Synthesis of N-citralbenzenamines by NaBH4/B(OH)3 system

Article abstract of DOI:10.13005/ojc/300149

Citral as α, β -unsaturated carbonyl compound has been reacted with structurally different anilines with sodium borohydride in the presence of boric acid for the synthesis of their corresponding Akatralbenzenamineswith good yields (75-85%)within 5 min in

Full text of DOI:10.13005/ojc/300149

ISSN: 0970-020 X
CODEN: OJCHEG
2014, Vol. 30, No. (1):
Pg. 359-360
ORIENTAL JOURNAL OF CHEMISTRY
An International Open Free Access, Peer Reviewed Research Journal
www.orientjchem.org
Synthesis of N-citralbenzenamines by
NaBH4/B(OH)3System
DAVOOD SETAMDIDEH* and MOHSEN MINAEE
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/300149
(Received: December 30, 2013; Accepted: February 01, 2014)
ABSTRACT
Citral as α, β-unsaturated carbonyl compound has been reacted with structurally different
anilines with sodium borohydride in the presence of boric acid for the synthesis of their corresponding
N-citralbenzenamineswith good yields (75-85%)within 5 min in CH3CNat room temperature.
Key words: NaBH4, B(OH)3, Citral, N-citralbenzenamines.
INTRODUCTION
carbonyl compoundfollow addition to carbonyl
group (1, 2-addition) to give the corresponding α,
β-unsaturatedN-benzenamines.
Reduction of α, β-unsaturated carbonyl
compounds can follow two pathways: addition to
carbonyl group (1,2-reduction) to give allylicproducts
or addition to the conjugated double bond (1,4-
reduction) to give saturated carbonyl compounds.
NaBH4 (common reducing agent) uses for the
1,2-reduction of conjugated carbonyl compounds
under different reducing system1-9. On the other
hands, in the synthetic project we needed some
N-citralbenzenamines.Also, recently we reported
a convenient system for direct reductive amination
of aldehydes by NaBH4/B(OH)3 system10.Therefore
we decide to use of this reducing system for the
synthesis of N-citralbenzenamines with this hope,the
reductive amination of citralas an α, β-unsaturated
RESULTS AND DISCUSSIONS
We have done the reductive amination
reactions based on the optimized reaction that has
7
been reported in the literature . These reactions
were carried out with molar ratio of citral (1 mmol),
anilines (1 mmol), B(OH)3 (1 mmol) and NaBH4
(1 mmol) in CH3CN (3 mL) at room temperature.
The reactionswere completed within 5 min with
75-85% yields of product as shown in scheme
1. In this reactions N-(3,7-dimethylocta-2,6-
dienyl) benzenamines (N-citralbenzenamines) as
major products have been produced more than

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SETAMDIDEH & MINAEE, Orient. J. Chem., Vol. 30(1), 359-360 (2014)
75%;butgeraniol and unreacted anlinesas by- Reductive amination of citral and aniline with
products less than 15%.
ExpERIMENTAL
NaBH4/Al(OH)3, A typical procedure
In a round-bottomed flask (10 mL) equipped
with a magnetic stirrer, a solution of citral (0.152
g, 1 mmol), aniline (0.093 g, 1 mmol) and Al(OH)3
The products were characterized by their (0.078, 1 mmol) in CH3CN (3 mL) was prepared.
1H NMR (400 MHz Bruker) or IR (PerkinElmer FT-IR The resulting mixture was stirred for 5 min at room
RXI) and comparison with authentic samples (melting temperature.Then the NaBH4 (0.036 g, 1 mmol) was
or boiling points). TLC was applied for the purity added to the reaction mixture and stirred at room
determination of substrates, products and reaction temperature. TLC monitored the progress of the
monitoring over silica gel 60 F254 aluminum sheet.
reaction (eluent; CCl4/Ether: 5/2). The reaction was
CHO
H
N
G
NaBH4 (1 mmol), B(OH)3 (1 mmol)
r.t.; CH3CN (3 mL), 5 min
+
NH2
G
G: H (85%), 4-Br (80%), 4-Me (80%), 2-MeO (75%), 4-MeO (80%), 4-NO2 (75%)
Scheme 1:
filtered after completion within 5 min. Evaporation citral with a variety of anilines to their corresponding
of the solvent and short column chromatography of N-citralbenzenaminesin good yields (75-80%) within
the resulting crude material over silica gel (eluent; 5 min at room temperature.Reduction reactions were
CCl4/Ether: 5/2) afforded the N-(3,7-dimethylocta- carried out with 1 molar equivalents of NaBH4 in the
2,6-dienyl)benzenamine(0.l95 g, 85%).
presence of 1molar amounts of B(OH)3.
CONCLUSION
ACKNOwLEDgEMENTS
In this investigation, we have shown that
The authors gratefully appreciated the
the combination reducing system of NaBH4/B(OH)3 financial support of this work by Mohsen minaee.
in CH3CN can be used for reductive amination of
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