BULLETIN OF THE
Note
KOREAN CHEMICAL SOCIETY
In summary, 2-substituted furo[2,3-b]quinolines and furo
28.58, 29.12, 100.57, 121.88, 124.42, 126.38, 127.12,
127.54, 128.11, 128.26, 144.04, 161.63, 162.26; MS (EI) m/z
225 [M+]; Anal. Calcd for C15H15NO: C, 79.97; H, 6.71; N,
6.22; Found: C, 79.92; H, 6.72; N, 6.24.
[3,2-c]quinolines were synthesized from the reaction of 3-
iodoquinolin-2-ol and 3-iodoquinolin-4-ol, respectively,
with diverse alkynes. The heteroannulation reaction pro-
ceeds with Sonogashira coupling followed by 5-endo-dig
cyclization in good isolated yields under copper and ligand
free conditions.
2-(5-Acetylthiophen-2-yl)furo[2,3-b]quinoline (9d). 70%;
pale yellow solid, mp 228–230ꢀC; 1H NMR (CDCl3) δ 2.60
(s, 3H, CH3), 7.11 (s, 1H, ArH), 7.51–7.55 (m, 1H, ArH),
7. 64–7.74 (m, 3H, ArH), 7.93 (d, J = 8 Hz, 1H, ArH), 8.10
(d, J = 8 Hz, 1H, ArH), 8.34 (s, 1H, ArH); 13C NMR
(CDCl3) δ 26.83, 102.04, 121.35, 122.44, 125.15, 126.72,
127.88, 128.43, 129.06, 129.25, 132.95, 139.31, 144.98,
145.12, 151.48, 156.77, 190.32; MS (EI) m/z 293 [M+];
Anal. Calcd for C17H11NO2S: C, 69.61; H, 3.78; N, 4.77;
Found: C, 69.58; H, 3.79; N, 4.76.
Experimental
General. 1H and 13C NMR spectra were recorded on a
JEOL JNM-AL400 Spectrometer (400 MHz for 1H and
100 MHz for 13C) using CDCl3 as the solvent and TMS as
internal standard. The GC-MS spectra were obtained using
a Shimadzu QP 1000 GC-MS. Elemental analyses were
carried out by an elemental analyzer (EA-1110). NCB-Pd
(OAc)2 catalyst and terminal alkyne were prepared by fol-
lowing a known procedure.11
Typical Procedure for the Synthesis of 9 and 11. In a
pressure tube, a suspension of Pd(OAc)2/C (5 mol %), 3-
iodoquinolin-2-ol (7) (0.5 mmol), LiCl (0.5 mmol), cesium
carbonate (1 mmol), and terminal alkyne (1.0 mmol) in
DMF (3 mL) was stirred for designated period of time at
110ꢀC. The reaction mixture was filtered and neutralized
with saturated NH4Cl solution, followed by extraction with
ethyl acetate. The crude product was purified by column
chromatography with the use of hexane and ethyl acetate as
eluents. 2-Phenyl-furo[2,3-b]quinoline (9a) was obtained in
80% yield as yellow solid. mp 180–183ꢀC; 1H NMR (CDCl3)
δ 7.10 (s, 1H, ArH), 7.40–7.44 (m, 1H, ArH), 7.47–7.52 (m,
3H, ArH), 7.69 (t, J = 8 Hz, 1H, ArH), 7.91 (d, J = 8 Hz,
1H, ArH), 7.96 (d, J = 8 Hz, 2H, ArH), 8.11 (d, J = 8 Hz,
1H, ArH), 8.29 (s, 1H, ArH); 13C NMR (CDCl3) δ 99.51,
122.03, 124.77, 125.40, 126.68, 127.70, 128.18, 128.35,
128.63, 128.87, 129.25, 129.71, 144.68, 157.56, 161.50; MS
(EI) m/z 245 [M+]; Anal. Calcd for C17H11NO: C, 83.25; H,
4.52; N, 5.71; Found : C, 83.27; H, 4.51; N, 5.72.
2-Quinolin-3-yl-furo[2,3-b]quinoline (9e). 69%, pale
1
yellow solid, mp 206–208ꢀC; H NMR (CDCl3) δ 7.36 (s,
1H, ArH), 7.49–7.54 (m, 2H, ArH), 7.71–7.79 (m, 2H,
ArH), 7.95 (t, J = 8 Hz, 2H, ArH), 8.14 (dd, J = 4.8,
3.2 Hz, 2H, ArH), 8.40 (s, 1H, ArH), 8.75 (s, 1H, ArH),
9.43 (s, 1H, ArH); 13C NMR (DMSO) δ 102.62, 115.10,
121.33, 121.97, 122.18, 124.96, 126.44, 127.07, 127.55,
127.75, 128.27, 128.77, 129.16, 129.60, 130.57, 131.53,
144.27, 147.36, 154.25, 160.94; MS (EI) m/z 296 [M+];
Anal. Calcd for C20H12N2O: C, 81.07; H, 4.08; N, 9.45;
Found: C, 81.05; H, 4.09; N, 9.44.
2-(Tetrahydropyran-2-yloxymethyl)furo[2,3b]quinoline
1
(9f ). 55%, pale yellow oil; H NMR (CDCl3) δ 1.54–2.04
(m, 6H, CH2), 3.56–3.61 (m, 1H, CH), 3.93–3.99 (m, 1H,
CH), 4.71 (d, J = 16 Hz, 1H, CH), 4.88 (d, J = 16 Hz, 2H,
CH2), 6.78 (s, 1H, ArH), 7.51–7.47 (m, 1H, ArH),
7.70–7.66 (m, 1H, ArH), 7.90 (d, J = 8 Hz, 1H, ArH), 8.09
(d, J = 8 Hz, 1H, ArH), 8.27 (s, 1H, ArH); 13C NMR
(CDCl3) δ 18.95, 25.33, 30.28, 61.43, 61.93, 97.94,
103.45, 120.94, 124.62, 126.30, 127.69, 128.30, 128.59,
128.63, 144.57, 157.14, 161.61; MS (EI) m/z 283 [M+];
Anal. Calcd for C17H17NO3: C, 72.07; H, 6.05; N, 4.94;
Found: C, 72.05; H, 6.07; N, 4.84.
The following compounds were prepared by following
the general procedure.
2-(2-Hydroxypropan-2-yl)furo[2,3-b]quinoline
(9g).
1
73%, pale yellow solid, mp 142–144ꢀC; H NMR (CDCl3)
δ 1.72 (s, 6H, CH3), 3.06 (br, 1H, OH), 6.68 (s, 1H, ArH),
7.49 (t, J = 8 Hz, 1H, ArH), 7.67 (t, J = 8 Hz, 1H, ArH),
7.88 (d, J = 8 Hz, 1H, ArH), 8.08 (d, J = 8 Hz, 1H, ArH),
8.22 (s, 1H, ArH); 13C NMR (CDCl3) δ 28.56 69.49,
98.82, 121.37, 124.68, 126.42, 127.68, 128.17, 128.62,
128.64, 144.32, 161.39, 165.58; MS (EI) m/z 227 [M+];
Anal. Calcd for C14H13NO2: C, 73.99; H, 5.77; N, 6.16;
Found: C, 73.95; H, 5.79; N, 6.19.
2-(Cyclohex-1-enyl)furo[2,3-b]quinolone (9b). 60%;
pale yellow solid, mp 90–93ꢀC; 1H NMR (CDCl3) δ
1.70–1.83 (m, 4H, CH2CH2), 2.31–2.41 (m, 4H, CH2CH2),
6.55 (s, 1H, ArH), 6.85 (s, 1H, ArH), 7.47 (t, J = 8 Hz,
1H, ArH), 7.65 (t, J = 8 Hz, 1H, ArH), 7.87 (d, J = 8 Hz,
1H, ArH), 8.06 (d, J = 8 Hz, 1H, ArH), 8.18 (s, 1H, ArH);
13C NMR (CDCl3) δ 21.99, 22.22, 24.48, 25.74, 98.28,
122.27, 124.52, 126.39, 126.54, 127.43, 127.57, 128.23,
128.26, 129.92, 158.98; MS (EI) m/z 249 [M+]. Anal.
Calcd for C17H15NO: C, 81.90; H, 6.06; N, 5.62; Found :
C, 81.92; H, 6.04; N, 5.61.
2-Butylfuro[2,3-b]quinoline (9c). 30%; pale yellow solid,
mp 78–80ꢀC; 1H NMR (CDCl3) δ 0.97 (t, 3H, CH3),
1.41–1.47 (m, 2H, CH2), 1.75–1.83 (m, 2H, CH2), 2.83 (t,
2H, CH2), 6.45 (s, 1H, ArH), 7.47 (t, 1H, ArH), 7.65 (t, 1H,
ArH), 7.87 (d, J = 8 Hz, 1H, ArH), 8.07 (d, J = 8 Hz, 1H,
ArH), 8.16 (s, 1H, ArH); 13C NMR (CDCl3) δ 13.80, 22.26,
Furo[2,3-b]quinolin-2-yl-methanol (9h). 25%, brown
1
oil; H NMR (CDCl3) δ 3.43 (br, 1H, OH), 4.85 (s, 2H,
CH2), 6.73 (s, 1H, ArH), 7.49 (t, J = 8 Hz, 1H, ArH), 7.68
(t, J = 8 Hz, 1H, ArH), 7.87 (d, J = 8 Hz, 1H, ArH), 8.06
(d, J = 8 Hz, 1H, ArH), 8.23 (s, 1H, ArH); 13C NMR
(CDCl3) δ 65.25, 102.14, 120.95, 121.20, 124.81, 126.30,
127.80, 128.91, 129.12, 130.58, 144.10, 159.45; MS
(EI) m/z 199 ([M+]; Anal. Calcd for C12H9NO2: C,
72.35; H, 4.55; N, 7.03; Found: C, 72.37; H, 4.53; N, 7.01.
Bull. Korean Chem. Soc. 2016, Vol. 37, 958–961
© 2016 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
960