Simple and efficient method for the preparation of aryl azides using sonication

Article abstract of DOI:10.1080/00397911.2010.535945

An efficient procedure for the preparation of aryl azides using sonication is described. The convenient sonication-mediated azidation protocol is applicable to aryl compounds under mild conditions with aqueous solution of sodium dichloroiodate and sodium

Full text of DOI:10.1080/00397911.2010.535945

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Simple and Efficient Method for the
Preparation of Aryl Azides Using
Sonication
Vikas N. Telvekar a & Kulbhushan A. Sasane a
a Department of Pharmaceutical Sciences and Technology, Institute
of Chemical Technology, Matunga, Mumbai, India
Accepted author version posted online: 07 Oct 2011.Version of
record first published: 16 Dec 2011.
To cite this article: Vikas N. Telvekar & Kulbhushan A. Sasane (2012): Simple and Efficient Method for
the Preparation of Aryl Azides Using Sonication, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 42:7, 1085-1089
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Synthetic Communications1, 42: 1085–1089, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.535945
SIMPLE AND EFFICIENT METHOD FOR THE
PREPARATION OF ARYL AZIDES USING SONICATION
Vikas N. Telvekar and Kulbhushan A. Sasane
Department of Pharmaceutical Sciences and Technology, Institute of
Chemical Technology, Matunga, Mumbai, India
GRAPHICAL ABSTRACT
Abstract An efficient procedure for the preparation of aryl azides using sonication is
described. The convenient sonication-mediated azidation protocol is applicable to aryl
compounds under mild conditions with aqueous solution of sodium dichloroiodate and
sodium azide. Aryl azides were obtained in excellent yields from a variety of aryl
compounds in short reaction times without affecting sensitive functional groups.
Keywords Aryl azides; sodium azide; sodium dichloroiodate; sonication
INTRODUCTION
Azides have wide applications in organic transformations such as in conversions
to heterocycles. While numerous methods are available for preparation of aliphatic
azides, there is limited choice for aryl azides. The most straightforward route for
the preparation of aryl azides involves replacement of amines with azide via diazotiza-
tion using sodium azide or azidotrimethylsilane.[1,2] A straightforward synthesis of
aryl azides from the corresponding amines is also accomplished using triflyl azide
or tert-butyl nitrite and azidotrimethylsilane.[3–5] Alternatively, aryl amines have been
transformed into aryl azides by treating the former with para-toluenesulfonyl azide in
the presence of a Grignard reagent or strong base.[6] Aryl azides have also been
prepared from arylmagnesium halides or aryl lithium reagents, generated from aryl
halides, and para-toluenesulfonyl azide.[7] Very recently, the coupling of aromatic
halides with sodium azide under catalysis with CuI-L-proline was reported to produce
aryl azides in good to excellent yields.[8] However, all these transformation require
long reaction time and either acidic or basic conditions, which are not compatible
Received June 18, 2010.
Address correspondence to Vikas N. Telvekar, Department of Pharmaceutical Sciences and
Technology, Institute of Chemical Technology, Matunga, Mumbai, India. E-mail: vikastelvekar@
rediffmail.com
1085

1086
V. N. TELVEKAR AND K. A. SASANE
Scheme 1. Anisole converted into 4-azidoanisole using sonication.
with many functional groups present in a substrate. Thus, there is scope for alterna-
tive reagent systems for preparation of aryl azides.
Recently, interest has increased for reduced reaction time, lower costs, and
simplified processes. These procedures usually combine supported reagents and
microwave[9,10] or ultrasonic irradiation[11–13] to carry out a wide range of reactions
in shorter reaction times and with high conversion and selectivity. A few examples
using sonication are synthesis of oligomannosides,[14] condensation reaction of
naphthol=aldehydes,[15] condensation reaction of aminopyrazoles=aldehydes,[16]
Suzuki–Miyaura cross-coupling reaction,[17] and glycosidation in carbohydrate
chemistry.[18] Our group has been working extensively on the development of novel
methodologies under mild reaction conditions using various hypervalent iodine
reagents. Sodium dichloroiodate is commercially available in a 50% water solution.
Recently we exploited this reagent for oxidation of alcohols.[19]
While working on this reagent, we found that the aqueous solution of sodium
dichloroiodate can be used for the direct preparation of aryl azides combined with
sonication in a short reaction time. Initially, we carried out the reaction with anisole
as a model substrate to explore the suitable reaction conditions (Scheme 1).
A mixture of anisole, aqueous sodium dichloroiodate solution, and sodium
azide was sonicated at room temperature (25 ꢀC). The starting material was consumed
within 10 min as indicated by thin-layer chromatography (TLC) analysis. After
workup and purification by silica-gel column chromatography, 4-azidoanisole was
isolated in 90% yield. The reaction is in general clean, and no other product
was observed in these reaction conditions. Without sonication but with stirring, the
reaction did not proceed at all at room temperature, even at more than 72 h. Heating
at 40–80 ꢀC led to the formation of other unidentified products.
RESULTS AND DISCUSSION
To explore the reaction scope, a variety of aryl compounds, prepared by
standard reported procedures, were converted to corresponding azides in moder-
ate to good yields in short reaction times, and the results are summarized in
Table 1.
It was found that either electron-rich or electron-deficient aryl compounds
were suitable for this reaction, giving aryl azide in moderate to good yields in short
reaction times (Table 1, entries 1–7). A variety of functional groups such as methoxy
and acetate tolerated these reaction conditions (Table 1, entries 4, 5, 8, and 9). This
feature would allow the use of the present method in the synthesis of a wide range of
aryl azides. No reaction was observed in the case of benzene even after a long
reaction time (Table 1, entry 10). A plausible mechanism for the aryl azidation is
proposed in Scheme 2.

PREPARATION OF ARYL AZIDES
1087
Table 1. Preparation of aryl azides using sodium dichloroiodate and sodium azide combination with
sonicationa
Entry
1
Substrateb
Product
Time (min)
10
Yield (%)c
82
2
3
10
10
83
85
4
5
10
10
90
88
6
7
15
15
70
72
8
9
15
15
45
83
82
10
—
NRd
aReaction conditions: Substrate (1.0 equiv), aqueous solution of sodium dichloroiodate (1.5 M,
1.01 equiv), and sodium azide (1.01 equiv) at room temperature combined with sonication.
bStarting compounds were prepared by standard reported procedures.
cIsolated yields after column chromatography and structures were confirmed by comparison of the IR
and 1H NMR spectra with those of authentic materials.[3,4,20–22]
dNo reaction.
In conclusion, a new environmentally friendly reaction system using aqueous
sodium dichloroiodate and sodium azide in combination with sonication has been
developed. This method is capable of converting various aryl compounds into corre-
sponding aryl azides at room temperature in short reaction times and gives moderate
to good yields.

1088
V. N. TELVEKAR AND K. A. SASANE
Scheme 2. Plausible mechanism for aryl azidation.
EXPERIMENTAL
Preparation of Aromatic Azides
Anisole (1g, 9.25mmol) and sodium azide (0.6 g, 9.4 mmol) were added to the
aqueous solution of sodium dichloroiodate (6.3 mL, 1.5 M, 9.4 mmol). The resultant
reaction mixture was placed in an ultrasonic bath (33 KHz) at room temperature until
the starting material was completely consumed (TLC). The reaction mixture was
extracted with ethyl acetate, and the organic phase was washed successively with
10% sodium bisulfate solution (2ꢁ 20mL), 10% sodium bicarbonate (2 ꢁ 15mL),
and water (2 ꢁ 20mL). The organic layer was dried over anhydrous sodium sulfate
and concentrated under reduced pressure to give the crude product. Pure 4-azidoanisole
was obtained as a brown oil after silica-gel column chromatography (10% EtOAc–
1
hexane). H NMR (CDCl3) d: 3.75 (3H, s,), 6.78 (2H, d, J ¼ 8.0 Hz), 7.40 (2H, d,
J ¼ 8.0 Hz). IR (KBr) cmꢂ1: 2107, 1599.
Ethyl-3-(4-azidophenyl)propanoate (Table 1, Entry 9)
1H NMR (300 MHz, CDCl3) d: 1.26 (3H, t, J ¼ 8.0 Hz), 2.53 (2H, t, J ¼ 7.0 Hz),
2.90 (2H, t, J ¼ 7.0 Hz), 4.10 (2H, q, J ¼ 8.0 Hz), 6.98 (2H, d, J ¼ 8.4 Hz), 7.18 (2H, d,
J ¼ 8.4 Hz); 13C NMR (125 MHz, CDCl3) d: 14.1, 29.2, 33.9, 61.2, 122, 127, 136, 139,
176; EI MS (m=z) 219 [Mþ]; IR (KBr) cmꢂ1: 2112, 1735, 1610.
ACKNOWLEDGMENT
K. A. S. gratefully acknowledges the Council of Scientific and Industrial
Research, Delhi, India, for financial support.
REFERENCES
1. Yujiro, N.; Naoto, H.; Yoshito, T. Thermal decomposition of vinyl azides in acrylic acid
derivatives: Synthesis of 1-vinyl aziridines. Chem. Lett. 1976, 901.

PREPARATION OF ARYL AZIDES
1089
2. Hubbard, A.; Okazaki, T.; Laali, K. K. Halo and azidodediazoniation of arenediazonium
tetrafluroborates with trimethylsilyl halides and trimethylsilyl azides and Sandmeyer-type
bromodediazoniation with Cu(I)Br in [BMIM][PF6] ionic liquid. J. Org. Chem. 2008,
73, 316.
3. Das, J.; Patil, S. N.; Awasthi, R.; Narasimhulu, C. P.; Trehan, S. An easy acess to aryl
azides from aryl amines under neutral conditions. Synthesis 2005, 1801.
4. Barral, K.; Adam, D.; Moorhouse, D.; Moses, J. E. Efficient conversion of aromatic
amines into azides: A one-pot synthesis of triazoles linkages. Org. Lett. 2007, 9, 1809.
5. Liu, Q.; Tor, Y. Simple conversion of aromatic amines into azides. Org. Lett. 2003, 5,
2571.
6. Nakajima, M.; Anselme, J. P. Diazo transfer reaction mediated by phase transfer
catalysts. Tetrahedron Lett. 1976, 4421.
7. Smith, P. A.; Rowe, C. D.; Bruner, L. B. Azides and amines from Grignard reagents and
tosyl azide. J. Org. Chem. 1969, 34, 3430.
8. Zhu, W.; Ma, D. Synthesis of aryl azides and vinyl azides via proline-promoted
CuI-catalyzed coupling reactions. Chem. Commun. 2004, 888.
9. Kappe, C. O. Controlled microwave heating in mordern organic synthesis. Angew. Chem.
Int. Ed. 2004, 43, 6250.
10. de la Hoz, A.; Diaz-Ortiz, A.; Moreno, A. Microwaves in organic synthesis: Thermal and
non-thermal microwave effects. Chem. Soc. Rev. 2005, 34, 164.
11. Cains, P. W.; Martin, P. D.; Price, C. J. The use of ultrasound in industrial chemical
synthesis and crystallization applications to synthetic chemistry. Org. Process. Res. Dev.
1998, 2, 34.
12. Mason, T. J. Ultrasound in synthetic organic chemistry. Chem. Soc. Rev. 1997, 26, 443.
13. Luche, J. L. Synthetically useful sonochemical reactions in solution. Ultrason. Sonochem.
1996, 3, S215.
14. Tanifum, C. T.; Chang, C.-W. T. Sonication-assisted oligomanoside synthesis. J. Org.
Chem. 2009, 74, 634.
15. Mirjalili, B. B. F.; Bamoniri, A.; Akbari, A. BF3 ꢃ SiO2: An efficient alternative for
synthesis of 14-aryl or alkyl-14H dibenzo[a,j]xanthenes. Tetrahedron Lett. 2008, 49, 6454.
16. Chenbanov, V. A.; Saraev, V. E.; Desenko, S. M.; Cherneko, V. N.; Knyazeva, I. V.;
Groth, U.; Glasnov, T. N.; Kappe, C. O. Tuning of chemo- and regioselectivities in
multicomponent condensations of 5-aminopyrazoles, dimedone, and aldehydes. J. Org.
Chem. 2008, 73, 5110.
17. de Souza, A. L. E.; de Silva, L. C.; Oliveira, B. L.; Antunes, O. A. C. Microwave and
ultrasound-assisted Suzuki–Miyaura cross-coupling reactios catalyzed by Pd=PVP. Tetra-
hedron Lett. 2008, 49, 3859.
18. Deng, S.; Gangadharmath, U.; Chang, C.-W. T. Sonochemistry: A powerful way of
enhancing the efficiency of carbohydrate synthesis. J. Org. Chem. 2006, 71, 5179.
19. Telvekar, V. N.; Jadhav, N. C. Simple system for oxidation of alcohols in aqueous
solution. Synth. Commun. 2008, 38, 3107.
20. Hu, M.; Li, J.; Yao, S. Q. In situ ‘‘click’’ assembly of small molecule matrix metallopro-
tease inhibitors containing zinc-chelating groups. Org. Lett. 2008, 10, 5529.
21. Tao, C. Z.; Cui, X.; Li, J.; Liu, A. X.; Liu, L.; Guo, Q. X. Copper-catalyzed synthesis of
aryl azides and 1-acyl-1,2,3-triazoles from boronic acids. Tetrahedron Lett. 2007, 48, 3525.
22. Ohba, Y.; Kubo, S.; Nakai, M.; Nagai, A.; Yashimoto, M. Synthesis of the 3H-azepines
utilizing the thermolysis of substituted aryl azides. Bull. Chem. Soc. Jpn. 1986, 59, 2317.