Synthesis of diazonaphthoquinones from naphthols by diazo-transfer reaction with 2-azido-1,3-dimethylimidazolinium chloride

Article abstract of DOI:10.1055/s-0030-1258568

An efficient synthetic method for the synthesis of diazonaphthoquinones from naphthols is described. A variety of diazonaphthoquinones were synthesized from the corresponding naphthols by the diazo transfer with 2-azido-1,3- dimethylimidazolinium chloride prepared by the reaction of 2-chloro-1,3- dimethylimidazorinium chloride and sodium azide. Georg Thieme Verlag Stuttgart New York.

Full text of DOI:10.1055/s-0030-1258568

LETTER
2503
Synthesis of Diazonaphthoquinones from Naphthols by Diazo-Transfer
Reaction with 2-Azido-1,3-dimethylimidazolinium Chloride
Synthesis of
Diazonapit
Department of Applied Chemistry, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu-shi, Fukuoka, 804-8550, Japan
Fax +81(93)8843304; E-mail: kita@che.kyutech.ac.jp
Received 22 July 2010
(route b).7 Although the diazo-transfer reaction is widely
Abstract: An efficient synthetic method for the synthesis of diazo-
used for the synthesis of acyclic a-diazo carbonyl com-
naphthoquinones from naphthols is described. A variety of diazo-
pounds,8 this is not a popular synthetic method for synthe-
naphthoquinones were synthesized from the corresponding
sis of diazoquinone (route c).6c,9 However, this method is
naphthols by the diazo transfer with 2-azido-1,3-dimethylimidazo-
linium chloride prepared by the reaction of 2-chloro-1,3-dimeth- convenient for the synthesis of diazoquinone, because
ylimidazorinium chloride and sodium azide.
phenol is more readily available than aminophenol deriv-
atives and o-quinones. To our knowledge, 2-azido-3-eth-
ylbenzothiazolium tetrafluoroborate (2) developed by
Balli et al. is the most efficient reagent for the diazo trans-
fer in the synthesis of diazoquinone.9 Using the thiazoli-
um salt 2, 1-diazo-2(1H)naphthalenone (3) has been
synthesized from 2-naphthol, while the yield is not high
(22%).
Key words: azides, diazo compounds, diazonaphthoquinone, diazo
transfer, quinone diazide
1,2-Diazoquinone derivatives 1 have attracted consider-
able attention because of their unique structure and reac-
tivity (Scheme 1).1 These compounds can be drawn diazo-
keto and diazonium phenolate resonance forms (1a and
1b, respectively) and exhibit characteristic reactivity like
on the basis of both the forms. For examples, like diazoni-
um salts, diazoquinones are employed for azo-coupling2
and transition-metal-catalyzed cross-coupling reactions.3
On the other hand, like a-diazocarbonyl compounds,
Wolff rearrangements have been reported,4 and these
rearrangements have been widely investigated for the de-
velopment of photoresists such as novolak-diazonaphtho-
quinone resist, which plays a crucial role in the
microminiaturization of electronics.5
Recently, we have reported that 2-azido-1,3-dimethylimi-
dazolinium chloride (4) is an efficient diazo-transfer re-
agent for 1,3-dicarbonyl compounds.10 In further study on
the diazo-transfer reaction with the imidazolinium salt 4,
we found that the salt has a good ability to mediate diazo
transfer to naphthols. In this letter, we describe the out-
come of this investigation.
Initially, the reaction of the azidoimidazolinium salt 4 and
2-naphthol was examined (Table 1, entry 1). 2-Naphthol
and triethylamine in THF was added to a solution of azi-
doimidazolinium salt 4 prepared by the reaction of 2-chlo-
ro-1,3-dimethylimidazolinium chloride and sodium azide
NH2
OH
OH
Table 1 Reaction of 2-Azido-1,3-dimethylimidazolinium Chloride
4 with 2- and 1-Naphthola
Cl–
–
route c
route b
N
+
Cl–
Cl
N
route a
naphthol
Et3N
NaN3
N
additive
+
product
MeN
NMe
O
N2
N2
+
MeCN
–20 °C, 30 min
THF, –20 °C
time
MeN
NMe
O
O
O–
4
1b
1a
Entry Naphthol
Additive
Time (min) Yield (%)b
Scheme 1 Synthesis of 1,2-diazoquinone derivatives
1
2
3
4
2-naphthol
2-naphthol
1-naphthol
1-naphthol
none
60
20
40
30
3 86
3 87
5 76
5 83
15-crown-5c
none
Generally 1,2-diazoquinones are synthesized from ami-
nophenols and o-quinones that are prepared from the cor-
responding phenol derivatives, by diazotization of
aminophenol derivatives and their successive deprotona-
tion (route a)1,6 and the monosulfonylhydrazonation of o-
quinones and the successive elimination of sulfinic acid
15-crown-5c
a The reactions were carried out by adding 0.9 mmol of naphthol and
1.8 mmol of Et3N in THF (4 mL) to 1.35 mmol azidoimidazolinium
chloride 4 in MeCN (2 mL) prepared by the reaction of 1.35 mmol of
2-chloro-1,3-dimethylimidazolinium chloride and 1.5 mmol of sodi-
um azide.
SYNLETT 2010, No. 16, pp 2503–2505
x
x
.x
x
.2
0
1
0
b Isolated yield.
Advanced online publication: 14.09.2010
DOI: 10.1055/s-0030-1258568; Art ID: U06910ST
© Georg Thieme Verlag Stuttgart · New York
c Conditions: 0.3 mmol of 15-crown-5 was added.

2504
M. Kitamura et al.
LETTER
Table 2 Synthesis of Diazoquinones by Diazo Transfer with 2-Azi-
do-1,3-dimethylimidazolinium Chloride 4a (continued)
in acetonitrile at –20 °C for 30 minutes. After stirring the
mixture for one hour, 1-diazo-2(1H)naphthalenone (3)
was formed in 86% yield.11–13 In the presence of 15-
crown-5, the reaction mixture became cleaner, and the re-
action was accelerated (entry 2). Next, the similar reaction
using 1-naphthol was examined (entries 3 and 4). In this
case, 2-diazo-1(2H)naphthalenone (5) was obtained re-
gioselectively,14 and the addition of 15-crown-5 was also
effective.
Entry ArOH
Time Product, yield (%)b
(min)
O
O
11
10
N2
14 (86)c,f
Table 2 Synthesis of Diazoquinones by Diazo Transfer with 2-Azi-
do-1,3-dimethylimidazolinium Chloride 4a
OH
e
12
120g
–
Entry ArOH
Time Product, yield (%)b
(min)
a Unless otherwise noted, the reactions were carried out by adding 0.9
mmol of ArOH and 1.8 mmol of Et3N in THF (4 mL) to 1.35 mmol
azidoimidazolinium chloride 4 in MeCN (2 mL) prepared by the re-
action of 1.35 mmol of 2-chloro-1,3-dimethylimidazolinium chloride
and 1.5 mmol of sodium azide in the presence of 15-crown-5 (0.3
mmol).
R5
OH
R5
O
R1
R2
N2
R2
R4
R3
R4
R3
b Isolated yield.
1
2
R3 = OMe; R1, R2, R4, R5 = H
60
60
6 73
c Yield determined by 1H NMR spectroscopy with 1,1,2,2-tetrachlo-
roethane as an internal standard.
R3 = Cl; R1, R2, R4, R5 = H
7 81
8 60
O
d Complex mixture. Any compounds were not identified.
e ArOH was recovered.
R1, R3 = H; R2 = CO2Et
R4, R5 = OMe
3
240
f Anthraquinone was obtained in 7% yield.
g At room temperature.
n-Bu
To examine the scope and limitations of this method, we
investigated the diazotization of various naphthol deriva-
tives (Table 2). 1-Naphthols were examined for this dia-
zo-transfer reaction as shown in entries 1–4. 2-
Nonsubstituted 1-naphthol gave 2-diazo derivatives in
good yields without any influence of the substituent on
C(3) or C(4) on naphthol (entries 1–3). When 1-naphthol
has a substituent at the C(2) position, the reaction became
complex, and 4-diazotized compound 9 was obtained in
23% yield (entry 4). The results of 2-naphthols are sum-
marized in entries 5–10. Various 1-nonsubstituted 2-
naphthols were converted to 1-diazonaphthoquinone in
good yields (entries 5–7); while 1-substituted 2-naphthols
did not yield corresponding diazo compounds (entries 8
and 9). Interestingly, 1-formyl-2-naphthol gave isoox-
azole 13 in 70% yield accompanied by 1-diazonaphtho-
quinone 3 (entry 10). Moreover, anthrone (antracen-9-ol
equivalent) gave the corresponding diazo compound 14 in
good yield (entry 11), while phenol could not be used for
this diazotization (entry 12).
4
R1 = Bu; R2, R3, R4, R5 = H
60
N2
9 23
N2
OH
O
R1
R2
R1
R2
5
6
7
R1 = H, R2 = CO2Me
R1 = H, R2 = CONHPh
R1 = Br, R2 = H
60
60
60
10 75
11 60 (93)c
12 79
R
OH
d
8
9
R = Br
180
120
–
e
R = 2-hydroxy-1-naphthyl
–
In conclusion, we have developed a general method for
the synthesis of diazonaphtoquinone from naphthol deriv-
atives by treatment with 2-azido-1,3-dimethylimidazolin-
ium chloride (4). Because of the ease of preparation of 4
and the common usage of naphthol, this method is likely
to find widespread use in organic synthesis and material
chemistry such as photoresist preparation.
N
O
10 R = CHO
30
13 70
3 10
Further studies on the scope, mechanistic evaluation, and
synthetic applications of this diazo-transfer reaction are in
progress.
Synlett 2010, No. 16, 2503–2505 © Thieme Stuttgart · New York

LETTER
Synthesis of Diazonaphthoquinones
2505
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Wang, J. Tetrahedron 2008, 64, 6577.
Acknowledgment
This work was supported by the Grant-in-Aid from the Ministry of
Education, Culture, Sports, Science, and Technology of Japan.
References and Notes
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2-diazo-1(2H)naphthalenone (5), see ref. 6, 7, and 9, and
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(12) Typical Procedure for the Preparation of 1-Diazo-
2(1H)naphthalenone (3)
[Caution: Although we have never had any trouble with
azidoimidazolinium salt 4, it is potentially explosive.]
To a solution of 2-chloro-1,3-dimethylimidazolinium
chloride (228 mg, 1.35 mmol) in MeCN (2 mL), NaN3 (99.4
mg, 1.5 mmol), and 15-crown-5 ether (0.06 mL, 0.3 mmol)
was added at –20 °C, and the mixture was stirred for 30 min.
2-Naphthol (130 mg, 0.90 mmol) and Et3N (0.25 mL, 1.8
mmol) in THF (4 mL) was added to the mixture, which was
stirred for 20 min. The reaction was quenched with H2O, and
organic materials were extracted three times with CH2Cl2.
The combined extracts were washed with H2O and brine,
and then, dried over anhyd Na2SO4. The solvent was
removed in vacuo to afford crude compounds. The crude
materials were purified by flash column chromatography
(silica gel: hexane–EtOAc = 4:1) to give
diazonaphthoquinone 3 in 86% yield.
(13) Spectral Data for 3
IR (ATR): 2333, 2221, 2084, 1616, 1558, 1479, 1452, 1394,
1346, 1304, 1251, 1203, 819, 613 cm–1. 1H NMR (400 MHz,
CDCl3): d = 7.62 (d, 1 H, J = 9.8 Hz) 7.57 (dd, 1 H, J = 7.8,
1.2 Hz) 7.51 (ddd, 1 H, J = 7.8, 7.8, 1.2 Hz), 7.28 (br d, 1 H,
J = 7.8 Hz), 7.27 (ddd, J = 7.8, 7.8, 1.2 Hz), 6.65 (d, 1 H,
J = 9.8 Hz). 13C NMR (100 MHz, CDCl3): d = 180.2, 140.2,
130.0, 129.7, 127.1, 125.9, 125.6, 124.7, 119.6, 77.2. Anal.
Calcd (%) for C10H6N2O: C, 70.58; H, 3.55; N, 16.46.
Found: C, 70.76; H, 3.70; N, 16.39. Mp 74–75 °C (dec.).
(14) Spectral Data for 5
IR (ATR): 2917, 2850, 2348, 2113, 1689, 1619, 1562 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.33 (d, 1 H, J = 8.0 Hz)
7.59 (ddd, 1 H, J = 8.0, 7.2, 1.4 Hz), 7.49 (d, 1 H, J = 7.2
Hz), 7.47 (ddd, 1 H, J = 8.0, 7.2, 1.4 Hz), 6.89 (d, 1 H,
J = 9.3 Hz), 6.58 (d, 1 H, J = 9.3 Hz). 13C NMR (100 MHz,
CDCl3): d = 180.2, 137.47, 132.6, 129.5, 128.2, 127.2,
125.3, 117.3, 116.2, 74.2. Anal. Calcd (%) for C10H6N2O: C,
70.58; H, 3.55; N, 16.46. Found: C, 70.20; H, 3.68; N, 16.74.
Mp 73.5–74 °C (dec.).
(8) For reviews, see: (a) Regitz, M. Angew. Chem., Int. Ed.
Synlett 2010, No. 16, 2503–2505 © Thieme Stuttgart · New York