Synthesis of quinolyl- and isoquinolyl heteroarylamines using palladium catalyzed suzuki cross-coupling reaction

Article abstract of DOI:10.3987/COM-05-10496

Quinolyl- and isoquinolylboronic acids are prepared from 5-bromoquinoline and 5-bromoisoquinoline, respectively, via halogen-metal exchange. Suzuki cross-coupling of these compounds with haloheteroarylamine leading to the corresponding heteroarylamine derivatives is described.{A figure is presented}.

Full text of DOI:10.3987/COM-05-10496

HETEROCYCLES, Vol. 65, No. 10, 2005
2505
HETEROCYCLES, Vol. 65, No. 10, 2005, pp. 2505 - 2511
Received, 27th June, 2005, Accepted, 15th August, 2005, Published online, 23rd August, 2005
SYNTHESIS OF QUINOLYL- AND
ISOQUINOLYL HETEROARYLAMINES USING
PALLADIUM CATALYZED SUZUKI
CROSS-COUPLING REACTION
Ihl Young Choi Lee,*,a Myung Hee Jung,a Hee-Jeong Lim,a and Hyo Won Lee*,b
aKorea Research Institute of Chemical Technology, Daejeon, 305-606, Korea
*Corresponding authors. Fax: +82-42-861-1291; e-mail: iychoi@krict.re.kr
bDepartment of Chemistry, Chungbuk National University, Cheongju, Chungbuk
361-763, Korea
Abstract – Quinolyl- and isoquinolylboronic acids are prepared from
5-bromoquinoline and 5-bromoisoquinoline, respectively, via halogen-metal
exchange. Suzuki cross-coupling of these compounds with haloheteroarylamine
leading to the corresponding heteroarylamine derivatives is described.
INTRODUCTION
The palladium catalyzed Suzuki cross-coupling reaction of aryl halides and heteroaryl halides with
boronic acids to construct biaryls and heterobiaryls is well known as one of the most versatile and utilized
reactions in organic synthesis.1 Synthesis of 6-aryl-2,4-diaminopyrimidines and triazines using palladium
catalyzed Suzuki cross-coupling was reported by Cooke et al. in 2001.2 Several groups have described the
palladium-catalyzed Suzuki coupling of quinoline halides or isoquinoline halide with phenylboronic acid
and quinolylboronic acid with aryl halides.3 There are a few examples to the synthesis of quinolylboronic
acid or quinolylboronic ester in the literature,4 but study of isoquinolylboronic acid has not been
published so far.
RESULTS AND DISCUSSION

2506
HETEROCYCLES, Vol. 65, No. 10, 2005
In our ongoing project to synthesize biologically active compounds as potential therapeutic agent for
inhibition of the sodium hydrogen exchanger (NHE),5 we needed to introduce heteroaryl with amino
group onto 5-quinolylboronic acids or 5-isoquinolylboronic acids. Following this strategy, first of all,
bromination of quinoline or isoquinoline gave 5-bromoquinoline (1a) or 5-bromoisoquinoline (1b) as
described in the literature.6 The subsequent reaction was the one-pot reaction composed of lithiation by
halo-metal exchange reaction and addition of trialkyl borate. In our reactions for the preparations of
5-quinolylboronic acid or 5-isoquinolylboronic acids, we found the standard addition of triisopropyl
borate gave poor yields. This difficulty was succumbed by the addition of trimethyl borate to the lithiated
intermediate resulted from the reaction of n-BuLi with bromide (1a-b) in THF at -78 oC. The yields from
1a-b to 2a-b were 45% and 56%, respectively.7
Scheme 1
Y
Y
X
1. n-BuLi, THF, -78 oC
2. Trimethyl borate
3. H2O, rt
X
B
Br
HO
OH
1a: X=C, Y=N
b: X=N, Y=C
2a: X=C, Y=N
b: X=N, Y=C
Cross-coupling reactions of 2a-b with amino heteroaryl halides were investigated under the standard
conditions using sodium carbonate as a base and (tetrakistriphenylphosphino)palladium as a catalyst. The
choice of solvent was important in this reaction. The experimental results were summarized in Table 1.
The coupling reaction seems to be dependent on solvent. At first, DME was our choice of the solvent for
Suzuki coupling reaction. In the case of Entries 1, 2, 7, and 8 , Suzuki coupling did not provide any good
yields due to poor solubility of 6-halo-2,4-diaminopyrimidine or triazine and quinolylboronic acid or
isoquinolylboronic acid in DME. When DME was switched to dioxane, better yields of products were
observed.8
CONCLUSION
Preparation of quinolyl- and isoquinolylboronic acid and their Suzuki cross-coupling reaction with
haloheteroarylamine to get corresponding heteroarylamines in good yields are achieved.
EXPERIMENTAL
1
13
General. H and C NMR spectra were recorded on Bruker AM-300 (300 MHz) and Bruker AM-500
(500 MHz) spectrometer. HRMS spectra were recorded on a Fision 800 Series Gas Chromatograph/Micromass
AutoSpec mass spectrometer. Elemental analyses were obtained using a CE instrument EA-1110
elemental analyzer. THF was distilled from sodium and benzophenone prior to use. Unless otherwise

HETEROCYCLES, Vol. 65, No. 10, 2005
2507
indicated in a specific experiment, all of the chemicals used were reagent grade and no other further
purification has been done. All reactions were carried out in oven dried and flame dried glassware under
nitrogen atmosphere. Analytical chromatography was performed on silica gel 60 F
plates (0.25 mm).
254
Flash chromatography was performed on E. Merck silica gel 230-400 mesh.
Table 1. Suzuki Reaction of 2a -b with Amino Hetero or Aromatic Halides
Boronic
acid
Boronic
acid
Halide
Product
Yield (%)
Yield (%)
49a
Entry
Entry
Halide
Product
NH2
N
NH2
N
Cl
Cl
N
N
N
N
N
90a
N
N
7
N
1
2b
2a
N
N
N
H2N
H2N
N
NH2
NH2
NH2
H2N
N
NH2
NH2
N
N
3
9
NH2
N
NH2
N
Cl
Cl
N
N
60a
N
66a
N
8
9
2
3
N
NH2
NH2
H2N
N
NH2
10
4
Br
Br
N
N
72b
70b
NH2
81b
76b
NH2
NH2
N
N
N
N
N
N
NH2
N
NH2
N
N
5
6
11
12
Br
N
N
Br
Br
NH2
NH2
4
5
10
NH2
NH2
NH2
NH2
N
N
Br
N
N
N
N
N
N
NH2
58b
88b
75b
99b
11
12
N
N
NH2
NH2
N
13
7
8
N
NH2
NH2
6
Br
Br
N
14
N
a: Dioxnae. b: DME
General Procedure for the Preparation of Quinolylboronic acids
To a solution of 5-bromoquinoline (2.00 g, 9.66 mmol) in THF (50 mL) was added n-butyllithium (1.6 M
in hexane, 12.0 mL, 19.2 mmol) dropwise at -78 oC. The reaction mixture was stirred for 45 min at -78 oC,
and then trimethyl borate (3.30 mL, 28.9 mmol) was added quickly. After stirring for 5 min at -78 oC, the
reaction mixture was allowed to warm rt and left to react for an additional hour. The mixture was
quenched by slow addition of 4% NaOH aqueous solution. THF was removed in vacuo and the aqueous
layer was acidified to pH 5-6 by dropwise addition of 3N HCl, keeping the internal temperature below 5
oC. Extraction with ethyl acetate, dryness with Na2SO4, and concentration gave crude crystals, which
were washed with 20% ethyl acetate in hexane to remove nonpolar materials. Crude crystals were
recrystallized with solvents.
5-Quinolylboronic acid (2a) 748 mg (45% yield). White solid (10% methanol in ethyl acetate) mp
183-184 oC; 1H NMR (300 MHz, DMSO-d6) δ 8.87 (d, J = 4.3 Hz, 1H), 8.85 (d, J = 8.3 Hz, 1H), 8.48 (s,

2508
HETEROCYCLES, Vol. 65, No. 10, 2005
2H), 8.03 (d, J = 8.3 Hz, 1H), 7.89 (dd, J = 7.0, 1.1 Hz, 1H), 7.74 (dd, J = 8.3, 7.0 Hz, 1H), 7.52 (dd, J =
8.3, 4.3 Hz, 1H); 13C NMR (125 MHZ, CD3CO2D) δ 150.50, 148.43, 139.11, 130.32, 122.17; Anal. Calcd
for C9H8NO2B: C, 62.49 ; H, 4.66 ; N, 8.10. Found: C, 62.12; H, 4.64; N, 7.87.
o
1
5-Isoquinolylboronic acid (2b): 931 mg (56% yield). White solid (methanol), mp 205 C (decomp); H
NMR (300 MHz, DMSO-d6) δ 9.13 (s, 1H), 8.31-8.29 (m, 3H), 8.14-8.12 (m, 1H), 7.93 (d, J = 8.0 Hz,
1H), 7.88 (dd, J = 7.0, 1.1 Hz,1H), 7.47 (dd, J = 8.0, 7.0 Hz, 1H); 13C NMR (125 MHz, CD3CO2D)
δ 147.9, 144.4, 143.9, 132.2, 131.7, 131.1, 128.9, 127.5; Anal. Calcd for C9H8NO2B: C, 62.49 ; H, 4.66 ;
N, 8.10. Found: C, 62.45 ; H, 4.74; N, 8.21.
Typical Procedure for the Cross Coupling Reactions (Compounds (3-4) and (9-10))
To a mixture of halide (1.0 mmol) and tetrakis(triphenylphosphino)palladium (0.045 mmol relative to
boronic acid) in dioxane (35 mL) was added boronic acid (1.5 mmol) followed by aqueous Na2CO3 (2 M,
1.0 mL). The reaction mixture was heated under reflux for 48 h. After the removal of dioxane in vacuo,
THF was added and the suspension was stirred for 1 h. The mixture was filtered, washed thoroughly with
THF and the filtrate was evaporated under the reduced pressure. Purification of the residue by column
chromatography on silica gel using 10% methanol in dichloromethane provided the corresponding
diamine as a white solid.
General Procedure for the Cross Coupling Reactions (Compounds (5-8) and (11-14))
To a mixture of halide (1.0 mmol) and tetrakis(triphenylphosphino)palladium (0.045 mmol) in DME (35
mL) was added boronic acid (1.5 mmol) followed by aqueous Na2CO3 (2 M, 1.0 mL). The reaction
mixture was heated under reflux for 2-5 h. After the removal of DME in vacuo, THF was added, and the
suspension was stirred for 1 h. The mixture was filtered, washed thoroughly with THF and the filtrate was
evaporated under the reduced pressure. Purification of the residue by column chromatography on silica
gel using ethyl acetate provided the corresponding amine as a white solid.
2,4-Diamino-6-quinolyl-1,3,5-triazine (3): White solid (methanol), mp 305 oC (decomp); IR (KBr) 3296,
3111, 1628, 1537, 1454, 796 cm-1; 1H NMR (500 MHz, DMSO-d6) δ 9.27 (td, J = 8.6, 0.8 Hz, 1H), 8.91
(dd, J = 4.1, 1.6 Hz, 1H), 8.13 ( d, J = 2.7 Hz, 1H), 8.12- 8.09 (m, 2H), 7.81 (dd, J =8.1, 7.6 Hz, 1H), 7.55
(dd, J = 8.6, 4.1 Hz, 1H), 6.90 (br s, 4H); 13C NMR (75 MHz, DMSO-d6) δ 172.4, 167.5, 150.6, 148.2,
135.9, 135.2, 131.6, 128.8, 128.6, 126.2, 121.8; HRMS (EI) Calcd for C12H10N6 (M+) 238.0967, found
238.0964.
o
2,4-Diamino-6-quinolylpyrimidine (4): White solid (methanol), mp 262-264 C; IR (KBr) 3315, 3147,
2958, 1585, 1423, 1423, 802 cm-1; 1H NMR (300 MHz, DMSO-d6) δ 8.92 (d, J = 4.0 Hz, 1H), 8.68 (d, J

HETEROCYCLES, Vol. 65, No. 10, 2005
2509
= 8.4 Hz, 1H), 8.06 (d, J = 8.4 Hz, 1H), 7.79 (t, J = 7.8 Hz, 1H), 7.64 (d, J = 7.1 Hz, 1H), 7.53 (dd, J =
13
8.3, 4.0 Hz, 1H), 6.48 (br s, 2H), 6.08 (br s, 2H), 5.96 (s, 1H); C NMR (75 MHz, DMSO-d6) δ 165.2,
164.0, 163.6, 150.8, 148.2, 138.7, 134.6, 129.9, 129.2, 126.7, 125.9, 121.7, 95.8; HRMS (EI) Calcd for
C13H11N5 (M+) 237.1014, found 237.1014. Anal. Calcd for C13H11N5: C, 65.81 ; H, 4.67 ; N, 29.52.
Found: C, 65.70 ; H, 4.54; N, 29.69.
o
2-Amino-5-quinolylpyrimidine (5): White solid (ethyl acetate), mp 260-261 C; IR (KBr) 3305, 3137,
1643, 1579, 1546, 1401, 806 cm-1; 1H NMR (300 MHz, DMSO-d6) δ 8.94 (d, J = 4.0 Hz, 1H), 8.61 (d, J
= 8.3 Hz, 1H), 8.25 (s, 1H), 8.08 (s, 1H), 8.06 (d, J = 8.3 Hz, 1H), 7.82 ( t, J = 7.6 Hz, 1H), 7.70 (d, J =
7.0 Hz, 1H), 7.53 (dd, J = 8.6, 4.0 Hz, 1H), 6.71 (br s, 2H); 13C NMR (75 MHz, DMSO-d6) δ 155.2, 150.7,
148.6, 142.8, 140.3, 136.2, 134.5, 131.5, 129.3, 129.2, 127.1, 126.3, 121.8; HRMS (EI) Calcd for
C13H10N4 (M+) 222.0905, found 222.0907.
o
2-Amino-5-quinolylpyridine (6): White solid (ethyl acetate), mp 156-157 C; IR (KBr) 3328, 3151,
1
1656, 1604, 1509, 1396 cm-1 ; H NMR (300 MHz, DMSO-d6) δ 9.37(s, 1H), 8.50 (d, J = 6.2 Hz, 1H),
8.11 (d, J = 7.8 Hz, 1H), 8.06 (d, J = 2.4 Hz, 1H), 7.76-7.67 (m, 3H), 7.57 (dd, J = 8.6, 2.4 Hz, 1H), 6.64
(d, J = 8.6 Hz, 1H), 6.22 (br s, 2H); 13C NMR (75 MHz, DMSO-d6) δ 159.7, 153.2, 148.4, 143. 6, 138.7,
136.4, 133.8, 130.9, 129.1, 127.6, 127.0, 122.4, 118.2, 107.9; HRMS (EI) Calcd for C14H11N3 (M+)
221.0953, found 221.0950.
o
2-Amino-5-quinolylpyrazine (7): White solid (ethyl acetate), mp 250-252 C; IR (KBr) 3307, 3141,
1546, 1401, 1396 cm-1 ; 1H NMR (300 MHz, CDCl3) δ 8.93 (d, J = 4.0, 1.2 Hz, 1H), 8.61 (d, J = 8.6 Hz,
1H), 8.25 (br s, 1H), 8.07 (s, 1H), 8.03 (dd, J = 8.5, 0.7 Hz, 1H), 7.79 (td, J = 8.4, 0.6 Hz, 1H), 7.67 (d, J
= 7.1 Hz, 1H), 7.53 (dd, J = 8.6, 4.0 Hz, 1H), 6.72 (br s, 1H); 13C NMR (75 MHz, CDCl3) δ 155.2, 150.7,
148.6, 142.8, 140.2, 136.2, 134.6, 131.5, 129.3, 129.2, 127.1, 126.3, 121.8; HRMS (EI) Calcd for
C13H10N4 (M+) 222.0905, found 222.0908.
o
1-Amino-3-quinolylbenzene (8): White solid (hexane-ethyl acetate), mp 146-147 C; IR (KBr) 3444,
3313, 3201, 3053, 1589, 1500, 1307, 804 cm-1 ;1H NMR (300 MHz, CDCl3) δ 8.91 (dd, J = 4.0, 1.7 Hz,
1H), 8.31 (d, J = 8.6 Hz, 1H), 8.11 (d, J = 8.3 Hz, 1H), 7.73 (dd, J = 8.3, 7.0 Hz, 1H), 7.49 (dd, J = 7.0,
0.8 Hz, 1H), 7.34 (dd, J = 8.6, 4.3 Hz, 1H), 7.27 (dd, J = 8.6, 7.5 Hz, 1H), 6.83 (d, J = 7.50 Hz, 1H),
6.78-6.76 (m, 2H), 3.77 (br s, 2H); 13C NMR (75 MHz, CDCl3) δ 150.6, 148.8, 146.9,141.1, 140.9, 135.1,
129.7, 129.3, 129.1, 127.3, 127.1, 121.4, 120.8, 117.0, 114.7; HRMS (EI) Calcd for C15H12N2 (M+)
220.1000, found 220.1001.
o
2,4-Diamino-6-isoquinolyl-1,3,5-triazine (9): White solid (methanol), mp 275 C (decomp); IR (KBr)
3405, 3309, 3176, 1623, 1539, 1429, 833 cm-1 ; 1H NMR (300 MHz, DMSO- d6) δ 9.41 (s, 1H), 8.82 (d, J
= 6.1 Hz, 1H), 8.51 (d, J = 6.1 Hz, 1H), 8.36 (d, J = 7.1 Hz, 1H), 8.24 (d, J = 7.8 Hz, 1H), 7.75 (t, J = 7.6
Hz, 1H), 6.90 (br s, 4H); 13C NMR (75 MHz, DMSO-d6) δ 172.2, 167.5, 153.2, 143.6, 134.2, 133.4, 132.6,

2510
HETEROCYCLES, Vol. 65, No. 10, 2005
130.6, 129.0, 126.9, 119.4; HRMS (EI) Calcd for C12H10N6 (M+) 238.0967, found 238.0964. Anal. Calcd
for C12H10N6: C, 60.50 ; H, 4.23 ; N, 35.27. Found: C, 60.16 ; H, 4.27 ; N, 34.74 .
o
2,4-Diamino-6-isoquinolylpyrimidine (10): White solid (methanol), mp 259-260 C; IR (KBr) 3415,
3309, 3168, 1619, 1583, 1421, 806 cm-1 ; 1H NMR (500 MHZ, CDCl3) δ 9.34 (s, 1H), 8.50 (d, J = 6.0 Hz,
1H), 8.15 (d, J = 8.2 Hz, 1H), 8.12 (dd, J = 6.0, 0.8 Hz, 1H), 7.82 (d, J = 7.0 Hz, 1H), 7.72 (t, J = 7.6 Hz,
1H), 6.45 (s, 2H), 6.06 (br s, 2H), 5.95 (s, 1H); 13C NMR (75 MHz, CDCl3) δ 165.2, 163.8, 153.1, 143.4,
137.1, 133.1, 130.6, 128.8, 128.7, 118.8, 95.6; HRMS (EI) Calcd for C13H11N5 (M+) 237.1014, found
237.1010. Anal. Calcd for C13H11N5: C, 65.81 ; H, 4.67 ; N, 29.52. Found: C, 65.72; H, 4.51; N, 29.63.
o
2-Amino-5-isoquinolylpyrimidine (11): White solid (ethyl acetate), mp 210-212 C; IR (KBr) 3315,
3139, 3031, 1660, 1598, 1504, 1357, 825 cm-1 ;1H NMR (300 MHz, DMSO-d6) δ 9.39 (s, 1H), 8.53 ( d, J
= 5.9 Hz, 1H), 8.42 (s, 2H), 8.15 (dd, J = 5.9, 3.2 Hz, 1H), 7.77-7.71 (m, 3H), 6.96 (br s, 2H); 13C NMR
(75 MHz, DMSO-d6) δ 161.7, 156.9, 151.5, 142.3, 132.0, 131.6, 129.6, 127.3, 126.0, 119.1, 116.2;
HRMS (EI) Calcd for C13H10N4 (M+) 222.0905, found 222.0904.
2-Amino-5-isoquinolylpyridine (12): White solid (ethyl acetate), mp 180-181 oC; IR (KBr) 3311, 3111,
1645, 1608, 1506, 1396, 804 cm-1 ; 1H NMR (300 MHz, DMSO-d6) δ 8.93 (dd, J = 4.1, 1.4 Hz, 1H), 8.26
(d, J = 8.6 Hz, 1H), 8.05-8.00 (m, 2H), 7.80 (dd, J = 8.6, 7.0 Hz, 1H), 7.56-7.50 (m, 1H), 6.63 (d, J = 8.6
Hz, 1H), 6.20 (br s, 2H); 13C NMR (75 MHz, DMSO-d6) δ 159.7, 150.7, 148.6, 148.5, 138.8, 138.0, 133.9,
129.5, 128.4, 127.2, 126.5, 122.7, 121.9, 107.9; HRMS (EI) Calcd for C14H11N3 (M+) 221.0953, found
221.0954.
o
2-Amino-5-isoquinolylpyrazine (13): White solid (hexane-ethyl acetate), mp 191-192 C; IR (KBr)
3336, 3160, 3023, 1664, 1581, 1546, 1396, 806 cm-1 ; 1H NMR (300 MHz, CDCl3) δ 9.32 (s, 1H), 8.54 (d,
J = 6.2 Hz, 1H), 8.31 (d, J = 1.4 Hz, 1H), 8.19 (d, J = 1.4 Hz, 1H), 7.68 (d, J = 7.6 Hz, 1H), 4.86 (br s,
13
2H); C NMR (75 MHz, CDCl3) δ 160.9, 160.6, 151.3, 150.3, 150.2, 141.9, 141.6, 139.2, 138.6, 136.8,
135.9, 134.5, 125.9; HRMS (EI) Calcd for C13H10N4 (M+) 222.0905, found 222.0902.
1-Amino-3-isoquinolylbenzene (14): oil. IR (KBr) 3434, 3340, 3214, 3053,1618, 1582, 1484, 1382, 723
cm-1 ; 1H NMR (300 MHz, CDCl3) δ 9.28 (s, 1H), 8.45 (d, J = 6.0 Hz, 1H), 7.94 (dd, J = 6.2, 3.3 Hz, 1H),
7.78 (d, J = 6.0 Hz, 1H), 7.64-7.61 (m, 2H), 7.30-7.24 (m, 1H), 6.83 (d, J = 7.5 Hz, 1H), 6.78- 6.76 (m,
2H), 3.90 (br s, 2H); 13C NMR (75 MHz, CDCl3) δ 152.4, 146.4, 142.8, 139.2, 133.9, 131.7, 130.4, 129.2,
128.6, 126.7, 126.6, 119.9, 118.6, 116.2, 114.2; HRMS (EI) Calcd for C15H12N2 (M+) 220.1000, found
220.1004.
ACKNOWLEDGEMENTS
This work was supported by the Ministry of Science Technology Grant (KN-0367-02).
.

HETEROCYCLES, Vol. 65, No. 10, 2005
2511
REFERENCES
1. For reviews, see: N. Miyaura and A. Suzuki, Chem. Rev., 1995, 95, 2457; A. Suzuki, J. Organomet.
Chem., 1999, 576, 147; S. P. Stanforth, Tetrahedron 1998, 54, 263; A. Suzuki, In Metal-Catalyzed
Cross-Coupling Reactions; ed. by F. Diederich and P. J. Stang, Wiley-VCH, Weinheim, Germany,
1998; Chapter 2.
2. G. Cooke, H. A. de Cremiers, V. M. Rotello, B. Tarbit, and P. E. Vanderstraeten, Tetrahedron, 2001,
57, 2787.
3. M. Ishikura, I. Oda, and M. Terashima, Heterocycles, 1985, 23, 2375; J. Stavenuiter, M. Hamzink, R.
van der Hulst, G. Zomer, G. Westra, and E. Kriek, Heterocycles, 1987, 26, 2711; N. M. Ali, A. Mckillop,
M. B. Mitchell, R. A. Rebelo, and P. J. Wallbank, Tetrahedron, 1992, 48, 8117; Y. Nakano and D.
Imai, Synthesis, 1997, 1425; I. Fenger and C. L. Drian, Tetrahedron Lett., 1998, 39, 4287; S. F.
Nielsen, D. Peters, and O. Axelsson, Synth. Commun., 2000, 30, 3501; M. Feuerstein, H. Doucet,
and M. Santelli, Tetrahedron Lett., 2001, 42, 5659; P. R. Parry, C. Wang, A. S. Batsanov, M. R.
Bryce, and B. Tarbit, J. Org. Chem., 2002, 67, 7541; T. Tagata and M. Nishida, J. Org. Chem., 2003,
68, 9412; M. Feuerstein, H. Doucet, and M. Santelli, J. Organomet. Chem., 2003, 687, 327.
4. For 3-Quinolineboronic acid see: W. Li, D. P. Nelson, M. S. Jensen, R. S. Hoerrner, D. Cai, R. D.
Larsen, and P. J. Reider, J. Org. Chem., 2002, 67, 5394; H. Matondo, S. Souirti, and M. Baboulene,
Synth. Commun., 2003, 33, 795. 8-Quinolineboronic acid see : R. L. Letsinger and S. H. Dandeganonker,
J. Am. Chem. Soc., 1959, 81, 498; K. Wada, T. Mizutani, and S. Kitagawa, J. Org. Chem., 2003, 68,
5123; R. Pohl, V. A. Montes, J. Shinar, and P. Anzenbacher Jr., J. Org. Chem., 2004, 69, 1723.
5. S. Ahmad, K. Ngu, D. W. Combs, S. C. Wu, D. S. Weinstein, W. Liu, B.-C. Chen, G. Chandrasena,
C. R. Dorso, M. Kirby, and K. S. Atwal, Bioorg. Med. Chem. Lett., 2004, 14, 177.
6. W. D. Brown and A. H. Gouliaev, Synthesis, 2002, 83.
7. V. G. Chapoulaud, J. Audoux, N. Ple, A. Turck, and G. Queguiner, Tetrahedron Lett., 1999, 40,
9005.
8. C. Zhang, J. Huang, M. L. Trudell, and S. P. Nolan, J. Org. Chem., 1999, 64, 3804.