Table 4 Isolated yields for direct amide formationa
Table 5 A comparison of “green-ness” between the catalyst/activators
in the preparation of N-benzylbenzamide
Catalyst
Entry Solvent (wt%)
Time/h Product
Yield (%)
Atom
Activators E-factora Mass intensity economy (%) Yieldb (%)
1
Toluene
0
9
18
24b
12
12
8
62
81
IBAc
251.7
31.8
22.6
17
397.3
32.9
67
92.13
53.9
48.5
85.3
92.13
50
92
82
72
81
CDId
DCC
2
Toluene
0
9
18
24
16
14
8
32
45
SOCl2
Sulfated
tungstate
25
26.3
9.3
a E-factor shown does not account for the waste produced in
the synthesis of activators. b Isolated yield of N-benzylbenzamide.
c ortho-N,N-diisopropylbenzylaminoboronic acid catalyst. d N,N-
carbonyldiimidazole.
3
4
Toluene
Toluene
0
24
24
0
18
33
0
8
15
24
14
12
24
83
96
Notes and references
5
6
Toluene
Toluene
0
9
18
24
18
18
18
56
72
1 D. J. C. Constable, P. J. Dunn, J. D. Hayler, G. R. Humphrey, J.
Leazer, R. J. Linderman, K. Lorenz, J. Manley, B. A. Pearlman, A.
Wells, A. Zaks and T. Y. Zhang, Green Chem., 2007, 9, 411–420.
2 L. J. Gooben, D. M. Ohlmann and P. P. Lange, Synthesis, 2009, 1,
160–164.
3 (a) R. C. Larock, in Comprehensive Organic Transformations,VCH,
New York: 1989, 972; (b) Y. S. Klausner and M. Bodansky, Synthesis,
1972, 453.
4 (a) C. Burnell-Curty and E. J. Roskamp, Tetrahedron Lett., 1993, 34,
5193; (b) J. D. Wilson and H. Weingarten, Can. J. Chem., 1970, 48,
983; (c) I. J. Levin, E. Turos and S. M. Weinred, Synth. Commun.,
1982, 12, 989; (d) M. Thorsen, T. P. Anderson, U. Pedersen, B. Yde
and S. Lawessons, Tetrahedron, 1985, 41, 5633; (e) U. Schmidt and M.
Dietsche, Angew. Chem., Int. Ed. Engl., 1982, 21, 143; (f) M. Ueda,
H. Olkawa, N. Kawaharasaki and Y. Imai, Bull. Chem. Soc. Jpn.,
1983, 56, 2485; (g) K. Takeda, I. Sawada, A. Suzuki and H. Ogura,
Tetrahedron Lett., 1983, 24, 4451; (h) So-Yeop Han and Young-Ah
Kim, Tetrahedron, 2004, 60, 2447–2467.
0
9
18
24
12
12
15
45
72
7
8
9
Xylene
Toluene
Xylene
0
8
12
24
18
16
23
81
98
0
12
24
12
18
98
0
12
16
24
18
18
22
78
86
5 (a) K. Ishihara, H. Kurihara and H. Yamamoto, J. Org. Chem.,
1996, 61, 4196–4197; (b) K. Ishihara, S. Ohara and H. Yamamoto,
Macromolecules, 2000, 33, 3511–3513; (c) K. Ishihara, S. Kondo and
H. Yamamoto, Synlett, 2001, 1371–1374; (d) K. Ishihara, S. Kondo
and H. Yamamoto, Org. Synth., 2002, 79, 176–185; (e) T. Maki, K.
Ishihara and H. Yamamoto, Org. Lett., 2006, 8, 1431–1434; (f) T.
Maki, K. Ishihara and H. Yamamoto, Tetrahedron, 2006, 8, 1431–
1434; (g) K. Arnold, A. S. Batsanov, B. Davies and A. Whiting, Green
Chem., 2008, 10, 124–134.
10
11
Toluene
Toluene
0
8
15
24
16
14
23
78
95
0
8
16
24
12
12
19
52
72
12
Toluene
0
7
12
24
18
12
26
84
96
6 P. Tang, Org. Synth., 2002, 81, 262.
7 R. M. al-zoubi, O. Marion and D. G. Hall, Angew. Chem., Int. Ed.,
2008, 47, 2876–2879.
8 J. W. Comerford, J. H. Clark, D. J. Macquarrie and S. W. Breeden,
Chem. Commun., 2009, 2562–2564.
9 R. Luque, V. Budarin, J. H. Clark and D. J. Macquarrie, Green Chem.,
2009, 11, 459–461.
a Conditions: acid (1.1 equiv), amine (1.0 equiv) and catalyst (appropri-
ate amount) reflux in a solvent with azeotropic removal of water. b No
significant increase in yield was observed after 12 h up to 24 h.
10 G. D. Yadav and A. D. Murkute, J. Catal., 2004, 224, 218–223.
11 P. Sharma, S. Vyas and A. Patel, J. Mol. Catal. A: Chem., 2004, 214,
281.
amidation between carboxylic acid and amines. By measure of
“green-ness” it appears to be a more promising green alternative
over conventional methodologies for amide synthesis.
The author (PSC) thanks University Grant Commission,
India and Centre for Green Technology, Mumbai for financial
support.
12 E. Rafiee, S. Eavani, S. Rashidzadeh and M. Joshaghani, Inorg. Chim.
Acta, 2009, 362, 3555–3562.
13 G. Romanelli, P. Vazquez, L. Pizzio, N. Quaranta, J. Autino, M.
Blanco and C. Caceres, Appl. Catal., A, 2004, 261, 163–170.
14 L. V. Anikina, G. L. Levit, A. M. Demin, Y. B. Vikharev, V. A. Safin,
T. V. Matveeva and V. P. Krasnov, Pharm. Chem. J., 2002, 36, 237.
1710 | Green Chem., 2010, 12, 1707–1710
This journal is
The Royal Society of Chemistry 2010
©