N,O-Benzyl Protection of Structurally Varied Amines and Phenols Using Wells-Dawson Heteropolyacid Catalyst

Full text of DOI:10.1080/00304948.2021.1877238

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
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N,O-Benzyl Protection of Structurally Varied
Amines and Phenols Using Wells-Dawson
Heteropolyacid Catalyst
Sara Boughaba, Zineb Aouf, Rachida Zerrouki & Nour Eddine Aouf
To cite this article: Sara Boughaba, Zineb Aouf, Rachida Zerrouki & Nour Eddine Aouf
(2021) N,O-Benzyl Protection of Structurally Varied Amines and Phenols Using Wells-Dawson
Heteropolyacid Catalyst, Organic Preparations and Procedures International, 53:3, 301-310, DOI:
10.1080/00304948.2021.1877238
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ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
2021, VOL. 53, NO. 3, 301–310
https://doi.org/10.1080/00304948.2021.1877238
EXPERIMENTAL PAPER
N,O-Benzyl Protection of Structurally Varied Amines and
Phenols Using Wells-Dawson Heteropolyacid Catalyst
Sara Boughabaa, Zineb Aoufa, Rachida Zerroukib, and Nour Eddine Aoufa
aDepartment of Chemistry, Laboratory of Applied Organic Chemistry, Bioorganic Chemistry Group,
b
Sciences Faculty, Badji Mokhtar-Annaba University, Annaba, Algeria; Department of Chemistry,
PEIRENE-Laboratory, University of Limoges UNILIM, Limoges, France
ARTICLE HISTORY Received 21 May 2020; Accepted 2 October 2020
In the last two decades, the investigation of green chemistry processes1 in the protec-
tion/deprotection2–3 of functional groups has received much attention. Acylation4–7 of
amine and hydroxyl groups is among the most used protective strategies in organic syn-
thesis. In the same vein, benzoylation8 is used for the N-protection of amino acids via
the widely-used Schotten-Bauman procedure.9 The benzoyl (Bz) group is one of the
most attractive protecting groups for amines, alcohols and phenols: this group is stable
under hydrogenolysis conditions; it can be easily introduced using such bases as pyri-
dine, TEA, or DMAP;10 and it can be removed by hydrolysis.11 There are a number of
reagents available for the benzoylation of amine and hydroxyl groups, including N-ben-
zoyltetrazole,12 benzoyl cyanide,13 benzoic anhydride,14 2-benzoylthio-1-methylpyridi-
nium chloride15 and benzoyl chloride. This last is widely used because of its ready
availability and low cost.
Benzolyation is a well-known reaction in classical organic chemistry. Among some of
the newer methods, a number of procedures have been developed for benzoylation
using acidic16–17 or basic18–19 conditions. Benzoylation of primary amines has even been
described without the use of any solvent or alkali.20 A catalyst-free and solvent-free pro-
cedure using ultrasound irradiation was also reported.21 No matter whether the methods
are classical or more up-to-date, many of them have such limitations as highly basic
conditions, long reaction times, low yields of products, environmental pollution caused
by toxic reagents and solvents, or the use of expensive catalysts.
In the furtherance of our research focused on efficient and reusable catalysts in
organic chemistry22–23 and the development of green synthetic methods for protection
of amine and hydroxyl groups,24–30 we have attempted to use Wells-Dawson heteropo-
lyacids (HPAs) as catalysts. HPAs have been demonstrated to be efficient and reusable
catalysts. They possess unique physico-chemical properties, such as super-acidity, high
thermal and chemical stability, the ability to accept and release electrons and high pro-
ton mobility, as well as the concomitant possibility of varying their acidities and oxidiz-
ing potentials.31–32
CONTACT Nour Eddine Aouf
noureddineaouf2003@yahoo.fr
Department of Chemistry, Laboratory of Applied
Organic Chemistry, Bioorganic Chemistry Group, Sciences Faculty, Badji Mokhtar-Annaba University, Box 12, 23000
Annaba, Algeria
ß 2021 Taylor & Francis Group, LLC

302
S. BOUGHABA ET AL.
Scheme 1. Benzoylation reactions using HPA.
In this paper, we report an alternative green method for the N-Bz and O-Bz protec-
tion of amines, phenols, aminoesters, aminoalcohols, ureas and sulfonamides using an
HPA (H6P2W18O62ꢀ14H2O) (Scheme 1). It is worth noting that our method is solvent-
free and thus adheres to a key green chemistry principle.
Firstly, in order to optimize the amount of the catalyst, the benzoylation of benzyl-
amine was carried out varying the amount of catalyst under solvent-free conditions at
room temperature. The reaction was monitored by TLC and was stopped when the
amine disappeared. The results show that the use of 3 mol% resulted in the highest yield
(93%) (Table 1).
On the basis of the above results, to extend the generality of the reaction, this proced-
ure was applied to structurally varied amines. The benzoylation of primary and second-
ary, aliphatic and aromatic amines afforded their corresponding N-Bz protected
derivatives within 1-5 min in 66-93% yields (mean 77%). In the case of aromatic amines,
the nature of the aryl substituent does not have a significant influence on the reaction
time and the yields of the reaction (Scheme 1 and Table 2).
With the optimal conditions (3 mol% of H6P2W18O62ꢀ14H2O, room temperature and
solvent-free), we evaluated the applicability of this protocol to the protection of
hydroxyl groups. The corresponding benzoyl esters were obtained within a maximum of
9 min with excellent yields (89-96%). Benzoylation of 4-hydroxyphenol led selectively to
the mono O-benzoylation (3p). In the benzoylation of hydroxyl groups, we also
observed that the aryl substituents on the aromatic ring do not have much effect on the
reaction times and the yields.
Using our protocol, benzoylation was carried out on two b-amino alcohols, namely,
ethanolamine and O-aminophenol. In each case, the N-Bz protected derivatives were
obtained in good yields (79 and 78% respectively) in 8 min. Thus our method showed
good chemoselectivity (compounds 3s, 3t). Benzoylation of S-a-aminoesters under the

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
303
Table 1. Optimization of the amount of the catalyst.
Catalyst (mol)
t (ꢁC)
Times (min)
Yields (%)
1.5%
3%
3%
rt
rt
rt
rt
5
7
3
5
54
62
93
93
4%
Table 2. Catalyzed N- and O-Benzoylation.
Entry
1
Product
3a20
Time(min)
3
Yield(%)
93
mp (ꢁC)(lit mpreference
105-106
)
(10520
)
2
3b
3c
3
4
2
2
3
5
4
2
2
3
2
2
1
9
7
6
4
8
8
2
2
7
2
82
79
81
86
70
69
66
74
81
72
79
77
74
96
89
90
91
79
78
94
89
75
94
120-123
(-)
100-101
3
(-)
4
3d20
3e
153-155
(153-15420
140-142
(-)
)
)
5
6
3f20
3g20
3h20
3i
155-156
(15620
)
7
208-209
(208-20920
150-153
8
(15020
)
9
85-87
(-)
69-71
(-)
92-95
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
3j
3k
(-)
3l20
3m21
3n21
3o
147-148
(147-14820
75-79
(-)
95-97
(-)
120-123
(-)
153-158
(-)
170-171
(-)
166-170
(-)
149-153
(-)
151-152
(-)
130-135
(-)
148-149
(-)
)
3p
3q
3r
3s
3t21
3u
3v
3w
3x
160-166
(-)
97-100
(-)
same reaction conditions was obtained after just a few minutes in excellent yields (3u
(94%), 3v (89%)). Selective reactivity in a sulfonamide was tested, and the results
showed that the benzoylation occurred only at the less highly substituted nitrogen atom.

304
S. BOUGHABA ET AL.
No bis-N,N’-Bz formation was observed. The mono-N-protected sulfonamide was syn-
thesized in good yield (3w (75%)). Similarly, in the case of the benzoylation of urea,
only the mono N-Bz derivative was observed (3x, 94%). We infer that the use of the
HPA in these reactions productively emphasizes the expected nucleophilicity of the sites
benzoylated.
In conclusion, our alternative protocol offers free-solvent conditions, excellent yields
and short reaction times, as well as regioselectivity and chemoselectivity. It is our hope
that the procedure will find expanded use; for example, it may be suitable for peptide
and nucleotide chemistry.
Experimental section
Commercially available chemicals were used without further purification. All reactions
were monitored by thin layer chromatography (TLC) on silica Merck 60 F254 precoated
aluminium plates. Melting points were determined in open capillary tubes on an elec-
tro-thermal apparatus and uncorrected. Mass spectra were recorded on a SHIMADZU
QP 1100 Ex mass spectrometer. IR spectra were recorded on a Perkin-Elmer FT-600
spectrometer. Microanalysis data were obtained on an Elementar Analyzer (Euro E.A.
1
3000-V3.0-single-2007). H NMR and 13C NMR were recorded with a Bruker spectrom-
eter at 300 and 75 MHz, respectively using CDCl3 as solvent. Chemical shifts are
reported in d units (ppm) with tetramethylsilane (TMS) as a reference. All coupling
constants (J) are reported in Hertz.
Preparation of Catalyst (H6P2W18O62ꢀ14H2O)
The catalyst was prepared by a polycondensation of tungstate ions under acidic condi-
tions in order to form the saturated heteropolyanion K6P2W18O62ꢀ12H2O, followed by
an extraction with ether in the presence of hydrochloric acid to get the acid form
(H6P2W18O62ꢀ14H2O).33–34 The IR spectrum of the acid Wells-Dawson compound
H6P2W18O62ꢀ14H2O shows the appropriate bands of W-O at 962, 914 and 769 cmꢂ1
and P-O at 1090 cmꢂ1 respectively. The 31P NMR shifts were determined for a 0.001 M
solution of polyanion in D2O solution and were referenced to H3PO4 (85%). We con-
firmed the purity of the product readily by phosphorus NMR; the single resonance peak
at d¼-12.44 ppm revealed a virtually pure product. In the present work, we found that
it could be recovered at the end of the reaction by simple filtration, leaving the way
open to recycling of the catalyst.
Typical benzoylation procedure
The procedure was done in a well-ventilated hood. In a 10 mL flask, benzoyl chloride
(1 mmol, 0.16 ml) was added to the appropriate amine or phenol (1 mmol) and the mix-
ture was stirred at room temperature in the presence of 0.003 g H6P2W18O62ꢀ14H2O as
catalyst under solvent-free conditions for the appropriate time. During the reaction, the
formation of hydrogen chloride gas was observed. After completion of the reaction (as
monitored by TLC), diethyl ether (8 mL) was added, and the products were obtained by

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
305
filtration. The products were then recrystallized from n-hexane/diethyl ether to give the
N-Bz and O-Bz derivatives in the yields specified in Table 2.
N-Benzylbenzamide (3a)
White solid, mp 105-106 ꢁC (lit mp 105 ꢁC20), Rf 0.55 (DCM/MeOH(9/1)). IR: (KBr,
1
cmꢂ1) 3315 (NH), 1640 (C ¼ O), 1579 (C ¼ C). H NMR (300 MHz, CDCl3) d 7.60-7.54
(m, 3H), 7.38 (d, J ¼ 6.9 Hz, 3H), 7.14-7.03 (m, 5H), 3.95 (s, 2H). 13C NMR (75.5 MHz,
CDCl3) d 167.57, 139.90, 134.74, 132.61, 131.21, 131.02, 127.31, 127.20, 125.13, 125.09,
123.59, 123.42. MSEI (m/z) 212.1 [M þ H]þ.
Anal. Calcd for C14H13NO: C, 79.59; H, 6.20; N, 6.63. Found: C, 79.62; H, 6.42;
N, 6.95.
N-Phenethylbenzamide (3b)
White solid, mp 120-123 ꢁC, Rf 0.56 (DCM/MeOH (9/1)). IR: (KBr, cmꢂ1) 3430 (NH),
1632 (C ¼ O), 1452 (C-N). MSEI (m/z) 226.1 [M þ H]þ.
Anal. Calcd for C14H13NO: C, 79.97; H, 6.71; N, 6.22. Found: 79.92; H, 6.75; N, 6.17
N-(1-Phenylethyl)benzamide (3c)
White solid, mp 100-101 ꢁC, Rf 0.55 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3355 (NH),
1
1634 (C ¼ O), 1519 (C ¼ C). H NMR (300 MHz, CDCl3) d 7.27-7.07 (m, 6H), 7.05-7.00
(m, 4H), 5.01 (q, J1¼9.9 Hz, J2¼9.6 Hz, 1H), 1.82 (d, J ¼ 11.4 Hz, 3H). 13C NMR
(75.5 MHz, CDCl3) d 167.23, 140.30, 135.42, 132.01, 128.01, 127.90, 126.67, 126.22,
123.55, 121.95, 121.88, 54.21, 20.15. MSEI (m/z) 226.1 [M þ H]þ.
Anal. Calcd for C15H15NO: C, 79.97; H, 6.71; N, 6.22. Found: C, 79.82; H, 6.52;
N, 6.05.
N-(3-Fluorophenyl)benzamide (3e)
White solid, mp 140-142 ꢁC, Rf 0.54 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3347 (NH),
1
1661 (C ¼ O), 1437 (C-N). H NMR (400 MHz, CDCl3) d 7.58 (d, J ¼ 6.8Hz, 2H), 7.39-
7.36 (m, 3H), 7.36 (s, 1H), 7.35-7.30 (m, 5H). 13C NMR (75.5 MHz, CDCl3) d 165.79,
164.29, 161.86, 139.52, 139.41, 134.62, 132.11, 130.21, 130.12, 128.89, 127.03, 115.38,
115.35, 111.41, 111.20, 107.81, 107.55. MSEI (m/z) 215.1 [M]þ.
Anal. Calcd for C13H10NOF: C, 72.55; H, 4.68; N, 6.51. Found: C, 72.92; H, 4.82;
N, 6.35.
N-(Thiazol-2-yl)benzamide (3h)
White solid, mp 150-153 ꢁC (lit mp 150 ꢁC20), Rf 0.50 (DCM-MeOH (9/1)). IR (KBr,
1
cmꢂ1): 3259 (NH), 1697 (C ¼ O), 1555(C ¼ C). H NMR (300 MHz, CDCl3) d 8.05 (d,
J ¼ 6.9 Hz, 2H), 7.66-6.49 (m, 3H), 7.00 (d, J ¼ 3.6 Hz, 1H), 6.93 (d, J ¼ 3.6 Hz, 1H). 13C
NMR (75.5 MHz, CDCl3) d 165.34, 162.09, 134.28, 132.04, 131.32, 128.21, 128.04,
127.92, 127.89, 110.49. MSEI (m/z) 205.1 [M þ H]þ.
Anal. Calcd for C10H8N2OS: C, 58.81; H, 3.95; N, 13.72. Found: C, 58.92; H, 3.82;
N, 13.95.

306
S. BOUGHABA ET AL.
N-(tert-Butyl)benzamide (3i)
White solid, mp 85-87 ꢁC, Rf 0.51 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3330 (NH),
1
1695 (C ¼ O), 1446(C-N). H NMR (300 MHz, CDCl3) d 7.81-7.26 (m, 4H), 7.04-6.87
(m, 1H), 3.90 (s, 9H).
Anal. Calcd for C11H15NO: C, 74.54; H, 8.53; N, 7.90. Found: C, 74.51; H, 8.58;
N, 7.96.
N-Propylbenzamide (3j)
White solid, mp 69-71 ꢁC, Rf 0.52 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3314 (NH),
1
1696 (C ¼ O), 1450 (C-N). H NMR (300 MHz, CDCl3) d 7.76 (d, J ¼ 9.0 Hz, 2H), 7.60
(d, J ¼ 6.0 Hz, 2H), 7.43-7.26 (m, 1H), 3.61 (t, J1¼3.0 Hz, J2¼6.0 Hz, 3H), 2.10-1.80 (m,
2H), 0.94 (t, J1¼6.0 Hz, J2¼9.0 Hz, 3H).
Anal. Calcd for C10H13NO: C, 73.59; H, 8.03; N, 8.58. Found: C, 73.51; H, 8.08;
N, 8.61.
N-Butylbenzamide (3k)
1
White solid, mp 92-95 ꢁC, Rf 0.50 (DCM-MeOH (9/1)). H NMR (300 MHz, CDCl3) d
7.77 (d, J ¼ 6.0 Hz, 2H), 7.61 (d, J ¼ 6.0 Hz, 2H), 7.43-7.31 (m, 1H), 3.21 (t, J1¼6.0 Hz,
J2¼9.0 Hz, 2H), 1.54-1.26 (m, 4H), 0.93 (t, J1¼6.0 Hz, J2¼9.0 Hz, 3H). 13C NMR
(75.5 MHz, CDCl3) d 165.28, 134.49, 128.21, 128.04, 127.92, 127.89, 18.65, 19.34, 10.49.
Anal. Calcd for C11H15NO: C, 74.54; H, 8.53; N, 7.90. Found: C, 74.49; H, 8.60;
N, 7.81.
N-Cyclohexylbenzamide (3l)
White solid, mp 147-148 ꢁC (lit mp 147-148 ꢁC20), Rf 0.55 (DCM-MeOH (9/1)). IR
1
(KBr, cmꢂ1): 3292 (NH), 1640 (C ¼ O), 1544 (C ¼ C). H NMR (300 MHz, CDCl3) d
7.86 (d, J ¼ 3.2Hz, 2H), 7.82 (s, 1H), 7.61 (t, J ¼ 4.9Hz, 1H), 7.42 (t, J ¼ 4.2Hz, 2H), 3.63
(m, 1H), 2.32 (m, 4H), 1.74 (m, 4H), 1.42 (m, 2H). 13C NMR (75.5 MHz, CDCl3) d
166.0, 130.2, 128.7, 119.5, 119.1, 47.6, 37.3, 25.9, 24.2. MSEI (m/z) 204.1 [M þ H]þ.
Anal. Calcd for C13H16NO: C, 76.81; H, 8.43; N, 6.89. Found: C, 76.90; H, 8.59;
N, 6.55.
Phenyl (piperidin-1-yl)methanone (3m)21
White solid, mp 75-79 ꢁC, Rf 0.48 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3293 (NH),
1652 (C ¼ O), 1492 (C ¼ C).
Anal. Calcd for C12H15NO: C, 76.16; H, 7.99; N, 7.40. Found: C, 76.11; H, 8.06; N, 7.31.
Phenyl (4-phenylpiperazin-1-yl)methanone (3n)
White solid, mp 95-97 ꢁC, Rf 0.52 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3451 (NH),
1
1631 (C ¼ O), 1599 (C ¼ C). H NMR (300 MHz, CDCl3) d 7.92 (d, J ¼ 1.8 Hz, 2H),
7.70 (m, 2H), 7.50 (m, 2H), 7.11 (t, J1¼14.7 Hz, J2¼15.3 Hz, 2H), 6.75 (d, J ¼ 3.9 Hz,
2H), 3.53 (t, J1¼3 Hz, J2¼1.5 Hz, 4H), 3.05 (t, J1¼3.9 Hz, J2¼7.2 Hz, 4H). 13C NMR
(75.5 MHz, CDCl3) d 167.50, 149.32, 139.20, 129.32, 129.03, 128.54, 128.22, 127.98,

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
307
127.75, 126.70, 120.83, 114.41, 114.20, 54.21, 54.02, 50.40, 50.35. MSEI (m/z)
267.1 [M]þ.
Anal. Calcd for C17H18N2O: C, 76.66; H, 6.81; N, 10.52. Found: C, 76.92; H, 6.89;
N, 10.35.
Phenyl benzoate (3o)
White solid, mp 120-123 ꢁC, Rf 0.55 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 1728
(C ¼ O), 1489 (C ¼ C).1H NMR (300 MHz, CDCl3) d 8.45 (d, J ¼ 3.6 Hz, 2H), 8.15 (t,
J1¼5.4 Hz, J2¼5.1 Hz, 2H), 7.68 (t, J1¼3.9 Hz, J2¼3.0 Hz, 1H), 7.48-7.19 (m, 5H). 13C
NMR (75.5 MHz, CDCl3) d 165.55, 148.89, 133.81, 132.66, 132.42, 130.45, 130.22,
128.54, 128.34, 127.92, 127.82, 123.25, 123.02, 117.82. MSEI (m/z) 199.1 [M þ H]þ.
Anal. Calcd for C12H10O : C, 78.77; H, 5.09. Found: C, 78.71; H, 5.13.
2
4-Hydroxyphenyl benzoate (3p)
White solid, mp 153-158 ꢁC, Rf 0.54 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3261 (OH),
1701 (C ¼ O). 1H NMR (300 MHz, CDCl3) d 7.30 (t, J ¼ 5.2 Hz, 2H), 7.26 (t,
J ¼ 14.8 Hz, 1H), 7.07-7.04 (m, 5H), 5.27 (s, 1H). 13C NMR (75.5 MHz, CDCl3) d
165.65, 156.78, 151.70, 133.81, 130.28, 130.21, 129.34, 128.65, 113.74, 113.39, 109.44.
MSEI (m/z) 214.1 [M]þ.
Anal. Calcd for C13H10O3: C, 72.89; H, 4.71. Found: C, 72.95; H, 4.65.
4-Bromophenyl benzoate (3q)
White solid, mp 170-171 ꢁC, Rf 0.50 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 1732
1
(C ¼ O), 1486 (C ¼ C). H NMR (300 MHz, CDCl3) d 7.15 (d, J ¼ 3.6 Hz, 2H), 7.68-7.33
(m, 5H), 7.22 (d, J ¼ 6.9 Hz, 2H). 13C NMR (75.5 MHz, CDCl3) d 165.31, 148.01, 133.89,
132.72, 132.56, 130.45, 130.22, 128.54, 128.34, 127.92, 127.89, 123.25, 118.93. MSEI (m/
z) 277.1 [M]þ.
Anal. Calcd for C13H9O2Br: C, 56.35; H, 3.27. Found: C, 56.55; H, 3.12.
4-Methoxyphenyl benzoate (3r)
White solid, mp 166-170 ꢁC, Rf 0.50 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 1712
(C ¼ O), 1496 (C ¼ C). MSEI (m/z) 228.1 [M]þ.
Anal. Calcd for C14H12O3: C, 73.67; H, 5.30. Found: C, 73.62; H, 5.36.
N-(2-Hydroxyethyl)benzamide (3s)
White solid, mp 149-153 ꢁC, Rf 0.51 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3244 (OH),
3045 (NH), 1614 (C ¼ O), 1520 (C ¼ C). 1H NMR (400 MHz, CDCl3) d 7.73 (d,
J ¼ 7.2 Hz, 2H), 7.45 (t, J1¼7.5 Hz, J2¼7.2 Hz, 1H), 7.36 (t, J1¼7.8 Hz, J2¼7.2 Hz, 2H),
7.05 (s, 1H), 3.76 (t, J1¼4.8 Hz, J2¼5.4 Hz, 2H), 3.55 (t, J1¼4.8 Hz, J2¼5.4 Hz, 2H), 3.02
(s, 1H). 13C NMR (75.5 MHz, CDCl3) d 165.28, 132.04, 128.28, 128.04, 127.92, 127.89,
63.43, 47.90. MSEI (m/z) 166.1 [M]þ.
Anal. Calcd for C9H11NO2: C, 65.44; H, 6.71; N, 8.48. Found: C, 65.63; H, 6.59;
N, 8.55.

308
S. BOUGHABA ET AL.
N-(2-Hydroxyphenyl) benzamide (3t)21
White solid, mp 151-152 ꢁC, Rf 0.46 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3523 (OH),
3277 (NH), 1617 (C ¼ O).
Anal. Calcd for C13H11NO2: C, 73.23; H, 5.20; N, 6.57. Found: C, 73.18; H, 5.27;
N, 6.60.
Methyl benzoylphenylalaninate (3u)
White solid, mp 130-135 ꢁC, Rf 0.61 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3262 (NH),
1727 (C ¼ O), 1603 (C ¼ O). MSEI (m/z) 284.3 [M þ 1]þ.
Anal. Calcd for C17H17NO3: C, 72.07; H, 6.05, N, 4.49. Found: C, 72.02; H, 6.12,
N, 4.52.
Methyl benzoylleucinate (3v)
White solid, mp 148-149 ꢁC, Rf 0.63 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3356 (NH),
1727 (C ¼ O), 1687 (C ¼ O). MSEI (m/z) 250.1 [M þ 1]þ.
Anal. Calcd for C14H19NO3: C, 67.45; H, 7.68, N, 5.62. Found: C, 67.39; H, 7.71
N, 5.64.
N-[[(Phenylmethyl)amino]sulfonyl]benzamide (3w)
White solid, mp 164-166 ꢁC, Rf 0.50 (DCM-MeOH (9/1)). IR (KBr, cmꢂ1): 3274 (NH),
1
1677 (C ¼ O), 1425 (C-N). H NMR (300 MHz, CDCl3) d 8.38 (s, NH, 1H), 7.86 (d,
J ¼ 1.5 Hz, 2H), 7.64-7.58 (m, 1H), 7.47 (t, J1¼6.3 Hz, J2¼7.2 Hz, 2H), 7.33-7.20 (m,
5H), 5.75 (s, NH, 1H), 4.29 (s, 2H).13C NMR (75.5 MHz, CDCl3) d 167.73, 143.43,
134.94, 132.04, 128.39, 128.21, 128.15, 128.13, 127.93, 127.89, 126.53, 126.42, 126.29,
43.24. MSEI (m/z) 290.3 [M]þ.
Anal. Calcd for C14H14N2O3S: C, 57.92; H, 4.86; N, 9.65. Found: C, 58.03; H, 4.94;
N, 9.55.
N-Carbamoylbenzamide (3x)
White solid, mp 97-100 ꢁC, Rf 0.45 (DCM/MeOH (9/1)). IR (KBr, cmꢂ1): 3377 (NH),
1
3290 (NH), 1645 (C ¼ O), 1541 (C ¼ C). H NMR (400 MHz, CDCl3) d 8.33 (s, NH,
1H), 7.64 (d, J ¼ 1.5 Hz, 2H), 7.61 (t, J1¼1.8 Hz, J2¼2.1 Hz, 1H), 7.59 (t, J1¼1.2 Hz,
J2¼1.2 Hz, 2H), 5.49 (s, NH, 1H). 13C NMR (75.5 MHz, CDCl3) d 167.47, 133.39,
129.09, 127.44. MSEI (m/z) 165.1 [M þ H]þ.
Anal. Calcd for C8H8N2O2: C, 58.53; H, 4.91; N, 17.09. Found: C, 58.64; H, 4.98;
N, 16.91
Acknowledgments
This work was supported financially by The General Directorate for Scientific Research and
Technological Development (DG-RSDT), Algerian Ministry of Scientific Research, Applied
Organic Laboratory (FNR 2000). We also thank Prof. Jacques Lebreton, Nantes University,
France, for his help in the identification of all compounds (NMR and MS).

ORGANIC PREPARATIONS AND PROCEDURES INTERNATIONAL
309
ORCID
Nour Eddine Aouf
http://orcid.org/0000-0003-1400-8444
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