4652
M. Chiurato et al. / Tetrahedron 66 (2010) 4647e4653
Mp: 180e182 ꢀC. IR (ATR-Ge,
n
cmꢁ1): 2935, 1732, 1571, 1431, 1316,
12.09 (s, 1H, OH), 7.95 (dd,
starting from 35 after purification by flash chromatography
(CH2Cl2/MeOH 98/2þ1% Et3N) in a quantitative manner. Mp:
230e232 ꢀC; IR (ATR-Ge, cmꢁ1): 1698, 1429, 1383, 1294, 1147. 1H
NMR (250 MHz, CDCl3):
1124, 1078. 1H NMR (250 MHz, CDCl3):
d
1H, J¼8.3,1.0 Hz, Har), 7.66e7.59 (m,1H, Har), 7.50e7.37 (m, 2H, Har),
n
4.55 (q, 2H, J¼6.8 Hz, CH2), 1.48 (t, 3H, J¼6.8 Hz, CH3). 13C NMR
d
8.44 (dd, J¼7.2, 1.0 Hz, 1H), 8.25(dd, J¼7.5,
(62.5 MHz, CDCl3):
d
163.8 (C]O), 155.0 (Cq), 148.7 (Cq), 133.1 (CH),
1.0 Hz, 1H), 7.78 (t, J¼7.8 Hz, 1H), 5.38 (dd, J¼11.6, 4.0 Hz, 1H), 4.79
(ddd, J¼14.0, 7.1, 3.0 Hz, 1H), 3.53e3.39 (m, 2H), 2.70e2.50 (m, 2H),
132.5(Cq), 132.4 (Cq), 130.5 (CH), 125.3 (CH), 116.8 (CH), 62.9 (CH2),
14.4 (CH3). ESI-MS m/z 219.5 [MþH]þ, 236.5 [MþNH4]þ.
2.08 (dd, J¼14.5, 11.7 Hz, 1H). 13C NMR (62.5 MHz, CDCl3):
d 204.4
(C]O), 164.1 (C]O), 139.2 (Cq), 135.3 (Cq), 130.7 (CH), 130.6 (CH),
127.6 (CH), 58.7 (CH), 44.5 (CH2), 39.5 (CH2), 37.3 (CH2). ESI-HRMS
m/z calcd for C11H11N2O2 [MþH]þ: 203.0821, found 203.0824.
5.3.13. Ethyl-3-trifluoromethanesulfonyloxy-quinoxaline-2-carboxyl-
ate (32). Under argon atmosphere,
a solution of 31 (1.0 g,
4.6 mmol) in CH2Cl2 (70.0 mL) was cooled at ꢁ10 ꢀC. Et3N (2.6 mL,
18.4 mmol) and Tf2O (3.1 mL, 18.4 mmol) were added. The reaction
was stirred at room temperature. After complete conversion
(monitored by TLC) water (20 mL) was added. The aqueous layers
were extracted with CH2Cl2 (20 mL) and EtOAc (10 mL). The com-
bined organic layers were dried with MgSO4, filtered, and evapo-
rated under reduced pressure. The dark oil was purified by
chromatography on silica gel (petroleum ether/EtOAc 2/1) to give
5.3.18. 70,80,100,10a0-Tetrahydro-50H-spiro[1,3-dioxolane-2,90-pyr-
azino[2,3-a]-indolizin]-50-one (37). According to the general pro-
cedure A, the compound 37 was obtained starting from 14 after
purification by flash chromatography (98:2þ1% Et3N, CH2Cl2/
MeOH) as a white solid (20%). Mp: 155e156 ꢀC; IR (ATR-Ge,
n,
cmꢁ1): 3445, 1645, 1265. 1H NMR (250 MHz, CDCl3):
d 8.77 (d,
J¼2.6 Hz, 1H), 8.64 (d, J¼2.6 Hz, 1H), 4.72 (dd, J¼12.4, 4.0 Hz, 1H),
4.63 (ddd, J¼13.4, 5.7, 1.7 Hz, 1H), 4.11e4.04 (m, 4H), 3.35 (td,
J¼13.0, 4.1 Hz, 1H), 2.53 (ddd, J¼13.0, 3.9, 2.4 Hz, 1H), 1.95e1.85 (m,
1H), 1.76 (td, J¼13.0, 5.7 Hz, 1H), 1.40 (t, J¼12.6 Hz, 1H). 13C NMR
32 (1.3 g, 80%) as white solid. Mp: 88e89 ꢀC; IR (ATR-Ge,
n
cmꢁ1):
1737, 1574e1420, 1324, 1126, 1084. 1H NMR (250 MHz, CDCl3):
d
8.36e8.32 (m, 1H, Har), 8.14e8.10 (m, 1H, Har), 7.99e7.94 (m, 2H,
Har), 4.61 (q, 2H, J¼7.2 Hz, CH2), 1.51 (t, 3H, J¼7.2 Hz, CH3). 13C NMR
(62.5 MHz, CDCl3): d 159.0 (C]O),146.1 (CH),146.0 (CH),130.0 (Cq),
(62.5 MHz, CDCl3):
d
162.1 (C]O), 147.8 (Cq), 141.5 (Cq), 141.0 (Cq),
128.1 (Cq), 107.0 (OeCqeO), 65.1 (OCH2), 65.0 (OCH2), 56.2 (CH),
38.3 (CH2), 37.2 (CH2), 34.1 (CH2). ESI-HRMS m/z calcd for
C12H14N3O3 [MþH]þ: 248.1035, found 248.1033.
137.5 (Cq), 134.2 (CH), 132.2 (CH), 130.5 (CHar), 129.0 (CH), 121.4
(CF3), 63.8 (CH2), 14.4 (CH3). ESI-MS m/z 351.5 [MþH]þ.
5.3.14. Diethyl quinoxaline-2,3-dicarboxylate (33). Compound 33
was obtained following the same procedure A as described for
compound 25, starting from the triflate 32 by using a mixture
(DMSO/EtOH 4/1) as solvent and dppp as a ligand. After purifica-
tion by flash chromatography (petroleum ether/EtOAc 65/35) 33
was obtained as a yellow solid in 24% yield. Mp: 90e92 ꢀC. IR
5.3.19. 7,8,10,10a-Tetrahydropyrazino[2,3-a]indolizine-5,9-dione
(38). According to the general procedure B, compound 38 was
obtained starting from 37 after purification by flash chromatogra-
phy (CH2Cl2/MeOH 98/2þ1% Et3N) in a 94% yield as a white solid.
Mp: >250 ꢀC; IR (ATR-Ge, cmꢁ1): 1696, 1429, 1379, 1294, 1150. 1H
n
NMR (250 MHz, CDCl3):
d
8.83 (d, J¼2.6 Hz, 1H), 8.70 (d, J¼2.6 Hz,
(ATR-Ge,
n
cmꢁ1): 2917, 2853, 1737, 1574, 1420, 1324, 1126, 1084. 1H
1H), 4.95e4.89 (m, 1H), 4.84 (dd, J¼12.3, 4.5 Hz, 1H), 3.57e3.45 (m,
NMR (250 MHz, CDCl3):
d 8.28e8.24 (m, 2H), 7.95e7.91 (m, 2H),
1H), 3.22 (ddd, J¼14.5, 5.1, 1.0 Hz, 1H), 2.67e2.60 (m, 2H), 2.31 (dd,
4.56 (q, J¼7.1 Hz, 2H), 1.48 (t, J¼7.1 Hz, 3H). 13C NMR (62.5 MHz,
J¼14.4, 12.2 Hz, 1H). 13C NMR (62.5 MHz, CDCl3):
d 204.0 (C]O),
CDCl3):
d
164.9 (2ꢂC]O), 144.3 (2ꢂCq), 141.5 (2ꢂCq), 132.6
162.9 (C]O), 158.3 (Cq), 146.7 (2ꢂCH), 144.4 (Cq), 56.7 (CH), 44.0
(CH2), 39.7 (CH2), 38.1 (CH2). ESI-HRMS m/z calcd for C10H10N3O2
[MþH]þ: 203.0773, found 204.0768.
(2ꢂCH), 130.0 (2ꢂCH), 63.0 (2ꢂCH2), 14.2 (2ꢂCH3). ESI-MS m/z
275.5 [MþH]þ.
5.3.15. Ethyl-3-formylquinoxaline-2-carboxylate (34). Compound
34 (17%) was obtained during the purification of 33 as a yellow
5.3.20. 5b0,60,80,90-Tetrahydro-110H-spiro[1,3-dioxolane-2,70-in-
dolizino[1,2-b]quinolin]-110-one (39). According to the general
procedure A, the compound 39 was obtained starting from 19 after
purification by flash chromatography (CH2Cl2/MeOH 99/1) as yel-
solid. Mp: 92e94 ꢀC IR (ATR-Ge,
n
cmꢁ1): 2917, 2853, 1737, 1683,
1556, 1318, 1133, 1079. 1H NMR (250 MHz, CDCl3):
d 9.55 (s, 1H),
8.34e8.30 (m, 1H), 8.22e8.18 (m, 1H), 7.92e7.86 (m, 2H), 4.61 (q,
low solid (30%). Mp: 178e180 ꢀC. IR (ATR-Ge,
n
cmꢁ1): 2966, 1682,
8.62
J¼7.1 Hz, 2H), 1.52 (t, J¼7.1 Hz, 3H). 13C NMR (62.5 MHz, CDCl3)
1633, 1524,1354,1294,1255,1176. 1H NMR (250 MHz, CDCl3):
d
d
182.5 (CHO), 164.3 (C]O), 145.2 (2ꢂCq), 143.8 (2ꢂCq), 132.4 (CH),
(s, 1H), 8.16 (d, J¼8.5 Hz, 1H), 8.00 (dd, J¼8.2, 1.1 Hz, 1H), 7.87e7.80
(m, 1H), 7.63 (m, 1H), 4.79 (dd, J¼12.2, 4.0 Hz,1H), 4.61 (ddd, J¼13.7,
5.5, 1.8 Hz, 1H), 4.16e4.05 (m, 4H), 3.35 (td, J¼12.6, 4.5 Hz, 1H), 2.67
(ddd, J¼12.9, 4.0, 2.2 Hz, 1H), 1.92e1.74 (m, 2H), 1.47 (t, J¼12.6 Hz,
131.1 (CH),130.8 (CH), 129.5 (CH), 62.8 (CH2), 14.5 (CH3). ESI-MS m/z
231.5 [MþH]þ.
5.3.16. 70,80,100,10a0-Tetrahydro-50H-spiro[1,3-dioxolane-2,90-pyrido
[2,3-a]indolizin]-50-one (35). According to the general procedure A,
the compound 35 was obtained starting from 7 after purification by
flash chromatography (CH2Cl2/MeOH 98/2) as yellow solid (30%).
1H). 13C NMR (62.5 MHz, CDCl3):
d 164.3 (C]O), 163.5 (Cq), 149.8
(Cq), 132.9 (CH), 131.5 (CH), 129.7 (CH), 129.3 (CH), 127.8 (Cq), 127.1
(CH), 123.8 (Cq), 107.4 (OeCqeO), 65.0 (OCH2), 64.9 (OCH2), 59.1
(CH), 45.0 (CH2), 40.1 (CH2), 37.7 (CH2); ESI-HRMS m/z calcd for
C17H17N2O3 [MþH]þ: 297.1239, found 297.1237.
Mp: 132e134 ꢀC. IR (ATR-Ge,
n
cmꢁ1): 1696, 1584, 1408, 1081, 1026.
8.69 (dd, J¼7.0, 1.6 Hz, 1H), 8.12 (dd,
1H NMR (400 MHz, CDCl3):
d
J¼7.5, 1.6 Hz, 1H), 7.40 (dd, J¼7.5, 5.0 Hz, 1H), 4.64 (dd, J¼12.3,
4.0 Hz, 1H), 4.53 (ddd, J¼13.5, 5.6, 1.6 Hz, 1H), 4.12e4.04 (m, 4H),
3.30 (td, J¼13.0, 4.2 Hz, 1H), 2.55 (ddd, J¼12.9, 4.0, 2.3 Hz, 1H),
1.89e1.84 (m, 1H), 1.74 (td, J¼13.1, 5.3 Hz, 1H), 1.38 (t, J¼12.6 Hz,
5.3.21. 5b,6,8,9-Tetrahydroindolizino[1,2-b]quinoline-7,11-dione
(40). According to the general procedure B, compound 40 was
obtained starting from 39 after purification by flash chromatogra-
phy (CH2Cl2/MeOH 98/2þ1% Et3N) in a 64% yield as a pale yellow
1H). 13C NMR (100 MHz, CDCl3):
d
165.1 (C]O), 164.5 (Cq), 152.3
solid. Mp: 216 ꢀC IR (ATR-Ge, cmꢁ1): 3412, 1691, 1634, 1508, 1422,
n
(CH), 132.1 (CH), 126.1 (Cq), 123.5 (CH), 107.4 (OeCqeO), 64.9
(2ꢂOCH2), 58.3 (CH), 38.5 (CH2), 36.6 (CH2), 34.3 (CH2). ESI-HRMS
m/z calcd for C13H15N2O3 [MþH]þ: 247.1083, found 247.1071.
1265. 1H NMR (250 MHz, CDCl3):
d
8.67 (s, 1H), 8.18 (d, J¼8.4 Hz,
1H), 8.03 (d, J¼8.0 Hz,1H), 7.87 (td, J¼8.4,1.4 Hz,1H), 7.67 (td, J¼8.0,
1.0 Hz, 1H), 4.92e4.90 (m, 1H), 4.86 (dd, J¼8.9, 4.6 Hz, 1H),
3.54e3.52 (m, 1H), 3.33 (dd, J¼14.5, 4.4 Hz, 1H), 2.66e2.60 (m, 2H),
5.3.17. 7,8,10,10a-Tetrahydropyrido[2,3-a]indolizine-5,9-dione (36).
According to the general procedure B, compound 36 was obtained
2.36 (dd, J¼14.4, 12.1 Hz, 1H). 13C NMR (62.5 MHz, CDCl3):
d 205.0
(C]O), 164.7 (C]O), 162.3 (Cq), 150.0 (Cq), 133.4 (CH), 131.2 (CH),