Efficient synthesis of azo dye labeled terpenes, sugars, and steroids using N-(4-arylazobenzoyl)-1H-benzotriazoles

Article abstract of DOI:10.1055/s-0029-1216786

N-(4-Arylazobenzoyl)-1H-benzotriazoles react with hydroxyterpenes, sugars, and steroids in the presence of 1,8-diazabicyclo[ 5.4.0]undec-7-ene (DBU) at room temperature in tetrahydrofuran to afford azo dye labeled terpenes, sugars, and steroids (45-82% yi

Full text of DOI:10.1055/s-0029-1216786

1708
PAPER
Efficient Synthesis of Azo Dye Labeled Terpenes, Sugars, and Steroids Using
N-(4-Arylazobenzoyl)-1H-benzotriazoles
Synthesis of
A
zo D
l
ye
L
ab
a
ele
d
T
erpe
n
nes, Sugars, and
S
t
R
eroids . Katritzky,*a Srinivasa R. Tala,a Nader E. Abo-Dya,a,b Zakaria K. Abdel-Samiib
a
Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
Fax +1(352)3929199; E-mail: katritzky@chem.ufl.edu
b
Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt
Received 13 November 2008; revised 29 December 2008
DMAP;11 (ii) acyl chlorides;7c,8a,9,12 (iii) diazotization of
aminobenzoates;6 (Scheme 1) and (iv) triphenylphos-
phine and diethyl azodicarboxylate.7c Optimum esterifica-
tion procedures require simple, stoichiometric procedures
with mild reaction conditions that do not affect other func-
tionalities and preserve the chirality of reagents. Methods
(i)–(iv) above do not meet all these requirements and we
now describe mild and efficient methods to label hydroxy-
terpenes, sugars, and steroids with azo dye carboxylic
acids.
Abstract: N-(4-Arylazobenzoyl)-1H-benzotriazoles react with
hydroxyterpenes, sugars, and steroids in the presence of 1,8-diaza-
bicyclo[5.4.0]undec-7-ene (DBU) at room temperature in tetrahy-
drofuran to afford azo dye labeled terpenes, sugars, and steroids
(45–82% yield).
Key words: azo dyes, acylations, steroids, sugars, terpenes
Azo dyes1 of biomolecules have become increasingly im-
portant because of their widespread utility as fluorescent
labels, quenchers and spectators for molecular recogni-
tion,2 for the facilitation of DNA molecular assembly,3
and for biochemical reactions4 and analysis.5 Azo dye la-
beled steroids play significant roles in liquid crystal
synthesis6 and act as thermally reversible gelators of or-
ganic fluids.7 Azo dye labeled terpenes can reversibly
control helical pitch in cholesteric materials,8a and have
been utilized as polymer-dispersed liquid crystal compos-
ite films.8b Azo dye labeled sugars have been used for sep-
aration and structure identification,9a and azo dye labeled
glycopyranosides may photoisomerize and interact with
lectin.9b
N-Acylbenzotriazoles are advantageous for N-, O-, C-, S-
acylation,13 especially where the corresponding acid chlo-
rides are unstable or difficult to prepare.14 Recently we re-
ported convenient preparations of azo dye labeled amino
acids and amines utilizing N-(4-arylazobenzoyl)-1H-ben-
zotriazoles 1.15 Herein, we describe convenient prepara-
tions of azo dye labeled diverse hydroxy compounds
utilizing N-(4-arylazobenzoyl)-1H-benzotriazoles 1 under
mild reaction conditions.
Treatment of N-(4-arylazobenzoyl)-1H-benzotriazoles 115
with equimolar amounts of hydroxyterpenes 2a–d, sugars
2e–g, and steroids 2h–j in the presence of equimolar
amounts of 1,8-diazabicyclo[5.4.0]undec-7-ene in tet-
rahydrofuran at room temperature afforded azo dye la-
beled terpenes 3a–i, sugars 3j–p, and steroids 3q–w in
Published routes for the labeling of hydroxyterpenes, sug-
ars, and steroids with azo dye carboxylic acids have used
(i) coupling reagents such as DCC, DMAP;8b,10 EDCl,
O
O
R1
R1
N
N
N
N
Cl
OH
ref. 7c,8a,9,12
R2OH
PPh3
R2OH,
EtOCON=NCOOEt
ref. 7c
base
O
R1
N
N
OR2
DCC, DMAP
ref. 8b,10
diazotization
ref. 6
R2OH
EDCI, DMAP
ref. 11
O
O
R1
R1
N
N
H2N
+
OR2
OH
Scheme 1
SYNTHESIS 2009, No. 10, pp 1708–1714
x
x.
x
x
.
2
0
0
9
Advanced online publication: 27.04.2009
DOI: 10.1055/s-0029-1216786; Art ID: M07108SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of Azo Dye Labeled Terpenes, Sugars, and Steroids
1709
Table 1 Reactions of N-(4-Arylazobenzoyl)-1H-benzotriazoles
1a–c with Hydroxy-Substituted Terpenes 2a–d To Yield Azo Dye
Labeled Terpenes 3a–i
good yields (Scheme 2, Tables 1– 3). These reactions
were completed in 12–36 hours (Tables 1– 3). Acylations
of both primary and secondary alcohols proceeded well
under these mild reaction conditions. Azo dye labeled ter-
penes 3a–i, sugars 3j–p, and steroids 3q–w were charac-
Entry
1
Terpene 2
Timea Yieldb
Mp (°C)
(h)
(%)
1
terized by H and 13C NMR and elemental analysis. No
racemization occurred in the case of chiral alcohols. Re-
tention of chirality of the azo dye labeled terpenes, sugars,
and steroids 3 was supported by chiral HPLC analysis us-
ing a Chirobiotic T column (MeOH, flow rate 1.0 mL/
min, detection at 254 nm,). Azo dye labeled terpenes, sug-
ars, and steroids 3 showed a single peak in HPLC analysis
(Table 4).
1
1a
12
82 (3a) 38–40
OH
geraniol (2a)
2
1a
24
64 (3b) 171–173
OH
(–)-menthol (2b)
O
DBU
R1
N N
R2OH
+
Bt
2, R2 = terpenyl,
sugar or
steroidal residue
THF, r.t.
3
4
1a
1a
24
12
75 (3c) 116–118
81 (3d) 82–84
1a, R1 = (Me)2N
1b, R1 = H
1c, R1 = OMe
OH
(+)-borneol (2c)
O
R1
N
N
OR2
OH
3,
45–82%
nerol (2d)
5
6
7
8
9
1b geraniol (2a)
12
12
24
24
12
82 (3e) 40–42
72 (3f) 38–40
59 (3g) 102–104
45 (3h) 45–47
82 (3i) 41–43
Scheme 2
1b nerol (2d)
N-(4-Arylazobenzoyl)-1H-benzotriazoles 1 are stable
crystalline reagents of choice especially when the corre-
sponding acid chlorides are unstable or difficult to isolate.
In comparison with literature data, our method utilizes: (i)
mild reaction conditions; (ii) yields of 45–82% (average
for 23 reactions is 65%); (iii) no racemization for chiral
compounds.
1b (+)-borneol (2c)
1b (–)-menthol (2b)
1c geraniol (2a)
a At room temperature.
b Isolated product yield.
Table 2 Reactions of N-(4-Arylazobenzoyl)-1H-benzotriazoles 1a–c with Sugars 2e–g To Yield Azo Dye Labeled Sugars 3j–p
Entry
1
Sugar 2
Timea (h)
Yieldb (%)
Mp (°C)
HO
O
O
O
O
1
1a
12
76 (3j)
158–160
O
1,2:3,4-di-O-isopropylidene-a-D-galactopyranose (2e)
O
O
O
2
3
1a
1a
24
24
68 (3k)
132–135
213–215
OH
O
O
1,2:5,6-di-O-isopropylidene-a-D-glucofuranose (2f)
O
O
O
O
65 (3l)
O
OH
2,3:5,6-di-O-isopropylidene-a-D-mannofuranose (2g)
Synthesis 2009, No. 10, 1708–1714 © Thieme Stuttgart · New York

1710
A. R. Katritzky et al.
PAPER
Table 2 Reactions of N-(4-Arylazobenzoyl)-1H-benzotriazoles 1a–c with Sugars 2e–g To Yield Azo Dye Labeled Sugars 3j–p (continued)
Entry
1
Sugar 2
Timea (h)
Yieldb (%)
53 (3m)
49 (3n)
Mp (°C)
98–100
98–99
4
5
6
7
1b
1b
1b
1c
1,2:5,6-di-O-isopropylidene-a-D-glucofuranose (2f)
2,3:5,6-di-O-isopropylidene-a-D-mannofuranose (2g)
1,2:3,4-di-O-isopropylidene-a-D-galactopyranose (2e)
1,2:3,4-di-O-isopropylidene-a-D-galactopyranose (2e)
24
24
12
12
70 (3o)
119–121
146–148
76 (3p)
a At room temperature.
b Isolated product yield.
Table 3 Reactions of N-(4-Arylazobenzoyl)-1H-benzotriazoles 1a–c with Steroids 2h–j To Yield Azo Dye Labeled Steroids 3q–w
Entry
1
Steroid 2
Timea (h)
Yieldb (%)
Mp (°C)
H
1
1a
24
71 (3q)
215–217
H
H
HO
cholesterol (2h)
H
H
H
2
3
1a
1a
24
24
70 (3r)
238–240
218–220
H
H
HO
H
stigmasterol (2i)
H
61 (3s)
H
H
HO
b-sitosterol (2j)
4
5
6
7
1b
1b
1b
1c
cholesterol (2h)
stigmasterol (2i)
b-sitosterol (2j)
cholesterol (2h)
36
36
36
12
55 (3t)
58 (3u)
47 (3v)
75 (3w)
186–188
202–204
184–186
178–180
a At room temperature.
b Isolated product yield.
Starting materials and solvents were purchased from common com-
mercial sources and used without additional purification. Melting
points were determined on Fisher melting apparatus and are uncor-
rected. Column chromatography was carried out using silica gel
200–425 mesh. HPLC analyses were performed on Shimadzu SPD-
20-A using a Chirobiotic T column with detection at 254 nm, a flow
rate of 1.0 mL/min and MeOH as the eluting solvent. 1H NMR (300
MHz) and 13C NMR (75 MHz) spectra were recorded on a 300 MHz
NMR spectrometer in CDCl3 or DMSO-d6. Elemental analyses
were performed on a Carlo Erba-1106 instrument. 1-(4-{[4-(Di-
methylamino)phenyl]diazenyl}benzoyl)-1H-benzotriazole (1a), 1-
[4-(phenyldiazenyl)benzoyl]-1H-benzotriazole (1b), and 1-{4-[(4-
methoxyphenyl)diazenyl]benzoyl}-1H-benzotriazole (1c) were
prepared by our previously reported method.15
In conclusion, a convenient and efficient method for the
preparation under mild and simple reaction conditions of
azo dye labeled terpenes, sugars, and steroids has been de-
veloped by reacting N-(4-arylazobenzoyl)-1H-benzotri-
azole with terpenes, sugars, and steroids in the presence of
1,8-diazabicyclo[5.4.0]undec-7-ene at room temperature.
All the azo dye labeled products were obtained under mild
reaction conditions in good yields with no detectable race-
mization for chiral compounds.
Synthesis 2009, No. 10, 1708–1714 © Thieme Stuttgart · New York

PAPER
Synthesis of Azo Dye Labeled Terpenes, Sugars, and Steroids
1711
5.50 (t, J = 6.9 Hz, 1 H), 5.51 (t, J = 6.9 Hz, 1 H), 6.74 (d, J = 8.7
Hz, 2 H), 7.85–7.92 (m, 4 H), 8.14 (d, J = 8.4 Hz, 2 H).
Table 4 HPLC Retention Time and Optical Rotation of Azo Dye
Labeled Terpenes, Sugars, and Steroids
13C NMR (75 MHz, CDCl3): d = 16.8, 17.9, 25.9, 26.5, 39.8, 40.5,
62.2, 111.7, 118.6, 122.2, 124.0, 125.7, 130.8, 132.1, 142.6, 143.9,
153.1, 156.1, 166.6.
23a
Entry
3
[a]D
tRb (min)
6.06
6.05
6.01
4.16
6.16
3.27
6.09
6.01
6.01
4.34
6.10
5.99
6.11
5.80
5.88
5.86
5.83
5.99
1
3a
3c
3g
3h
3j
–21.0
–13.0
–80.0
–47.0
–64.0
–32.0
+61.0
–54.0
+49.0
–34.0
–40.0
+97.0
+80.0
+84.0
+37.0
+20.0
+54.0
+24.0
Anal. Calcd for C25H31N3O2: C, 74.04; H, 7.70; N, 10.36. Found: C,
73.74; H, 8.01; N, 10.31.
2
3
(1S,2R,5S)(E)-2-Isopropyl-5-methylcyclohexyl 4-{[4-(Dimethyl-
amino)phenyl]diazenyl}benzoate (3b)
Orange microcrystals; yield: 0.07 g (64%); mp 171.0–173.0 °C.
4
5
1H NMR (300 MHz, CDCl3): d = 0.81 (d, J = 6.6 Hz, 2 H), 0.94 (d,
J = 6.3 Hz, 6 H), 1.09–1.20 (m, 2 H), 1.56–1.64 (m, 3 H), 1.73 (d,
J = 10.8 Hz, 3 H), 2.00 (t, J = 5.7 Hz, 1 H), 2.14 (d, J = 12.6 Hz, 1
H), 3.12 (s, 6 H), 4.12–5.02 (m, 1 H), 6.76 (d, J = 8.7 Hz, 2 H),
7.86–7.93 (m, 4 H), 8.14 (d, J = 7.8 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 16.8, 21.0, 22.3, 23.9, 26.7, 31.7,
34.5, 40.5, 41.2, 47.5, 75.1, 111.7, 122.1, 125.7, 130.8, 131.9,
132.7, 152.8, 155.2, 165.7.
6
3k
3l
7
8
3m
3n
3o
3p
3q
3r
3s
9
10
Anal. Calcd for C25H33N3O2: C, 73.68; H, 8.16; N, 10.31. Found: C,
73.98; H, 8.53; N, 10.26.
11
(1S,2R,4S)(E)-1,7,7-Trimethylbicyclo[2.2.1]heptan-2-yl 4-{[4-
(Dimethylamino)phenyl]diazenyl}benzoate (3c)
Orange microcrystals; yield: 0.083 g (75%); mp 116.0–118.0 °C.
12
13
1H NMR (300 MHz, CDCl3): d = 0.93 (d, J = 2.1 Hz, 6 H), 0.98 (s,
3 H), 1.12–1.18 (m, 1 H), 1.29–1.47 (m, 2 H), 1.73–1.88 (m, 2 H),
2.13–2.24 (m, 1 H), 2.40–2.55 (m, 1 H), 3.11 (s, 6 H), 5.14 (d, J = 9
Hz, 1 H), 6.76 (d, J = 9.3 Hz, 2 H), 7.84–7.93 (m, 4 H), 8.16 (d,
J = 8.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 13.9, 19.2, 20.0, 27.6, 28.3, 37.1,
40.5, 45.2, 48.1, 49.3, 80.9, 111.7, 122.2, 125.7, 130.7, 131.1,
143.9, 153.1, 156.1, 166.8.
14
15
3t
16
3u
3v
3w
17
18
a (c 1.0, MeOH).
Anal. Calcd for C25H31N3O2: C, 74.04; H, 7.70; N, 10.36. Found: C,
74.04; H, 8.08; N, 10.00.
(Z)-3,7-Dimethylocta-2,6-dienyl 4-{(E)-[4-(Dimethyl-
amino)phenyl]diazenyl}benzoate (3d)
Orange microcrystals; yield: 0.089 g (81%); mp 82.0–84.0 °C.
(E)-1-{4-[(4-Methoxyphenyl)diazenyl]benzoyl}-1H-benzotri-
azole (1c)
Orange microcrystals; yield: 1 g (90%); mp 155–157.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.61 (s, 3 H), 1.68 (s, 3 H), 1.81
(s, 3 H) 2.14–2.23 (m, 4 H), 3.11 (s, 6 H), 4.81 (d, J = 7.2 Hz, 2 H),
5.13 (t, J = 6.3 Hz, 1 H), 5.52 (t, J = 7.2 Hz, 1 H), 6.74 (d, J = 9.3
Hz, 2 H), 7.84–7.92 (m, 4 H), 8.13 (d, J = 8.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 17.9, 23.8, 25.9, 26.9, 32.5, 62.1,
119.3, 122.8, 123.3, 129.4, 130.8, 131.9, 132.4, 132.5, 143.2, 152.8,
155.2, 166.3.
1H NMR (300 MHz, CDCl3): d = 3.92 (s, 3 H), 7.03 (d, J = 8.7 Hz,
2 H), 7.58 (t, J = 7.5 Hz, 1 H), 7.74 (t, J = 7.5 Hz, 1 H), 7.98–8.06
(m, 4 H), 8.18 (d, J = 8.1 Hz, 1 H), 8.38 (d, J = 8.7 Hz, 2 H), 8.44
(d, J = 9.6 Hz, 1 H).
13C NMR (75 MHz, CDCl3): d = 55.9, 114.6, 115.1, 120.5, 122.6,
125.6, 126.7, 130.7, 132.4, 133.2, 146.0, 147.3, 155.8, 163.1, 166.5.
Anal. Calcd for C20H15N5O2: C, 67.22; H, 4.23; N, 19.60. Found: C,
66.97; H, 4.15; N, 19.55.
Anal. Calcd for C25H31N3O2: C, 74.04; H, 7.70; N, 10.36. Found: C,
74.06 H, 8.15; N, 9.69.
Azo Dye Labeled Terpenes 3a–i, Sugars 3j–p, and Steroids
3q–w; General Procedure
(E)-3,7-Dimethylocta-2,6-dienyl 4-[(E)-Phenyldiazenyl]ben-
zoate (3e)
Orange microcrystals; yield: 0.09 g (82%); mp 40.0–42.0 °C.
To a mixture of diazenylbenzotriazole 1 (0.1 g) and hydroxy com-
pound 2 (1 equiv) in anhyd THF (8 mL) was added DBU (1 equiv)
and the mixture was stirred at r.t. for 12–36 h. Solvent was evapo-
rated under reduced pressure and flash chromatography of the crude
product (silica gel, hexanes–EtOAc, 95:5) gave the corresponding
azo dye labeled products 3 in good yield.
1H NMR (300 MHz, CDCl3): d = 1.62 (s, 3 H), 1.69 (s, 3 H), 1.79
(s, 3 H), 2.14 (br s, 4 H), 4.87 (d, J = 6.9 Hz, 2 H), 5.13 (br s, 1 H),
5.05 (t, J = 6.9 Hz, 1 H), 7.52 (d, J = 6.3 Hz, 3 H), 7.94 (d, J = 7.5
Hz, 4 H), 8.19 (d, J = 8.1 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 16.8, 17.9, 25.9, 26.5, 39.8, 62.4,
118.6, 122.8, 123.3, 123.9, 129.4, 130.8, 131.9, 132.1, 132.4, 142.8,
152.8, 155.3, 166.3.
(E)-3,7-Dimethylocta-2,6-dienyl 4-{(E)-[4-(Dimethyl-
amino)phenyl]diazenyl}benzoate (3a)
Orange microcrystals; yield: 0.09 g (82%); mp 82.0–84.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.62 (s, 3 H), 1.69 (s, 3 H), 1.79
(s, 3 H), 2.11–2.16 (m, 4 H), 3.11 (s, 6 H), 4.85 (d, J = 6.9 Hz, 2 H),
Anal. Calcd for C23H26N2O2: C, 76.21; H, 7.23; N, 7.73. Found: C,
76.08; H, 7.51; N, 7.74.
Synthesis 2009, No. 10, 1708–1714 © Thieme Stuttgart · New York

1712
A. R. Katritzky et al.
PAPER
(Z)-3,7-Dimethylocta-2,6-dienyl 4-[(E)-Phenyldiazenyl]ben-
zoate (3f)
1 H), 4.67 (dd, J = 2.4, 7.8 Hz, 1 H), 5.58 (d, J = 7.8 Hz, 1 H), 6.76
(d, J = 9.3 Hz, 2 H), 7.84–7.91 (m, 4 H), 8.15 (d, J = 8.7 Hz, 2 H).
Orange microcrystals; yield: 0.08 g (72%); mp 35.0–37.0 °C.
13C NMR (75 MHz, CDCl3): d = 24.7, 25.2, 26.2, 26.3, 40.5, 64.2,
66.4, 70.8, 70.9, 71.4, 96.6, 109.1, 109.9, 111.7, 122.2, 125.7,
130.2, 130.9, 143.9, 153.1, 156.3, 166.4.
1H NMR (300 MHz, CDCl3): d = 1.63 (s, 3 H), 1.70 (s, 3 H), 1.83
(s, 3 H), 2.13–2.24 (m, 4 H), 4.85 (d, J = 7.2 Hz, 2 H), 5.14 (t,
J = 7.2 Hz, 1 H), 5.53 (t, J = 7.2 Hz, 1 H), 7.51–7.57 (m, 3 H), 7.94–
7.98 (m, 4 H), 8.20 (d, J = 8.7 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 17.9, 23.8, 25.9, 26.9, 32.4, 62.1,
119.3, 122.8, 123.3, 123.7, 129.4, 130.8, 131.9, 132.4, 132.5 143.2,
152.7, 155.2, 166.3.
Anal. Calcd for C27H33N3O7: C, 63.39; H, 6.50; N, 8.21. Found: C,
63.48; H, 6.73; N, 8.15.
4-O-(4-{(E)-[4-(Dimethylamino)phenyl]diazenyl}benzoyl)-
1,2:5,6-di-O-isopropylidene-a-D-glucofuranose (3k)
Orange microcrystals; yield: 0.09 g (68%); mp 132.0–135.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.27 (s, 3 H), 1.33 (s, 3 H), 1.42
(s, 3 H), 1.56 (s, 3 H), 3.11 (s, 6 H), 4.08–4.18 (m, 2 H), 4.32–4.42
(m, 2 H), 4.66 (d, J = 3.9 Hz, 1 H), 5.51 (d, J = 2.7 Hz, 1 H), 5.98
(d, J = 3.6 Hz, 1 H), 6.75 (d, J = 9.0 Hz, 2 H), 7.85–7.92 (m, 4 H),
8.12 (d, J = 8.4 Hz, 2 H).
Anal. Calcd for C23H26N2O2: C, 76.21; H, 7.23; N, 7.73. Found: C,
76.28; H, 7.56; N, 7.69.
(1S,2R,4S)(E)-1,7,7-Trimethylbicyclo[2.2.1]heptan-2-yl 4-(Phe-
nyldiazenyl)benzoate (3g)
Orange microcrystals; yield: 0.065 g (59%); mp 102.0–104.0 °C.
1H NMR (300 MHz, CDCl3): d = 0.95 (s, 6 H), 1.00 (s, 3 H), 1.14–
1.20 (m, 1 H), 1.32–1.49 (m, 2 H), 1.77–1.85 (m, 2 H), 2.13–2.18
(m, 1 H), 2.47–2.55 (m, 1 H), 5.16 (d, J = 9.3 Hz, 1 H), 7.54 (d,
J = 6.3 Hz, 3 H), 7.96–7.99 (m, 4 H), 8.20–8.24 (m, 2 H).
13C NMR (75 MHz, CDCl3): d = 16.7, 21.0, 22.2, 23.8, 26.7, 31.6,
34.5, 41.1, 47.4, 75.4, 122.8, 123.3, 129.4, 130.8, 131.8, 132.7,
152.7, 155.2, 165.7.
13C NMR (75 MHz, CDCl3): d = 25.4, 26.4, 26.9, 27.0, 40.5, 67.5,
72.8, 76.9, 80.2, 83.6, 105.3, 109.6, 111.6, 112.5, 122.2, 122.3,
125.8, 129.5, 130.9, 133.0, 143.8, 153.2, 156.5, 165.1.
Anal. Calcd for C27H33N3O7: C, 63.39; H, 6.50; N, 8.21. Found: C,
63.69; H, 6.59; N, 8.59.
2,3:5,6-Di-O-isopropylidene-a-D-mannofuranosyl (4-{(E)-[4-
(Dimethylamino)phenyl]diazenyl}benzoate (3l)
Orange microcrystals; yield: 0.09 g (65%); mp 213.0–215.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.39 (s, 6 H), 1.47 (s, 3 H), 1.54
(s, 3 H), 3.11 (s, 6 H), 4.05–4.18 (m, 3 H), 4.42–4.49 (m, 1 H), 4.89–
4.98 (m, 2 H), 6.39 (s, 1 H), 6.76 (d, J = 9.0 Hz, 2 H), 7.87 (d,
J = 8.4 Hz, 2 H), 7.91 (d, J = 9.0 Hz, 2 H), 8.11 (d, J = 8.4 Hz, 2 H).
Anal. Calcd for C23H26N2O2: C, 76.21; H, 7.23; N, 7.73. Found: C,
76.22; H, 7.58; N, 7.69.
(1S,2R,5S)(E)-2-Isopropyl-5-methylcyclohexyl 4-(Phenyldiaze-
nyl)benzoate (3h)
Orange microcrystals; yield: 0.05 g (45%); mp 45.0–47.0 °C.
1H NMR (300 MHz, CDCl3): d = 0.83 (d, J = 6.9 Hz, 3 H), 0.88–
1.01 (m, 7 H), 1.09–1.22 (m, 2 H), 1.56–1.64 (m, 2 H), 1.68–1.77
(m, 2 H), 1.97–2.02 (m 1 H), 2.15–2.19 (m, 1 H), 4.94–5.02 (m, 1
H), 7.53–7.58 (m, 3 H), 7.95 (d, J = 7.8 Hz, 4 H), 8.20–8.22 (d,
J = 8.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 13.8, 19.2, 20.0, 27.6, 28.3, 37.1,
45.2, 48.1, 49.3, 81.1, 122.8, 123.4, 129.4, 130.7, 131.9, 132.8
152.8, 155.3, 166.5.
13C NMR (75 MHz, CDCl3): d = 24.9, 25.3, 26.2, 27.2, 37.6, 40.5,
67.1, 73.1, 79.6, 82.8, 85.4, 101.8, 103.6, 109.6, 111.6, 122.2,
125.8, 129.4, 131.0, 143.8, 152.2, 156.5, 164.9.
Anal. Calcd for C27H33N3O7: C, 63.39; H, 6.50; N, 8.21. Found: C,
63.12; H, 6.73; N, 7.85.
4-O-(4-{(E)-[Phenyldiazenyl]benzoyl})-1,2:5,6-di-O-isopropyl-
idene-a-D-glucofuranose (3m)
Orange microcrystals; yield: 0.08 g (53%); mp 98.0–100.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.29 (s, 3 H), 1.34 (s, 3 H), 1.43
(s, 3 H), 1.58 (s, 3 H), 4.13–4.23 (m, 2 H), 4.36–4.49 (m, 2 H), 4.72
(d, J = 4.2 Hz, 1 H), 5.59 (d, J = 2.7 Hz, 1 H), 6.03 (d, J = 3.9 Hz, 1
H), 7.53–7.59 (m, 3 H), 7.95–7.99 (m, 4 H), 8.17–8.20 (m, 2 H).
Anal. Calcd for C23H23N2O2: C, 75.79; H, 7.74; N, 7.69. Found: C,
76.08; H, 8.01; N, 7.67.
(E)-3,7-Dimethylocta-2,6-dienyl 4-[(E)-(4-Methoxyphenyl)diaz-
enyl]benzoate (3i)
Orange microcrystals; yield: 0.09 g (82%); mp 41.0–43.0 °C.
13C NMR (75 MHz, CDCl3): d = 25.4, 26.4, 26.9, 27.1, 67.5, 72.8,
77.1, 80.2, 83.6, 105.3, 109.7, 112.6, 123.0, 123.4, 129.4, 130.9,
131.3, 132.1, 152.7, 155.6, 164.9.
1H NMR (300 MHz, CDCl3): d = 1.61 (s, 3 H), 1.68 (s, 3 H), 1.79
(s, 3 H), 2.07–2.15 (m, 4 H), 3.90 (s, 3 H), 4.87 (d, J = 6.9 Hz, 2 H),
5.11 (t, J = 6.3 Hz, 1 H), 5.50 (t, J = 6.9 Hz, 1 H), 7.02 (d, J = 8.7
Hz, 2 H), 7.93 (m, 4 H), 8.18 (d, J = 8.7 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 16.8, 17.9, 25.9, 26.5, 39.8, 55.8,
62.3, 114.5, 118.5, 122.5, 123.9, 125.4, 130.8, 131.8, 132.1, 142.7,
147.2, 155.5, 162.8, 166.4.
Anal. Calcd for C25H28N2O7: C, 64.09; H, 6.02; N, 5.98. Found: C,
63.80; H, 6.20; N, 5.90.
2,3:5,6-Di-O-isopropylidene-a-D-mannofuranosyl 4-[(E)-Phen-
yldiazenyl]benzoate (3n)
Orange microcrystals; yield: 0.07 g (49%); mp 98.0–100 °C.
Anal. Calcd for C24H28N2O3: C, 73.44; H, 7.19; N, 7.14. Found: C,
73.74; H, 7.49; N, 7.07.
1H NMR (300 MHz, CDCl3): d = 1.40 (s, 6 H), 1.49 (s, 3 H), 1.55
(s, 3 H), 4.07–4.20 (m, 3 H), 4.45–4.50 (m, 1 H), 4.91–4.93 (m, 1
H), 4.97–5.00 (m, 1 H), 6.41 (s, 1 H), 7.54 (d, J = 5.7 Hz, 3 H), 7.97
(d, J = 7.5 Hz, 4 H), 8.17 (d, J = 8.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 24.9, 25.4, 26.2, 27.2, 67.1, 73.1,
79.6, 82.9, 85.4, 102.0, 109.6, 113.6, 122.00, 123.4, 129.4, 131.0,
131.2, 132.1, 152.7, 155.6, 164.6.
6-O-(4-{(E)-[4-(Dimethylamino)phenyl]diazenyl}benzoyl)-
1,2:3,4-di-O-isopropylidene-a-D-galactopyranose (3j)
Orange microcrystals; yield: 0.105 g (76%); mp 158.0–160.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.34 (s, 3 H), 1.37 (s, 3 H), 1.48
(s, 3 H), 1.53 (s, 3 H), 3.11 (s, 6 H), 4.18–4.22 (m, 1 H), 4.34–4.37
(m, 2 H), 4.45 (dd, J = 7.2, 11.4 Hz, 1 H), 4.55 (dd, J = 5.1, 11.4 Hz,
Anal. Calcd for C25H28N2O7: C, 64.09; H, 6.02; N, 5.98. Found: C,
63.77; H, 6.02; N, 5.84.
Synthesis 2009, No. 10, 1708–1714 © Thieme Stuttgart · New York

PAPER
Synthesis of Azo Dye Labeled Terpenes, Sugars, and Steroids
1713
6-O-(4-[(E)-Phenyldiazenyl]benzoyl}-1,2:3,4-O-isopropylidene-
a-D-galactopyranose (3o)
Orange microcrystals; yield: 0.1 g (70%); mp 119.0–121.0 °C.
b-Sitost-6-en-3-yl 4-{(E)-[4-(Dimethylamino)phenyl]diaze-
nyl}benzoate (3s)
Orange microcrystals; yield 0.105 g (61%); mp 218.0–220.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.40 (s, 3 H), 1.42 (s, 3 H), 1.55
(s, 3 H), 1.59 (s, 3 H), 4.24–4.29 (m, 1 H), 4.39–4.43 (m, 2 H), 4.52
(dd, J = 7.5, 11.4 Hz, 1 H), 4.62 (dd, J = 4.8, 11.4 Hz, 1 H), 4.72
(dd, J = 2.1, 7.8 Hz, 1 H), 5.63 (d, J = 5.1 Hz, 1 H), 7.53–7.62 (m,
3 H), 7.97–8.02 (m, 4 H), 8.25 (d, J = 8.4 Hz, 2 H).
1H NMR (300 MHz, CDCl3): d = 0.71 (s, 3 H), 0.82–0.89 (m, 10 H),
0.93 (d, J = 6.0 Hz, 3 H), 1.04–1.09 (m, 6 H), 1.15–1.34 (m, 11 H),
1.48–1.61 (m, 6 H), 1.70–2.05 (m, 6 H), 2.50 (d, J = 6.9 Hz, 2 H),
3.12 (s, 6 H), 4.84–4.94 (m, 1 H), 5.44 (s, 1 H), 6.77 (d, J = 9.0 Hz,
2 H), 7.85–7.93 (m, 4 H), 8.15 (d, J = 8.1 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 24.7, 25.2, 26.2, 26.3, 64.4, 66.4,
70.7, 70.9, 71.4, 96.5, 103.6, 109.0, 109.9, 122.8, 123.4, 129.4,
131.0, 131.9, 152.7, 155.4, 166.1.
13C NMR (75 MHz, CDCl3): d = 11.9, 12.0, 18.8, 19.1, 19.4, 19.9,
21.1, 23.1, 24.3, 26.1, 27.9, 28.3, 29.2, 31.9, 32.0, 34.0, 36.2, 36.7,
37.1, 38.3, 39.8, 40.3, 42.3, 45.9, 50.1, 56.1, 56.7, 74.7, 111.5,
121.9, 122.8, 125.5, 130.5, 130.9, 139.7, 143.7, 152.9, 155.9, 165.8.
Anal. Calcd for C25H28N2O7: C, 64.09; H, 6.02; N, 5.98. Found: C,
63.90; H, 6.23; N, 5.73.
Anal. Calcd for C44H63N3O2: C, 79.35; H, 9.53; N, 6.31. Found: C,
79.45; H, 9.58; N, 6.14.
6-O-{4-[(E)-(4-Methoxyphenyl)diazenyl]benzoyl}-1,2:3,4-di-O-
isopropylidene-a-D-galactopyranose (3p)
Cholest-6-en-3-yl 4-[(E)-Phenyldiazenyl]benzoate (3t)
Orange microcrystals; yield: 0.1 g (55%); mp 186.0–188.0 °C
(Lit.7c 310.0 °C).
1H NMR (300 MHz, CDCl3): d = 0.66–0.74 (m, 3 H), 0.83–1.42 (m,
26 H), 1.42–1.68 (m, 6 H), 1.72–1.88 (m, 2 H), 1.92–2.06 (m, 4 H),
2.50 (d, J = 8.1 Hz, 2 H), 4.86–4.96 (m, 1 H), 5.45 (br s, 1 H), 7.50–
7.59 (m, 3 H), 7.94–7.98 (m, 4 H), 8.20 (d, J = 8.4 Hz, 2 H).
Orange microcrystals; yield: 0.1 g (76%); mp 146.0–148.0 °C.
1H NMR (300 MHz, CDCl3): d = 1.34 (s, 3 H), 1.36 (s, 3 H), 1.49
(s, 3 H), 1.53 (s, 3 H), 3.89 (s, 3 H), 4.19–4.22 (m, 1 H), 4.33–4.37
(m, 2 H), 4.46 (dd, J = 7.5, 11.4 Hz, 1 H), 4.56 (dd, J = 4.8, 11.4 Hz,
1 H), 4.66 (dd, J = 2.4, 7.8 Hz, 1 H), 5.58 (d, J = 7.8 Hz, 1 H), 7.02
(d, J = 9 Hz, 2 H), 7.88–7.96 (m, 4 H), 8.18 (d, J = 8.1 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 24.7, 25.2, 26.2, 26.3, 55.8, 64.3,
66.4, 70.7, 70.9, 71.3, 96.5, 109.0, 109.9, 114.5, 122.5, 125.4,
130.9, 131.3, 147.2, 155.6, 162.9, 166.2.
13C NMR (75 MHz, CDCl3): d = 12.1, 18.9, 19.6, 21.3, 22.8, 23.1,
24.0, 24.5, 28.1, 28.2, 28.5, 32.2, 32.0, 36.0, 36.4, 36.9, 37.2, 38.4,
39.7, 39.9, 42.5, 50.2, 56.3, 56.9, 75.2, 122.8, 123.1, 123.3, 129.0,
129.3, 130,8, 131.9, 132.7, 139.8, 152.8, 155.2, 165.6.
Anal. Calcd for C26H30N2O8: C, 62.64; H, 6.07; N, 5.62. Found: C,
62.90; H, 6.25; N, 5.49.
Anal. Calcd for C40H54N2O2: C, 80.76; H, 9.15; N, 4.71. Found: C,
80.72; H, 9.55; N, 4.69.
Cholest-6-en-3-yl 4-{(E)-[4-(Dimethylamino)phenyl]diaze-
nyl}benzoate (3q)
Stigmasta-6,22-dien-3-yl 4-[(E)-Phenyldiazenyl]benzoate (3u)
Orange microcrystals; yield: 0.11 g (58%); mp 202.0–204.0 °C.
Orange microcrystals; yield: 0.125 g (71%); mp 215.0–217.0 °C
(Lit.7c 302–306 °C).
1H NMR (300 MHz, CDCl3): d = 0.72 (s, 3 H), 0.81–0.88 (m, 10 H),
1.01–1.13 (m, 9 H), 1.16–1.30 (m, 6 H), 1.38–1.63 (m, 6 H), 1.65–
1.80 (m, 2 H), 1.92–2.07 (m, 5 H), 2.50 (d, J = 7.8 Hz, 2 H), 4.85–
4.96 (m, 1 H), 4.99–5.07 (m, 1 H), 5.13–5.22 (m, 1 H), 5.44 (d,
J = 4.2 Hz, 1 H), 7.52–7.58 (m, 3 H), 7.95–7.98 (m, 4 H), 8.20 (d,
J = 2.7 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 12.3, 12.5, 19.2, 19.6, 21.3, 21.4,
21.5, 24.6, 25.7, 28.1, 29.2, 32.1, 32.2, 36.9, 37.3, 38.5, 39.9, 40.8,
42.5, 50.3, 51.5, 56.12, 57.0, 75.2, 122.8, 123.1, 123.4, 129.4,
129.5, 130.8, 131.8, 132.8, 138.6, 139.8, 152.8, 155.2, 165.7.
1H NMR (300 MHz, CDCl3): d = 0.69 (s, 3 H), 0.86 (d, J = 6.6 Hz,
6 H), 0.94 (d, J = 9.6 Hz, 3 H), 0.99-1.04 (m, 3 H), 1.04–1.12 (m, 4
H), 1.15–1.23 (m, 6 H), 1.26–1.29 (m, 2 H), 1.34–1.42 (m, 4 H),
1.45–1.61 (m, 4 H), 1.71–1.84 (m, 2 H), 1.91–2.05 (m, 4 H), 2.48
(d, J = 7.8 Hz, 2 H), 3.11 (s, 6 H), 4.82–4.94 (m, 1 H), 5.42 (d,
J = 4.5 Hz, 1 H), 6.74 (d, J = 9.0 Hz, 2 H), 7.84–7.92 (m, 4 H), 8.13
(d, J = 7.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 12.1, 18.9, 19.6, 21.3, 22.8, 23.1,
24.1, 24.5, 28.1, 28.2, 28.5, 32.1, 32.2, 36.0, 36.4, 36.9, 37.3, 38.5,
39.7, 40.0, 40.5, 42.5, 50.3, 56.3, 56.9, 74.9, 111.7, 122.1, 123.0,
125.7, 130.7, 131.0, 139.9, 143.9, 153.1, 156.1, 165.9.
Anal. Calcd for C42H56N2O2: C, 81.24; H, 9.09; N, 4.51. Found: C,
81.55; H, 9.62; N, 4.50.
Anal. Calcd for C42H59N3O2: C, 79.07; H, 9.64; N, 6.59. Found: C,
78.51; H, 9.77; N, 6.28.
b-Sitost-6-en-3-yl 4-[(E)-Phenyldiazenyl]benzoate (3v)
Orange microcrystals; yield: 0.09 g (47%); mp 184.0–186.0 °C.
Stigmasta-6,22-dien-3-yl 4-{(E)-[4-(Dimethylamino)phenyl]di-
azenyl}benzoate (3r)
Orange microcrystals; yield: 0.12 g (70%); mp 238.0–240.0 °C.
1H NMR (300 MHz, CDCl3): d = 0.70 (s, 3 H), 0.82–0.89 (m, 10 H),
0.93–1.09 (m, 11 H), 1.14–1.33 (m, 11 H), 1.46–1.77 (m, 4 H),
1.80–2.06 (m, 5 H), 2.50 (d, J = 7.8 Hz, 2 H), 4.85–4.98 (m, 1 H),
5.44 (d, J = 3.9 Hz, 1 H), 7.50–7.58 (m, 3 H), 7.95 (d, J = 8.1 Hz, 4
H), 8.20 (d, J = 8.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 12.1, 12.2, 19.0, 19.3, 19.6, 20.0,
21.3, 23.3, 24.5, 26.3, 28.1, 28.47, 29.3, 32.1, 32.2, 34.1, 36.4, 36.9,
37.2, 38.4, 39.9, 42.4 46.03 50.2, 56.2, 56.9, 75.2, 122.8, 123.1,
123.6, 129.4, 130.8, 131.9, 132.7, 139.8, 152.8, 155.2, 165.6.
1H NMR (300 MHz, CDCl3): d = 0.72 (s, 3 H), 0.80–0.87 (m, 10 H),
0.92–1.09 (m, 9 H), 1.16–1.27 (m, 6 H), 1.39–1.62 (m, 8 H), 1.68–
1.84 (m, 2 H), 1.92–2.04 (m, 5 H), 2.49 (d, J = 7.8 Hz, 2 H), 3.12 (s,
6 H), 4.83–4.94 (m, 1 H), 4.99–5.07 (m, 1 H), 5.14–5.22 (m, 1 H),
5.44 (d, J = 3.6 Hz, 1 H), 6.76 (d, J = 9.3 Hz, 2 H), 7.85–7.93 (m, 4
H), 8.14 (d, J = 8.4 Hz, 2 H).
13C NMR (75 MHz, CDCl3): d = 12.3, 12.5, 19.2, 19.6, 21.3, 21.5,
24.6, 25.6, 28.1, 29.2, 32.1, 36.9, 37.3, 38.5, 39.9, 40.5, 40.7, 42.4,
50.3, 51.5, 56.2, 57.0, 74.9, 111.7, 122.1, 13.0, 125.7, 129.5, 130.7,
131.5, 138.6, 139.9,144.0, 153.1, 156.1, 166.0.
Anal. Calcd for C42H58N2O2: C, 80.98; H, 9.38; N, 4.50. Found: C,
81.00; H, 9.95; N, 4.55.
Cholest-6-en-3-yl 4-[(E)-(4-Methoxyphenyl)diazenyl]benzoate
Anal. Calcd for C44H61N3O2: C, 79.59; H, 9.26; N, 6.33. Found: C,
79.63; H, 9.40; N, 6.16.
(3w)
Orange microcrystals; yield: 0.125 g (75%); mp 178.0–180.0 °C
(Lit.7c 302–306 °C).
Synthesis 2009, No. 10, 1708–1714 © Thieme Stuttgart · New York

1714
A. R. Katritzky et al.
PAPER
1H NMR (300 MHz, CDCl3): d = 0.69 (s, 3 H), 0.86 (d, J = 6.6 Hz,
6 H), 0.92 (d, J = 6.6 Hz, 3 H), 0.99–1.18 (m, 12 H), 1.22–1.28 (m,
3 H), 1.34–1.42 (m, 3 H), 1.45–1.60 (m, 5 H), 1.70–2.04 (m, 6 H),
2.48 (d, J = 7.8 Hz, 2 H), 3.90 (s, 3 H), 4.82–4.94 (m, 1 H), 5.43 (d,
J = 4.2 Hz, 1 H), 7.02 (d, J = 9.0 Hz, 2 H), 7.89–7.97 (m, 4 H), 8.17
(d, J = 8.7 Hz, 2 H).
Martinez, K.; Tan, W. Analyst (Cambridge, U.K.) 2005, 130,
1002. (e) Gunnlaugsson, T.; Kelly, J. M.; Nieuwenhuyzen,
M.; O’Brien, M. K. Tetrahedron Lett. 2003, 44, 8571.
(f) Maung, J.; Mallari, J. P.; Girtsman, T. A.; Wu, L. Y.;
Rowley, J. A.; Santiago, N. M.; Brunelle, A. N.; Berkman,
C. E. Bioorg. Med. Chem. 2004, 12, 4969.
(6) (a) Apreutesei, D.; Lisa, G.; Hurduc, N.; Scutaru, D.
J. Therm. Anal. Calorim. 2006, 83, 335. (b) Apreutesei, D.;
Lisa, G.; Akutsu, H.; Hurduc, N.; Nakatsuji, S.; Scutaru, D.
Appl. Organomet. Chem. 2005, 19, 1022.
(7) (a) Kazutara, M.; Aoki, M.; Nishi, T.; Ikeda, A.; Shinkai, S.
J. Chem. Soc., Chem. Commun. 1991, 1715. (b) Ono, Y.;
Nakashima, K.; Sano, M.; Hojo, J.; Shinkai, S. J. Mater.
Chem. 2001, 11, 2412. (c) Murata, K.; Aoki, M.; Suzuki, T.;
Harada, T.; Kawabata, H.; Komori, T.; Ohseto, F.; Ueda, K.;
Shinkai, S. J. Am. Chem. Soc. 1994, 116, 6664.
13C NMR (75 MHz, CDCl3): d = 12.1, 18.9, 19.6, 21.3, 22.8, 23.1,
24.1, 24.5, 28.1, 28.2, 28.5, 32.1, 32.2, 36.0, 36.4, 36.9, 37.3, 38.4,
39.7, 40.0, 42.5, 50.3, 55.8, 56.4, 56.9, 75.1, 114.5, 122.5, 123.1,
125.4, 130.7, 132.1, 139.8, 147.2, 155.5, 162.8, 165.7.
Anal. Calcd for C41H56N2O3: C, 78.80; H, 9.35; N, 4.48. Found: C,
78.52; H, 9.27; N, 4.47.
Acknowledgment
(8) (a) Bobrovsky, A. Y.; Boiko, N. I.; Shibaev, V. P.; Springer,
J. Liq. Cryst. 2001, 28, 919. (b) Liu, J.-H.; Wang, H.-Y.
J. Appl. Polym. Sci. 2004, 91, 789.
We thank Dr. C. D. Hall for helpful discussions.
(9) (a) Coleman, G. H.; Rees, D. E.; Sundberg, R. L.;
McCloskey, C. M. J. Am. Chem. Soc. 1945, 67, 381.
(b) Srinivas, O.; Mitra, N.; Surolia, A.; Jayaraman, N. J. Am.
Chem. Soc. 2002, 124, 2124.
(10) Liu, X.-M.; Yang, B.; Wang, Y.-L.; Wang, J.-Y. Biochim.
Biophys. Acta Biomembr. 2005, 1720, 28.
(11) Gunnlaugsson, T.; Kelly, J. M.; Nieuwenhuyzen, M.;
O’Brien, A. M. K. Tetrahedron Lett. 2003, 44, 8571.
(12) Nutting, W. H.; Jewell, R. A.; Rapoport, H. J. Org. Chem.
1970, 35, 505.
(13) (a) Katritzky, A. R.; Suzuki, K.; Wang, Z. Synlett 2005,
1656. (b) Katritzky, A. R.; Angrish, P.; Suzuki, K. Synthesis
2006, 411. (c) Katritzky, A. R.; Angrish, P.; Hur, D.; Suzuki,
K. Synthesis 2005, 397. (d) Katritzky, A. R.; Suzuki, K.;
Singh, S. K.; He, H.-Y. J. Org. Chem. 2003, 68, 5720.
(e) Katritzky, A. R.; He, H.-Y.; Suzuki, K. J. Org. Chem.
2000, 65, 8210. (f) Katritzky, A. R.; Wang, M.; Yang, H.;
Zhang, S.; Akhmedov, N. G. ARKIVOC 2002, (viii), 134.
(g) Katritzky, A. R.; Shestopalov, A. A.; Suzuki, K.
ARKIVOC 2005, (vii), 36. (h) Katritzky, A. R.; Tala, S. R.;
Singh, S. K. Synthesis 2006, 3231.
References
(1) (a) Natansohn, A.; Rochon, P. Chem. Rev. 2002, 102, 4139.
(b) Pieroni, O.; Fissi, A.; Angelini, N.; Lenci, F. Acc. Chem.
Res. 2001, 34, 9. (c) Ichimura, K. Chem. Rev. 2000, 100,
1847. (d) Leclair, S.; Mathew, L.; Giguere, M.; Motallebi,
S.; Zhao, Y. Macromolecules 2003, 36, 9024. (e)Nakatsuji,
S.; Fujino, M.; Hasegawa, S.; Akutsu, H.; Yamada, J.-i.;
Gurman, V. S.; Vorobiev, A. Kh. J. Org. Chem. 2007, 72,
2021. (f) Philip, B.; Sreekumar, K. J. Polym. Sci.: Part A:
Polym. Chem. 2002, 40, 2868.
(2) (a) Koshi, Y.; Nakata, E.; Yamane, H.; Hamachi, I. J. Am.
Chem. Soc. 2006, 128, 10413. (b) Bergbreiter, D. E.;
Osburn, P. L.; Li, C. Org. Lett. 2002, 4, 737.
(c) Bergbreiter, D. E.; Li, C. Org. Lett. 2003, 5, 2445.
(d) Wang, L. S.; Birembaut, F.; Brocklesby, W. S.; Frey, J.
G.; Bradley, M. Anal. Chem. 2005, 77, 2247.
(3) (a) Kubota, M.; Ono, A. Tetrahedron Lett. 2004, 45, 5755.
(b) Asanuma, H.; Shirasuka, K.; Takarada, T.; Komiyama,
M. J. Am. Chem. Soc. 2003, 125, 2217.
(4) (a) Rose, T. M.; Prestwich, G. D. Org. Lett. 2006, 8, 2575.
(b) Grossmann, T. N.; Seitz, O. J. Am. Chem. Soc. 2006, 128,
15596.
(5) (a) Yang, C. J.; Martinez, K.; Lin, H.; Tan, W. J. Am. Chem.
Soc. 2006, 128, 9986. (b) Yang, C. J.; Martinez, K.; Lin, H.;
Tan, W. J. Am. Chem. Soc. 2005, 127, 12772. (c) Wang, L.;
Yang, C. J.; Medley, C. D.; Benner, S. A.; Tan, W. J. Am.
Chem. Soc. 2005, 127, 15664. (d) Tan, L.; Li, Y.; Drake, T.
J.; Moroz, L.; Wang, K.; Li, J.; Munteanu, A.; Yang, C. J.;
(14) (a) Katritzky, A. R.; Belyakov, S. A. Aldrichimica Acta
1998, 31, 35. (b) Katritzky, A. R.; Li, J.; Xie, J. Tetrahedron
1999, 55, 8263.
(15) Katritzky, A. R.; Chen, Q.-Y.; Tala, S. R. Org. Biomol.
Chem. 2008, 6, 2400.
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