NaBH4/C: A convenient system for reductive amination of aldehydes

Article abstract of DOI:10.13005/ojc/300145

In this context, NaBH₄ in the presence of activated charcoal has been used for thereductive aminationofa variety of aldehydes withanilines. Tne reductive amination reactions have been performed within 60-100 min in THFunder reflux conditionsin high to excellent yields of products (85-90%).

Full text of DOI:10.13005/ojc/300145

ISSN: 0970-020 X
CODEN: OJCHEG
2014, Vol. 30, No. (1):
Pg. 341-344
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Free Access, Peer Reviewed Research Journal
www.orientjchem.org
NaBH4/C: A Convenient System for
Reductive Amination of Aldehydes
SAJJAD TAIE HASANLOIE and DAVOOD SETAMDIDEH*
Department of Chemistry, College of Sciences, Mahabad Branch,
Islamic Azad University, Mahabad, Iran.
*Corresponding author e-mail: d.setamdideh@mahabad-iau.ac.ir
http://dx.doi.org/10.13005/ojc/300145
(Received: December 30, 2013; Accepted: February 06, 2014)
ABSTRACT
In this context, NaBH4 in the presence of activated charcoal has been used for thereductive
aminationofa varietyof aldehydes withanilines.The reductive amination reactions have been performed
within 60-100 min in THFunder reflux conditionsin high to excellent yields of products (85-90%).
Key words: NaBH4, Charcoal, Reductive amination, Aldehydes, Amines
INTRODUCTION
RESULTS AND DISCUSSIONS
The reductive aminationreaction is a
suitable procedure for the preparation of amines
from their corresponding of aldehydes. Because,
other approaches such as: the reduction of nitro,
cyano, azide, carboxamide compounds or the
alkylation of amines are often problemssuch as:
harsh reaction conditions, overalkylation, low
chemical selectivity and generally poor yields. The
reductive aminationreactionhas been carried out by
sodium borohydridewith different reducing system1-
15.But, in continuing our efforts for the development
of new reducing systems 16-28,in this context, we
have reported the reductive amination reaction
of aldehydes with anilines by NaBH4/C system in
THF.
In the past, we have distributed some
application of activated charcoal as catalyst in
different reducing system such as: NaBH4/C for the
reduction of carbonyl compounds27and the reduction
of nitro arenes28.Recently, we have reported
Zn(BH4)2/C is an efficient reducing system for the
reduction of carbonyl compounds20.Here in, we have
used NaBH4/C as convenient system for reductive
amination of aldehydes with anilines.
For this goal, the model reaction has
been performed by reductive amination of
benzaldehydeand aniline.This reaction was carried
outwith different molar ratio of the benzaldehyde/
aniline/charcoal/NaBH4in different solvents for the

HASANLOIE & SETAMDIDEH, Orient. J. Chem., Vol. 30(1), 341-344 (2014)
342

343
HASANLOIE & SETAMDIDEH, Orient. J. Chem., Vol. 30(1), 341-344 (2014)
optimazition reaction conditions. Our experiments of benzaldehye (1 mmol) and aniline (1 mmol)
have been shown that using 0.5 gof activated to N-benzylaniline. The reductive aminationwas
charcoalin THF (5 mL) under reflux conditions is the completed within 60 min with 85% yields of product
best conditions to complete the reductive amination as shown in scheme 1.
CHO
NH2
NaBH4 (1 mmol), Charcoal (0.5 g)
THF (5 mL), reflux, 60 min, 85%
CH2 NH
+
Scheme 1
The various structurally different aldehydes activated charcoal(0.5 g) was preparedinTHF (5 mL).
and anilines have been used by this reducing Then the NaBH4 (0.036 g, 1 mmol) was added to the
system.Experiments have been shown the reaction mixture and stirred under reflux conditions.
correspondingsecondary amines were obtained in TLC monitored the progress of the reaction (eluent;
excellent yields (85-90%) within 60-100 min(Table 1); CCl4/Ether: 5/2). The reaction was filtered after
therefore the efficiency of this protocol was further completion within 60 min. Evaporation of the solvent
examined for the reductive amination of aldehydes. and short column chromatography of the resulting
The influence of activated charcoal is not clear but crude material over silica gel (eluent; CCl4/Ether:
we have reported 26-27 sodium borohydride is slowly 5/2) afforded the N-benzylaniline (0.l53 g, 85% yield,
decomposed by activated charcoal.Consequently, it Table 1, entry 1).
is liberated hydrogen gas in situ.Thus, the generated
molecular hydrogen accelerate the reduction
reaction.
CONCLUSION
In this research, we have shown that
the NaBH4/charcoalis convenient system for the
reductive amination of a variety of aldehydes and
ExpERIMENTAL
The products were characterized by their anilines to their corresponding secondary amines.
1H NMR (400 MHzBruker)or IR (PerkinElmer FT-IR The reduction reactions were accomplished with
RXI) and comparison with authentic samples (melting NaBH4 (1 mmol) and activated charcoal (0.5 g) in
or boiling points). TLC was applied for the purity THFunder reflux conditions.High efficiency of the
determination of substrates, products and reaction reduction reactions and easy work-up procedure
monitoring over silica gel 60 F254 aluminum sheet.
makes as an attractive new protocol for reductive
amination of aldehydes.
Reductive amination of banzaldehyde and
aniline with NaBH4/Charcoal system (typical
procedure)
ACKNOwLEDgEMENTS
In a round-bottomed flask (10 mL) equipped
The authors gratefully appreciated the
with a magnetic stirrer, a solution of benzaldehyde financial support of this work by the research council
(0.106 g, 1 mmol), aniline (0.093 g, 1 mmol) and of Islamic Azad University branch of Mahabad.
REFERENCES
1.
2.
3.
Alinezhad, H.;Tollabian, Z.Bull.Korean Chem.
Soc., 81: 1927( 2010).
Alinezhad, H.;Tajbakhsh, M.;Mahdavi,
N.Synth. Commun.,40: 951( 2010).
Alinezhad, H.;Tajbakhsh, M.;Hamidi, N.Turk.
J. Chem.,34: 307(2010).
Alinezhad, H.;Tajbakhsh, M.;Zare, M.Synth.
Commun.,39: 2907( 2009).
Heydari, A.;Khaksar, S.;Akbari, J.Esfandyari,
M.;Pourayoubi, M.;.Tajbakhsh, M.Tetrahedron
4.
5.

HASANLOIE & SETAMDIDEH, Orient. J. Chem., Vol. 30(1), 341-344 (2014)
344
Lett.,48:1135( 2007).
17.
18.
Setamdideh, D.;Khezri, B.; Mollapour, M.
Orient. J. Chem., 27: 991(2011).
Setamdideh, D.;Khezri, B.;Rahmatollahzadeh,
M.;Aliporamjad, A.Asian J. Chem.
24:3591(2012).
Setamdideh, D.;Rafig, M.E-J. Chem.,9:2345
(2012).
Setamdideh, D.;Rahmatollahzadeh, M.J. Mex.
Chem. Soc.,56:169 (2012).
Setamdideh, D.;Khezri, B.;Rahmatollahzadeh,
M.J. Serb. Chem. Soc.,79:1 (2013).
Mohamadi, M.;Setamdideh, D.;Khezri, B.Org.
Chem. Inter., doi:10.1155/2013/127585
(2013).
6.
Heydari, A.;Arefi, A.;Esfandyari, M.J. Mol.
Catal. A: Chem., 274: 169( 2007).
Reddy, P. S.;Kanjilal, S.;Sunitha, S.; Prasad,
R. B. N.Tetrahedron Lett.,48:, 8807(2007).
Saidi, M.R.;Stan Brown, R.;Ziyaei-Halimjani,
A.J. Iran. Chem. Soc.4:, 194 (2007).
Cho, B.T.; Kang, S. K.Tetrahedron, 61:5725(
2005).
Saxena, I.; Borah, R.;Sarma, J. C.J. Chem.
Soc., Perkin Trans. 1: 503 (2000).
Neidigh, K. A.; Avery, M. A.; .Williamson, J.
S.; Bhattacharyya, S.J. Chem. Soc., Perkin
Trans. 1: 2527 (1998).
7.
8.
19.
20.
21.
22.
9.
10.
11.
12.
13.
Varma, R. S.Dahiya, R.Tetrahedron
Lett.,54:6293(1998).
Brussee, J.; van Benthem,R. A.T.M.; Kruse,
C.G.; Gen,A. v. d.Tetrahedron: Asymmetry,
1:163(1990).
Setamdideh, D.; Hasani, S.; Noori, S. J. Chin.
Chem. Soc.,60: 1267 (2013).
Pourhanafi, S.;Setamdideh, D.; Khezri, B.
Orient. J. Chem.29: 709 (2013).
23.
24.
25.
26.
27.
28.
LatifiMmaghani, E.;Setamdideh, D.Orient.J.
Chem.29: 953 (2013).
Kamari, R.;Setamdideh, D.Orient.J.Chem.29:
497 (2013).
Setamdideh, D.; Khaledi, L. S. Afr. J. Chem.,
66: 150 (2013).
Setamdideh, D.; Karimi, Z.; Alipouramjad, A.
J. Chin. Chem. Soc., 60: 590 (2013).
Zeynizadeh, B.;Setamdideh, D. Z .
NaturforschB., 61b: 1275 (2006).
Zeynizadeh, B.;Setamdideh, D. Synth.
Commun.,36: 2699 (2006).
14.
15.
16.
Setamdideh, D.; Karimi, Z.; Rahimi, F. Orient.
J. Chem., 27: 1621(2011).