N,N’-2-hydroxyethyltartramide (7)
white solid; yield: 81%; mp 168–170 °C; [ ]D +26.5 (c = 0.4,
The crude reaction mixture was dried in vacuum, the residue puri-
fied by flash chromatography (MeOH–CH2Cl2, 1:4) and recrystal-
lized from MeOH–Et2O to furnish 7 as a white solid; yield: 68%;
mp 145–146 °C; [ ]D20 +2.0 (c = 0.8, H2O).
MeOH).
IR (KBr): 3323 (OH), 1643 (C=O), 1064 cm–1 (C–O).
1H NMR (DMSO-d6): = 0.87 (t, 6 H, 3J = 6.5 Hz, CH3), 1.26–1.42
(m, 16 H, CH2), 2.99–3.14 (m, 4 H, NHCH2), 4.10 (d, 1 H, 3J = 4.9
Hz, CH), 4.21 (d, 1 H, 3J = 6.5 Hz, CH), 5.51 (d, 1 H, 3J = 6.5 Hz,
OH), 5.75 (d, 1 H, 3J = 4.9 Hz, OH), 7.52 (t, 1 H, 3J = 5.7 Hz, NH),
7.66 (t, 1 H, 3J = 5.7 Hz, NH).
IR (KBr): 3331 (OH), 1649 (C=O), 1070 cm–1 (C–O).
3
1H NMR (D2O): = 3.36 (t, 4 H, J = 5.3 Hz, CH2), 3.62 (t, 4 H,
3J = 5.3 Hz, CH2N), 4.49 (s, 1 H, CH), 4.52 (s, 1 H, CH).
13C NMR (D2O): = 43.8, 62.5, 74.9, 176.5.
13C NMR (DMSO-d6): = 14.5, 22.6, 26.5, 29.6, 29.7, 31.6, 73.1,
74.2, 172.4.
EI-MS: m/z (%) = 237 (M + 1, 100), 177 (8), 148 (12), 120 (60).
EI-MS: m/z (%) = 316 (M+, 19), 272 (39), 244 (100), 188 (87), 128
(30).
Anal. Calcd for C8H16O6N2: C, 40.68; H, 6.78; N, 11.86. Found: C,
40.60; H, 6.96; N, 11.49.
Anal. Calcd for C16H32O4N2: C, 60.73; H, 10.19; N, 8.85. Found: C,
60.36; H, 10.11; N, 8.59.
(R,R)-(+)-Di-N,N’-2-methoxyethyltartramide (8)
The crude reaction mixture was dried in vacuum, purified by flash
chromatography (MeOH–CH2Cl2, 1:9) and recrystallized from
MeOH–Et2O to give 8 as a white solid; yield: 65%; mp 106 °C;
[ ]D20 +2.6 (c = 0.9, H2O).
(R,R)-(+)-Di-N,N’-butyltartramide (4)
After cooling, the reaction mixture was dissolved in CH2Cl2 and
washed with H2O. The organic layer was dried (MgSO4), concen-
trated in vacuo and recrystallized from EtOAc–petroleum ether to
obtain 4 as a white solid; yield: 71%; mp 189 °C (Lit.11 mp 193 °C);
[ ]D20 +19.7 (c = 1.03, MeOH).
IR (KBr): 3267 (OH), 1649 (C=O), 1109 cm–1 (C–O).
1H NMR (DMSO-d6): = 3.23-3.47 (m, 14 H, CH2NH, CH2OMe,
3
OCH3), 4.12 (d, 1 H, 3J = 4.9 Hz, CH), 4.21 (d, 1 H, J = 7.2 Hz,
IR (KBr): 3323 (OH), 1643 (C=O), 1089 cm–1 (C–O).
CH), 5.65 (d, 1 H, 3J = 7.2 Hz, OH), 5.87 (d, 1 H, 3J = 4.9 Hz, OH)
7.45 (t, 1 H, 3J = 5.7 Hz, NH), 7.62 (t, 1 H, 3J = 5.7 Hz, NH).
1H NMR (DMSO-d6): = 0.86 (t, 6 H, 3J = 6.8 Hz, CH3), 1.20–1.47
(m, 8 H, CH2), 2.98–3.13 (m, 4 H, NHCH2), 4.08 (d, 1 H, 3J = 4.6
Hz, CH), 4.19 (d, 1 H, 3J = 6.9 Hz, CH), 5.50 (d, 1 H, 3J = 6.9 Hz,
OH), 5.70 (d, 1 H, 3J = 4.6 Hz, OH), 7.50 (t, 1 H, 3J = 6.1 Hz, NH),
7.63 (t, 1 H, 3J = 6.1 Hz, NH).
13C NMR (DMSO-d6): = 13.7, 19.5, 31.3, 37.9, 72.5, 73.7, 170.7,
171.8;
13C NMR (DMSO-d6): = 37.9, 38.1, 58.0, 58.1, 70.5, 72.5, 73.8,
170.9, 172.2.
EI-MS: m/z (%) = 265 (M + 1, 7), 190 (25), 162 (100), 130 (75), 113
(9).
Anal. Calcd for C10H20O6N2: C, 45.44; H, 7.63; N, 10.59. Found: C,
45.73; H, 7.69; N, 10.37.
EI-MS: m/z (%) = 261 (M + 1, 33), 218 (9), 188 (9), 160 (100), 131
(26);
(R,R)-(+)-Di-N,N’-3-methoxypropyltartramide (9)
The crude reaction mixture was dried in vacuum, purified by flash
chromatography (MeOH–CH2Cl2 1:9) and recrystallized from
MeOH/Et2O mixture to afford 9 as a white solid; yield: 60%; mp
114 °C; [ ]D20 +20.4 (c = 1.0, MeOH).
(R,R)-(+)-Di-N,N’-cyclohexyltartramide (5)
After cooling, the reaction mixture was stirred with H2O and fil-
tered. The resultant solid was washed with petroleum ether, filtered
and recrystallized from EtOAc–petroleum ether to give 5 as a yel-
low solid; yield: 30%; mp 194 °C; [ ]D20 +9.3 (c = 0.6, MeOH).
IR (KBr): 3348 (OH), 1630 (C=O), 1128 cm–1 (C–O).
1H NMR (DMSO-d6): = 1.0–1.40 (m, 12 H, cyclohexyl), 1.50–
1.78 (m, 8 H, cyclohexyl), 3.68–3.71 (m, 2 H, NHCH), 4.06 (s, 1 H,
IR (KBr): 3273 (OH), 1643 (C=O), 1128 cm–1 (C–O).
1H NMR (DMSO-d6): = 1.61–1.71 (m, 4 H, CH2), 3.12–3.39 (m,
3
14 H, OCH3, NHCH2, CH2OMe), 4.21 (d, 2 H, J = 6.5 Hz, CH),
5.53 (d, 2 H, 3J = 7 Hz, CH), 7.55 (t, 1 H, 3J = 5.75 Hz, NH), 7.72,
(t, 1 H, 3J = 5.75 Hz, NH).
Synthesis 2001, No. 16, 2441–2444 ISSN 0039-7881 © Thieme Stuttgart · New York

2444
F. Massicot et al.
PAPER
13C NMR (DMSO-d6): = 29.2, 35.7, 35.9, 57.9, 69.4, 69.9, 72.6,
73.8, 171.9.
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Anal. Calcd for C12H24O6N2: C, 49.31; H, 8.22; N, 9.59. Found: C,
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After cooling, the reaction mixture was dried in vacuum, the residue
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crystallized from EtOAc to obtain 10 as a white solid; yield: 73%;
mp 178 °C; [ ]D20 +200.16 (c = 1.27, pyridine).
IR (KBr): 3365 (OH), 1655 (C=O), 1077 cm–1 (C–O).
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(m, 2 H, OH), 7.22–7.30 (m, 2 H, pyridine), 7.38–7.42 (m, 2 H, py-
3
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135 (66), 109 (62).
Anal. Calcd for C16H18O4N4: C, 58.18; H, 5.45; N, 16.96. Found: C,
58.28; H, 5.20; N, 16.82.
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Acknowledgement
This work was supported by the “Contrat de Plan Etat-Région”, pro-
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Synthesis 2001, No. 16, 2441–2444 ISSN 0039-7881 © Thieme Stuttgart · New York