Guanidinium iodide/urea hydrogen peroxide-catalyzed azidation of β-dicarbonyl compounds with trimethylsilyl azide

Article abstract of DOI:10.1016/j.tet.2016.07.015

We present an efficient synthesis of α-azido-β-dicarbonyl compounds from β-dicarbonyl compounds and trimethylsilyl azide, catalyzed by guanidinium hypoiodite. The reaction can be run in air at ambient temperature (up to 40?°C) and is not sensitive to moisture. The substrate scope is broad, including cyclic and linear β-dicarbonyl compounds, and the α-azide products are obtained in 55%–99% yield.

Full text of DOI:10.1016/j.tet.2016.07.015

Tetrahedron xxx (2016) 1e5
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Guanidinium iodide/urea hydrogen peroxide-catalyzed azidation of
b-dicarbonyl compounds with trimethylsilyl azide
*
Koji Yasui , Kohei Kojima, Takanari Kato, Minami Odagi, Masaru Kato,
*
Kazuo Nagasawa
Department of Biotechnology and Life Science, Faculty of Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo
184-8588, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
We present an efficient synthesis of a-azido-b-dicarbonyl compounds from b-dicarbonyl compounds and
Received 11 May 2016
Received in revised form 4 July 2016
Accepted 5 July 2016
Available online xxx
trimethylsilyl azide, catalyzed by guanidinium hypoiodite. The reaction can be run in air at ambient
temperature (up to 40 ꢀC) and is not sensitive to moisture. The substrate scope is broad, including cyclic
and linear
b
-dicarbonyl compounds, and the
a-azide products are obtained in 55%e99% yield.
Ó 2016 Published by Elsevier Ltd.
Keywords:
Guanidinium iodide
Hypoiodite
Azidation
Metal-free reaction
CeH functionalization
1. Introduction
b-dicarbonyl compounds to generate CeN bonds in the presence of
a catalytic amount of sodium iodide and a stoichiometric amount of
In recent years, oxidative bond-forming reactions with Ie/IOe
catalytic systems have drawn considerable attention.1 Since hypo-
iodite (represented by IOX or IOe) is easily generated in situ from
iodine or iodide with oxidants under mild conditions, this system
has been used in a variety of oxidative coupling reactions as an
environmentally benign process.2e5 In these catalytic systems, the
powerful oxidizing abilities of hypoiodites enable bond-forming
reactions between nucleophiles without the need for pre-
functionalization. Among reactive nucleophiles, azide anions and
IBX-SO3K as the terminal oxidant (Scheme 1-1).8a Although this
reaction is applicable to a wide range of b-dicarbonyl compounds,
formation of by-products from IBX-SO3K remains an issue. More
recently, Prabhu and co-workers reported hypoiodite-catalyzed
azidation of b-dicarbonyl compounds based on a hypoiodite cata-
lytic system of tetrabutylammonium iodide and a stoichiometric
amount of tert-butyl hydroperoxide under heating (Scheme 1-2).8b
On the other hand, our group has recently reported tri-
azabicyclodecene hypoiodite (TBD$IOH) catalysis for oxidative
nitroalkylation of
-ketoamides under mild conditions,5a and we
considered that a similar approach might be applicable for oxida-
tive -azidation of -dicarbonyl compounds. In this paper, we de-
scribe an operationally simple and environmentally friendly
method for the synthesis of -azido- -dicarbonyl compounds
a-
a
-carbons of carbonyl compounds are an attractive combination to
b
generate synthetically useful -azido carbonyl compounds, which
a
are useful in multistep synthesis as amino acid precursors, or as
precursors for cycloaddition with alkynes, i.e., Huisgen reaction.6e8
However, only two methods have been reported for hypoiodite-
catalyzed oxidative azidation (Scheme 1).8 In 2012, Kirsch and co-
workers reported the reaction of nucleophilic sodium azide and
a
b
a
b
based on an oxidative coupling strategy utilizing a guanidinium
hypoiodite catalytic system (Scheme 1-3).
2. Results and discussion
Initially, we investigated the reactivity of guanidinium iodides in
the oxidative azidation of
and trimethylsilyl azide (TMSN3) (1.1 equiv) in the presence of
b-keto ester 1a, derived from 1-indanone,
* Corresponding authors. Tel./fax: þ81 42 388 7295; e-mail addresses: kyasui@cc.
tuat.ac.jp (K. Yasui), knaga@cc.tuat.ac.jp (K. Nagasawa).
http://dx.doi.org/10.1016/j.tet.2016.07.015
0040-4020/Ó 2016 Published by Elsevier Ltd.
Please cite this article in press as: Yasui, K.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.07.015

2
K. Yasui et al. / Tetrahedron xxx (2016) 1e5
TBD, i.e., TBD$HCl, did not catalyze the reaction at all, iodine anion
is mandatory for the reaction (entry 9). It is noteworthy that this
reaction did not proceed with a stoichiometric amount of trivalent
iodine reagent iodobenzene diacetate (PIDA) or [bis(tri-
fluoroacetoxy)indo]benzene (PIFA) (entries 10, 11).
Among the conditions we examined, the combination of TBD$HI
and UHP, i.e., entry 7, gave the best result. Thus, we next in-
vestigated the scope of the reaction under the optimized condi-
tions. As summarized in Table 2, all of the tested indanone-derived
b-keto esters were converted into the corresponding azide prod-
ucts 2bel in high yields (75%e99%). A bulky substituent at the ester
group did not decrease the yield: 2bed were obtained in 90%e98%
yields. Electron-donating and electron-withdrawing groups as well
as disubstitution on the aromatic group were also tolerated,
affording products in 75%e95% yields (2ee2i). Substrates with
methyl substitution on the aromatic group gave the corresponding
products 2je2l in high yields (95%e99%). Indanone-derived b-keto
amides 1me1o, including Weinreb amide 1n, also gave the corre-
sponding products in high yields (92%e95%). Noteworthy, the re-
action of Weinreb amide 1n was easily scaled-up to 2 g-scale.
Moreover, the reactions of various non-fused
pounds 1qe1s proceeded smoothly, generating the corresponding
compounds 2qe2s in moderate to high yields (70%e92%). Acyclic
b-dicarbonyl com-
b
-
dicarbonyl compounds also provided corresponding azides 2t and
2u in 55% and 85% yields, respectively.
Scheme 1.
a-Azidation of b-dicarbonyl compounds.
Table 2
Scope of the azidation of 1,3-dicarbonyl compoundsa,b
hydrogen peroxide (30%, 1.2 equiv) in acetonitrile (Table 1). As
shown in entry 1, azide 2a was obtained in 94% yield by using the
cyclic guanidinium salt triazabicyclodecene hydroiodide (TBD$HI).
On the other hand, the yield of 2a dropped to 71% when tetrame-
thylguanidinium iodide (TMG$HI) was used (entry 2). To compare
the reactivity of onium iodides, tetrabutylammonium iodide and
pyridinium iodide (Py$HI) were also examined and these catalysts
were found to be less effective for the reaction (66% and 32% yields
of 2a, respectively; entries 3, 4). Next, various oxidants were tested
in the presence of TBD$HI (entries 5e7). In the case of urea hy-
drogen peroxide (UHP), the yield of 2a was increased to 96% (entry
7). With sodium azide as an alternative azide anion source, the
yield of 2a was only 52% (entry 8). Since the hydrochloric acid salt of
Table 1
Optimization of the reactiona
Entry
Onium iodide
Oxidant
Time (h)
Yield of 2a (%)b
c
1
2
3
4
5
6
TBD$HI
TMG$HI
nBu4NI
Py$HI
H2O2
1
2.5
3
94
71
66
32
88
74
96
52
0
c
H2O2
c
H2O2
c
H2O2
3
TBD$HI
TBD$HI
TBD$HI
TBD$HI
TBD$HCl
PIDAf
CHP
TBHPd
UHP
UHP
UHP
d
1.5
3.5
1
2
1
7
8e
9
10
11
1
1
0
0
PIFAf
d
Py$HI¼pyridinium iodide, TMG$HI¼tetramethylguanidinium iodide, TBD$HI¼-
triazabicyclodecene hydroiodide, TBHP¼tert-butyl hydroperoxide, CHP¼cumene
hydroperoxide, UHP¼urea hydrogen peroxide.
a
Reaction conditions: b-keto ester 1a (0.1 mmol), TMSN3 (0.11 mmol), onium iodide
(0.01 mmol), oxidant (0.12 mmol), MeCN (1.0 mL), under air, at room temperature.
b
a
Isolated yield.
30% H2O2 was used.
70% TBHP in H2O was used.
NaN3 (1.1 equiv) was used instead of TMSN3.
Reaction conditions: β-dicarbonyl compound (0.1 mmol), TMSN3 (0.11
c
mmol), TBD·HI (0.01 mmol), UHP (0.12 mmol), MeCN (1 mL), in air, at
room temperature. b Isolated yield. c 2.30 g (9.12 mmol) scale. d TMSN3 (0.22
mmol), TBD·HI (0.02 mmol), UHP (0.24 mmol) at 40 °C.
d
e
f
A stoichiometric amount of trivalent iodine reagent (0.12 mmol) was used.
Please cite this article in press as: Yasui, K.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.07.015

K. Yasui et al. / Tetrahedron xxx (2016) 1e5
3
The mechanism of this reaction was examined (Scheme 2).
Firstly, hypoiodite IOe should be generated by reaction of Ie with
urea hydrogen peroxide (Scheme 2-1).2g This hypoiodite species
the combined organic layer was washed with brine, dried over
MgSO4. After removing solvent under reduced pressure, the residue
was purified by flash column chromatography (n-hexane/ethyl
acetate¼1:1) to afford title compound 1n as a white solid (2.35 g,
would react with b
-ketoester 1a to form iodoenolate 3,2a followed
by nucleophilic azidation with trimethylsilyl azide (Scheme 2-2). It
is also possible that the hypoiodite species reacts first with trime-
thylsilyl azide to form iodine azide, followed by nucleophilic re-
96% yield). 1H NMR (300 MHz, CDCl3)
d
7.73 (d, J¼7.5 Hz, 1H), 7.59
(td, J¼7.5, 0.9 Hz, 1H), 7.48 (d, J¼7.5 Hz, 1H), 7.36 (t, J¼7.5 Hz, 1H),
4.28 (dd, J¼8.4, 3.9 Hz, 1H), 3.46 (dd, J¼17.1, 3.9 Hz, 1H), 3.32 (dd,
action with
b-ketoester 1a (Scheme 2-3). It is noteworthy that,
J¼17.1, 8.4 Hz, 1H), 3.26 (s, 3H); 13C NMR (75 MHz, CDCl3)
d 201.5,
under the optimized conditions (Table 1, entry 9), addition of
a radical scavenger such as dibutylhydroxytoluene (BHT) did not
affect the azidation reaction of 1a, since 2a was still obtained in 98%
yield. Thus, a radical mechanism is ruled out.
170.2, 154.2, 135.5, 135.0, 127.5, 126.4, 124.3, 61.6, 50.1, 32.2, 30.6;
FTIR (neat) 3019, 2360, 1716, 1654, 1216, 755, 669 cmꢂ1; HRMS (ESI,
MþNa) calcd for C12H13N1Na1O3 242.0793, found 242.0799.
4.2.2. 2-(Piperidine-1-carbonyl)-2,3-dihydro-1H-inden-1-one
ꢀ
(1o). To a suspension of activated MS4A (600 mg) in toluene
(10 mL) was added
b-ketoester 1a (380 mg, 2.00 mmol) and pi-
peridine (397 L, 4.00 mmol) under N2 atmosphere. The resulting
m
mixture was heated at 70 ꢀC for 20 h. The reaction mixture was then
cooled to ambient temperature, and filtered through a pad of Celite,
and the filtrates were concentrated in vacuo. The residue was pu-
rified by column chromatography on silica gel (n-hexane/ethyl ac-
etate, 9:1 to 2:1 as eluent) to give title compound 1o as a white
solid (400 mg, 82%). 1H NMR (300 MHz, CDCl3)
d
7.64 (d, J¼7.5 Hz,
1H), 7.58 (td, J¼7.5, 1.2 Hz, 1H), 7.49 (d, J¼7.5 Hz, 1H), 7.34 (t,
J¼7.5 Hz, 1H), 4.93 (dd, J¼7.5, 3.6 Hz, 1H), 3.88e3.80 (m, 1H), 3.80
(dd, J¼17.4, 3.6 Hz, 1H), 3.80e3.68 (m, 1H), 3.66e3.53 (m, 1H),
3.53e3.40 (m, 1H), 3.28 (dd, J¼17.4, 7.5 Hz, 1H), 1.95e1.50 (m, 6H);
Scheme 2. Proposed mechanism of the azidation reaction.
13C NMR (75 MHz, CDCl3)
d 201.7, 166.0, 154.6, 135.4, 135.1, 127.4,
126.4, 124.2, 50.4, 47.6, 43.6, 30.6, 26.5, 25.6, 24.5; FTIR (neat) 3019,
2360, 1216, 750, 669 cmꢂ1
HRMS (ESI, MþNa) calcd for
15H17N1Na1O2 266.1157, found 266.1196.
3. Conclusion
;
C
In conclusion, we have developed a method for synthesis of
azido- -dicarbonyl compounds based on oxidative azidation of
a
b
-
-
b
4.3. Synthesis of
a
-azido-b-dicarbonyl compounds
dicarbonyl compounds in the presence of hypoiodite generated
from UHP as an oxidant and a catalytic amount of TBD$HI. A wide
range of b-dicarbonyl compounds is available for the reaction under
General procedure for
a
-azidation of
b
-dicarbonyl compounds.
these conditions. This direct and simple oxidative catalytic reaction
is expected to be a powerful and practically useful approach to
obtain a-azido-substituted b-dicarbonyl compounds.
4.3.1. Methyl 2-azido-1-oxo-2,3-dihydro-1H-indene-2-carboxylate
(2a). To a stirred solution of -dicarbonyl compound 1a (19.0 mg,
0.100 mmol) in acetonitrile (1.0 mL) was added TBD$HI (2.7 mg,
0.01 mmol), TMSN3 (14.5 L, 0.11 mmol) and UHP (11.3 mg,
0.12 mmol) at ambient temperature. After stirring for 1 h at this
temperature, the reaction was quenched with a 10% aqueous so-
lution of Na2S2O3. The aqueous layer was extracted with ethyl ac-
etate (ꢁ2) and the combined organic layer was washed with brine
and then dried over MgSO4. After removing solvent under reduced
pressure, the residue was purified by flash column chromatography
b
m
4. Experimental section
4.1. General remarks
Flash chromatography was performed using silica gel 60
(spherical, particle size 0.040e0.100 mm; Kanto Co., Inc., Japan). 1H
and 13C NMR spectra were recorded on JEOL EX300, ECA/ECX400
instruments. Chemical shifts in chloroform-d was reported in the
(n-hexane/ethyl acetate¼5:1) to afford
a-azido-b-dicarbonyl com-
pound 2a (22.2 mg, 96% yield). NMR data correspond to the re-
ported values.7c (Detail of the reaction conditions was shown in
Table 2).
scale relative to chloroform-d (1H NMR;
d
d
¼7.26 ppm, 13C NMR;
¼77.0 ppm) as an internal reference. Data for 1H NMR were re-
ported as follows: chemical shift (
d
ppm), multiplicity (s¼singlet,
d¼doublet, t¼triplet, q¼quartet, m¼multiplet, br¼broad), coupling
4.3.2. Isopropyl 2-azido-1-oxo-2,3-dihydro-1H-indene-2-
carboxylate (2c). The title compound was synthesized according
constant (Hz), integration. Data for 13C NMR were reported in terms
of chemical shift (d ppm). IR spectra were measured on JASCO FT/IR-
420 spectrometer. Mass spectra were recorded on JEOL JMS-T100X
spectrometer.
to the general procedure from
b-dicarbonyl compound 1c (93%
yield, colorless oil). 1H NMR (400 MHz, CDCl3)
d
7.83 (d, J¼7.2 Hz,
1H), 7.68 (t, J¼7.2 Hz, 1H), 7.48e7.43 (m, 2H), 5.13 (dq, J¼6.0, 6.0 Hz,
1H), 3.65 (d, J¼17.6 Hz, 1H), 3.02 (d, J¼17.6 Hz, 1H), 1.26 (d, J¼6.0 Hz,
4.2. Synthesis of
b-dicarbonyl compounds 1
3H),1.24 (d, J¼6.0 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d 197.5, 168.0,
152.1, 136.3, 133.0,128.3, 126.4, 125.6, 71.1, 70.1, 38.4, 21.6, 21.5; FTIR
(neat) 3020, 2116, 1744, 1718, 1216, 756, 669 cmꢂ1; HRMS (ESI,
MþNa) calcd for C13H13N3Na1O3 282.0855, found 282.0846.
4.2.1. N-Methoxy-N-methyl-1-oxo-2,3-dihydro-1H-indene-2-
carboxamide (1n). To a stirred solution of 1-indanone (1.47 g,
11.2
mmol)
and
N-methoxy-N-methyl-1H-imidazole-1-
carboxamide (5.20 g, 33.5 mmol) in THF (110 mL), was added
NaH (4.48 g, 112 mmol) at ambient temperature under N2 atmo-
sphere. The reaction mixture was then heated to 60 ꢀC. After stir-
ring for 30 min, the reaction mixture was cooled to 0 ꢀC and water
was added. The water layer was extracted with ethyl acetate (ꢁ3),
4.3.3. Methyl 2-azido-5-chloro-1-oxo-2,3-dihydro-1H-indene-2-
carboxylate (2f). The title compound was synthesized according
to the general procedure from
yield, white solid). 1H NMR (300 MHz, CDCl3)
1H), 7.47 (d, J¼1.2 Hz, 1H), 7.44 (dd, J¼8.4, 1.2 Hz, 1H), 3.81 (s, 3H),
b
-dicarbonyl compound 1f (80%
d
7.75 (d, J¼8.4 Hz,
Please cite this article in press as: Yasui, K.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.07.015

4
K. Yasui et al. / Tetrahedron xxx (2016) 1e5
3.65 (d, J¼17.7 Hz, 1H), 3.01 (d, J¼17.7 Hz, 1H); 13C NMR (75 MHz,
3H), 3.56 (d, J¼17.1 Hz, 1H), 2.92 (d, J¼17.1 Hz, 1H), 2.42 (s, 3H); 13
C
CDCl3)
d
196.0, 168.5, 153.4, 143.2, 131.4, 129.3, 126.7, 126.6, 70.1,
NMR (75 MHz, CDCl3) d 197.6, 169.0, 151.0, 137.0, 135.8, 132.7, 128.6,
53.7, 38.1; FTIR (neat) 3446, 3020, 2115, 1755, 1721, 1600, 1216, 769,
669 cmꢂ1; HRMS (ESI, MþNa) calcd for C11H8Cl1N3Na1O3 288.0152,
found 288.0145.
123.0, 70.0, 53.5, 37.5, 17.7; FTIR (neat) 3020, 2112, 1752, 1718, 1609,
1437, 1330, 1216, 1052, 752, 669 cmꢂ1; HRMS (ESI, MþNa) calcd for
C12H11N3Na1O3 268.0698, found 268.0686.
4.3.4. Methyl 2-azido-5-bromo-1-oxo-2,3-dihydro-1H-indene-2-
4.3.10. 2-Azido-N-benzyl-1-oxo-2,3-dihydro-1H-indene-2-
carboxylate (2g). The title compound was synthesized according
carboxamide (2m). The title compound was synthesized according to
to the general procedure from
b
-dicarbonyl compound 1g (80%
the general procedure from
b-dicarbonyl compound 1m (95% yield,
yield, white solid). 1H NMR (300 MHz, CDCl3)
d
7.69 (d, J¼8.4 Hz,
pale yellow solid). 1H NMR (300 MHz, CDCl3)
d
7.82 (d, J¼7.8 Hz, 1H),
1H), 7.66 (s, 1H), 7.60 (d, J¼8.4 Hz, 1H), 3.81 (s, 3H), 3.65 (d,
7.70 (t, J¼7.2 Hz, 1H), 7.52 (d, J¼7.5 Hz, 1H), 7.45 (t, J¼7.8 Hz, 1H),
7.39e7.27 (m, 5H), 7.10 (br, 1H), 4.51 (dd, J¼15.0, 6.0 Hz, 1H), 4.45 (dd,
J¼17.7 Hz, 1H), 3.02 (d, J¼17.7 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d
196.2, 168.5, 153.4, 132.2, 131.8, 129.8, 126.7, 70.0, 53.7, 38.1; FTIR
J¼15.0, 6.0 Hz, 1H), 4.05 (d, J¼17.1 Hz, 1H), 3.26 (d, J¼17.1 Hz, 1H); 13
C
(neat) 2114, 1755, 1721, 1595, 1263, 1179, 1058, 909 cmꢂ1; HRMS
(ESI, MþNa) calcd for
11H881Br1N3Na1O3 333.9626 and
11H879Br1N3Na1O3 331.9647, found 333.9604 and 331.9617.
NMR (75 MHz, CDCl3) d 198.0, 166.2, 152.4, 137.2, 136.7, 133.3, 128.8,
C
128.4, 127.7, 127.6, 126.4, 125.4, 72.7, 44.0, 37.6; FTIR (neat) 3019, 2115,
1724, 1678, 1608, 1528, 1216, 759, 668 cmꢂ1; HRMS (ESI, MþNa) calcd
for C17H14N4Na1O2 329.1014, found 329.1058.
C
4.3.5. Methyl 2-azido-5,6-dimethoxy-1-oxo-2,3-dihydro-1H-indene-
2-carboxylate (2h). The title compound was synthesized according
4.3.11. 2-Azido-N-methoxy-N-methyl-1-oxo-2,3-dihydro-1H-indene-
to the general procedure from
b
-dicarbonyl compound 1h (83%
2-carboxamide (2n). The title compound was synthesized accord-
yield, pale yellow solid). 1H NMR (400 MHz, CDCl3)
d
7.66 (s, 1H),
ing to the general procedure from
b-dicarbonyl compound 1n (92%
7.60 (s, 1H), 4.39 (s, 3H), 4.32 (s, 3H), 4.21 (s, 3H), 3.98 (d, J¼17.6 Hz,
yield, white solid). 1H NMR (300 MHz, CDCl3)
d
7.87 (d, J¼7.2 Hz,
1H), 3.34 (d, J¼17.6 Hz, 1H); 13C NMR (100 MHz, CDCl3)
d
195.6,
1H), 7.66 (t, J¼7.2 Hz, 1H), 7.45 (t, J¼7.2 Hz, 1H), 7.44 (d, J¼7.2 Hz,
1H), 3.44 (d, J¼17.1 Hz, 1H), 3.25 (s, 3H), 3.23 (s, 3H), 3.05 (d,
169.2, 157.0, 150.2, 147.9, 125.6, 107.1, 105.4, 70.6, 56.4, 56.2, 53.5,
38.2; FTIR (neat) 3022, 2112, 1749, 1707, 1592, 1505, 1464, 1439,
1320, 1275, 1133, 1104, 1051, 749, 668 cmꢂ1; HRMS (ESI, MþNa)
calcd for C13H13N3Na1O5 314.0753, found 314.0768.
J¼17.1 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d 196.6, 168.8, 150.8, 135.7,
133.6, 128.1, 126.4, 125.1, 71.6, 59.8, 38.4, 32.9; FTIR (neat) 2924,
2116, 1717, 1671, 1457, 986, 691 cmꢂ1; HRMS (ESI, MþNa) calcd for
C12H12N4Na1O3 283.0807, found 283.0805.
4.3.6. Methyl 6-azido-5-oxo-6,7-dihydro-5H-indeno[5,6-d][1,3]diox-
ole-6-carboxylate (2i). The title compound was synthesized
4.3.12. 2-Azido-2-(piperidine-1-carbonyl)-2,3-dihydro-1H-inden-1-
according to the general procedure from
b
-dicarbonyl compound 1i
one (2o). The title compound was synthesized according to the
(95% yield, pale yellow solid). 1H NMR (300 MHz, CDCl3)
d
7.12 (s,
general procedure from
b-dicarbonyl compound 1o (92% yield,
1H), 6.82 (s, 1H), 6.11 (s, 2H), 3.80 (s, 3H), 3.54 (d, J¼17.1 Hz, 1H),
white solid). 1H NMR (300 MHz, CDCl3)
d
7.85 (d, J¼7.6 Hz, 1H), 7.65
2.89 (d, J¼17.1 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d
195.0, 169.0,
(td, J¼7.6, 1.2 Hz, 1H), 7.44 (t, J¼7.6 Hz, 1H), 3.75e3.25 (m, 4H), 3.47
155.8, 150.2, 149.1, 127.3, 105.5, 103.5, 102.8, 70.6, 53.5, 38.3; FTIR
(neat) 3020, 2360, 2112, 1749, 1713, 1473, 1319, 1268, 1216, 1040,
759, 669 cmꢂ1; HRMS (ESI, MþNa) calcd for C12H9N3Na1O5
298.0440, found 298.0452.
(d, J¼17.1 Hz, 1H), 3.14 (d, J¼17.1 Hz, 1H); 13C NMR (75 MHz, CDCl3)
d
197.6, 165.7, 150.0, 136.0, 133.7, 128.5, 126.4, 125.5, 71.7, 38.6, 25.8,
24.4; FTIR (neat) 3015, 2944, 2861, 2107, 1724,1636,1443,1216, 908,
759, 667 cmꢂ1; HRMS (ESI, MþNa) calcd for C15H16N4Na1O2
307.1171, found 307.1136.
4.3.7. Methyl 2-azido-6-methyl-1-oxo-2,3-dihydro-1H-indene-2-
carboxylate (2j). The title compound was synthesized according
4.3.13. Methyl 2-azido-1-oxo-1,2,3,4-tetrahydronaphthalene-2-car-
to the general procedure from
b
-dicarbonyl compound 1j (99%
7.62 (s, 1H),
boxylate (2p). The title compound was synthesized according to
yield, pale yellow solid). 1H NMR (300 MHz, CDCl3)
d
the general procedure from
b-dicarbonyl compound 1p (84% yield,
7.50 (d, J¼7.8 Hz, 1H), 7.35 (d, J¼7.8 Hz, 1H), 3.79 (s, 3H), 3.66 (d,
brown oil). 1H NMR (300 MHz, CDCl3)
d
8.10 (d, J¼7.8 Hz,1H), 7.55 (t,
J¼17.4 Hz, 1H), 2.98 (d, J¼17.4 Hz, 1H), 2.42 (s, 3H); 13C NMR
J¼7.5 Hz, 1H), 7.37 (t, J¼7.5 Hz, 1H), 7.27 (d, J¼7.5 Hz, 1H), 3.85 (s,
3H), 3.15 (ddd, J¼16.8, 9.6, 4.8 Hz, 1H), 2.93 (dt, J¼16.8, 4.8 Hz, 1H),
(75 MHz, CDCl3) d 197.3, 169.0, 149.4, 138.6, 137.8, 133.1, 126.1, 125.4,
70.5, 53.5, 38.1, 21.0; FTIR (neat) 3019, 2121, 1752, 1718, 1495, 1435,
1216, 1051, 753, 669 cmꢂ1
HRMS (ESI, MþNa) calcd for
12H11N3Na1O3 268.0698, found 268.0652.
2.62 (ddd, J¼14.8, 9.6, 4.8 Hz, 1H), 2.22 (dt, J¼14.8, 4.8 Hz, 1H); 13
C
;
NMR (100 MHz, CDCl3) d 189.3, 169.1, 143.4, 134.6, 129.9, 128.7,
C
128.6,127.3, 70.9, 53.3, 31.4, 24.8; FTIR (neat) 3020, 2111,1750,1683,
1602, 1436, 1304, 1216, 1072, 754, 669 cmꢂ1; HRMS (ESI, MþNa)
calcd for C12H11N3NaO3 268.0698, found 268.0691.
4.3.8. Methyl 2-azido-5-methyl-1-oxo-2,3-dihydro-1H-indene-2-
carboxylate (2k). The title compound was synthesized according
to the general procedure from
b-dicarbonyl compound 1k (95%
yield, yellow solid). 1H NMR (300 MHz, CDCl3)
d
7.72 (d, J¼8.1 Hz,
Acknowledgements
1H), 7.27 (s, 1H), 7.25 (d, J¼8.1 Hz, 1H), 3.79 (s, 3H), 3.62 (d,
J¼17.7 Hz, 1H), 2.98 (d, J¼17.7 Hz, 1H), 2.47 (s, 3H); 13C NMR
We thank a Grant-in-Aid for Scientific Research on Innovative
Areas ‘Advanced Molecular Transformations by Organocatalysts’
(No. 23105013) from The Ministry of Education, Culture, Sports,
Science and Technology, Japan.
(75 MHz, CDCl3) d 196.7, 169.1,152.5,148.2,130.6,129.7,126.7, 125.4,
70.3, 53.5, 38.3, 22.3; FTIR (neat) 3021, 2122, 1752, 1719, 1270, 1217,
758, 668 cmꢂ1; HRMS (ESI, MþNa) calcd for C12H11N3Na1O3
268.0698, found 268.0687.
4.3.9. Methyl 2-azido-4-methyl-1-oxo-2,3-dihydro-1H-indene-2-
carboxylate (2l). The title compound was synthesized according
Supplementary data
to the general procedure from
yield, pale yellow solid). 1H NMR (300 MHz, CDCl3)
J¼7.5 Hz, 1H), 7.49 (d, J¼7.5 Hz, 1H), 7.37 (t, J¼7.5 Hz, 1H), 3.81 (s,
b
-dicarbonyl compound 1l (99%
d
7.67 (d,
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2016.07.015.
Please cite this article in press as: Yasui, K.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.07.015

K. Yasui et al. / Tetrahedron xxx (2016) 1e5
5
Middleton, K. R.; Zhu, C.; Nemykin, V. N.; Zhdankin, V. V. Angew. Chem., Int. Ed.
2012, 51, 8059; (f) Cai, Z. J.; Wang, S. Y.; Ji, S. J. Org. Lett. 2013, 15, 5226; (g) Wang,
R.; Liu, H.; Yue, L.; Zhang, X.; Tan, Q.; Pan, R. Tetrahedron Lett. 2014, 55, 2233; (h)
Zhang, X.; Wang, M.; Li, P.; Wang, L. Chem. Commun. 2014, 50, 8006.
4. For cycloaddition reactions, see: (a) Wong, Y. C.; Tseng, C. T.; Kao, T. T.; Yeh, Y. C.;
Shia, K. S. Org. Lett. 2012, 14, 6024; (b) Xie, J.; Jiang, H.; Cheng, Y.; Zhu, C. Chem.
Commun. 2012, 48, 979; (c) Kloeckner, U.; Finkbeiner, P.; Nachtsheim, B. J. J. Org.
Chem. 2013, 78, 2751; (d) Yoshimura, A.; Zhu, C.; Middleton, K. R.; Todora, A. D.;
Kastern, B. J.; Maskaev, A. V.; Zhdankin, V. V. Chem. Commun. 2013, 49, 4800; (e)
Huang, H. M.; Li, Y. J.; Ye, Q.; Yu, W. B.; Han, L.; Jia, J. H.; Gao, J. R. J. Org. Chem.
2014, 79, 1084.
References and notes
1. For reviews, see: (a) Uyanik, M.; Ishihara, K. ChemCatChem 2012, 4, 177; (b)
Hypervalent Iodine Chemistry: Preparation, Structure, and Synthetic Applications of
Polyvalent Iodine Compounds; Zhdankin, V. V., Ed.; John Wiley & Sons: Chichester,
2013; (c) Samanta, R.; Matcha, K.; Antonchick, A. P. Eur. J. Org. Chem. 2013, 5769;
(d) Wu, X. F.; Gong, J. L.; Qi, X. Org. Biomol. Chem. 2014, 12, 5807; (e) Liu, D.; Lei, A.
Chem.dAsian J. 2015, 10, 806.
2. For selected example of CeO bond-forming reactions at a-positions of carbonyls,
see: (a) Uyanik, M.; Okamoto, H.; Yasui, T.; Ishihara, K. Science 2010, 328, 1376;
(b) Uyanik, M.; Suzuki, D.; Yasui, T.; Ishihara, K. Angew. Chem., Int. Ed. 2011, 50,
5331 Angew. Chem. 2011, 123, 5443; (c) Wei, W.; Wang, Y.; Yin, J.; Xue, J.; Li, Y.
Org. Lett. 2012, 14, 1158; (d) Wei, L.; Xue, J.; Liu, H.; Wang, W.; Li, Y. Org. Lett. 2012,
14, 5302; (e) Guo, S.; Yu, J. T.; Dai, Q.; Yang, H.; Cheng, J. Chem. Commun. 2014, 50,
6240; (f) Boominathan, S. S. K.; Hu, W. P.; Senadi, G. C.; Vandavasi, J. K.; Wang, J. J.
Chem. Commun. 2014, 50, 6726; (g) Uyanik, M.; Hayashi, H.; Ishihara, K. Science
2014, 345, 291 Benzylic position, see; (h) Huang, J.; Li, L. T.; Li, H. Y.; Husan, E.;
Wang, P.; Wang, B. Chem. Commun. 2012, 48, 10204; (i) Niu, L.; Yang, H.; Yang, D.;
Fu, H. Adv. Synth. Catal. 2012, 354, 2211; (j) Majji, G.; Guin, S.; Gogoi, A.; Rout, S.
K.; Patel, B. K. Chem. Commun. 2013, 49, 3031; (k) Liu, L.; Yun, L.; Wang, Z.; Fu, X.;
Yan, C. H. Tetrahedron Lett. 2013, 54, 5383 Other examples, see; (l) Chen, L.; Shi,
E.; Liu, Z.; Chen, S.; Wei, W.; Li, H.; Xu, K.; Wan, X. Chem.dEur. J. 2011, 17, 4085;
(m) Xue, Q.; Xie, J.; Xu, P.; Hu, K.; Cheng, Y.; Zhu, C. ACS Catal. 2013, 3, 1365; (n)
Yu, H.; Shen, J. Org. Lett. 2014, 16, 3204; (o) Xu, W.; Nachtsheim, B. Org. Lett. 2015,
17, 1585.
5. For CeC bond-forming reaction at the a-position of carbonyls, see: (a) Yasui, K.;
Kato, T.; Kojima, K.; Nagasawa, K. Chem. Commun. 2015, 51, 2290 Benzylic po-
sition, see; (b) Rodrìguez, A.; Moran, W. J. Org. Lett. 2011, 13, 2220; (c) Nobuta, T.;
Fujiya, A.; Yamaguchi, T.; Tada, N.; Miura, T.; Itoh, A. RSC Adv. 2013, 3, 10189; (d)
Nobuta, T.; Tada, N.; Fujiya, A.; Kariya, A.; Miura, T.; Itoh, A. Org. Lett. 2013, 15,
574; (e) Dhineshkumar, J.; Lamani, M.; Alagiri, K.; Prabhu, K. R. Org. Lett. 2013, 15,
1092 The other example, see; (f) Zhang, C.; Liu, C.; Shao, Y.; Bao, X.; Wan, X.
Chem.dEur. J. 2013, 19, 17917.
€
6. Selected reviews, see: (a) Brase, S.; Gil, C.; Knepper, K.; Zimmermann, V. Angew.
Chem., Int. Ed. 2005, 44, 5188; (b) Organic Azides: Syntheses and Applications;
€
ꢁ
Brase, S., Banert, K., Eds.; Wiley: Chichester, 2009; (c) Patonay, T.; Konya, K.;
ꢁ
ꢁ
ꢁ
Juhasz-Toth, E. Chem. Soc. Rev. 2011, 40, 2797.
7. Selected recent examples of -azidation of b-dicarbonyl compounds, see: (a)
a
Kashinath, D.; Budin, G.; Baati, R.; Meunier, S.; Wagner, A. Tetrahedron Lett. 2009,
50, 5379; (b) Shibatomi, K.; Soga, Y.; Narayama, A.; Fujisawa, I.; Iwasa, S. J. Am.
Chem. Soc. 2012, 134, 9836; (c) Vita, M. V.; Waser, J. Org. Lett. 2013, 15, 3246; (d)
Deng, Q.-H.; Bleith, T.; Wadepohl, H.; Gade, L. H. J. Am. Chem. Soc. 2013, 135, 5356;
(e) Galligan, M. J.; Akula, R.; Ibrahim, H. Org. Lett. 2014, 16, 600.
3. For selected example of CeN bond-forming reaction at the
a-position of car-
bonyls, see: (a) Zhang, J.; Jiang, J.; Li, Y.; Zhao, Y.; Wan, X. Org. Lett. 2013, 15, 3222;
(b) Lv, Y.; Li, Y.; Xiong, T.; Lu, Y.; Liu, Q.; Zhang, Q. Chem. Commun. 2014, 50, 2367
Benzylic position, see; (c) Xue, Q.; Xie, J.; Li, H.; Cheng, Y.; Zhu, C. Chem. Commun.
2013, 49, 3700 Other examples, see; (d) Froehr, T.; Sindlinger, C. P.; Kloeckner, U.;
Finkbeiner, P.; Nachtsheim, B. J. Org. Lett. 2011, 13, 3754; (e) Yoshimura, A.;
8. (a) Harschneck, T.; Hummel, S.; Kirsch, S. F.; Klahn, P. Chem.dEur. J. 2012, 18,
1187; (b) Dhineshkumar, J.; Prabhu, K. R. Eur. J. Org. Chem. 2016, 447.
Please cite this article in press as: Yasui, K.; et al., Tetrahedron (2016), http://dx.doi.org/10.1016/j.tet.2016.07.015